2007
Fusion of human hematopoietic progenitor cells and murine cardiomyocytes
is mediated by alpha4beta1 integrin/vascular cell adhesion molecule-1
interaction.
Zhang S et al. Circ Res. 2007 Mar 16;100(5):693-702. Epub 2007 Feb 15.
Abstract: Fusion of transplanted stem cells and host cells has been proposed as a major mechanism for the generation of hepatocytes, Purkinje neurons, and cardiomyocytes. However, the mechanism of cell fusion has not been precisely defined. Furthermore, the consequence of cell fusion remains unclear. We have previously shown that adult peripheral blood CD34-positive cells injected into severe combined immune deficiency (SCID) mice can transform into cardiomyocytes, endothelial cells, and smooth muscle cells following experimentally induced myocardial infarction and that most of the newly formed cardiomyocytes result from cell fusion. We therefore undertook this study to define the mechanism and consequences of cell fusion. Here we show that hypoxia and cytokines increase fusion of human peripheral blood CD34-positive cells and murine cardiomyocytes in vitro by up to 7-fold, and this is blocked by anti-alpha4beta1 or anti-vascular cell adhesion molecule (VCAM)-1. In vivo, fusion of progenitor cells and cardiomyocytes can also be blocked by anti-alpha4beta1 or anti-VCAM-1, but not by anti-vascular endothelial growth factor. On the other hand, generation of human-derived endothelial cells is blocked by anti-vascular endothelial growth factor but not by anti-alpha4beta1 antibodies. Two months following transplant, a high percentage of fused cells expressed cyclin B1 and incorporated bromodeoxyuridine. Thus, hematopoietic progenitor cell and cardiomyocyte fusion is mediated by alpha4beta1/VCAM-1 interaction, leading to cell cycle reentry and cellular proliferation.
Pericytes of human skeletal muscle are myogenic precursors distinct from satellite cells.
Dellavalle A et al. Nat Cell Biol. 2007 Mar;9(3):255-67. Epub 2007 Feb 11.
Abstract: Cells derived from blood vessels of human skeletal muscle can regenerate skeletal muscle, similarly to embryonic mesoangioblasts. However, adult cells do not express endothelial markers, but instead express markers of pericytes, such as NG2 proteoglycan and alkaline phosphatase (ALP), and can be prospectively isolated from freshly dissociated ALP(+) cells. Unlike canonical myogenic precursors (satellite cells), pericyte-derived cells express myogenic markers only in differentiated myotubes, which they form spontaneously with high efficiency. When transplanted into severe combined immune deficient-X-linked, mouse muscular dystrophy (scid-mdx) mice, pericyte-derived cells colonize host muscle and generate numerous fibres expressing human dystrophin. Similar cells isolated from Duchenne patients, and engineered to express human mini-dystrophin, also give rise to many dystrophin-positive fibres in vivo. These data show that myogenic precursors, distinct from satellite cells, are associated with microvascular walls in the human skeletal muscle, may represent a correlate of embryonic 'mesoangioblasts' present after birth and may be a promising candidate for future cell-therapy protocols in patients.
Differentiation of human adult skin-derived neuronal precursors into mature neurons.
Gingras M et al. J Cell Physiol. 2007 Feb;210(2):498-506.
Abstract: The isolation of autologous neuronal precursors from skin-derived precursor cells extracted from adult human skin would be a very efficient source of neurons for the treatment of various neurodegenerative diseases. The purpose of this study was to demonstrate that these neuronal precursors were able to differentiate into mature neurons. We isolated neuronal precursors from breast skin and expanded them in vitro for over ten passages. We showed that 48% of these cells were proliferating after the first passage, while this growth rate decreased after the second passage. We demonstrated that 70% of these cells were nestin-positive after the third passage, while only 17% were neurofilament M-positive after 7 days of differentiation. These neuronal precursors expressed betaIII tubulin, the dendritic marker MAP2 and the presynaptic marker synaptophysin after 7 days of in vitro maturation. They also expressed the postsynaptic marker PSD95 and the late neuronal markers NeuN and neurofilament H after 21 days of differentiation, demonstrating they became terminally differentiated neurons. These markers were still expressed after 50 days of culture. The generation of autologous neurons from an accessible adult human source opens many potential therapeutic applications and has a great potential for the development of experimental studies on normal human neurons.
The quantitative trait gene latexin influences the size of the hematopoietic stem cell population in mice.
Liang Y et al. Nat Genet. 2007 Feb;39(2):178-88. Epub 2007 Jan 14.
Abstract: We mapped quantitative trait loci that accounted for the variation in hematopoietic stem cell (HSC) numbers between young adult C57BL/6 (B6) and DBA/2 (D2) mice. In reciprocal chromosome 3 congenic mice, introgressed D2 alleles increased HSC numbers owing to enhanced proliferation and self-renewal and reduced apoptosis, whereas B6 alleles had the opposite effects. Using oligonucleotide arrays, real-time PCR and protein blots, we identified latexin (Lxn), a gene whose differential transcription and expression was associated with the allelic differences. Expression was inversely correlated with the number of HSCs; therefore, ectopic expression of Lxn using a retroviral vector decreased stem cell population size. We identified clusters of SNPs upstream of the Lxn transcriptional start site, at least two of which are associated with potential binding sites for transcription factors regulating stem cells. Thus, promoter polymorphisms between the B6 and D2 alleles may affect Lxn gene expression and consequently influence the population size of hematopoietic stem cells.
Tethered EGF Provides a Survival Advantage to Mesenchymal Stem Cells
Fan VH et al. Stem Cells 2007 Jan 18; [Epub ahead of print]
Abstract: Mesenchymal stem cells (MSC) can act as a pluripotent source of reparative cells during injury and therefore have great potential in regenerative medicine and tissue engineering. However, the response of MSC to many growth factors and cytokines is unknown. Many envisioned applications of MSC, such as treating large defects in bone, involve in vivo implantation of MSC attached to a scaffold, a process that creates an acute inflammatory environment that may be hostile to MSC survival. Here, we investigate cellular responses of MSC on a biomaterial surface covalently modified with epidermal growth factor (EGF). We find that surface-tethered EGF promotes both cell spreading and survival more strongly than saturating concentrations of soluble EGF. By sustaining MEK-ERK signaling, tethered EGF increases the contact of MSC with an otherwise moderately adhesive synthetic polymer and confers resistance to cell death induced by the proinflammatory cytokine, FasL. We conclude that tethered EGF may offer a protective advantage to MSC in vivo during acute inflammatory reactions to tissue engineering scaffolds. The tethered EGF-modified polymers described here could be used together with structural materials to construct MSC scaffolds for the treatment of hard-tissue lesions, such as large bony defects.
Hematopoietic reconstitution by multipotent adult progenitor cells: precursors to long-term hematopoietic stem cells
Marta Serafini and Catherine M. Verfaillie et. al., The Journal of Experimental Medicine; doi:10.1084/jem.20061115; Epub 2007 Jan 16.
Abstract: For decades, in vitro expansion of transplantable hematopoietic stem cells (HSCs) has been an elusive goal. Here, we demonstrate that multipotent adult progenitor cells (MAPCs), isolated from green fluorescent protein (GFP)-transgenic mice and expanded in vitro for >40–80 population doublings, are capable of multilineage hematopoietic engraftment of immunodeficient mice. Among MAPC-derived GFP+CD45.2+ cells in the bone marrow of engrafted mice, HSCs were present that could radioprotect and reconstitute multilineage hematopoiesis in secondary and tertiary recipients, as well as myeloid and lymphoid hematopoietic progenitor subsets and functional GFP+ MAPC-derived lymphocytes that were functional. Although hematopoietic contribution by MAPCs was comparable to control KTLS HSCs, approximately 103-fold more MAPCs were required for effi cient engraftment. Because GFP+ host-derived CD45.1+ cells were not observed, fusion is not likely to account for the generation of HSCs by MAPCs.
Isolation and functional characterization
of murine prostate stem cells
Devon A. Lawson et al., Proc Natl Acad Sci U S A. 2007 Jan 2;104(1):181-6.
Epub 2006 Dec 21.
Abstract: The ability to isolate prostate stem cells is essential to explore their role in prostate development and disease. In vitro prostate colony- and sphere-forming assays were used to quantitatively measure murine prostate stem/progenitor cell enrichment and self-renewal. Cell surface markers were screened for their ability to positively or negatively enrich for cells with enhanced growth potential in these assays. Immunohistochemical and FACS analyses demonstrate that specific cell surface markers can be used to discriminate prostate stromal (CD34(+)), luminal epithelial (CD24(+)CD49f(-)), basal epithelial (CD24(+)CD49f(+)), hematopoietic (CD45(+), Ter119(+)), and endothelial (CD31(+)) lineages. Sorting for cells with a CD45(-)CD31(-)Ter119(-)Sca-1(+)CD49f(+) antigenic profile results in a 60-fold enrichment for colony- and sphere-forming cells. These cells can self-renew and expand to form spheres for many generations and can differentiate to produce prostatic tubule structures containing both basal and luminal cells in vivo. These cells also localize to the basal cell layer within the region of the gland that is proximal to the urethra, which has been identified as the prostate stem cell niche. Prostate stem cells can be isolated to a purity of up to 1 in 35 by using this antigenic profile. The remarkable similarity in cell surface profile between prostate and mammary gland stem cells suggests these markers may be conserved among epithelial stem cell populations.
2006
Ex Vivo Large-Scale Generation of Human Platelets from Cord
Blood CD34+ Cells
Takuya Matsunaga et al., Stem Cells. 2006 2006 Dec;24(12):2877-87.
Epub 2006 Sep 7.
Abstract: In the present investigation, we generated
platelets (PLTs) from cord blood (CB) CD34(+) cells using a three-phase
culture system. We first cultured 500 CB CD34(+) cells on telomerase
gene-transduced human stromal cells (hTERT stroma) in serum-free
medium supplemented with stem cell factor (SCF), Flt-3/Flk-2 ligand
(FL), and thrombopoietin (TPO) for 14 days. We then transferred
the cells to hTERT stroma and cultured for another 14 days with
fresh medium containing interleukin-11 (IL-11) in addition to the
original cytokine cocktail. Subsequently, we cultured the cells
in a liquid culture medium containing SCF, FL, TPO, and IL-11 for
another 5 days to recover PLT fractions from the supernatant, which
were then gel-filtered to purify the PLTs. The calculated yield
of PLTs from 1.0 unit of CB (5 x 10(6) CD34(+) cells) was 1.26 x
10(11)-1.68 x 10(11) PLTs. These numbers of PLTs are equivalent
to 2.5-3.4 units of random donor-derived PLTs or 2/5-6/10 of single-apheresis
PLTs. The CB-derived PLTs exhibited features quite similar to those
from peripheral blood in morphology, as revealed by electron micrographs,
and in function, as revealed by fibrinogen/ADP aggregation, with
the appearance of P-selectin and activated glycoprotein IIb-IIIa
antigens. Thus, this culture system may be applicable for large-scale
generation of PLTs for future clinical use.
Functional Neuronal Differentiation of Bone
Marrow-Derived Mesenchymal Stem Cells
Philippe Tropel et al., Stem Cells. 2006 Dec;24(12):2868-76. Epub
2006 Aug 10.
Abstract: Recent results have shown the ability
of bone marrow cells to migrate in the brain and to acquire neuronal
or glial characteristics. In vitro, bone marrow-derived MSCs can
be induced by chemical compounds to express markers of these lineages.
In an effort to set up a mouse model of such differentiation, we
addressed the neuronal potentiality of mouse MSCs (mMSCs) that we
recently purified. These cells expressed nestin, a specific marker
of neural progenitors. Under differentiating conditions, mMSCs display
a distinct neuronal shape and express neuronal markers NF-L (neurofilament-light,
or neurofilament 70 kDa) and class III beta-tubulin. Moreover, differentiated
mMSCs acquire neuron-like functions characterized by a cytosolic
calcium rise in response to various specific neuronal activators.
Finally, we further demonstrated for the first time that clonal
mMSCs and their progeny are competent to differentiate along the
neuronal pathway, demonstrating that these bone marrow-derived stem
cells share characteristics of widely multipotent stem cells unrestricted
to mesenchymal differentiation pathways.
Bone Marrow Transplantation Attenuates the
Myopathic Phenotype of a Muscular Mouse Model of Spinal Muscular
Atrophy
Nouzha Salah-Mohellibi et al., Stem Cells. 2006 Dec;24(12):2723-32.
Epub 2006 Aug 3.
Abstract: Bone marrow (BM) transplantation was
performed on a muscular mouse model of spinal muscular atrophy that
had been created by mutating the survival of motor neuron gene (Smn)
in myofibers only. This model is characterized by a severe myopathy
and progressive loss of muscle fibers leading to paralysis. Transplantation
of wild-type BM cells following irradiation at a low dose (6 Gy)
improved motor capacity (+85%). This correlated with a normalization
of myofiber number associated with a higher number of regenerating
myofibers (1.6-fold increase) and an activation of CD34 and Pax7
satellite cells. However, BM cells had a very limited capacity to
replace or fuse to mutant myofibers (2%). These data suggest that
BM transplantation was able to attenuate the myopathic phenotype
through an improvement of skeletal muscle regeneration of recipient
mutant mice, a process likely mediated by a biological activity
of BM-derived cells. This hypothesis was further supported by the
capacity of muscle protein extracts from transplanted mutant mice
to promote myoblast proliferation in vitro (1.6-fold increase).
In addition, a tremendous upregulation of hepatocyte growth factor
(HGF), which activates quiescent satellite cells, was found in skeletal
muscle of transplanted mutants compared with nontransplanted mutants.
Eventually, thanks to the Cre-loxP system, we show that BM-derived
muscle cells were strong candidates harboring this biological activity.
Taken together, our data suggest that a biological activity is likely
involved in muscle regeneration improvement mediated by BM transplantation.
HGF may represent an attractive paracrine mechanism to support this
activity.
Increased generation of neuronal progenitors
after ischemic injury in the aged adult human forebrain.
Macas J, et al., J Neurosci. 2006 Dec 13;26(50):13114-9.
Abstract: The adult human brain retains the capacity
to generate new neurons in the hippocampal formation (Eriksson et
al., 1998) and neuronal progenitor cells (NPCs) in the forebrain
(Bernier et al., 2000), but to what extent it is capable of reacting
to injuries, such as ischemia, is not known. We analyzed postmortem
tissue from normal and pathological human brain tissue (n = 54)
to study the cellular response to ischemic injury in the forebrain.
We observed that cells expressing the NPC marker polysialylated
neural adhesion cell molecule (PSA-NCAM) are continuously generated
in the adult human subventricular zone (SVZ) and migrate along the
olfactory tracts. These cells were not organized in migrating chains
as in the adult rodent rostral migratory stream, and their number
was lower in the olfactory tracts of brains from old (56-81 years
of age) compared with young (29 + 36 years of age) individuals.
Moreover, we show that in brains of patients of advanced age (60-87
years of age), ischemia led to an elevated number of Ki-67-positive
cells in the ipsilateral SVZ without concomitant apoptotic cell
death. Additionally, ischemia led to an increased number of PSA-NCAM-positive
NPCs close to the lateral ventricular walls, compared with brains
of comparable age without obvious neuropathologic changes. These
results suggest that the adult human brain retains a capacity to
respond to ischemic injuries and that this capacity is maintained
even in old age.
A neurovascular niche for neurogenesis after
stroke.
Ohab JJ, et al., J Neurosci. 2006 Dec 13;26(50):13007-16.
Abstract: Stroke causes cell death but also birth
and migration of new neurons within sites of ischemic damage. The
cellular environment that induces neuronal regeneration and migration
after stroke has not been defined. We have used a model of long-distance
migration of newly born neurons from the subventricular zone to
cortex after stroke to define the cellular cues that induce neuronal
regeneration after CNS injury. Mitotic, genetic, and viral labeling
and chemokine/growth factor gain- and loss-of-function studies show
that stroke induces neurogenesis from a GFAP-expressing progenitor
cell in the subventricular zone and migration of newly born neurons
into a unique neurovascular niche in peri-infarct cortex. Within
this neurovascular niche, newly born, immature neurons closely associate
with the remodeling vasculature. Neurogenesis and angiogenesis are
causally linked through vascular production of stromal-derived factor
1 (SDF1) and angiopoietin 1 (Ang1). Furthermore, SDF1 and Ang1 promote
post-stroke neuroblast migration and behavioral recovery. These
experiments define a novel brain environment for neuronal regeneration
after stroke and identify molecular mechanisms that are shared between
angiogenesis and neurogenesis during functional recovery from brain
injury.
Spontaneous Fusion and Non-clonal Growth of
Adult Neural Stem Cells
Sebastian Jessberger et al., Stem Cells, published online December
21, 2006; doi:10.1634/stemcells.2006-0620.
Abstract: Multipotent neural stem cells (NSCs) can be isolated
from various regions of the adult brain and propagated in vitro.
Recent reports have suggested spontaneous fusion events among NSCs
when grown as free-floating neurospheres that may affect the genetic
composition of NSC cultures. We used adult NSCs expressing either
red fluorescent protein (RFP) or green fluorescent protein (GFP)
to analyze the fusion frequency of rat and mouse NSCs. Fluorescence
activated cell sorting (FACS) revealed, that under proliferating
conditions approximately 0.2% of rat and mouse NSCs coexpressed
RFP and GFP, irrespective of whether the cells were grown as neurospheres
(mouse NSCs) or as attached monolayers (rat and mouse NSCs). Fused
cells did not proliferate and could not be propagated, suggesting
that aberrantly fused cells are not viable. Furthermore, we found
that neither neurospheres nor monolayers grew clonally, as even
very low-density cultures had spheres containing both GFP- and RFP-expressing
cells and monolayer patches with GFP- and RFP-expressing cells in
close proximity. The non-clonal growth between distinct NSC populations
strongly suggests the use of careful and precise culture conditions,
such as single cell assays, to characterize potency and growth of
NSCs in vitro.
Designer Self-Assembling Peptide Nanofiber
Scaffolds for Adult Mouse Neural Stem Cell 3-Dimensional Cultures
Fabrizio Gelain et al., PLoS ONE 1. e119., i:10.1371/journal.pone.0000119,
December 2006.
Abstract: Biomedical researchers have become increasingly
aware of the limitations of conventional 2-dimensional tissue cell
culture systems, including coated Petri dishes, multi-well plates
and slides, to fully address many critical issues in cell biology,
cancer biology and neurobiology, such as the 3-D microenvironment,
3-D gradient diffusion, 3-D cell migration and 3-D cell-cell contact
interactions. In order to fully understand how cells behave in the
3-D body, it is important to develop a well-controlled 3-D cell
culture system where every single ingredient is known. Here we report
the development of a 3-D cell culture system using a designer peptide
nanofiber scaffold with mouse adult neural stem cells. We attached
several functional motifs, including cell adhesion, differentiation
and bone marrow homing motifs, to a self-assembling peptide RADA16
(Ac-RADARADARADARADA-COHN2). These functionalized peptides undergo
self-assembly into a nanofiber structure similar to Matrigel. During
cell culture, the cells were fully embedded in the 3-D environment
of the scaffold. Two of the peptide scaffolds containing bone marrow
homing motifs significantly enhanced the neural cell survival without
extra soluble growth and neurotrophic factors to the routine cell
culture media. In these designer scaffolds, the cell populations
with b-Tubulin+, GFAP+ and Nestin+ markers are similar to those
found in cell populations cultured on Matrigel. The gene expression
profiling array experiments showed selective gene expression, possibly
involved in neural stem cell adhesion and differentiation. Because
the synthetic peptides are intrinsically pure and a number of desired
function cellular motifs are easy to incorporate, these designer
peptide nanofiber scaffolds provide a promising controlled 3-D culture
system for diverse tissue cells, and are useful as well for general
molecular and cell biology.
Mesenchymal Stem Cell-Mediated Functional
Tooth Regeneration in Swine
Wataru Sonoyama et al., PLoS ONE 2006 Dec 20;1:e79.
Abstract: Mesenchymal stem cell-mediated tissue
regeneration is a promising approach for regenerative medicine for
a wide range of applications. Here we report a new population of
stem cells isolated from the root apical papilla of human teeth
(SCAP, stem cells from apical papilla). Using a minipig model, we
transplanted both human SCAP and periodontal ligament stem cells
(PDLSCs) to generate a root/periodontal complex capable of supporting
a porcelain crown, resulting in normal tooth function. This work
integrates a stem cell-mediated tissue regeneration strategy, engineered
materials for structure, and current dental crown technologies.
This hybridized tissue engineering approach led to recovery of tooth
strength and appearance.
Transplantation of Mesenchymal Stem Cells
is an Optimal Approach for Plastic Surgery
Dianji Fang et al., Stem Cells, published online December 14,
2006; doi:10.1634/stemcells.2006-0576.
Abstract: Mesenchymal stem cells (MSCs) are able
to differentiate into a variety of cell types, offering promising
approaches for stem-cell-mediated tissue regeneration. Here we explored
the potential of utilizing MSCs to reconstruct orofacial tissue,
thereby, altering the orofacial appearance. We demonstrated that
bone marrow MSCs were capable of generating bone structures and
bone-associated marrow elements on the surfaces of the orofacial
bone. This resulted in significant re-contouring of the facial appearance
in mouse and swine. Notably, the newly formed bone/marrow tissues
integrated with the surfaces of the recipient bones and re-established
a functional bone marrow organ-like system. These data suggested
that MSC-mediated tissue regeneration led to a body structure extension,
with the re-establishment of all functional components necessary
for maintaining the bone/marrow organ. In addition, we found that
the subcutaneous transplantation of another population of MSCs,
the human periodontal ligament stem cells (PDLSCs) could form substantial
amounts of collagen fibers and improve facial wrinkles in mouse.
By contrast, bone marrow MSCs failed to survive at 8 weeks post-transplantation
under the conditions used for the PDLSC transplantation. This study
suggested that the mutual interactions between donor MSCs and recipient
microenvironment determine long-term outcome of the functional tissue
regeneration.
Granulocyte-Colony–Stimulating Factor
Mobilizes Bone Marrow Stem Cells in Patients With Subacute Ischemic
Stroke The Stem Cell Trial of Recovery EnhanceMent After Stroke
(STEMS) Pilot Randomized, Controlled Trial (ISRCTN 16784092)
Nikola Sprigg et al., Stroke. 2006 Dec; 37(12):2979-83. Epub 2006
Nov 2.
Background and Purpose: Loss of motor function
is common after stroke and leads to significant chronic disability.
Stem cells are capable of self-renewal and of differentiating into
multiple cell types, including neurones, glia, and vascular cells.
We assessed the safety of granulocyte-colony-stimulating factor
(G-CSF) after stroke and its effect on circulating CD34+ stem cells.
METHODS: We performed a 2-center, dose-escalation, double-blind,
randomized, placebo-controlled pilot trial (ISRCTN 16784092) of
G-CSF (6 blocks of 1 to 10 microg/kg SC, 1 or 5 daily doses) in
36 patients with recent ischemic stroke. Circulating CD34+ stem
cells were measured by flow cytometry; blood counts and measures
of safety and functional outcome were also monitored. All measures
were made blinded to treatment.
RESULTS: Thirty-six patients, whose mean+/-SD age was 76+/-8 years
and of whom 50% were male, were recruited. G-CSF (5 days of 10 microg/kg)
increased CD34+ count in a dose-dependent manner, from 2.5 to 37.7
at day 5 (area under curve, P=0.005). A dose-dependent rise in white
cell count (P<0.001) was also seen. There was no difference between
treatment groups in the number of patients with serious adverse
events: G-CSF, 7/24 (29%) versus placebo 3/12 (25%), or in their
dependence (modified Rankin Scale, median 4, interquartile range,
3 to 5) at 90 days.
CONCLUSIONS: G-CSF is effective at mobilizing bone marrow CD34+
stem cells in patients with recent ischemic stroke. Administration
is feasible and appears to be safe and well tolerated. The fate
of mobilized cells and their effect on functional outcome remain
to be determined.
Successful treatment of AL amyloidosis with
high-dose melphalan and autologous stem cell transplantation in
patients over age 65
David C. Seldin et al., Blood. 2006 Dec 1;108(12):3945-7. Epub
2006 Aug 22.
Abstract: Recently, protocols using high-dose melphalan
chemotherapy and autologous peripheral blood stem cell transplantation
(HDM/SCT) have been developed for the treatment of patients with
immunoglobulin light chain (AL) amyloidosis. Although peritransplantation
mortality is greater than for other hematologic diseases, treatment
leads to durable hematologic complete responses, improvements in
organ function and quality of life, and extended survival in a substantial
proportion of patients. To determine whether this treatment can
be applied to older patients, we have analyzed HDM/SCT treatment
outcomes for 65 patients (aged 65 years or older) with AL amyloidosis
compared with outcomes for 280 younger patients. For patients over
age 65 years who meet the same eligibility criteria as younger patients,
toxicity, hematologic remission rate, and survival were not significantly
different from those observed in younger patients, indicating that
older patients should not be excluded a priori from consideration
for HDM/SCT treatment.
Isolation of an adult blood-derived progenitor
cell population capable of differentiation into angiogenic, myocardial
and neural lineages
Yael Porat et al., British Journal of Haematology. 2006 Dec;135(5):703-14.
Abstract: Blood-derived adult stem cells were previously
considered impractical for therapeutic use because of their small
numbers. This report describes the isolation of a novel human cell
population derived from the peripheral blood, termed synergetic
cell population (SCP), and defined by the expression of CD31Bright,
CD34+, CD45)/Dim and CD34Bright, but not lineage-specific features.
The SCP was capable of differentiating into a variety of cell lineages
upon exposure to defined culture conditions. The resulting cells
exhibited morphological, immunocytochemical and functional characteristics
of angiogenic, neural or myocardial lineages. Angiogenic cell precursors
(ACPs) expressed CD34, CD133, KDR, Tie-2, CD144, von Willebrand
factor, CD31Bright, concomitant binding of Ulex-Lectin and uptake
of acetylated low density lipoprotein (Ac-LDL), secreted interleukin-8,
vascular endothelial growth factor and angiogenin and formed tube-like
structures in vitro. The majority of CD31Bright ACP cells demonstrated
Ac-LDL uptake. Neural cell precursors (NCPs) expressed the neuronal
markers Nestin, bIII-Tubulin, and Neu-N, the glial markers GFAP
and O4, and responded to neurotransmitter stimulation. Myocardial
cell precursors (MCPs) expressed Desmin, cardiac Troponin and Connexin
43. In conclusion, the simple and rapid method of SCP generation
and the resulting considerable quantities of lineage-specific precursor
cells makes it a potential source of autologous treatment for a
variety of diseases.
Myeloid progenitors differentiate intomicroglia and promote
vascular repair in a model of ischemic retinopathy
Matthew R. Ritter et al., J. Clin. Invest. 2006 Dec;116(12):3266-76.
Epub 2006 Nov 16.
Abstract: Vision loss associated with ischemic
diseases such as retinopathy of prematurity and diabetic retinopathy
are often due to retinal neovascularization. While significant progress
has been made in the development of compounds useful for the treatment
of abnormal vascular permeability and proliferation, such therapies
do not address the underlying hypoxia that stimulates the observed
vascular growth. Using a model of oxygen-induced retinopathy, we
demonstrate that a population of adult BM-derived myeloid progenitor
cells migrated to avascular regions of the retina, differentiated
into microglia, and facilitated normalization of the vasculature.
Myeloid-specific hypoxia-inducible factor 1alpha (HIF-1alpha) expression
was required for this function, and we also demonstrate that endogenous
microglia participated in retinal vascularization. These findings
suggest what we believe to be a novel therapeutic approach for the
treatment of ischemic retinopathies that promotes vascular repair
rather than destruction.
Cytokine-induced differentiation of multipotent adult
progenitor cells into functional smooth muscle cells
J. Ross et al.
J. Clin. Invest. 2006 Dec;116(12):3139-49. Epub 2006 Nov 9.
Abstract: Smooth muscle formation and function are critical in development
and postnatal life. Hence, studies aimed at better understanding
SMC differentiation are of great importance. Here, we report that
multipotent adult progenitor cells (MAPCs) isolated from rat, murine,
porcine, and human bone marrow demonstrate the potential to differentiate
into cells with an SMC-like phenotype and function. TGF-beta1 alone
or combined with PDGF-BB in serum-free medium induces a temporally
correct expression of transcripts and proteins consistent with smooth
muscle development. Furthermore, SMCs derived from MAPCs (MAPC-SMCs)
demonstrated functional L-type calcium channels. MAPC-SMCs entrapped
in fibrin vascular molds became circumferentially aligned and generated
force in response to KCl, the L-type channel opener FPL64176, or
the SMC agonists 5-HT and ET-1, and exhibited complete relaxation
in response to the Rho-kinase inhibitor Y-27632. Cyclic distention
(5% circumferential strain) for 3 weeks increased responses by 2-
to 3-fold, consistent with what occurred in neonatal SMCs. These
results provide evidence that MAPC-SMCs are phenotypically and functionally
similar to neonatal SMCs and that the in vitro MAPC-SMC differentiation
system may be an ideal model for the study of SMC development. Moreover,
MAPC-SMCs may lend themselves to tissue engineering applications.
Human stem/progenitor cells from bone marrow promote
neurogenesis of endogenous neural stem cells in the hippocampus
of mice.
Munoz JR, et al.
Proc Natl Acad Sci U S A. 2005 Dec 13;102(50):18171-6. Epub 2005
Dec 5.
Abstract: Stem/progenitor cells from bone marrow and other sources
have been shown to repair injured tissues by differentiating into
tissue-specific phenotypes, by secreting chemokines, and, in part,
by cell fusion. Here we prepared the stem/progenitor cells from
human bone marrow (MSCs) and implanted athem into the dentate gyrus
of the hippocampus of immunodeficient mice. The implanted human
MSCs markedly increased the proliferation of endogenous neural stem
cells that expressed the stem cell marker Sox2. Labeling of the
mice with BrdUrd demonstrated that, 7 days after implantation of
the human MSCs, BrdUrd-labeled endogenous cells migrated throughout
the dorsal hippocampus (positive for doublecortin) and expressed
markers for astrocytes and for neural or oligodendrocyte progenitors.
Subpopulations of BrdUrd-labeled cells exhibited short cytoplasmic
processes immunoreactive for nerve growth factor and VEGF. By 30
days after implantation, the newly generated cells expressed markers
for more mature neurons and astrocytes. Also, subpopulations of
BrdUrd-labeled cells exhibited elaborate processes immunoreactive
for ciliary neurotrophic factor, neurotrophin-4/5, nerve growth
factor, or VEGF. Therefore, implantation of human MSCs stimulated
proliferation, migration, and differentiation of the endogenous
neural stem cells that survived as differentiated neural cells.
The results provide a paradigm to explain recent observations in
which MSCs or related stem/progenitor cells were found to produce
improvements in disease models even though a limited number of the
cells engrafted.
Autologous serum-derived cultivated oral epithelial transplants
for severe ocular surface disease.
Ang LP, et al.
Arch Ophthalmol. 2006 Nov;124(11):1543-51.
OBJECTIVE: To evaluate the use of autologous serum (AS)-derived
cultivated oral epithelial transplants for the treatment of severe
ocular surface disease.
METHODS: We used AS from 10 patients with severe ocular surface
disease and total limbal stem cell deficiency to develop autologous
cultivated oral epithelial equivalents. These were compared with
epithelial equivalents derived from conventional fetal bovine serum-supplemented
medium. Surgery involved removal of the corneal pannus and surrounding
diseased tissue and transplantation of the AS-derived epithelial
equivalents. The oral equivalents were analyzed by review of histologic
and immunohistochemical findings.
RESULTS: Oral epithelial sheets cultivated in AS- and fetal bovine
serum-supplemented media were similar in morphology, and both formed
basement membrane assembly proteins important for maintaining graft
integrity. Complete corneal epithelialization was achieved within
2 to 5 days postoperatively. The ocular surface remained stable
without major complications in all eyes during a mean +/- SD follow-up
of 12.6 +/- 3.9 months. The visual acuity improved by more than
2 lines in 9 of 10 eyes, with transplanted oral epithelium surviving
up to 19 months.
CONCLUSION: The successful use of an AS-derived oral epithelial
equivalent to treat severe ocular surface disease represents an
important advance in the pursuit of completely autologous xenobiotic-free
bioengineered ocular equivalents for clinical transplantation.
Tracking Neural Stem Cells in Patients with Brain
Trauma
Jianhong Zhu, et al.
N Engl J Med. 2006 Nov 30;355(22):2376-8.
To the Editor: Regeneration of damaged brain tissue with neural
stem cells is a promising strategy for reversing neurologic deficits.1
Superparamagnetic iron oxide nanoparticles have been used to label
and track dendritic cells in the experimental treatment of melanoma2
and in experiments in animals. We report the feasibility of labeling
neural stem cells from humans (two patients for whom written informed
consent was provided by next of kin) with superparamagnetic iron
oxide nanoparticles and tracking them with the use of magnetic resonance
imaging (MRI).
Antibody Targeting of Stem Cells to Infarcted Myocardium
Randall J. Lee et al.
Stem Cells, published online November 30, 2006; doi:10.1634/stemcells.2005-0602.
Abstract: Hematopoietic stem cell therapy for myocardial repair
is limited by the number of stem cells that migrate to, engraft
in and proliferate at sites of injured myocardium. To alleviate
this limitation, we studied whether a strategy using a bispecific
antibody could target human stem cells specifically to injuredmyocardium
and preserve myocardial function. Using a xenogeneic rat model whereby
ischemic injury was induced by transient ligation of the left anterior
descending artery (LAD), we determined the ability of a bispecific
antibody to target human CD34+ cells to specific antigens expressed
in ischemic injured myocardium. A bispecific antibody comprised
of an anti-CD45 antibody recognizing the common leukocyte antigen
found on hematopoietic stem cells (HSC) and an antibody recognizing
myosin light chain, an organ-specific injury antigen expressed by
infarcted myocardium was prepared by chemical conjugation. CD34+
cells armed and unarmed with this BiAb were injected intravenously
in rats 2 days post-myocardial injury. Immunohistochemistry studies
showed that the armed CD34+ cells specifically localized to the
infracted region of the heart, co-localized with troponin T stained
cells and co-localized with vascular structures. Compared to unarmed
CD34+ cells, the bispecific antibody improved delivery of the stem
cells to injured myocardium and such targeted delivery was correlated
with improved myocardial function five weeksfollowing infarction
(p<0.01). Bispecific antibody targeting offers a unique means
to improve the delivery of stem cells to facilitate organ repair
and a tool to study stem cell biology.
Stem Cells, Myocardial Regeneration and Methodological
Artifacts
Piero Anversa et al.
Stem Cells, published online November 30, 2006; doi:10.1634/stemcells.2006-0623.
Abstract: This review discusses the controversy that has permeated
the field of myocardial regeneration in the last three decades.
The notion of the heart as a terminally differentiated postmitotic
organ has been so strong that observations promoting the opposite
paradigm have been questioned technically and conceptually. The
possibility of misinterpretation of results collected with cellular,
molecular, and morphological methodologies has been the prevailing
position in the scientific community. Myocardial regeneration mediated
by activation of endogenous progenitor cells or by engraftment and
differentiation of primitive cells from the bone marrow has been
rejected strongly in an attempt to defend an unrealistic view of
the heart. This article provides evidence in support of the notion
that the heart is an organ regulated by a stem cell compartment
responsible for cardiac homeostasis and repair.
Improved clinical outcome after intracoronary administration
of bone-marrow-derived progenitor cells in acute myocardial infarction:
final 1-year results of the REPAIR-AMI trial.
Schachinger V, et al.
Eur Heart J. 2006 Dec;27(23):2775-83. Epub 2006 Nov 10.
AIMS: To investigate the clinical outcome after intracoronary administration
of autologous progenitor cells in patients with acute myocardial
infarction (AMI).
METHODS AND RESULTS: Using a double-blind, placebo-controlled multicentre
trial design, we randomized 204 patients with successfully reperfused
AMI to receive intracoronary infusion of bone-marrow-derived progenitor
cells (BMCs) or placebo medium into the infarct artery 3-7 days
after successful infarct reperfusion therapy. At 12 months, the
pre-specified cumulative endpoint of death, myocardial infarction,
or necessity for revascularization was significantly reduced in
the BMC group compared with placebo (P=0.009). Likewise, the combined
endpoint death, recurrence of myocardial infarction, and rehospitalization
for heart failure was significantly (P=0.006) reduced in patients
receiving intracoronary BMC administration. Intracoronary administration
of BMC remained a significant predictor of a favourable clinical
outcome by Cox regression analysis, adjusting for classical predictors
of poor outcome after AMI.
CONCLUSION: Intracoronary administration of BMCs is associated with
a significant reduction of the occurrence of major adverse cardiovascular
events after AMI. Large-scale studies are warranted to confirm the
effects of BMC administration on mortality and morbidity in patients
with AMIs.
In Vitro and in Vivo Arterial Differentiation of Human
Multipotent Adult Progenitor Cells
Xabier L. Aranguren et al.
Blood First Edition Paper. prepublished online November 7, 2006;
DOI 10.1182/blood-2006-06-030411.
Abstract: Many stem cell types have been shown to differentiate
into endothelial cells (ECs), however, their specification to arterial
or venous endothelium remains unexplored. We tested whether a specific
arterial or venous EC fate could be induced in human Multipotent
Adult Progenitor Cells (hMAPCs) and AC133+ cells (hAC133+). In vitro,
in the presence of VEGF165, hAC133+ cells only adopted a venous
and microvascular EC phenotype, while hMAPCs differentiated into
both arterial and venous ECs, possibly because hMAPCs expressed
significantly more sonic hedgehog (Shh) and its receptors, as well
as Notch 1 and 3 receptors and some of their ligands. Accordingly,
blocking either of those pathways attenuated in vitro arterial EC
differentiation from hMAPCs. Complementarily, stimulating these
pathways by addition of Delta-like 4 (Dll-4), a Notch ligand, and
Shh to VEGF165 further boosted arterial differentiation in hMAPCs
both in vitro and in an in vivo matrigel model. These results represent
the first demonstration of adult stem cells with the potential to
be differentiated into different types of ECs in vitro and in vivo
and provide a useful human model to study arterio-venous specification.
Therapeutic strategies for Parkinson.s disease based
on the modulation of adult neurogenesis
Martine Geraerts et al.
Stem Cells, published online November 2, 2006; doi:10.1634/stemcells.2006-0364.
Abstract: Parkinson.s disease (PD) is a progressive neurodegenerative
disorder, affecting millions of people world-wide. To date, treatment
strategies are mainly symptomatic and aimed at increasing dopamine
levels in the degenerating nigrostriatal system. Hope rests upon
the development of effective neurorestorative or neuroregenerative
therapies based on gene and stem cell therapy or a combination of
both. The results of experimental therapies based on transplanting
exogenous dopamine-rich fetal cells or growth factor (GDNF) overexpression
into the brain of Parkinson.s disease patients encourage future
cell- and gene-based strategies. The endogenous neural stem cells
of the adult brain provide an alternative and attractive cell source
for neuroregeneration. Prior to designing endogenous stem cell therapies,
one has to investigate the possible impact of PD on adult neuronal
stem cell pools and their neurogenic potential. We review the experimental
data obtained in animal models or based on analysis of patients.
brain prior to describing different treatment strategies. Strategies
aiming to enhance neuronal stem cell proliferation and/or differentiation
in the striatum or the substantia nigra will have to be compared
in animal models and selected prior to clinical studies.
Mesoangioblast stem cells ameliorate muscle function
in dystrophic dogs.
Sampaolesi M et al.
Nature. 2006 Nov 30;444(7119):574-9. Epub 2006 Nov 15.
Abstract: Duchenne muscular dystrophy remains an untreatable genetic
disease that severely limits motility and life expectancy in affected
children. The only animal model specifically reproducing the alterations
in the dystrophin gene and the full spectrum of human pathology
is the golden retriever dog model. Affected animals present a single
mutation in intron 6, resulting in complete absence of the dystrophin
protein, and early and severe muscle degeneration with nearly complete
loss of motility and walking ability. Death usually occurs at about
1 year of age as a result of failure of respiratory muscles. Here
we report that intra-arterial delivery of wild-type canine mesoangioblasts
(vessel-associated stem cells) results in an extensive recovery
of dystrophin expression, normal muscle morphology and function
(confirmed by measurement of contraction force on single fibres).
The outcome is a remarkable clinical amelioration and preservation
of active motility. These data qualify mesoangioblasts as candidates
for future stem cell therapy for Duchenne patients.
Transplantation of human neural stem cells exerts
neuroprotection in a rat model of Parkinson's disease.
Yasuhara T et al.
J Neurosci. 2006 Nov 29;26(48):12497-511.
Abstract: Neural stem cells (NSCs) possess high potencies of self-renewal
and neuronal differentiation. We explored here whether transplantation
of human NSCs cloned by v-myc gene transfer, HB1.F3 cells, is a
feasible therapeutic option for Parkinson's disease. In vivo, green
fluorescent protein-labeled HB1.F3 cells (200,000 viable cells in
3 microl of PBS) when stereotaxically transplanted (same-day lesion-transplant
paradigm) into the 6-hydroxydopamine-lesioned striatum of rats significantly
ameliorated parkinsonian behavioral symptoms compared with controls
(vehicle, single bolus, or continuous minipump infusion of trophic
factor, or killed cell grafts). Such graft-derived functional effects
were accompanied by preservation of tyrosine hydroxylase (TH) immunoreactivity
along the nigrostriatal pathway. Grafted HB1.F3 cells survived in
the lesioned brain with some labeled with neuronal marker mitogen-activated
protein 2 and decorated with synaptophysin-positive terminals. Furthermore,
endogenous neurogenesis was activated in the subventricular zone
of transplanted rats. To further explore the neuroprotective mechanisms
underlying HB1.F3 cell transplantation, we performed cell culture
studies and found that a modest number of HB1.F3 cells were TH and
dopamine and cAMP-regulated phosphoprotein 32 positive, although
most cells were nestin positive, suggesting a mixed population of
mature and immature cells. Administration of the HB1.F3 supernatant
to human derived dopaminergic SH-SY5Y cells and fetal rat ventral
mesencephalic dopaminergic neurons protected against 6-hydroxydopamine
neurotoxicity by suppressing apoptosis through Bcl-2 upregulation,
which was blocked by anti-stem cell factor antibody alone, the phosphatidylinositol
3-kinase/Akt inhibitor LY294002 [2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one]
alone, or a combination of both. These results suggest that HB1.F3
cell transplantation exerts neuroprotective effects against dopaminergic
depletion in vitro and in vivo because of trophic factor secretion
and neuronal differentiation.
Adipose Tissue-Derived Mesenchymal Stem Cells Have
In Vivo Immunosuppressive Properties Applicable for the Control
of the Graft-Versus-Host Disease
Rosa Yanez et al.
Stem Cells. 2006 Nov;24(11):2582-91. Epub 2006 Jul 27.
Abstract: Previous studies have shown the relevance of bone marrow-
derived MSCs (BM-MSCs) in controlling graft-versus- host disease
(GVHD) after allogeneic transplantation. Since adipose tissue-derived
MSCs (Ad-MSCs) may constitute a good alternative to BM-MSCs, we
have expanded MSCs derived from human adipose tissue (hAd-MSCs)
and mouse adipose tissue (mAd-MSCs), investigated the immunoregulatory
properties of these cells, and evaluated their capacity to control
GVHD in mice. The phenotype and immunoregulatory properties of expanded
hAd-MSCs were similar to those of human BM-MSCs. Moreover, hAd-MSCs
inhibited the proliferation and cytokine secretion of human primary
T cells in response to mitogens and allogeneic T cells. Similarly,
ex vivo expanded mAd-MSCs had an equivalent immunophenotype and
exerted immunoregulatory properties similar to those of hAd-MSCs.
Moreover, the infusion of mAd-MSCs in mice transplanted with haploidentical
hematopoietic grafts controlled the lethal GVHD that occurred in
control recipient mice. These findings constitute the first experimental
proof that Ad-MSCs can efficiently control the GVHD associated with
allogeneic hematopoietic transplantation, opening new perspectives
for the clinical use of Ad-MSCs.
Side Population Cells Isolated from Porcine Dental
Pulp Tissue with Self-Renewal and Multipotency for Dentinogenesis,
Chondrogenesis, Adipogenesis, and Neurogenesis
Koichiro Iohara et al.
Stem Cells. 2006 Nov;24(11):2493-503. Epub 2006 Jul 27.
Abstract: Dental pulp has the potential to form dentin as a regenerative
response to caries. This regeneration is mediated by stem/progenitor
cells. Thus, stem cell therapy might be of potential utility in
induction of reparative dentin. We isolated side population (SP)
cells from dental pulp based on the exclusion of the DNA binding
dye Hoechst 33342 by flow cytometry and compared its self-renewal
capacities and multipotency with non-SP cells and primary pulp cells.
The cumulative cell number of the SP cells was greater than the
non-SP cells and primary pulp cells. Bmi1 was continuously expressed
in SP cells, suggesting longer proliferative lifespan and self-renewal
capacity of SP cells. Next, the maintenance of the multilineage
differentiation potential of pulp SP cells was investigated. Expression
of type II collagen and aggrecan confirmed chondrogenic conversion
(30%) of SP cells. SP cells expressed peroxisome proliferator-activated
receptor _ and adaptor protein 2, showing adipogenic conversion.
Expression of mRNA and proteins of neurofilament and neuromodulin
confirmed neurogenic conversion (90%). These results demonstrate
that pulp SP cells maintain multilineage differentiation potential.
We further examined whether bone morphogenetic protein 2 (BMP2)
could induce differentiation of pulp SP cells into odontoblasts.
BMP2 stimulated the expression of dentin sialophosphoprotein (Dspp)
and enamelysin in three-dimensional pellet cultures. Autogenous
transplantation of the Bmp2-supplemented SP cells on the amputated
pulp stimulated the reparative dentin formation. Thus, adult pulp
contains SP cells, which are enriched for stem cell properties and
useful for cell therapy with BMP2 for dentin regeneration.
Bone Marrow-Derived Cells Contribute to Podocyte Regeneration
and Amelioration of Renal Disease in a Mouse Model of Alport Syndrome
Evangelia I. Prodromidi et al.
Stem Cells. 2006 Nov;24(11):2448-55. Epub 2006 Jul 27.
Abstract: In a model of autosomally recessive Alport syndrome, mice
that lack the alpha3 chain of collagen IV (Col4alpha3(-/-)) develop
progressive glomerular damage leading to renal failure. The proposed
mechanism is that podocytes fail to synthesize normal glomerular
basement membrane, so the collagen IV network is unstable and easily
degraded. We used this model to study whether bone marrow (BM) transplantation
can rectify this podocyte defect by correcting the deficiency in
Col4alpha3. Female C57BL/6 Col4alpha3(-/-) (-/-) mice were transplanted
with whole BM from male wild-type (+/+) mice. Control female -/-
mice received BM from male -/- littermates. Serum urea and creatinine
levels were significantly lower in recipients of +/+ BM compared
with those of -/- BM 20 weeks post-transplant. Glomerular scarring
and interstitial fibrosis were also significantly decreased. Donor-derived
cells were detected by in situ hybridization (ISH) for the Y chromosome,
and fluorescence and confocal microscopy indicated that some showed
an apparent podocyte phenotype in mice transplanted with +/+ BM.
Glomeruli of these mice showed small foci of staining for alpha3(IV)
protein by immunofluorescence. alpha3(IV) mRNA was detectable by
reverse transcription-polymerase chain reaction and ISH in some
mice transplanted with +/+ BM but not -/- BM. However, a single
injection of mesenchymal stem cells from +/+ mice to irradiated
-/- recipients did not improve renal disease. Our data show that
improved renal function in Col4alpha3(-/-) mice results from BM
transplantation from wild-type donors, and the mechanism by which
this occurs may in part involve generation of podocytes without
the gene defect.
Leukemia inhibitory factor promotes neural stem cell
self-renewal in the adult brain.
Bauer S, Patterson PH.
J Neurosci. 2006 Nov 15;26(46):12089-99.
Abstract: Although neural stem cells (NSCs) persist in various areas
of the adult brain, their contribution to brain repair after injury
is very limited. Treatment with exogenous growth factors can mitigate
this limitation, suggesting that the brain environment is normally
deficient in permissive cues and that it may be possible to stimulate
the latent regenerative potential of endogenous progenitors with
appropriate signals. We analyzed the effects of overexpressing the
cytokine leukemia inhibitory factor (LIF) on adult neurogenesis
in the normal brain. We found that LIF reduces neurogenesis in the
olfactory bulb and subventricular zone by acting directly on NSCs.
LIF appears to promote NSC self-renewal, preventing the emergence
of more differentiated cell types. This ultimately leads to an expansion
of the NSC pool. Our results have implications for the development
of therapeutic strategies for brain repair and suggest that LIF
may be useful, in combination with other factors, in promoting regeneration
in the adult brain.
Thymosin beta4 induces adult epicardial progenitor
mobilization and neovascularization.
Smart N, et al.
Nature. 2006 Nov 15; [Epub ahead of print]
Abstract: Cardiac failure has a principal underlying aetiology of
ischaemic damage arising from vascular insufficiency. Molecules
that regulate collateral growth in the ischaemic heart also regulate
coronary vasculature formation during embryogenesis. Here we identify
thymosin beta4 (Tbeta4) as essential for all aspects of coronary
vessel development in mice, and demonstrate that Tbeta4 stimulates
significant outgrowth from quiescent adult epicardial explants,
restoring pluripotency and triggering differentiation of fibroblasts,
smooth muscle cells and endothelial cells. Tbeta4 knockdown in the
heart is accompanied by significant reduction in the pro-angiogenic
cleavage product N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP).
Although injection of AcSDKP was unable to rescue Tbeta4 mutant
hearts, it significantly enhanced endothelial cell differentiation
from adult epicardially derived precursor cells. This study identifies
Tbeta4 and AcSDKP as potent stimulators of coronary vasculogenesis
and angiogenesis, and reveals Tbeta4-induced adult epicardial cells
as a viable source of vascular progenitors for continued renewal
of regressed vessels at low basal level or sustained neovascularization
following cardiac injury.
Multipotent flk-1+ cardiovascular progenitor cells
give rise to the cardiomyocyte, endothelial, and vascular smooth
muscle lineages.
Kattman SJ, et al.
Dev Cell. 2006 Nov;11(5):723-32.
Abstract: Cell-tracing studies in the mouse indicate that the cardiac
lineage arises from a population that expresses the vascular endothelial
growth factor receptor 2 (VEGFR2, Flk-1), suggesting that it may
develop from a progenitor with vascular potential. Using the embryonic
stem (ES) cell differentiation model, we have identified a cardiovascular
progenitor based on the temporal expression of the primitive streak
(PS) marker brachyury and Flk-1. Comparable progenitors could also
be isolated from head-fold stage embryos. When cultured with cytokines
known to function during cardiogenesis, individual cardiovascular
progenitors generated colonies that displayed cardiomyocyte, endothelial,
and vascular smooth muscle (VSM) potential. Isolation and characterization
of this previously unidentified population suggests that the mammalian
cardiovascular system develops from multipotential progenitors.
Multipotent stromal cells from human marrow home to
and promote repair of pancreatic islets and renal glomeruli in diabetic
NOD/scid mice.
Lee RH, et al.
Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17438-43. Epub 2006
Nov 6.
Abstract: We tested the hypothesis that multipotent stromal cells
from human bone marrow (hMSCs) can provide a potential therapy for
human diabetes mellitus. Severe but nonlethal hyperglycemia was
produced in NOD/scid mice with daily low doses of streptozotocin
on days 1-4, and hMSCs were delivered via intracardiac infusion
on days 10 and 17. The hMSCs lowered blood glucose levels in the
diabetic mice on day 32 relative to untreated controls (18.34 mM
+/- 1.12 SE vs. 27.78 mM +/- 2.45 SE, P = 0.0019). ELISAs demonstrated
that blood levels of mouse insulin were higher in the hMSC-treated
as compared with untreated diabetic mice, but human insulin was
not detected. PCR assays detected human Alu sequences in DNA in
pancreas and kidney on day 17 or 32 but not in other tissues, except
heart, into which the cells were infused. In the hMSC-treated diabetic
mice, there was an increase in pancreatic islets and beta cells
producing mouse insulin. Rare islets contained human cells that
colabeled for human insulin or PDX-1. Most of the beta cells in
the islets were mouse cells that expressed mouse insulin. In kidneys
of hMSC-treated diabetic mice, human cells were found in the glomeruli.
There was a decrease in mesangial thickening and a decrease in macrophage
infiltration. A few of the human cells appeared to differentiate
into glomerular endothelial cells. Therefore, the results raised
the possibility that hMSCs may be useful in enhancing insulin secretion
and perhaps improving the renal lesions that develop in patients
with diabetes mellitus.
Engraftment of Donor-Derived Epithelial Cells in Multiple
Organs Following Bone Marrow Transplantation into Newborn Mice
Emanuela M. Bruscia et al.
Stem Cells. 2006 Oct;24(10):2299-308. Epub 2006 Jun 22.
Abstract: Bone marrow-derived cells (BMDCs) can engraft as epithelial
cells throughout the body, including in the lung, liver, and gastrointestinal
(GI) tract following transplantation into lethally irradiated adult
recipients. Except for rare disease models in which marrow-derived
epithelial cells have a survival advantage over endogenous cells,
the currently attained levels of epithelial engraftment of BMDCs
are too low to be of therapeutic benefit. Here we tested whether
the degree of bone marrow to epithelial engraftment would be higher
if bone marrow transplantation (BMT) were performed on 1-day-old
mice, when tissues are undergoing rapid growth and remodeling. BMT
into newborn mice after multiple different regimens allowed for
robust hematopoietic engraftment, as well as the development of
rare donor-derived epithelial cells in the GI tract and lung but
not in the liver. The highest epithelial engraftment (0.02%) was
obtained in mice that received a preparative regimen of two doses
of busulfan in utero. When BMDCs were transplanted into myelosuppressed
newborn mice that lacked expression of the cystic fibrosis transmembrane
conductance regulator (CFTR) protein, the chloride channel that
is not functional in patients with cystic fibrosis, the engrafted
mice showed partial restoration of CFTR channel activity, suggesting
that marrow-derived epithelial cells in the GI tract were functional.
However, BMT into newborn mice, regardless of the myeloablative
regimen used, did not increase the number of bone marrow-derived
epithelial cells over that which occurs after BMT into lethally
irradiated adult mice.
Improved Liver Function in Patients with Liver Cirrhosis
After Autologous Bone Marrow Cell Infusion Therapy
Shuji Terai et al.
Stem Cells. 2006 Oct;24(10):2292-8. Epub 2006 Jun 15.
Abstract: Supplementation of mesenchymal stem cells (MSCs) during
hematopoietic stem cell (HSC) transplantation alleviates complications
such as graft-versus-host disease, leading to a speedy recovery
of hematopoiesis. To meet this clinical demand, a fast MSC expansion
method is required. In the present study, we examined the feasibility
of using a rotary bioreactor system to expand MSCs from isolated
bone marrow mononuclear cells. The cells were cultured in a rotary
bioreactor with Myelocult medium containing a combination of supplementary
factors, including stem cell factor and interleukin-3 and -6. After
8 days of culture, total cell numbers, Stro-1(+)CD44(+)CD34(-) MSCs,
and CD34(+)CD44(+)Stro-1(-) HSCs were increased 9-, 29-, and 8-fold,
respectively. Colony-forming efficiency-fibroblast per day of the
bioreactor-treated cells was 1.44-fold higher than that of the cells
without bioreactor treatment. The bioreactor-expanded MSCs showed
expression of primitive MSC markers endoglin (SH2) and vimentin,
whereas markers associated with lineage differentiation, including
osteocalcin (osteogenesis), type II collagen (chondrogenesis), and
C/EBP-alpha (CCAAT/enhancer-binding protein-alpha) (adipogenesis),
were not detected. Upon induction, the bioreactor-expanded MSCs
were able to differentiate into osteoblasts, chondrocytes, and adipocytes.
We conclude that the rotary bioreactor with the modified Myelocult
medium reported in this study may be used to rapidly expand MSCs.
Transforming growth factor alpha promotes sequential
conversion of mature astrocytes into neural progenitors and stem
cells.
Sharif A, et al.
Oncogene. 2006 Oct 23; [Epub ahead of print]
Abstract: An instability of the mature cell phenotype is thought
to participate to the formation of gliomas, primary brain tumors
deriving from astrocytes and/or neural stem cells. Transforming
growth factor alpha (TGFalpha) is an erbB1 ligand overexpressed
in the earliest stages of gliomas, and exerts trophic effects on
gliomal cells and astrocytes. Here, we questioned whether prolonged
TGFalpha exposure affects the stability of the normal mature astrocyte
phenotype. We first developed astrocyte cultures devoid of residual
neural stem cells or progenitors. We demonstrate that days of TGFalpha
treatment result in the functional conversion of a population of
mature astrocytes into radial glial cells, a population of neural
progenitors. TGFalpha-generated radial glial cells support embryonic
neurons migration, and give birth to cells of the neuronal lineage,
expressing neuronal markers and the electrophysiological properties
of neuroblasts. Lengthening TGFalpha treatment to months results
in the delayed appearance of cells with neural stem cells properties:
they form floating cellular spheres that are self-renewing, can
be clonally derived from a single cell and differentiated into cells
of the neuronal lineage. This study uncovers a novel population
of mature astrocytes capable, in response to a single epigenetic
factor, to regress progressively into a neural stem-like cell stage
via an intermediate progenitor stage.Oncogene advance online publication,
23 October 2006; doi:10.1038/sj.onc.1210071.
Risk-adapted craniospinal radiotherapy followed by
high-dose chemotherapy and stem-cell rescue in children with newly
diagnosed medulloblastoma (St Jude Medulloblastoma-96): long-term
results from a prospective, multicentre trial.
Gajjar A, et al.
Lancet Oncol. 2006 Oct;7(10):813-20.
BACKGROUND: Current treatment for medulloblastoma, which includes
postoperative radiotherapy and 1 year of chemotherapy, does not
cure many children with high-risk disease. We aimed to investigate
the effectiveness of risk-adapted radiotherapy followed by a shortened
period of dose-intense chemotherapy in children with medulloblastoma.
METHODS: After resection, patients were classified as having average-risk
medulloblastoma (< or = 1.5 cm2 residual tumour and no metastatic
disease) or high-risk medulloblastoma (> 1.5 cm2 residual disease
or metastatic disease localised to neuraxis) medulloblastoma. All
patients received risk-adapted craniospinal radiotherapy (23.4 Gy
for average-risk disease and 36.0-39.6 Gy for high-risk disease)
followed by four cycles of cyclophosphamide-based, dose-intensive
chemotherapy. Patients were assessed regularly for disease status
and treatment side-effects. The primary endpoint was 5-year event-free
survival; we also measured overall survival. This study is registered
with ClinicalTrials.gov, number NCT00003211.
FINDINGS: Of 134 children with medulloblastoma who underwent treatment
(86 average-risk, 48 high-risk), 119 (89%) completed the planned
protocol. No treatment-related deaths occurred. 5-year overall survival
was 85% (95% CI 75-94) in patients in the average-risk group and
70% (54-84) in those in the high-risk group (p=0.04); 5-year event-free
survival was 83% (73-93) and 70% (55-85), respectively (p=0.046).
For the 116 patients whose histology was reviewed centrally, histological
subtype correlated with 5-year event-free survival (p=0.04): 84%
(74-95) for classic histology, 77% (49-100) for desmoplastic tumours,
and 57% (33-80) for large-cell anaplastic tumours.
INTERPRETATION: Risk-adapted radiotherapy followed by a shortened
schedule of dose-intensive chemotherapy can be used to improve the
outcome of patients with high-risk medulloblastoma.
Embryonic-like stem cells from umbilical cord blood
and potential for neural modeling
McGuckin C et al.
Acta Neurobiol. Exp (2006) 66: 321-329.
Abstract: Stem cells offer the distinct prospect of changing the
face of human medicine. However, although they have potential to
form different tissues, are still in the early stages of development
as therapeutic interventions. The three most used stem cell sources
are umbilical cord blood, bone marrow and human embryos. Whilst,
cord blood is now used to treat over 70 disorders, at the time of
writing this manuscript, not a single disease has been overcome
or ameliorated using human embryonic stem cells. Advancing stem
cell medicine requires ethically sound and scientifically robust
models to develop tomorrow’s medicines. Media attention, however,
distracts from this reality; it is important to remember that stem
cells are a new visitor to the medical world and require more research.
Here we describe the utility of human cord blood to develop neural
models that are necessary to take stem cells to the next level –
into human therapies.
Aging does not alter the number or phenotype of putative
stem/progenitor cells in the neurogenic region of the hippocampus
Bharathi Hattiangady, Ashok K. Shetty
Neurobiol Aging (2006). doi:10.1016/j.neurobiolaging.2006.09.015.
Abstract: To investigate whether dramatically waned dentate neurogenesis
during aging is linked to diminution in neural stem/progenitor cell
(NSC) number, we counted cells immunopositive for Sox-2 (a putative
marker of NSCs) in the subgranular zone (SGZ) of young, middle-aged
and aged F344 rats. The young SGZ comprised ~50,000 Sox-2+ cells
and this amount did not diminish with aging. Quantity of GFAP+ cells
and vimentin+ radial glia also remained stable during aging in this
region. Besides, in all age groups, analogous fractions of Sox-2+
cells expressed GFAP (astrocytes/NSCs), NG-2 (oligodendrocyte-progenitors/NSCs),
vimentin (radial glia), S-100_ (astrocytes) and doublecortin (new
neurons). Nevertheless, analyses of Sox-2+ cells with proliferative
markers insinuated an increased quiescence of NSCs with aging. Moreover,
the volume of rat-endothelial-cell-antigen-1+ capillaries (vascular-niches)
within the SGZ exhibited an age-related decline, resulting in an
increased expanse between NSCs and capillaries. Thus, decreased
dentate neurogenesis during aging is not attributable to altered
number or phenotype of NSCs. Instead, it appears to be an outcome
of increased quiescence of NSCs due to changes in NSC milieu.
MCP-3 is a myocardial mesenchymal stem cell homing
factor
Soren Schenk, et al.
Stem Cells, published online October 19, 2006; doi:10.1634/stemcells.2006-0293.
Abstract: Mesenchymal stem cells (MSC) have received attention for
their therapeutic potential in a number of disease states including
bone formation, diabetes, stem cell engraftment following marrow
transplantation, graft verse host disease, and heart failure. Despite
this diverse interest the molecular signals regulating MSC trafficking
to sites of injury are unclear. MSC are known to transiently home
to the freshly infracted myocardium. To identify MSC homing factors,
we determined chemokine expression pattern as a function of time
after MI. We merged these profiles with chemokine receptors expressed
on MSC but not cardiac fibroblasts, which do not home following
MI. This analysis identified MCP-3 as a potential MSC homing factor.
Over-expression of MCP-3 1 month after MI restored MSC homing to
the heart. Following serial infusions of MSC cardiac function improved
in MCP-3 expressing hearts (88.7%, p<0.001), but not in control
hearts (8.6%, p=0.47). MSC engraftment was not associated with differentiation
into cardiac myocytes. Rather MSC engraftment appeared to result
in recruitment of myofibroblasts and remodeling of the collagen
matrix. These data indicate that MCP-3 is an MSC homing factor;
local over-expression of MCP-3 recruits MSC to sites of injured
tissue and improves cardiac remodeling independent of cardiac myocyte
regeneration.
Cells isolated from umbilical cord tissue rescue photoreceptors
and visual functions in a rodent model of retinal disease
R. D. Lund et al.
Stem Cells, published online October 19, 2006; doi:10.1634/stemcells.2006-0308.
Abstract: Progressive photoreceptor degeneration resulting from
genetic and other factors is a leading and largely untreatable cause
of blindness worldwide. The object of this study was to find a cell
type that is effective in slowing the progress of such degeneration
in an animal model of human retinal disease, is safe and could be
generated in sufficient numbers for clinical application. We have
compared efficacy of four human derived cell types in preserving
photoreceptor integrity and visual functions after injection into
the subretinal space of the Royal College of Surgeons rat early
in the progress of degeneration. Umbilical tissue-derived cells,
placenta-derived cells, and mesenchymal stem cells were studied;
dermal fibroblasts served as cell controls. At various ages up to
100 days, electroretinogram responses, spatial acuity and luminance
threshold were measured. Both umbilical-derived and mesenchymal
cells significantly reduced the degree of functional deterioration
in each test. The effect of placental cells was little better than
controls. Umbilical tissue-derived cells gave large areas of photoreceptor
rescue; mesenchymal stem cells gave only localized rescue. Fibroblasts
gave sham levels of rescue. Donor cells were confined to the subretinal
space. There was no evidence of cell differentiation into neurons,
of tumor formation or other untoward pathology. Since the umbilical
tissue-derived cells demonstrated the best photoreceptor rescue
and unlike mesenchymal stem cells were capable of sustained population
doublings without karyotypic changes, it is proposed that they may
provide utility as a cell source for the treatment of retinal degenerative
diseases such as retinitis pigmentosa.
Sarcoma Derived from Cultured Mesenchymal Stem Cells
Jakub Tolar et al.
Stem Cells, published online October 12, 2006; doi:10.1634/stemcells.2005-0620.
Abstract: To study the biodistribution of Mesenchymal Stem Cells
(MSCs), we labeled adult murine C57BL/6 MSCs with firefly luciferase
and DsRed2 fluorescent protein using non-viral Sleeping Beauty transposons,
and co-infused labeled MSCs with bone marrow into irradiated allogeneic
recipients. Using in vivo whole body imaging, luciferase signals
were shown to be increased between weeks 3 and 12. Unexpectedly,
some mice with the highest luciferase signals died and all surviving
mice developed foci of sarcoma in lungs. Two mice also developed
sarcomas in their extremities. Common cytogenetic abnormalities
were identified in tumor cells isolated from different animals.
Original MSC cultures not labeled with transposons, as well as independently
isolated cultured MSCs were found to be cytogenetically abnormal.
Moreover, primary MSC.s derived from the bone marrow of both BALB/c
and C57BL/6 mice showed cytogenetic aberrations after several passages
in vitro, showing that transformation was not a strain specific
nor rare event. Clonal evolution was observed in vivo suggesting
that the critical transformation event(s) occurred before infusion.
Mapping of the transposition insertion sites did not identify an
obvious transposon related genetic abnormality and p53 was not overexpressed.
Infusion of MSC-derived sarcoma cells resulted in malignant lesions
in secondary recipients. This new sarcoma cell line, S1, is unique
in having a cytogenetic profile similar to human sarcoma and contains
bioluminescent and fluorescent genes making it useful for investigations
of cellular biodistribution and tumor response to therapy in vivo.
More importantly, our study indicates that sarcoma can evolve from
MSC cultures.
Transcoronary transplantation of progenitor cells
after myocardial infarction.
Assmus B, et al.
N Engl J Med. 2006 Sep 21;355(12):1222-32.
BACKGROUND: Pilot studies suggest that intracoronary transplantation
of progenitor cells derived from bone marrow (BMC) or circulating
blood (CPC) may improve left ventricular function after acute myocardial
infarction. The effects of cell transplantation in patients with
healed myocardial infarction are unknown.
METHODS: After an initial pilot trial involving 17 patients, we
randomly assigned, in a controlled crossover study, 75 patients
with stable ischemic heart disease who had had a myocardial infarction
at least 3 months previously to receive either no cell infusion
(23 patients) or infusion of CPC (24 patients) or BMC (28 patients)
into the patent coronary artery supplying the most dyskinetic left
ventricular area. The patients in the control group were subsequently
randomly assigned to receive CPC or BMC, and the patients who initially
received BMC or CPC crossed over to receive CPC or BMC, respectively,
at 3 months' follow-up.
RESULTS: The absolute change in left ventricular ejection fraction
was significantly greater among patients receiving BMC (+2.9 percentage
points) than among those receiving CPC (-0.4 percentage point, P=0.003)
or no infusion (-1.2 percentage points, P<0.001). The increase
in global cardiac function was related to significantly enhanced
regional contractility in the area targeted by intracoronary infusion
of BMC. The crossover phase of the study revealed that intracoronary
infusion of BMC was associated with a significant increase in global
and regional left ventricular function, regardless of whether patients
crossed over from control to BMC or from CPC to BMC.
CONCLUSIONS: Intracoronary infusion of progenitor cells is safe
and feasible in patients with healed myocardial infarction. Transplantation
of BMC is associated with moderate but significant improvement in
the left ventricular ejection fraction after 3 months. 2006 Massachusetts
Medical Society
Intracoronary bone marrow-derived progenitor cells
in acute myocardial infarction.
Schachinger V, et al.
N Engl J Med. 2006 Sep 21;355(12):1210-21.
BACKGROUND: Pilot trials suggest that the intracoronary administration
of autologous progenitor cells may improve left ventricular function
after acute myocardial infarction.
METHODS: In a multicenter trial, we randomly assigned 204 patients
with acute myocardial infarction to receive an intracoronary infusion
of progenitor cells derived from bone marrow (BMC) or placebo medium
into the infarct artery 3 to 7 days after successful reperfusion
therapy.
RESULTS: At 4 months, the absolute improvement in the global left
ventricular ejection fraction (LVEF) was significantly greater in
the BMC group than in the placebo group (mean [+/-SD] increase,
5.5+/-7.3% vs. 3.0+/-6.5%; P=0.01). Patients with a baseline LVEF
at or below the median value of 48.9% derived the most benefit (absolute
improvement in LVEF, 5.0%; 95% confidence interval, 2.0 to 8.1).
At 1 year, intracoronary infusion of BMC was associated with a reduction
in the prespecified combined clinical end point of death, recurrence
of myocardial infarction, and any revascularization procedure (P=0.01).
CONCLUSIONS: Intracoronary administration of BMC is associated with
improved recovery of left ventricular contractile function in patients
with acute myocardial infarction. Large-scale studies are warranted
to examine the potential effects of progenitor-cell administration
on morbidity and mortality. 2006 Massachusetts Medical Society
Intracoronary injection of mononuclear bone marrow
cells in acute myocardial infarction.
Lunde K, et al.
N Engl J Med. 2006 Sep 21;355(12):1199-209.
BACKGROUND: Previous studies have shown improvement in left ventricular
function after intracoronary injection of autologous cells derived
from bone marrow (BMC) in the acute phase of myocardial infarction.
We designed a randomized, controlled trial to further investigate
the effects of this treatment.
METHODS: Patients with acute ST-elevation myocardial infarction
of the anterior wall treated with percutaneous coronary intervention
were randomly assigned to the group that underwent intracoronary
injection of autologous mononuclear BMC or to the control group,
in which neither aspiration nor sham injection was performed. Left
ventricular function was assessed with the use of electrocardiogram-gated
single-photon-emission computed tomography (SPECT) and echocardiography
at baseline and magnetic resonance imaging (MRI) 2 to 3 weeks after
the infarction. These procedures were repeated 6 months after the
infarction. End points were changes in the left ventricular ejection
fraction (LVEF), end-diastolic volume, and infarct size.
RESULTS: Of the 50 patients assigned to treatment with mononuclear
BMC, 47 underwent intracoronary injection of the cells at a median
of 6 days after myocardial infarction. There were 50 patients in
the control group. The mean (+/-SD) change in LVEF, measured with
the use of SPECT, between baseline and 6 months after infarction
for all patients was 7.6+/-10.4 percentage points. The effect of
BMC treatment on the change in LVEF was an increase of 0.6 percentage
point (95% confidence interval [CI], -3.4 to 4.6; P=0.77) on SPECT,
an increase of 0.6 percentage point (95% CI, -2.6 to 3.8; P=0.70)
on echocardiography, and a decrease of 3.0 percentage points (95%
CI, 0.1 to -6.1; P=0.054) on MRI. The two groups did not differ
significantly in changes in left ventricular end-diastolic volume
or infarct size and had similar rates of adverse events.
CONCLUSIONS: With the methods used, we found no effects of intracoronary
injection of autologous mononuclear BMC on global left ventricular
function. 2006 Massachusetts Medical Society
Integrins Are Markers of Human Neural Stem Cells
Peter E. Hall et al.
Stem Cells. 2006 Sep;24(9):2078-84. Epub 2006 May 11.
Abstract: The identification of markers for the isolation of human
neural stem cells (hNSCs) is essential for studies of their biology
and therapeutic applications. This study investigated expression
of the integrin receptor family by hNSCs as potential markers. Selection
of alpha6(hi) or beta1(hi) cells by fluorescence-activated cell
sorting led to an enrichment of human neural precursors, as shown
by both neurosphere forming assays and increased expression of prominin-1,
sox2, sox3, nestin, bmi1, and musashi1 in the beta1(hi) population.
Cells expressing high levels of beta1 integrin also expressed prominin-1
(CD133), a marker previously used to isolate hNSCs, and selection
using integrin beta1(hi) cells or prominin-1(hi) cells was found
to be equally effective at enriching for hNSCs from neurospheres.
Therefore, integrin subunits alpha6 and beta1 are highly expressed
by human neural precursors and represent convenient markers for
their prospective isolation.
High Yield of Cells Committed to the Photoreceptor
Fate from Expanded Mouse Retinal Stem Cells
Faten Merhi-Soussi et al.
Stem Cells. 2006 Sep;24(9):2060-70. Epub 2006 Apr 27.
Abstract: The purpose of the present work was to generate, from
retinal stem cells (RSCs), a large number of cells committed toward
the photoreceptor fate in order to provide an unlimited cell source
for neurogenesis and transplantation studies. We expanded RSCs (at
least 34 passages) sharing characteristics of radial glial cells
and primed the cells in vitro with fibroblast growth factor (FGF)-2
for 5 days, after which cells were treated with the B27 supplement
to induce cell differentiation and maturation. Upon differentiation,
cells expressed cell type-specific markers corresponding to neurons
and glia. We show by immunocytochemistry analysis that a subpopulation
of differentiated cells was committed to the photoreceptor lineage
given that these cells expressed the photoreceptor proteins recoverin,
peripherin, and rhodopsin in a same ratio. Furthermore, cells infected
during the differentiation procedure with a lentiviral vector expressing
green fluorescent protein (GFP) under the control of either the
rhodopsin promoter or the interphotoreceptor retinoidbinding protein
(IRBP) promoter, expressed GFP. FGF-2 priming increased neuronal
differentiation while decreasing glia generation. Reverse transcription-polymerase
chain reaction analyses revealed that the differentiated cells expressed
photoreceptor-specific genes such as Crx, rhodopsin, peripherin,
IRBP, and phosphodiesterase-_. Quantification of the differentiated
cells showed a robust differentiation into the photoreceptor lineage:
Approximately 25%–35% of the total cells harbored photoreceptor
markers. The generation of a significant number of nondifferentiated
RSCs as well as differentiated photoreceptors will enable researchers
to determine via transplantation studies which cells are the most
adequate to integrate a degenerating retina.
Bioreactor Expansion of Human Adult Bone Marrow-Derived
Mesenchymal Stem Cells
Xi Chen et al.
Stem Cells. 2006 Sep;24(9):2052-9. Epub 2006 May 25.
Abstract: Supplementation of mesenchymal stem cells (MSCs) during
hematopoietic stem cell (HSC) transplantation alleviates complications
such as graft-versus-host disease, leading to a speedy recovery
of hematopoiesis. To meet this clinical demand, a fast MSC expansion
method is required. In the present study, we examined the feasibility
of using a rotary bioreactor system to expand MSCs from isolated
bone marrow mononuclear cells. The cells were cultured in a rotary
bioreactor with Myelocult medium containing a combination of supplementary
factors, including stem cell factor and interleukin-3 and -6. After
8 days of culture, total cell numbers, Stro-1(+)CD44(+)CD34(-) MSCs,
and CD34(+)CD44(+)Stro-1(-) HSCs were increased 9-, 29-, and 8-fold,
respectively. Colony-forming efficiency-fibroblast per day of the
bioreactor-treated cells was 1.44-fold higher than that of the cells
without bioreactor treatment. The bioreactor-expanded MSCs showed
expression of primitive MSC markers endoglin (SH2) and vimentin,
whereas markers associated with lineage differentiation, including
osteocalcin (osteogenesis), type II collagen (chondrogenesis), and
C/EBP-alpha (CCAAT/enhancer-binding protein-alpha) (adipogenesis),
were not detected. Upon induction, the bioreactor-expanded MSCs
were able to differentiate into osteoblasts, chondrocytes, and adipocytes.
We conclude that the rotary bioreactor with the modified Myelocult
medium reported in this study may be used to rapidly expand MSCs.
Multi-potent mesenchymal stromal cells in blood
Qiling He et al.
Stem Cells. published online Sep 14, 2006; DOI: 10.1634/stemcells.2006-0335.
Abstract: Peripheral blood-derived multi-potent mesenchymal stromal
cells circulate in low number. They share, though not all, but most
of the surface markers with bone marrow-derived multi-potent mesenchymal
stromal cells, possess diverse and complicated gene expression characteristics,
and are capable of differentiating along and even beyond mesenchymal
lineages. Although their origin and physio-pathological function
are still unclear, their presence in the adult peripheral blood
might relate to some interesting but controversial subjects in the
filed of adult stem cell biology, such as systemic migration of
bone marrowderived multi-potent mesenchymal stromal cells and the
existence of common hematopoietic-mesenchymal precursors. In this
review, current studies /knowledge about peripheral blood-derived
multi-potent mesenchymal stromal cells is summarized and the above-mentioned
topics are discussed.
Effective cell and gene therapy in a murine model
of Gaucher disease.
Enquist IB, et al.
Proc Natl Acad Sci U S A. 2006 Sep 12;103(37):13819-24. Epub 2006
Sep 5.
Abstract: Gaucher disease (GD) is a lysosomal storage disorder due
to an inherited deficiency in the enzyme glucosylceramidase (GCase)
that causes hepatosplenomegaly, cytopenias, and bone disease as
key clinical symptoms. Previous mouse models with GCase deficiency
have been lethal in the perinatal period or viable without displaying
the clinical features of GD. We have generated viable mice with
characteristic clinical symptoms of type 1 GD by conditionally deleting
GCase exons 9-11 upon postnatal induction. Both transplantation
of WT bone marrow (BM) and gene therapy through retroviral transduction
of BM from GD mice prevented development of disease and corrected
an already established GD phenotype. The gene therapy approach generated
considerably higher GCase activity than transplantation of WT BM.
Strikingly, both therapeutic modalities normalized glucosylceramide
levels and practically no infiltration of Gaucher cells could be
observed in BM, spleen, and liver, demonstrating correction at 5-6
months after treatment. The findings demonstrate the feasibility
of gene therapy for type 1 GD in vivo. Our type 1 GD mice will serve
as an excellent tool in the continued efforts toward development
of safe and efficient cell and gene therapy for type 1 GD.
Isolation and characterization of multipotent progenitor
cells from the Bowman's capsule of adult human kidneys.
Sagrinati C, et al.
J Am Soc Nephrol. 2006 Sep;17(9):2443-56. Epub 2006 Aug 2.
Abstract: Regenerative medicine represents a critical clinical goal
for patients with ESRD, but the identification of renal adult multipotent
progenitor cells has remained elusive. It is demonstrated that in
human adult kidneys, a subset of parietal epithelial cells (PEC)
in the Bowman's capsule exhibit coexpression of the stem cell markers
CD24 and CD133 and of the stem cell-specific transcription factors
Oct-4 and BmI-1, in the absence of lineage-specific markers. This
CD24+CD133+ PEC population, which could be purified from cultured
capsulated glomeruli, revealed self-renewal potential and a high
cloning efficiency. Under appropriate culture conditions, individual
clones of CD24+CD133+ PEC could be induced to generate mature, functional,
tubular cells with phenotypic features of proximal and/or distal
tubules, osteogenic cells, adipocytes, and cells that exhibited
phenotypic and functional features of neuronal cells. The injection
of CD24+CD133+ PEC but not of CD24-CD133- renal cells into SCID
mice that had acute renal failure resulted in the regeneration of
tubular structures of different portions of the nephron. More important,
treatment of acute renal failure with CD24+CD133+ PEC significantly
ameliorated the morphologic and functional kidney damage. This study
demonstrates the existence and provides the characterization of
a population of resident multipotent progenitor cells in adult human
glomeruli, potentially opening new avenues for the development of
regenerative medicine in patients who have renal diseases.
Human neural stem cells target experimental intracranial
medulloblastoma and deliver a therapeutic gene leading to tumor
regression.
Kim SK, et al.
Clin Cancer Res. 2006 Sep 15;12(18):5550-6.
PURPOSE: Medulloblastoma, a malignant pediatric brain tumor, is
incurable in about one third of patients despite multimodal treatments.
In addition, current therapies can lead to long-term disabilities.
Based on studies of the extensive tropism of neural stem cells (NSC)
toward malignant gliomas and the secretion of growth factors common
to glioma and medulloblastoma, we hypothesized that NSCs could target
medulloblastoma and be used as a cellular therapeutic delivery system.
Experimental Design: The migratory ability of HB1.F3 cells (an immortalized,
clonal human NSC line) to medulloblastoma was studied both in vitro
and in vivo. As proof-of-concept, we used HB1.F3 cells engineered
to secrete the prodrug activating enzyme cytosine deaminase. We
investigated the potential of human NSCs to deliver a therapeutic
gene and reduce tumor growth.
RESULTS: The migratory capacity of HB1.F3 cells was confirmed by
an in vitro migration assay, and corroborated in vivo by injecting
chloromethylbenzamido-Dil-labeled HB1.F3 cells into the hemisphere
contralateral to established medulloblastoma in nude mice. In vitro
studies showed the therapeutic efficacy of HB1.F3-CD on Daoy cells
in coculture experiments. In vitro therapeutic studies were conducted
in which animals bearing intracranial medulloblastoma were injected
ipsilaterally with HB1.F3-CD cells followed by systemic 5-flourocytosine
treatment. Histologic analyses showed that human NSCs migrate to
the tumor bed and its boundary, resulting in a 76% reduction of
tumor volume in the treatment group (P<0.01).
CONCLUSION: These studies show for the first time the potential
of human NSCs as an effective delivery system to target and disseminate
therapeutic agents to medulloblastoma.
A phase 2 study of high-activity( 186)Re-HEDP with
autologous peripheral blood stem cell transplant in progressive
hormone-refractory prostate cancer metastatic to bone.
O'Sullivan JM, et al.
Eur J Nucl Med Mol Imaging. 2006 Sep;33(9):1055-1061. Epub 2006
Mar 30.
PURPOSE: We investigated the potential for improvement in disease
control by use of autologous peripheral blood stem cell transplant
(PBSCT) to permit administration of high activities of (186)Re-hydroxyethylidene
diphosphonate (HEDP) in patients with progressive hormone-refractory
prostate cancer (HRPC).
METHODS: Eligible patients had progressive HRPC metastatic to bone,
good performance status and minimal soft tissue disease. Patients
received 5,000 MBq of (186)Re-HEDP i.v., followed 14 days later
by PBSCT. Response was assessed using PSA, survival, pain scores
and quality of life.
RESULTS: Thirty-eight patients with a median age of 67 years (range
50-77) and a median PSA of 57 ng/ml (range 4-3,628) received a median
activity of 4,978 MBq (186)Re-HEDP (range 4,770-5,100 MBq). The
most serious toxicity was short-lived grade 3 thrombocytopenia in
8 (21%) patients. The median survival of the group is 21 months
(95%CI 18-24 months) with Kaplan-Meier estimated 1- and 2-year survival
rates of 83% and 40% respectively. Thirty-one patients (81%, 95%
CI 66-90%) had stable or reduced PSA levels 3 months post therapy
while 11 (29%, 95% CI 15-49%) had PSA reductions of >50% lasting
>4 weeks. Quality of life measures were stable or improved in
27 (66%) at 3 months.
CONCLUSION: We have shown that it is feasible and safe to deliver
high-activity radioisotope therapy with PBSCT to men with metastatic
HRPC. Response rates and survival data are encouraging; however,
further research is needed to define optimal role of this treatment
approach.
Adipose-derived stem and progenitor cells as fillers
in plastic and reconstructive surgery.
Moseley TA, et al.
Plast Reconstr Surg. 2006 Sep;118(3 Suppl):121S-128S.
Abstract: Plastic surgeons are keenly aware of the principle "replace
like with like." This principle underlies much of the rationale
behind the clinical use of autologous fat transplantation, despite
the procedure's drawbacks. Autologous fat transplantation is frequently
used for a variety of cosmetic and reconstructive indications not
limited to posttraumatic defects of the face and body, involutional
disorders such as hemifacial atrophy, sequelae of radiation therapy,
and many aesthetic uses such as lip and facial augmentation and
wrinkle therapy. However, the limitations of fat transplantation
are well known, particularly the long-term unpredictability of volume
maintenance. Regenerative cell-based strategies such as those encompassing
the use of stem cells hold tremendous promise for augmentation of
the soft-tissue space. Preclinical studies and early clinical series
show that adipose-derived stem cells offer the possibility of finally
fulfilling the key principle of replacing like with like as an aesthetic
filler, without the drawbacks of current technology.
Ex Vivo Expansion Does Not Alter the Capacity of Umbilical
Cord Blood CD34_ Cells to Generate Functional T Lymphocytes and
Dendritic Cells
LADAN KOBARI et al.
Stem Cells. 2006;24:2150–2157.
Abstract: We examined whether ex vivo expansion of umbilical cord
blood progenitor cells affected their capacity to generate immune
cells such as T lymphocytes (TLs) and dendritic cells (DCs). The
capacity to generate TLs from cord blood CD34_ cells expanded for
14 days (d14) was compared with that of nonexpanded CD34_ cells
(d0) using fetal thymus organ cultures or transfer into nonobese
diabetic/severe combined immunodeficient mice. The cell preparations
yielded comparable percentages of immature (CD4_CD8_, CD4_CD8_)
TLs and functional mature (CD3_CD4_, CD3_CD8_) TLs with an analogous
TCR (T-cell receptor)-V_ repertoire pattern. As regards DCs, d0
and d14 CD34_ cells also yielded similar percentages of CD1a_ DCs
with the same expression levels of HLA-DR, costimulatory and adhesion
molecules, and chemokine receptors. DCs derived from either d14
or d0 CD34_ stimulated allogeneic TLs to the same extent, and the
cytokine pattern production of these allogeneic TLs was similar
with no shift toward a predominant Th1 or Th2 response. Even though
the intrinsic capacity of d14 CD34_ cells to generate DCs was 13-fold
lower than that of d0 CD34_ cells, this reduction was offset by
the prior amplification of the CD34_ cells, resulting in the overall
production of 15-fold more DCs. These data indicate that ex vivo
expansion of CD34_ cells does not impair T lymphopoiesis nor DC
differentiation capacity.
In Vivo Bone Formation by Human Bone Marrow Stromal
Cells: Reconstruction of the Mouse Calvarium and Mandible
MAHESH H. MANKANI et al.
Stem Cells. 2006 Sep;24(9):2140-9. Epub 2006 Jun 8.
Abstract: Bone marrow stromal cells (BMSCs) contain a subset of
multipotent cells with the potential to repair hard-tissue defects.
Mouse BMSCs, combined with a collagen carrier, can close critical-sized
homologous mouse calvarial defects, but this new bone has a poor
union with the adjacent calvarium. When human BMSCs are transplanted
for the purpose of engineering new bone, best results can be achieved
if the cells are combined with hydroxyapatite/tricalcium phosphate
(HA/TCP) particles. Here, we demonstrate that transplantation of
cultured human BMSCs in conjunction with HA/TCP particles can be
used successfully to close mouse craniofacial bone defects and that
removal of the periosteum from the calvarium significantly enhances
union with the transplant. Transplants were followed for up to 96
weeks and were found to change in morphology but not bone content
after 8 weeks; this constitutes the first description of human BMSCs
placed long-term to heal bone defects. New bone formation continued
to occur in the oldest transplants, confirmed by tetracycline labeling.
Additionally, the elastic modulus of this engineered bone resembled
that of the normal mouse calvarium, and our use of atomic force
microscopy (AFM)-based nanoindentation offered us the first opportunity
to compare these small transplants against equally minute mouse
bones. Our results provide insights into the long-term behavior
of newly engineered orthotopic bone from human cells and have powerful
implications for therapeutic human BMSC transplantation.
Growth factor-stimulated generation of new cortical
tissue and functional recovery after stroke damage to the motor
cortex of rats.
Kolb B, et al.
J Cereb Blood Flow Metab. 2006 Sep 20; [Epub ahead of print]
Abstract: Recent studies suggest that proliferation in the adult
forebrain subventricular zone increases in response to a forebrain
stroke and intraventricular infusions of growth factors enhance
this response. The potential for growth factor infusions to regenerate
the damaged motor cortex and promote recovery of motor function
after stroke has not been examined. Here, we report that intraventricular
infusions of epidermal growth factor and erythropoietin together,
but not individually, promote substantial regeneration of the damaged
cerebral cortex and reverse impairments in spontaneous and skilled
motor tasks, in a rat model of stroke. Cortical regeneration and
functional recovery occurred even when growth factor administration
was delayed for up to 7 days after the stroke-induced lesion. Cell
tracking demonstrated the contribution of neural precursors originating
in the forebrain subventricular zone to the regenerated cortex.
Strikingly, removal of the regenerated cortical tissue reversed
the growth factor-induced functional recovery. These findings reveal
that specific combinations of growth factors can mobilize endogenous
adult neural stem cells to promote cortical tissue re-growth and
functional recovery after stroke.Journal of Cerebral Blood Flow
& Metabolism advance online publiaction, 20 September 2006;
doi:10.1038/sj.jcbfm.9600402.
Synergy between immune cells and adult neural stem/progenitor cells promotes functional recovery from spinal cord injury.