Long-term survival of dopamine neurons derived from parthenogenetic primate embryonic stem cells (cyno-1) after transplantation

Mitomycin-C treatment during differentiation of induced pluripotent stem cell-derived dopamine neurons reduces proliferation without compromising survival or function in vivo

Nongenetic methodologies to reduce undesirable proliferation would be valuable when generating dopamine neurons from stem cells for transplantation in Parkinson's disease (PD). To this end, we modified an established method for controlled differentiation of human induced pluripotent stem cells (iPSCs) into midbrain dopamine neurons using two distinct methods: omission of FGF8 or the in‐process use of the DNA cross‐linker mitomycin‐C (MMC). We transplanted the cells to athymic rats with unilateral 6‐hydroxydopamine lesions and monitored long‐term survival and function of the grafts. Transplants of cells manufactured using MMC had low proliferation while still permitting robust survival and function comparable to that seen with transplanted dopamine neurons derived using genetic drug selection. Conversely, cells manufactured without FGF8 survived transplantation but exhibited poor in vivo function. Our results suggest that MMC can be used to reduce the number of proliferative cells in stem cell‐derived postmitotic neuron preparations for use in PD cell therapy.

Protective Mechanism and Treatment of Neurogenesis in Cerebral Ischemia

Stroke is the fifth leading cause of death worldwide and is a main cause of disability in adults. Neither currently marketed drugs nor commonly used treatments can promote nerve repair and neurogenesis after stroke, and the repair of neurons damaged by ischemia has become a research focus. This article reviews several possible mechanisms of stroke and neurogenesis and introduces novel neurogenic agents (fibroblast growth factors, brain-derived neurotrophic factor, purine nucleosides, resveratrol, S-nitrosoglutathione, osteopontin, etc.) as well as other treatments that have shown neuroprotective or neurogenesis-promoting effects.

Human Clinical-Grade Parthenogenetic ESC-Derived Dopaminergic Neurons Recover Locomotive Defects of Nonhuman Primate Models of Parkinson's Disease

Clinical application of stem cell derivatives requires clinical-grade cells and sufficient preclinical proof of safety and efficacy, preferably in primates. We previously successfully established a clinical-grade human parthenogenetic embryonic stem cell (hPESC) line, but the suitability of its subtype-specific progenies for therapy is not clear. Here, we compared the function of clinical-grade hPESC-derived midbrain dopaminergic (DA) neurons in two canonical protocols in a primate Parkinson's disease (PD) model. We found that the grafts did not form tumors and produced variable but apparent behavioral improvement for at least 24 months in most monkeys in both groups. In addition, a slight DA increase in the striatum correlates with significant functional improvement. These results demonstrated that clinical-grade hPESCs can serve as a reliable source of cells for PD treatment. Our proof-of-concept findings provide preclinical data for China's first ESC-based phase I/IIa clinical study of PD (ClinicalTrials.gov number NCT03119636).

Cell Replacement to Reverse Brain Aging: Challenges, Pitfalls, and Opportunities

Current antiaging strategies focusing on druggable targets have met with relatively limited success to date. Replacement of cells, tissues, and organs could provide an alternative means for targeting age-induced damage and potentially eliminating some of it. However, before this is a viable option, numerous challenges need to be addressed. Most notably, whether the brain, which defines our self-identity, is amenable to replacement therapies is unclear. Here, we consider whether progressive cell replacement is a potential approach to reverse brain aging without grossly altering function. We focus mainly on the neocortex, seat of our highest cognitive functions, because of abundant knowledge on neocortical development, plasticity, and how the neocortex can functionally incorporate new neurons. We outline the primary challenges for brain cell replacement, and key areas that require further investigation.

Effects of Passage Number and Differentiation Protocol on the Generation of Dopaminergic Neurons from Rat Bone Marrow-Derived Mesenchymal Stem Cells

Multiple studies have demonstrated the ability of mesenchymal stem cells (MSCs) to differentiate into dopamine-producing cells, in vitro and in vivo, indicating their potential to be used in the treatment of Parkinson’s disease (PD). However, there are discrepancies among studies regarding the optimal time (i.e., passage number) and method for dopaminergic induction, in vitro. In the current study, we compared the ability of early (P4) and later (P40) passaged bone marrow-derived MSCs to differentiate into dopaminergic neurons using two growth-factor-based approaches. A direct dopaminergic induction (DDI) was used to directly convert MSCs into dopaminergic neurons, and an indirect dopaminergic induction (IDI) was used to direct MSCs toward a neuronal lineage prior to terminal dopaminergic differentiation. Results indicate that both early and later passaged MSCs exhibited positive expression of neuronal and dopaminergic markers following either the DDI or IDI protocols. Additionally, both early and later passaged MSCs released dopamine and exhibited spontaneous neuronal activity following either the DDI or IDI. Still, P4 MSCs exhibited significantly higher spiking and bursting frequencies as compared to P40 MSCs. Findings from this study provide evidence that early passaged MSCs, which have undergone the DDI, are more efficient at generating dopaminergic-like cells in vitro, as compared to later passaged MSCs or MSCs that have undergone the IDI.

Ceramide and S1P Signaling in Embryonic Stem Cell Differentiation

Bioactive sphingolipids are important regulators for stem cell survival and differentiation. Most recently, we have coined the term "morphogenetic lipids" for sphingolipids that regulate stem cells during embryonic and postnatal development. The sphingolipid ceramide and its derivative, sphingosine-1-phosphate (S1P), can act synergistically as well as antagonistically on embryonic stem (ES) cell differentiation. We show here simple as well as state-of-the-art methods to analyze sphingolipids in differentiating ES cells and discuss new protocols to use ceramide and S1P analogs for the guided differentiation of mouse ES cells toward neuronal and glial lineage.

Mouse Parthenogenetic Embryonic Stem Cells with Biparental-Like Expression of Imprinted Genes Generate Cortical-Like Neurons That Integrate into the Injured Adult Cerebral Cortex

One strategy for stem cell-based therapy of the cerebral cortex involves the generation and transplantation of functional, histocompatible cortical-like neurons from embryonic stem cells (ESCs). Diploid parthenogenetic Pg-ESCs have recently emerged as a promising source of histocompatible ESC derivatives for organ regeneration but their utility for cerebral cortex therapy is unknown. A major concern with Pg-ESCs is genomic imprinting. In contrast with biparental Bp-ESCs derived from fertilized oocytes, Pg-ESCs harbor two maternal genomes but no sperm-derived genome. Pg-ESCs are therefore expected to have aberrant expression levels of maternally expressed (MEGs) and paternally expressed (PEGs) imprinted genes. Given the roles of imprinted genes in brain development, tissue homeostasis and cancer, their deregulation in Pg-ESCs might be incompatible with therapy. Here, we report that, unexpectedly, only one gene out of 7 MEGs and 12 PEGs was differentially expressed between Pg-ESCs and Bp-ESCs while 13 were differentially expressed between androgenetic Ag-ESCs and Bp-ESCs, indicating that Pg-ESCs but not Ag-ESCs, have a Bp-like imprinting compatible with therapy. In vitro, Pg-ESCs generated cortical-like progenitors and electrophysiologically active glutamatergic neurons that maintained the Bp-like expression levels for most imprinted genes. In vivo, Pg-ESCs participated to the cortical lineage in fetal chimeras. Finally, transplanted Pg-ESC derivatives integrated into the injured adult cortex and sent axonal projections in the host brain. In conclusion, mouse Pg-ESCs generate functional cortical-like neurons with Bp-like imprinting and their derivatives properly integrate into both the embryonic cortex and the injured adult cortex. Collectively, our data support the utility of Pg-ESCs for cortical therapy. Stem Cells 2018;36:192-205.

Transplantation in the nonhuman primate MPTP model of Parkinson's disease: update and perspectives

In order to calibrate stem cell exploitation for cellular therapy in neurodegenerative diseases, fundamental and preclinical research in NHP (nonhuman primate) models is crucial. Indeed, it is consensually recognized that it is not possible to directly extrapolate results obtained in rodent models to human patients. A large diversity of neurological pathologies should benefit from cellular therapy based on neural differentiation of stem cells. In the context of this special issue of Primate Biology on NHP stem cells, we describe past and recent advances on cell replacement in the NHP model of Parkinson's disease (PD). From the different grafting procedures to the various cell types transplanted, we review here diverse approaches for cell-replacement therapy and their related therapeutic potential on behavior and function in the NHP model of PD.

Derivation of Functional Dopamine Neurons from Embryonic Stem Cells

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the selective degeneration of dopaminergic (DA) neurons in the substantia nigra of the midbrain. Pharmacological treatment of PD has been a prevailing strategy. However, it has some limitations because its effectiveness gradually decreases and side effects develop. As an alternative, cell transplantation therapy has been tried. Although transplantation of fetal ventral mesencephalic cells looks promising for the treatment of PD in some cases, ethical and technical problems in obtaining large numbers of human fetal brain tissues also lead to difficulty in its clinical application. Our recent studies showed that a high yield of DA neurons could be derived from embryonic stem (ES) cells and they efficiently induced behavioral recovery in a PD animal model. Here we summarize methods for generation of functional DA neurons from ES cells for application to PD models.

The role of nonhuman primate models in the development of cell-based therapies for Parkinson's disease

Through the course of over three decades, nonhuman primate (NHP) studies on cell-based therapies (CBTs) for Parkinson’s disease (PD) have provided insight into the feasibility, safety and efficacy of the approach, methods of cell collection and preparation, cell viability, as well as potential brain targets. Today, NHP research continues to be a vital source of information for improving cell grafts and analyzing how the host affects graft survival, integration and function. Overall, this article aims to discuss the role that NHP models of PD have played in CBT development and highlights specific issues that need to be considered to maximize the value of NHP studies for the successful clinical translation of CBTs.

Parthenogenesis and Human Assisted Reproduction

Parthenogenetic activation of human oocytes obtained from infertility treatments has gained new interest in recent years as an alternative approach to create embryos with no reproductive purpose for research in areas such as assisted reproduction technologies itself, somatic cell, and nuclear transfer experiments and for derivation of clinical grade pluripotent embryonic stem cells for regenerative medicine. Different activating methods have been tested on human and nonhuman oocytes, with varying degrees of success in terms of parthenote generation rates, embryo development stem cell derivation rates. Success in achieving a standardized artificial activation methodology for human oocytes and the subsequent potential therapeutic gain obtained from these embryos depends mainly on the availability of gametes donated from infertility treatments. This review will focus on the creation of parthenotes from clinically unusable oocytes for derivation and establishment of human parthenogenetic stem cell lines and their potential applications in regenerative medicine.

Ascorbic acid improves pluripotency of human parthenogenetic embryonic stem cells through modifying imprinted gene expression in the Dlk1-Dio3 region

Introduction

Human parthenogenetic embryonic stem cells (hpESCs) are generated from artificially activated oocytes, however, the issue of whether hpESCs have equivalent differentiation ability to human fertilized embryonic stem cells remains controversial.

Methods

hpESCs were injected into male severe combined immunodeficiency (SCID) mice and the efficiency of teratoma formation was calculated. Then the gene expression and methylation modification were detected by real time-PCR and bisulfate methods.

Results

Comparison of five hpESCs with different differentiation abilities revealed that levels of paternal genes in the Dlk1-Dio3 region on chromosome 14 in the hpESCs with high differentiation potential are enhanced, but strictly methylated and silenced in the hpESCs with lower differentiation potential. Treatment with ascorbic acid, rescued their ability to support teratoma formation and altered the expression profiles of paternally expressed genes in hpESCs that could not form teratoma easily. No differences in the expression of other imprinting genes were evident between hpESCs with higher and lower differentiation potential, except for those in the Dlk1-Dio3 region.

Conclusions

The Dlk1-Dio3 imprinting gene cluster distinguishes the differentiation ability of hpESCs. Moreover, modification by ascorbic acid may facilitate application of hpESCs to clinical settings in the future by enhancing their pluripotency.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0054-9) contains supplementary material, which is available to authorized users.

Successful function of autologous iPSC-derived dopamine neurons following transplantation in a non-human primate model of Parkinson's disease

Autologous transplantation of patient-specific induced pluripotent stem cell (iPSC)-derived neurons is a potential clinical approach for treatment of neurological disease. Preclinical demonstration of long-term efficacy, feasibility, and safety of iPSC-derived dopamine neurons in non-human primate models will be an important step in clinical development of cell therapy. Here, we analyzed cynomolgus monkey (CM) iPSC-derived midbrain dopamine neurons for up to 2 years following autologous transplantation in a Parkinson's disease (PD) model. In one animal, with the most successful protocol, we found that unilateral engraftment of CM-iPSCs could provide a gradual onset of functional motor improvement contralateral to the side of dopamine neuron transplantation, and increased motor activity, without a need for immunosuppression. Postmortem analyses demonstrated robust survival of midbrain-like dopaminergic neurons and extensive outgrowth into the transplanted putamen. Our proof of concept findings support further development of autologous iPSC-derived cell transplantation for treatment of PD.

Brief report: Parthenogenetic embryonic stem cells are an effective cell source for therapeutic liver repopulation

Parthenogenesis is the development of an oocyte without fertilization. Mammalian parthenogenetic (PG) embryos are not viable, but can develop into blastocysts from which embryonic stem cells (ESCs) have been derived in mouse and human. PG ESCs are frequently homozygous for alleles encoding major histocompatibility complex (MHC) molecules. MHC homozygosity permits much more efficient immune matching than MHC heterozygosity found in conventional ESCs, making PG ESCs a promising cell source for cell therapies requiring no or little immune suppression. However, findings of restricted differentiation and proliferation of PG cells in developmental chimeras have cast doubt on the potential of PG ESC derivatives for organ regeneration. To address this uncertainty, we determined whether PG ESC derivatives are effective in rescuing mice with lethal liver failure due to deficiency of fumarylacetoacetate hydrolase (Fah). In developmental chimeras generated by injecting wild-type PG ESCs into Fah-deficient blastocysts, PG ESCs differentiated into hepatocytes that could repopulate the liver, provide normal liver function, and facilitate long-term survival of adult mice. Moreover, after transplantation into adult Fah-deficient mice, PG ESC-derived hepatocytes efficiently engrafted and proliferated, leading to high-level liver repopulation. Our results show that--despite the absence of a paternal genome--PG ESCs can form therapeutically effective hepatocytes.

Expression of vascular endothelial growth factor-C (VEGF-C) and its receptor (VEGFR-3) in the glial reaction elicited by human mesenchymal stem cell engraftment in the normal rat brain

To determine whether vascular endothelial growth factor-C (VEGF-C) and its receptor (VEGFR-3) are involved in the glial reaction elicited by transplanted mesenchymal stem cells (MSCs), we examined the cellular localization of VEGF-C and VEGFR-3 proteins in the striatum of adult normal rats that received bone marrow-derived human MSCs. The MSC grafts were infiltrated with activated microglia/macrophages and astrocytes over a 2-week period post-transplantation, which appeared to parallel the loss of transplanted MSCs. VEGF-C/VEGFR-3 was expressed in activated microglia/macrophages recruited to the graft site, where the induction of VEGF-C protein was rather late compared with that of its receptor. VEGF-C protein was absent or very weak on day 3, whereas VEGFR-3 immunoreactivity was evident within the first three days. Furthermore, within three days, VEGF-C could be detected in the brain macrophages localized immediately adjacent to the needle track. At the same time, almost all the brain macrophages in both regions expressed VEGFR-3. Reactive astrocytes at the graft site expressed VEGFR-3, but not VEGF-C. These data demonstrated the characteristic time- and cell-dependent expression patterns for VEGF-C and VEGFR-3 within the engrafted brain tissue, suggesting that they may contribute to neuroinflammation in MSC transplantation, possibly through the recruitment and/or activation of microglia/macrophages and astrogliosis.

Analysis of human embryonic stem cells with regulatable expression of the cell adhesion molecule l1 in regeneration after spinal cord injury

Cell replacement therapy is one potential avenue for central nervous system (CNS) repair. However, transplanted stem cells may not contribute to long-term recovery of the damaged CNS unless they are engineered for functional advantage. To fine tune regenerative capabilities, we developed a human neural cell line expressing L1, a regeneration-conducive adhesion molecule, under the control of a doxycycline regulatable Tet-off promoter. Controlled expression of L1 is desired because overexpression after regenerative events may lead to adverse consequences. The regulated system was tested in several cell lines, where doxycycline completely eliminated green fluorescent protein or L1 expression by 3-5 days in vitro. Increased colony formation as well as decreased proliferation were observed in H9NSCs without doxycycline (hL1-on). To test the role of L1 in vivo after acute compression spinal cord injury of immunosuppressed mice, quantum dot labeled hL1-on or hL1-off cells were injected at three sites: lesion; proximal; and caudal. Mice transplanted with hL1-on cells showed a better Basso Mouse Scale score, when compared to those with hL1-off cells. As compared to the hL1-off versus hL1-on cell transplanted mice 6 weeks post-transplantation, expression levels of L1, migration of transplanted cells, and immunoreactivity for tyrosine hydroxylase were higher, whereas expression of chondroitin sulfate proteoglycans was lower. Results indicate that L1 expression is regulatable in human stem cells by doxycycline in a nonviral engineering approach. Regulatable expression in a prospective nonleaky Tet-off system could hold promise for therapy, based on the multifunctional roles of L1, including neuronal migration and survival, neuritogenesis, myelination, and synaptic plasticity.

Inducing human parthenogenetic embryonic stem cells into islet‑like clusters

In order to determine whether human parthenogenetic embryonic stem (hpES) cells have the potential to differentiate into functional cells, a modified four-step protocol was used to induce the hpES cells into islet-like clusters (ILCs) in vitro. Growth factors activin A, retinoic acid, nicotinamide, Exendin-4 and betacellulin were added sequentially to the hpES cells at each step. The terminally differentiated cells were shown to gather into ILCs. Immunohistochemistry and semi quantitative polymerase chain reaction analyses demonstrated that the ILCs expressed islet specific hormones and functional markers. Furthermore, an insulin release test indicated that the clusters had the same physiological function as islets. The ILCs derived from hpES cells shared similar characteristics with islets. These results indicate that hpES cell-derived ILCs may be used as reliable material for the treatment of type I diabetes mellitus.

Cell based therapies in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. It is characterized by bradykinesia, hypokinesia/ akinesia, rigidity, tremor, and postural instability, caused by dopaminergic (DA) striatal denervation. The prevalence of PD increases from 50 years of age with steep rise after age 60 years. Current treatment of PD relies heavily on replacing lost dopamine either with its precursor L-dopa or dopamine agonists (ropinirole, pramipexole, bromocriptine, lisuride etc). Other pharmacological measures like catechol-O-methyltrasferase (COMT) inhibitors like entacopone, telcapone and monoamine oxidase B (MAO-B) inhibitors like selegiline and rasagiline are also useful, while L-dopa remains the gold standard in the treatment of PD. Emerging therapies are focusing on cell based therapeutics derived from various sources.

Neurotherapeutic effect of cord blood derived CD45+ hematopoietic cells in mice after traumatic brain injury

Treatment of traumatic brain injury (TBI) is still an unmet need. Cell therapy by human umbilical cord blood (HUCB) has shown promising results in animal models of TBI and is under evaluation in clinical trials. HUCB contains different cell populations but to date, only mesenchymal stem cells have been evaluated for therapy of TBI. Here we present the neurotherapeutic effect, as evaluated by neurological score, using a single dose of HUCB-derived mononuclear cells (MNCs) upon intravenous (IV) administration one day post-trauma in a mouse model of closed head injury (CHI). Delayed (eight days post-trauma) intracerebroventricular administration of MNCs showed improved neurobehavioral deficits thereby extending the therapeutic window for treating TBI. Further, we demonstrated for the first time that HUCB-derived pan-hematopoietic CD45 positive (CD45(+)) cells, isolated by magnetic sorting and characterized by expression of CD45 and CD11b markers (96-99%), improved the neurobehavioral deficits upon IV administration, which persisted for 35 days. The therapeutic effect was in a direct correlation to a reduction in the lesion volume and decreased by pre-treatment of the cells with anti-human-CD45 antibody. At the site of brain injury, 1.5-2 h after transplantation, HUCB-derived cells were identified by near infrared scanning and immunohistochemistry using anti-human-CD45 and anti-human-nuclei antibodies. Nerve growth factor and vascular endothelial growth factor levels were differentially expressed in both ipsilateral and contralateral brain hemispheres, thirty-five days after CHI, measured by enzyme-linked immunosorbent assay. These findings indicate the neurotherapeutic potential of HUCB-derived CD45(+) cell population in a mouse model of TBI and propose their use in the clinical setting of human TBI.

Concise review: parthenote stem cells for regenerative medicine: genetic, epigenetic, and developmental features

Embryonic stem cells (ESCs) have the potential to provide unlimited cells and tissues for regenerative medicine. ESCs derived from fertilized embryos, however, will most likely be rejected by a patient's immune system unless appropriately immunomatched. Pluripotent stem cells (PSCs) genetically identical to a patient can now be established by reprogramming of somatic cells. However, practical applications of PSCs for personalized therapies are projected to be unfeasible because of the enormous cost and time required to produce clinical-grade cells for each patient. ESCs derived from parthenogenetic embryos (pESCs) that are homozygous for human leukocyte antigens may serve as an attractive alternative for immunomatched therapies for a large population of patients. In this study, we describe the biology and genetic nature of mammalian parthenogenesis and review potential advantages and limitations of pESCs for cell-based therapies.

Improved cell therapy protocols for Parkinson's disease based on differentiation efficiency and safety of hESC-, hiPSC-, and non-human primate iPSC-derived dopaminergic neurons

The main motor symptoms of Parkinson's disease are due to the loss of dopaminergic (DA) neurons in the ventral midbrain (VM). For the future treatment of Parkinson's disease with cell transplantation it is important to develop efficient differentiation methods for production of human iPSCs and hESCs-derived midbrain-type DA neurons. Here we describe an efficient differentiation and sorting strategy for DA neurons from both human ES/iPS cells and non-human primate iPSCs. The use of non-human primate iPSCs for neuronal differentiation and autologous transplantation is important for preclinical evaluation of safety and efficacy of stem cell-derived DA neurons. The aim of this study was to improve the safety of human- and non-human primate iPSC (PiPSC)-derived DA neurons. According to our results, NCAM(+) /CD29(low) sorting enriched VM DA neurons from pluripotent stem cell-derived neural cell populations. NCAM(+) /CD29(low) DA neurons were positive for FOXA2/TH and EN1/TH and this cell population had increased expression levels of FOXA2, LMX1A, TH, GIRK2, PITX3, EN1, NURR1 mRNA compared to unsorted neural cell populations. PiPSC-derived NCAM(+) /CD29(low) DA neurons were able to restore motor function of 6-hydroxydopamine (6-OHDA) lesioned rats 16 weeks after transplantation. The transplanted sorted cells also integrated in the rodent brain tissue, with robust TH+/hNCAM+ neuritic innervation of the host striatum. One year after autologous transplantation, the primate iPSC-derived neural cells survived in the striatum of one primate without any immunosuppression. These neural cell grafts contained FOXA2/TH-positive neurons in the graft site. This is an important proof of concept for the feasibility and safety of iPSC-derived cell transplantation therapies in the future.

Combined flow cytometric analysis of surface and intracellular antigens reveals surface molecule markers of human neuropoiesis

Surface molecule profiles undergo dynamic changes in physiology and pathology, serve as markers of cellular state and phenotype and can be exploited for cell selection strategies and diagnostics. The isolation of well-defined cell subsets is needed for in vivo and in vitro applications in stem cell biology. In this technical report, we present an approach for defining a subset of interest in a mixed cell population by flow cytometric detection of intracellular antigens. We have developed a fully validated protocol that enables the co-detection of cluster of differentiation (CD) surface antigens on fixed, permeabilized neural cell populations defined by intracellular staining. Determining the degree of co-expression of surface marker candidates with intracellular target population markers (nestin, MAP2, doublecortin, TUJ1) on neuroblastoma cell lines (SH-SY5Y, BE(2)-M17) yielded a combinatorial CD49f^-/CD200^high surface marker panel. Its application in fluorescence-activated cell sorting (FACS) generated enriched neuronal cultures from differentiated cell suspensions derived from human induced pluripotent stem cells. Our data underlines the feasibility of using the described co-labeling protocol and co-expression analysis for quantitative assays in mammalian neurobiology and for screening approaches to identify much needed surface markers in stem cell biology.

[Cell therapy for stroke: from myth to reality]

INTRODUCTION

Stroke is one of the leading causes of death and disability worldwide. Intravenous recombinant tissue plasminogen activator is the only available therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window and cannot stimulate endogenous repair and regeneration of damaged brain tissue. Stem cell-based approaches hold much promise as potential novel treatments to restore neurological function after stroke.

STATE OF THE ART

In this review, we summarize data from preclinical and clinical studies to investigate the potential application of stem cell therapies for treatment of stroke. Stem cells have been proposed as a potential source of new cells to replace those lost due to central nervous system injury, as well as a source of trophic molecules to minimize damage and promote recovery. Various stem cells from multiple sources can generate neural cells that survive and form synaptic connections after transplantation in the stroke-injured brain. Stem cells also exhibit neurorevitalizing properties that may ameliorate neurological deficits through stimulation of neurogenesis, angiogenesis and inhibition of inflammation.

PERSPECTIVES/CONCLUSION

Performed in stroke, cell therapy would decrease brain damage and reduce functional deficits. After the damage has been done, it would still improve neurological functions by activating endogenous repair. Nevertheless, many questions raised by experimental studies particularly related to long-term safety and technical details of cell preparation and administration must be resolved before wider clinical use.

Cellular programming and reprogramming: sculpting cell fate for the production of dopamine neurons for cell therapy

Pluripotent stem cells are regarded as a promising cell source to obtain human dopamine neurons in sufficient amounts and purity for cell replacement therapy. Importantly, the success of clinical applications depends on our ability to steer pluripotent stem cells towards the right neuronal identity. In Parkinson disease, the loss of dopamine neurons is more pronounced in the ventrolateral population that projects to the sensorimotor striatum. Because synapses are highly specific, only neurons with this precise identity will contribute, upon transplantation, to the synaptic reconstruction of the dorsal striatum. Thus, understanding the developmental cell program of the mesostriatal dopamine neurons is critical for the identification of the extrinsic signals and cell-intrinsic factors that instruct and, ultimately, determine cell identity. Here, we review how extrinsic signals and transcription factors act together during development to shape midbrain cell fates. Further, we discuss how these same factors can be applied in vitro to induce, select, and reprogram cells to the mesostriatal dopamine fate.

Prolonged maturation culture favors a reduction in the tumorigenicity and the dopaminergic function of human ESC-derived neural cells in a primate model of Parkinson's disease

For the safe clinical application of embryonic stem cells (ESCs) for neurological diseases, it is critical to evaluate the tumorigenicity and function of human ESC (hESC)-derived neural cells in primates. We have herein, for the first time, compared the growth and function of hESC-derived cells with different stages of neural differentiation implanted in the brains of primate models of Parkinson's disease. We herein show that residual undifferentiated cells expressing ESC markers present in the cell preparation can induce tumor formation in the monkey brain. In contrast, a cell preparation matured by 42-day culture with brain-derived neurotrophic factor/glial cell line-derived neurotrophic factor (BDNF/GDNF) treatment did not form tumors and survived as primarily dopaminergic (DA) neurons. In addition, the monkeys with such grafts showed behavioral improvement for at least 12 months. These results support the idea that hESCs, if appropriately matured, can serve as a source for DA neurons without forming any tumors in a primate brain.

Recent therapeutic strategies for spinal cord injury treatment: possible role of stem cells

Spinal cord injury (SCI) often results in significant dysfunction and disability. A series of treatments have been proposed to prevent and overcome the formation of the glial scar and inhibitory factors to axon regrowth. In the last decade, cell therapy has emerged as a new tool for several diseases of the nervous system. Stem cells act as minipumps providing trophic and immunomodulatory factors to enhance axonal growth, to modulate the environment, and to reduce neuroinflammation. This capability can be boosted by genetical manipulation to deliver trophic molecules. Different types of stem cells have been tested, according to their properties and the therapeutic aims. They differ from each other for origin, developmental stage, stage of differentiation, and fate lineage. Related to this, stem cells differentiating into neurons could be used for cell replacement, even though the feasibility that stem cells after transplantation in the adult lesioned spinal cord can differentiate into neurons, integrate within neural circuits, and emit axons reaching the muscle is quite remote. The timing of cell therapy has been variable, and may be summarized in the acute and chronic phases of disease, when stem cells interact with a completely different environment. Even though further experimental studies are needed to elucidate the mechanisms of action, the therapeutic, and the side effects of cell therapy, several clinical protocols have been tested or are under trial. Here, we report the state-of-the-art of cell therapy in SCI, in terms of feasibility, outcome, and side effects.

In vitro differentiation of human parthenogenetic stem cells into neural lineages

Human parthenogenetic stem cells are derived from the inner cell mass of blastocysts obtained from unfertilized oocytes that have been stimulated to develop without any participation of male gamete. As parthenogenesis does not involve the destruction of a viable human embryo, the derivation and use of human parthenogenetic stem cells does not raise the same ethical concerns as conventional embryonic stem cells. Human parthenogenetic stem cells are similar to embryonic stem cells in their proliferation and multilineage in vitro differentiation capacity. The aim of this study is to derive multipotent neural stem cells from human parthenogenetic stem cells that are stable to passaging and cryopreservation, and have the ability to further differentiate into functional neurons. Immunocytochemistry, quantitative real-time PCR, or FACS were used to confirm that the derived neural stem cells express neural markers such as NES, SOX2 and MS1. The derived neural stem cells keep uniform morphology for at least 30 passages and can be spontaneously differentiated into cells with neuron morphology that express TUBB3 and MAP2, and fire action potentials. These results suggest that parthenogenetic stem cells are a very promising and potentially unlimited source for the derivation of multipotent neural stem cells that can be used for therapeutic applications.

Evaluation of nano-biphasic calcium phosphate ceramics for bone tissue engineering applications: in vitro and preliminary in vivo studies

Reconstruction of critical sized bone injuries is a major problem that continues to inspire the design of new materials and grafts. Natural ceramics (hydroxyapatite (HA) coralline HA, or synthetic HA) and β-tricalcium phosphate (β-TCP) are being explored for use as scaffolds in bone tissue engineering, among several other materials. The present study evaluated the bone forming capacity of nanosize bioceramics synthesized in situ in poly-vinyl alcohol (PVA) with different ratios of HA and β-TCP; the Ca/P ratio was 1.62 for bioceramic P1, 1.60 for P2 and 1.58 for P3. Further osteogenesis in vitro with mesenchymal stem cells (MSC) acquired from different sources for osteogenesis in vitro and their bone healing properties in vivo were also evaluated. MSC isolated from human placenta, Wharton's jelly from umbilical cord, fetal bone marrow and adipose tissue, cultured in the presence of nanosize bioceramic particles, were monitored for osteogenic differentiation. Placental cells showed the best osteogenic potential of the different MSC studied on the basis of expression of osteogenic markers. Complete regeneration of the damaged region was observed in vivo when MSC derived from placenta were used with nanoceramic (Ca/P ratio 1.58) in the experimental defect created in the femur of Wistar rats. Even small variation in the Ca/P ratio can alter the outcome of tissue constructs.

Ceramide and sphingosine-1-phosphate signaling in embryonic stem cell differentiation

Recent studies show that bioactive lipids are important regulators for stem cell survival and differentiation. The sphingolipid ceramide and its derivative, sphingosine-1-phosphate (S1P), can act synergistically on embryonic stem (ES) cell differentiation. We show here simple methods to analyze sphingolipids in differentiating ES cells and to use ceramide and S1P analogs for the guided differentiation of mouse ES cells toward neuronal and glial lineage.

Derivation of dopaminergic neurons from pluripotent stem cells

Midbrain dopamine neurons play a critical role in motor function and in reward-related motivational behaviors. The goal of developing a renewable source of human midbrain dopamine neurons was prompted by the pioneering studies on the use of human fetal dopamine neurons as an experimental therapy for the treatment of Parkinson's disease. More recently, dopamine neurons have also turned into an important tool for modeling of Parkinson's disease in patient-specific induced pluripotent stem cell lines. Protocols for the directed differentiation of mouse ESCs into midbrain dopamine neurons have been developed more than a decade ago and the successful derivation of human midbrain dopamine neurons was reported soon after. However, the initial human ESC reports were unable to demonstrate efficient in vivo dopamine neuron engraftment. Only very recently, those challenges have been overcome by using an alternative differentiation strategy that is based on deriving midbrain dopamine neurons via a distinct midbrain floor plate intermediate. With those novel tools in hand, it should now become possible to test the full potential of midbrain dopamine neurons in regenerative medicine and human disease modeling. However, several challenges remain such as the need to develop strategies that can enrich for selective subtypes of midbrain dopamine neurons, techniques to control postmitotic dopamine neuron maturation, and finally, clinical grade differentiation protocols that enable the production dopamine neurons suitable for human cell therapy.

Subretinal transplantation of putative retinal pigment epithelial cells derived from human embryonic stem cells in rat retinal degeneration model

OBJECTIVE

To differentiate the human embryonic stem cells (hESCs) into the retinal pigment epithelium (RPE) in the defined culture condition and determine its therapeutic potential for the treatment of retinal degenerative diseases.

METHODS

The embryoid bodies were formed from hESCs and attached on the matrigel coated culture dishes. The neural structures consisting neural precursors were selected and expanded to form rosette structures. The mechanically isolated neural rosettes were differentiated into pigmented cells in the media comprised of N2 and B27. Expression profiles of markers related to RPE development were analyzed by reverse transcription-polymerase chain reaction and immunostaining. Dissociated putative RPE cells (10(5) cells/5 µL) were transplanted into the subretinal space of rat retinal degeneration model induced by intravenous sodium iodate injection. Animals were sacrificed at 1, 2, and 4 weeks after transplantation, and immnohistochemistry study was performed to verify the survival of the transplanted cells.

RESULTS

The putative RPE cells derived from hESC showed characteristics of the human RPE cells morphologically and expressed molecular markers and associated with RPE fate. Grafted RPE cells were found to survive in the subretinal space up to 4 weeks after transplantation, and the expression of RPE markers was confirmed with immunohistochemistry.

CONCLUSION

Transplanted RPE cells derived from hESC in the defined culture condition successfully survived and migrated within subretinal space of rat retinal degeneration model. These results support the feasibility of the hESC derived RPE cells for cell-based therapies for retinal degenerative disease.

Cellular therapy and induced neuronal replacement for Huntington's disease

Huntington's disease (HD) is an inherited, relentlessly progressive neurodegenerative disease with an invariably fatal outcome. HD is inherited in an autosomal dominant fashion, and is characterized pathologically by the loss of cortical and striatal neurons, and clinically by involuntary choreiform movements accompanied by progressive cognitive impairment and emotional lability. The disorder is caused by an expanded cystosine adenine guanine (CAG) tri-nucleotide repeat encoding polyglutamine (polyQ) in the first exon of the Huntingtin gene. There is a correlation between the number of CAG repeats and disease onset, such that in patients with CAG repeat lengths of 36 to 60, disease symptoms typically manifest after 35 years of age, whereas CAG repeat lengths >60 yield the more severe juvenile form of the disease. Even though mutant huntingtin is expressed throughout the brain, it is characterized by the selective degeneration of medium spiny neurons of the caudate and putamen, which heralds more widespread neuronal degeneration with disease progression. The mechanisms of cell dysfunction and death in HD have been the subjects of a number of studies, which have led to therapeutic strategies largely based on the amelioration of mutant huntingtin-related metabolic impairment and cellular toxicity. Each of these approaches has aimed to delay or stop the preferential degeneration of medium spiny neurons early in the disease course. Yet, in later stages of the disease, after cell death has become prominent, cell replacement therapy (whether by direct cell transplantation or by the mobilization of endogenous progenitors) may comprise a stronger potential avenue for therapy. In this review, we will consider recent progress in the transplantation of fetal striatal cells to the HD brain, as well as emerging alternative sources for human striatal progenitor cells. We will then consider the potential application of gene therapy toward the induction of striatal neurogenesis and neuronal recruitment, with an eye toward its potential therapeutic use in HD.

Downregulation of H19 improves the differentiation potential of mouse parthenogenetic embryonic stem cells

Parthenogenetic embryonic stem cells (P-ESCs) offer an alternative source of pluripotent cells, which hold great promise for autologous transplantation and regenerative medicine. P-ESCs have been successfully derived from blastocysts of several mammalian species. However, compared with biparental embryonic stem cells (B-ESCs), P-ESCs are limited in their ability to fully differentiate into all 3 germ layers. For example, it has been observed that there is a differentiation bias toward ectoderm derivatives at the expense of endoderm and mesoderm derivatives-muscle in particular-in chimeric embryos, teratomas, and embryoid bodies. In the present study we found that H19 expression was highly upregulated in P-ESCs with more than 6-fold overexpression compared with B-ESCs. Thus, we hypothesized that manipulation of the H19 gene in P-ESCs would alleviate their limitations and allow them to function like B-ESCs. To test this hypothesis we employed a small hairpin RNA approach to reduce the amount of H19 transcripts in mouse P-ESCs. We found that downregulation of H19 led to an increase of mesoderm-derived muscle and endoderm in P-ESCs teratomas similar to that observed in B-ESCs teratomas. This phenomenon coincided with upregulation of mesoderm-specific genes such as Myf5, Myf6, and MyoD. Moreover, H19 downregulated P-ESCs differentiated into a higher percentage of beating cardiomyocytes compared with control P-ESCs. Collectively, these results suggest that P-ESCs are amenable to molecular modifications that bring them functionally closer to true ESCs.

Cell transplantation and gene therapy in Parkinson's disease

Parkinson's disease is a progressive neurodegenerative disorder affecting, in part, dopaminergic motor neurons of the ventral midbrain and their terminal projections that course to the striatum. Symptomatic strategies focused on dopamine replacement have proven effective at remediating some motor symptoms during the course of disease but ultimately fail to deliver long-term disease modification and lose effectiveness due to the emergence of side effects. Several strategies have been experimentally tested as alternatives for Parkinson's disease, including direct cell replacement and gene transfer through viral vectors. Cellular transplantation of dopamine-secreting cells was hypothesized as a substitute for pharmacotherapy to directly provide dopamine, whereas gene therapy has primarily focused on restoration of dopamine synthesis or neuroprotection and restoration of spared host dopaminergic circuitry through trophic factors as a means to enhance sustained controlled dopamine transmission. This seems now to have been verified in numerous studies in rodents and nonhuman primates, which have shown that grafts of fetal dopamine neurons or gene transfer through viral vector delivery can lead to improvements in biochemical and behavioral indices of dopamine deficiency. However, in clinical studies, the improvements in parkinsonism have been rather modest and variable and have been plagued by graft-induced dyskinesias. New developments in stem-cell transplantation and induced patient-derived cells have opened the doors for the advancement of cell-based therapeutics. In addition, viral-vector-derived therapies have been developed preclinically with excellent safety and efficacy profiles, showing promise in clinical trials thus far. Further progress and optimization of these therapies will be necessary to ensure safety and efficacy before widespread clinical use is deemed appropriate.

Tracking stem cell differentiation in the setting of automated optogenetic stimulation

Membrane depolarization has been shown to play an important role in the neural differentiation of stem cells and in the survival and function of mature neurons. Here, we introduce a microbial opsin into ESCs and develop optogenetic technology for stem cell engineering applications, with an automated system for noninvasive modulation of ESC differentiation employing fast optogenetic control of ion flux. Mouse ESCs were stably transduced with channelrhodopsin-2 (ChR2)-yellow fluorescent protein and purified by fluorescence activated cell sorting (FACS). Illumination of resulting ChR2-ESCs with pulses of blue light triggered inward currents. These labeled ESCs retained the capability to differentiate into functional mature neurons, assessed by the presence of voltage-gated sodium currents, action potentials, fast excitatory synaptic transmission, and expression of mature neuronal proteins and neuronal morphology. We designed and tested an apparatus for optically stimulating ChR2-ESCs during chronic neuronal differentiation, with high-speed optical switching on a custom robotic stage with environmental chamber for automated stimulation and imaging over days, with tracking for increased expression of neural and neuronal markers. These data point to potential uses of ChR2 technology for chronic and temporally precise noninvasive optical control of ESCs both in vitro and in vivo, ranging from noninvasive control of stem cell differentiation to causal assessment of the specific contribution of transplanted cells to tissue and network function.

Embryonic stem cells in non-human primates: An overview of neural differentiation potential

Non-human primate (NHP) embryonic stem (ES) cells show unlimited proliferative capacities and a great potential to generate multiple cell lineages. These properties make them an ideal resource both for investigating early developmental processes and for assessing their therapeutic potential in numerous models of degenerative diseases. They share the same markers and the same properties with human ES cells, and thus provide an invaluable transitional model that can be used to address the safety issues related to the clinical use of human ES cells. Here, we review the available information on the derivation and the specific features of monkey ES cells. We comment on the capacity of primate ES cells to differentiate into neural lineages and the current protocols to generate self-renewing neural stem cells. We also highlight the signalling pathways involved in the maintenance of these neural cell types. Finally, we discuss the potential of monkey ES cells for neuronal differentiation.

Stem cells from human-exfoliated deciduous teeth can differentiate into dopaminergic neuron-like cells

Stem cells from human exfoliated deciduous teeth (SHED) have been identified as a novel population of postnatal stem cells capable of differentiating into neural cells, odontogenic cells, and adipocytes. SHED were reported to differentiate into neural cells based on cellular morphology and the expression of early neuronal markers when cultured under neural inductive conditions. This study therefore investigated the therapeutic efficacy of SHED in alleviating Parkinson's disease (PD) in a rat model. We found that SHED could be induced to form neural-like spheres in a medium optimized for neural stem cells in vitro. After incubation with a cocktail of cytokines including sonic hedgehog, fibroblast growth factor 8, glial cell line-derived neurotrophic factor, and forskolin, these SHED-derived spheres further differentiated into a cell population that contained specific dopaminergic neurons. Moreover, transplantation of SHED spheres into the striatum of parkinsonian rats partially improved the apomorphine-evoked rotation of behavorial disorders compared to transplantation of control SHED. Our data indicate that SHED, potentially derived from neural crest cells, may be an optimal source of postnatal stem cells for PD treatment.

Germline competency of parthenogenetic embryonic stem cells from immature oocytes of adult mouse ovary

Parthenogenetic embryonic stem cells (pESCs) have been generated in several mammalian species from parthenogenetic embryos that would otherwise die around mid-gestation. However, previous reports suggest that pESCs derived from in vivo ovulated (IVO) mature oocytes show limited pluripotency, as evidenced by low chimera production, high tissue preference and especially deficiency in germline competence, a critical test for genetic integrity and pluripotency of ESCs. Here, we report efficient generation of germline-competent pESC lines (named as IVM pESCs) from parthenogenetic embryos developed from immature oocytes of adult mouse ovaries following in vitro maturation (IVM) and artificial activation. In contrast, pESCs derived from IVO oocytes show defective germline competence, consistent with previous reports. Further, IVM pESCs resemble more ESCs from fertilized embryos (fESCs) than do IVO pESCs on genome-wide DNA methylation and global protein profiles. In addition, IVM pESCs express higher levels of Blimp1, Lin28 and Stella, relative to fESCs, and in their embryoid bodies following differentiation. This may indicate differences in differentiation potentially to the germline. The mechanisms for acquisition of pluripotency and germline competency of IVM pESCs from immature oocytes remain to be determined.

There is more to a lipid than just being a fat: sphingolipid-guided differentiation of oligodendroglial lineage from embryonic stem cells

Dr. Robert K. Yu's research showed for the first time that the composition of glycosphingolipids is tightly regulated during embryo development. Studies in our group showed that the glycosphingolipid precursor ceramide is also critical for stem cell differentiation and apoptosis. Our new studies suggest that ceramide and its derivative, sphingosine-1-phosphate (S1P), act synergistically on embryonic stem (ES) cell differentiation. When using neural precursor cells (NPCs) derived from ES cells for transplantation, residual pluripotent stem (rPS) cells pose a significant risk of tumor formation after stem cell transplantation. We show here that rPS cells did not express the S1P receptor S1P1, which left them vulnerable to ceramide or ceramide analog (N-oleoyl serinol or S18)-induced apoptosis. In contrast, ES cell-derived NPCs expressed S1P1 and were protected in the presence of S1P or its pro-drug analog FTY720. Consistent with previous studies, FTY720-treated NPCs differentiated predominantly toward oligodendroglial lineage as tested by the expression of the oligodendrocyte precursor cell (OPC) markers Olig2 and O4. As the consequence, a combined administration of S18 and FTY720 to differentiating ES cells eliminated rPS cells and promoted oligodendroglial differentiation. In addition, we show that this combination promoted differentiation of ES cell-derived NPCs toward oligodendroglial lineage in vivo after transplantation into mouse brain.

Stem cells and cell replacement therapy for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder caused by a progressive degeneration of the midbrain dopamine (DA) neurons in the substantia nigra pars compacta (SNc) that predominantly affects the ventral population projecting to the dorsal striatum and leads to a gradual dysfunction of the motor system. There is currently no cure for PD. Pharmacological and surgical (e.g. deep brain stimulation) interventions can alleviate some of the symptoms, but lose their efficacy over time. The distinct loss of DA neurons in the SN offers the opportunity to assay neuronal cell replacement, and the clinical transplantation of fetal midbrain neuroblasts in PD patients has shown that this approach is feasible. However, there are multiple problems associated with the use of fetus-derived material, including limited availability. DA neurons derived from stem cells (SC) represent an alternative and unlimited cell source for cell replacement therapies. Currently, human pluripotent SC, such as embryonic (ES), and most recently, induced pluripotent stem cells (iPS), and multipotent (tissue-specific) adult SC are available, although the methodology for a reliable and efficient production of DA neurons necessary for biomedical applications is still underdeveloped. Here, we discuss some essentials for SC and SC-derived DA neurons to become therapeutic agents.

Generation of pluripotent stem cells from eggs of aging mice

Oocytes can reprogram genomes to form embryonic stem (ES) cells. Although ES cells largely escape senescence, oocytes themselves do senesce in the ovaries of most mammals. It remains to be determined whether ES cells can be established using eggs from old females, which exhibit reproductive senescence. We attempted to produce pluripotent stem cell lines from artificial activation of eggs (also called pES) from reproductive aged mice, to determine whether maternal aging affects pES cell production and pluripotency. We show that pES cell lines were generated with high efficiency from reproductive aged (old) mice, although parthenogenetic embryos from these mice produced fewer ES clones by initial two passages. Further, pES cell lines generated from old mice showed telomere length, expression of pluripotency molecular markers (Oct4, Nanog, SSEA1), alkaline phosphatase activity, teratoma formation and chimera production similar to young mice. Notably, DNA damage was reduced in pES cells from old mice compared to their progenitor parthenogenetic blastocysts, and did not differ from that of pES cells from young mice. Also, global gene expression differed only minimally between pES cells from young and old mice, in contrast to marked differences in gene expression in eggs from young and old mice. These data demonstrate that eggs from old mice can generate pluripotent stem cells, and suggest that the isolation and in vitro culture of ES cells must select cells with high levels of DNA and telomere integrity, and/or with capacity to repair DNA and telomeres.

Characterization of a novel embryonic stem cell line from an ICSI-derived blastocyst in the African green monkey

Several cell types from the African green monkey (Cercopithecus aethiops), such as red blood cells, primary culture cells from kidney, and the Vero cell line, are valuable sources for biomedical research and testing. Embryonic stem (ES) cells that are established from blastocysts have pluripotency to differentiate into these and other types of cells. We examined an in vitro culture system of zygotes produced by ICSI in African green monkeys and attempted to establish ES cells. Culturing with and without a mouse embryonic fibroblast (MEF) cell monolayer resulted in the development of ICSI-derived zygotes to the blastocyst stage, while culturing with a buffalo rat liver cell monolayer yielded no development (3/14, 21.4% and 6/31, 19.4% vs 0/23, 0% respectively; P<0.05). One of the nine blastocysts, which had been one of the zygotes co-cultured with MEF cells, formed flat colonies consisting of cells with large nuclei, similar to other primate ES cell lines. The African green monkey ES (AgMES) cells expressed pluripotency markers, formed teratomas consisting of three embryonic germ layer tissues, and had a normal chromosome number. Furthermore, expression of the germ cell markers CD9 and DPPA3 (STELLA) was detected in the embryoid bodies, suggesting that AgMES cells might have the potential ability to differentiate into germ cells. The results suggested that MEF cells greatly affected the quality of the inner cell mass of the blastocysts. In addition, AgMES cells would be a precious resource for biomedical research such as other primate ES cell lines.

Effects of developmental age, brain region, and time in culture on long-term proliferation and multipotency of neural stem cell populations

Neural stem cells (NSCs) in the murine subventricular zone (SVZ) niche allow life-long neurogenesis. During the first postnatal month and throughout aging, the decrease of neuroblasts and the rise of astrocytes results in diminished neurogenesis and increased astrocyte:neuron ratio. Also, a different neurogenic activity characterizes the SVZ periventricular region (LV, lateral ventricle) as compared to its rostral extension (RE). In order to investigate whether and to what extent these physiological modifications may be ascribed to intrinsic changes of the endogenous NSC/progenitor features, we performed a functional analysis on NSCs isolated and cultured from LV and RE tissues at distinct postnatal stages that are marked by striking modifications to the SVZ niche in vivo. We evaluated the effect of age and brain region on long-term proliferation and multipotency, and characterized the cell type composition of NSC-derived progeny, comparing this make-up to that of region- and age-matched primary neural cultures. Furthermore, we analyzed the effect of prolonged in vitro expansion on NSC functional properties. We documented age- and region-dependent differences on the clonogenic efficiency and on the long-term proliferative capacity of NSCs. Also, we found age- and region-dependent quantitative changes in the cell composition of NSC progeny (decreased quantity of neurons and oligodendrocytes; increased amount of astroglial cells) and these differences were maintained in long-term cultured NSC populations. Overall, these data strengthen the hypothesis that age- and region-dependent differences in neurogenesis (observed in vivo) may be ascribed to the changes in the intrinsic developmental program of the NSC populations.