Evaluation of progenitor cell cultures from human embryos for neurotransplantation

BMPRII+ neural precursor cells isolated and characterized from organotypic neurospheres: an in vitro model of human fetal spinal cord development

Roof plate secretion of bone morphogenetic proteins (BMPs) directs the cellular fate of sensory neurons during spinal cord development, including the formation of the ascending sensory columns, though their biology is not well understood. Type-II BMP receptor (BMPRII), the cognate receptor, is expressed by neural precursor cells during embryogenesis; however, an in vitro method of enriching BMPRII+ human neural precursor cells (hNPCs) from the fetal spinal cord is absent. Immunofluorescence was undertaken on intact second-trimester human fetal spinal cord using antibodies to BMPRII and leukemia inhibitory factor (LIF). Regions of highest BMPRII+ immunofluorescence localized to sensory columns. Parenchymal and meningeal-associated BMPRII+ vascular cells were identified in both intact fetal spinal cord and cortex by co-positivity with vascular lineage markers, CD34/CD39. LIF immunostaining identified a population of somas concentrated in dorsal and ventral horn interneurons, mirroring the expression of LIF receptor/CD118. A combination of LIF supplementation and high-density culture maintained culture growth beyond 10 passages, while synergistically increasing the proportion of neurospheres with a stratified, cytoarchitecture. These neurospheres were characterized by BMPRII+/MAP2ab+/-/βIII-tubulin+/nestin-/vimentin-/GFAP-/NeuN- surface hNPCs surrounding a heterogeneous core of βIII-tubulin+/nestin+/vimentin+/GFAP+/MAP2ab-/NeuN- multipotent precursors. Dissociated cultures from tripotential neurospheres contained neuronal (βIII-tubulin+), astrocytic (GFAP+), and oligodendrocytic (O4+) lineage cells. Fluorescence-activated cell sorting-sorted BMPRII+ hNPCs were MAP2ab+/-/βIII-tubulin+/GFAP-/O4- in culture. This is the first isolation of BMPRII+ hNPCs identified and characterized in human fetal spinal cords. Our data show that LIF combines synergistically with high-density reaggregate cultures to support the organotypic reorganization of neurospheres, characterized by surface BMPRII+ hNPCs. Our study has provided a new methodology for an in vitro model capable of amplifying human fetal spinal cord cell numbers for > 10 passages. Investigations of the role BMPRII plays in spinal cord development have primarily relied upon mouse and rat models, with interpolations to human development being derived through inference. Because of significant species differences between murine biology and human, including anatomical dissimilarities in central nervous system (CNS) structure, the findings made in murine models cannot be presumed to apply to human spinal cord development. For these reasons, our human in vitro model offers a novel tool to better understand neurodevelopmental pathways, including BMP signaling, as well as spinal cord injury research and testing drug therapies.

The Effect of Heat Shock on Myogenic Differentiation of Human Skeletal-Muscle-Derived Mesenchymal Stem/Stromal Cells

Muscle injuries, degenerative diseases and other lesions negatively affect functioning of human skeletomuscular system and thus quality of life. Therefore, the investigation of molecular mechanisms, stimulating myogenic differentiation of primary skeletal-muscle-derived mesenchymal stem/stromal cells (SM-MSCs), is actual and needed. The aim of the present study was to investigate the myogenic differentiation of CD56 (neural cell adhesion molecule, NCAM)-positive and -negative SM-MSCs and their response to the non-cytotoxic heat stimulus. The SM-MSCs were isolated from the post operation muscle tissue, sorted by flow cytometer according to the CD56 biomarker and morphology, surface profile, proliferation and myogenic differentiation has been investigated. Data show that CD56(+) cells were smaller in size, better proliferated and had significantly higher levels of CD146 (MCAM) and CD318 (CDCP1) compared with the CD56(-) cells. At control level, CD56(+) cells significantly more expressed myogenic differentiation markers MYOD1 and myogenin (MYOG) and better differentiated to the myogenic direction. The non-cytotoxic heat stimulus significantly stronger stimulated expression of myogenic markers in CD56(+) than in CD56(-) cells that correlated with the multinucleated cell formation. Data show that regenerative properties of CD56(+) SM-MSCs can be stimulated by an extracellular stimulus and be used as a promising skeletal muscle regenerating tool in vivo.

Effect of Transplantation of Neural Stem and Progenitor Cells on Memory in Animals with Alzheimer's Type Neurodegeneration

The effects of systemic and intracerebral transplantation of human fetal neural stem and progenitor cells were studied on the model of olfactory bulbectomy in mice with developing signs of sporadic Alzheimer's disease. It was found that transplantation of these cells at certain stages of disease development contributed to improvement of spatial memory and preservation of hippocampal neurons in these animals.

Analysis of Neural Stem Cells from Human Cortical Brain Structures In Vitro

Comparative immunohistochemical analysis of the neocortex from human fetuses showed that neural stem and progenitor cells are present in the brain throughout the gestation period, at least from week 8 through 26. At the same time, neural stem cells from the first and second trimester fetuses differed by the distribution, morphology, growth, and quantity. Immunocytochemical analysis of neural stem cells derived from fetuses at different gestation terms and cultured under different conditions showed their differentiation capacity. Detailed analysis of neural stem cell populations derived from fetuses on gestation weeks 8-9, 18-20, and 26 expressing Lex/SSEA1 was performed.

Antitumorigenic effect of interferon-β by inhibition of undifferentiated glioblastoma cells

Glioma stem-like cells (GSCs) are undifferentiated cells that are considered to be an origin of glioblastomas. Furthermore, they may contribute to treatment resistance and recurrence in glioblastomas. GSCs differentiate into differentiated glioma cells (non-glioma stem-like cells: non-GSCs), and interconversion might occur between GSCs and non-GSCs. We investigated whether interferon-beta (IFN-β) could exert any efficacy towards GSCs or such interconversion processes. The neural stem cell marker CD133 and pluripotency marker Nanog in GSCs were analyzed to evaluate their differentiation levels. GSCs were considered to undergo differentiation into non-GSCs upon serum exposure, since the expression of CD133 and Nanog in the GSCs was negatively affected. Furthermore, the cells regained their undifferentiated features upon removal of the serum. However, we verified that IFN-β reduced cell proliferation and tumor sphere formation in GSCs, and induced suppression of the restoration of such undifferentiated features. In addition, we also confirmed that IFN-β suppressed the acquisition process of undifferentiated features in human malignant glioma cell lines. Our data thus suggest that IFN-β could be an effective agent not only through its cell growth inhibitory effect on GSCs but also as a means of targeting the interconversion between GSCs and non-GSCs, indicating the possibility of IFN-β being used to prevent treatment resistance and recurrence in glioblastomas, via the inhibition of undifferentiated features.

Combined Transplantation of Human Neuronal and Mesenchymal Stem Cells following Spinal Cord Injury

Transplantation of human fetal neural stem cells (hNSCs) previously demonstrated significant functional recovery after spinal cord contusion in rats. Other studies indicated that human mesenchymal stem cells (hMSCs) can home to areas of damage and cross the blood-brain barrier. The purpose of this article is to determine if combined administration of mesenchymal stem cells and neuronal stem cells improves functional outcomes in rats. The study design was a randomized controlled animal trial. Female adult Long-Evans hooded rats underwent laminectomy at T10 level. Moderate spinal cord contusion at T10 level was induced by the MASCIS Impactor. Four groups were identified. The MSC + NSC group received hMSCs intravenously (IV) immediately after spinal cord injury (acute) and returned 1 week later (subacute) for injection of hNSC directly at site of injury. The MSC-only group received hMSC IV acutely and cell media subacutely. The NSC-only group received cell media IV acutely and hNSC subacutely. The control group received cell media IV acutely and subacutely. Subjects were assessed for 6 weeks using Basso, Beattie, Bresnahan Locomotor Rating Score. Twenty-four subjects were utilized, six subjects in each group. Statistically significant functional improvement was seen in the MSC + NSC group and the NSC-only group versus controls (p = 0.027, 0.042, respectively). The MSC-only group did not demonstrate a significant improvement over control (p = 0.145). Comparing the MSC + NSC group and the NSC-only group, there was no significant difference (p = 0.357). Subacute transplantation of hNSCs into contused spinal cord of rats led to significant functional recovery when injected either with or without acute IV administration of hMSCs. Neither hMSCs nor addition of hMSC to hNSC resulted in significant improvement.

Long-term expansion of human foetal neural progenitors leads to reduced graft viability in the neonatal rat brain

We previously reported that early passage human foetal neural progenitors (hFNPs) survive long-term in the rodent host brain whereas late passage cells disappear at later post-graft survival times. The extent to which this finding is related to changes in the expanded FNPs or in the adult host brain environment was not determined. Here we report the effect of expanding hFNPs for different periods of time in vitro on their ability to survive transplantation into the neonatal rat hippocampus, a generally more permissive environment than the adult rat brain. After 2 and 8 weeks in vitro, transplanted hFNPs formed large grafts, most of which survived well until at least 12 weeks. However, following continued expansion, hFNPs formed smaller grafts, and cells transplanted after 20 weeks expansion produced no surviving grafts, even at early survival times. To determine whether this could be due to a dilution of "true" neural stem cells through more differentiated progeny over time in culture, we derived homogeneous neural stem (NS) cells grown as a monolayer from the 8 week expanded hFNPs. These cells homogeneously expressed the neural stem cell markers sox-2, 3CB2 and nestin and were expanded for 5 months before transplantation into the neonatal rat brain. However, these cells exhibited a similar survival profile to the long-term expanded FNPs. These results indicate that, while the cellular phenotype of neural stem cells may appear to be stable in vitro using standard markers, expansion profoundly influences the ability of such cells to form viable grafts.

TGF-beta increases glioma-initiating cell self-renewal through the induction of LIF in human glioblastoma

Glioma-initiating cells (GICs) are responsible for the initiation and recurrence of gliomas. Here, we identify a molecular mechanism that regulates the self-renewal capacity of patient-derived GICs. We show that TGF-beta and LIF induce the self-renewal capacity and prevent the differentiation of GICs. TGF-beta induces the self-renewal capacity of GICs, but not of normal human neuroprogenitors, through the Smad-dependent induction of LIF and the subsequent activation of the JAK-STAT pathway. The effect of TGF-beta and LIF on GICs promotes oncogenesis in vivo. Some human gliomas express high levels of LIF that correlate with high expression of TGF-beta2 and neuroprogenitor cell markers. Our results show that TGF-beta and LIF have an essential role in the regulation of GICs in human glioblastoma.

Donor-derived brain tumor following neural stem cell transplantation in an ataxia telangiectasia patient

BACKGROUND

Neural stem cells are currently being investigated as potential therapies for neurodegenerative diseases, stroke, and trauma. However, concerns have been raised over the safety of this experimental therapeutic approach, including, for example, whether there is the potential for tumors to develop from transplanted stem cells.

METHODS AND FINDINGS

A boy with ataxia telangiectasia (AT) was treated with intracerebellar and intrathecal injection of human fetal neural stem cells. Four years after the first treatment he was diagnosed with a multifocal brain tumor. The biopsied tumor was diagnosed as a glioneuronal neoplasm. We compared the tumor cells and the patient's peripheral blood cells by fluorescent in situ hybridization using X and Y chromosome probes, by PCR for the amelogenin gene X- and Y-specific alleles, by MassArray for the ATM patient specific mutation and for several SNPs, by PCR for polymorphic microsatellites, and by human leukocyte antigen (HLA) typing. Molecular and cytogenetic studies showed that the tumor was of nonhost origin suggesting it was derived from the transplanted neural stem cells. Microsatellite and HLA analysis demonstrated that the tumor is derived from at least two donors.

CONCLUSIONS

This is the first report of a human brain tumor complicating neural stem cell therapy. The findings here suggest that neuronal stem/progenitor cells may be involved in gliomagenesis and provide the first example of a donor-derived brain tumor. Further work is urgently needed to assess the safety of these therapies.

Human neural stem cells and astrocytes, but not neurons, suppress an allogeneic lymphocyte response

Transplantation of human neural stem cells (NSCs) and their derivatives is a promising future treatment for neurodegenerative disease and traumatic nervous system lesions. An important issue is what kind of immunological reaction the cellular transplant and host interaction will result in. Previously, we reported that human NSCs, despite expressing MHC class I and class II molecules, do not trigger an allogeneic T cell response. Here, the immunocompetence of human NSCs, as well as differentiated neural cells, was further studied. Astrocytes expressed both MHC class I and class II molecules to a degree equivalent to that of the NSCs, whereas neurons expressed only MHC class I molecules. Neither the NSCs nor the differentiated cells triggered an allogeneic lymphocyte response. Instead, these potential donor NSCs and astrocytes, but not the neurons, exhibited a suppressive effect on an allogeneic immune response. The suppressive effect mediated by NSCs most likely involves cell-cell interaction. When the immunogenicity of human NSCs was tested in an acute spinal cord injury model in rodent, a xenogeneic rejection response was triggered. Thus, human NSCs and their derived astrocytes do not initiate, but instead suppress, an allogeneic response, while they cannot block a graft rejection in a xenogeneic setting.

Neural stem cells in the mammalian brain

New fundamental results on stem cell biology have been obtained in the past 15 years. These results allow us to reinterpret the functioning of the cerebral tissue in health and disease. Proliferating stem cells have been found in the adult brain, which can be involved in postinjury repair and can replace dead cells under specific conditions. Numerous genomic mechanisms controlling stem cell proliferation and differentiation have been identified. The involvement of stem cells in the genesis of malignant tumors has been demonstrated. Neural stem cell tropism toward tumors has been shown. These findings suggest new lines of research on brain functioning and development. Stem cells can be used to develop radically new treatments of neurodegenerative and cancer diseases of the brain.

Therapeutic potentials of human embryonic stem cells in Parkinson's disease

The loss of dopaminergic neurons of the substantia nigra is the pathological hallmark characteristic of Parkinson's disease (PD). The strategy of replacing these degenerating neurons with other cells that produce dopamine has been the main approach in the cell transplantation field for PD research. The isolation, differentiation, and long-term cultivation of human embryonic stem cells and the therapeutic research discovery made in relation to the beneficial properties of neurotrophic and neural growth factors has advanced the transplantation field beyond dopamine-producing cells. The present review addresses recent advances in human embryonic stem cell experimentation in relation to treating PD, as well as cell transplantation techniques in conjunction with alternative therapeutics.

Allorecognition of human neural stem cells by peripheral blood lymphocytes despite low expression of MHC molecules: role of TGF-beta in modulating proliferation

Neural stem cells (NSCs) transplantation has been proposed as a means of restoring damaged brain tissue, a possibility rendered more likely by reports of low NSCs immunogenicity in various experimental models because of low expression of MHC class I and II as well as co-stimulatory molecules. We investigated the immunogenicity of a human NSC line grown in normal culture conditions and in the presence of pro-inflammatory cytokines IFN-gamma and tumor necrosis factor alpha by one-way mixed lymphocyte reaction (MLR) experiments with peripheral blood lymphocytes from eight HLA-incompatible donors. NSCs stimulated lymphocyte proliferation in almost all donors tested, with stimulation indices in the range of the low-end distribution curve of MLR between donors. The healthy subject that gave negative MLR results was the best compatible donor with respect to NSC haplotype. Since we observed low MLR responses overall, we studied if NSCs might exert any immunomodulatory activity. We detected transcription and release of the immunomodulatory molecule transforming growth factor beta (TGF-beta)-1; moreover, the addition of TGF-beta1 in MLR experiments down-regulated proliferative responses. To further confirm the immunological potential of human NSCs, we studied xenogeneic recognition of NSCs by immunocompetent cells derived from C57BL/6 mice, showing that NSCs can elicit an allo(xeno) response ex vivo. Our data indicate that NSCs have low but not negligible immunogenic potential that is sufficient to activate peripheral lymphocytes. Secretion of TGF-beta1 might balance the immunogenicity of NSCs. Nevertheless, the possibility that allo-NSCs grafting might induce in the long term an immune activation, thus vanishing their therapeutical effect, should not be overlooked and deserves further investigation.

Structure and cell composition of spheres cultured from human fetal retina

The structure and cell composition of spheres obtained by culturing human fetal retinal cells after 15, 18, 22-23, and 24 weeks of gestation were studied. The cells were cultured as neurospheres: in serum-free medium with growth factors, in which they formed floating spheres. Immunocytochemical analysis showed that cell proliferation in the spheres decreased with increasing fetal age. Stem/progenitor cells, neuroblasts, and photoreceptors were detected in the spheres. Glial cells were detected only in spheres originating from 22- and 24-week fetuses. All spheres, irrespective of age and duration of culturing, consisted of numerous cell rosettes, each histotypically similar to the neuroblastic layer of the developing retina.

Neural stem cells and their role in recovery processes in the nervous system

Published data and our own results on the identification, cultivation, and potential therapeutic utilization of regional stem cells from humans and animals are reviewed. Pluripotent stem cells have been shown to proliferate in the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus of the hippocampal formation in adult human and animal brains. Data on the hierarchical organization of genetic networks in controlling individual development suggest a possible functional role for repeat mini-and microsatellite DNA sequences in stem cell differentiation. Methods of using human bone marrow as a source of stem cells for restoring damaged tissue in the brain are discussed. Heat-shock proteins have been found to block the formation of glial scars after neural transplantation. The viability of stem cells after transplantation can be increased by transfer of genes for neurotrophic growth factors into the genomes of the neurons undergoing transplantation.

Transplantation of human umbilical cord blood cells in the repair of CNS diseases

Cell transplantation therapies have been used to treat certain neurodegenerative diseases such as Parkinson's and Huntington's disease. However, ethical concerns over the use of fetal tissues, and the inherent complexities of standardising the procurement, processing and transplantation methods of this tissue, have prompted the search for a source of cells that have less ethical stigmatisations, are readily available and can be easily standardised. Several sources of human cells that meet these principles have been under investigation. Cells from human umbilical cord blood (HUCB) are one source that is consistent with these principles; therefore, they have become of great interest in the field of cellular repair/replacement for the treatment of CNS diseases and injury. This review will focus on the advantages of HUCB cells as a source for cellular transplantation therapies, recent studies that have examined the potential of these cells in vitro to be directed towards neural phenotypes, and in vivo studies that have investigated the functional recovery of animals in a number of models of CNS injury and disease following administration of HUCB cells.

Human Fetal Neural Stem Cells in Rat Brain: Effects of Preculturing and Transplantation

The fate of human fetal stem/progenitor cells transplanted into rat brain depends on conditions of preculturing (long or short) and state and site of transplantation. Human nestin-positive stem cells cultured according to the short protocol did not migrate into hypoxic and normal brain after transplantation, but actively migrated in damaged spinal cord. After transplantation of long-cultured cells into the brain mainly committed neuroblasts and solitary nestin-positive cells migrated from the site of transplantation into the brain.

Human central nervous system tissue culture: a historical review and examination of recent advances

Tissue culture has been and continues to be widely used in medical research. Since the beginning of central nervous system (CNS) tissue culture nearly 100 years ago, the scientific community has contributed innumerable protocols and materials leading to the current wide variety of culture systems. While nonhuman cultures have traditionally been more widely used, interest in human CNS tissue culture techniques has accelerated since the middle of the last century. This has been fueled largely by the desire to model human physiology and disease in vitro with human cells. We review the history of human CNS tissue culture summarizing advances that have led to the current breadth of options available. The review addresses tissue sources, culture initiation, formats, culture ware, media, supplements and substrates, and maintenance. All of these variables have been influential in the development of culturing options and the optimization of culture survival and propagation.

Transplantation of cultured human neural stem cells in rabbits with experimental laser-induced damage to the retina

Cultured neural stem/progenitor cells from human fetal brain were transplanted into the retrobulbar and suprachoroid space in rabbits with laser-induced damage to the retina. Transplanted cells survived, retained multipotent activity, migrated into the zone of injury, and stimulated reparation and regeneration in the traumatized retina.

MHC expression after human neural stem cell transplantation to brain contused rats

Human neural stem cells survive and improve motor function after transplantation to the contused brain. However, the transplants might be rejected and that depends on the graft immunogenicity, the host immunological status and the immunosuppression strategy. We transplanted human neural stem cells to rats with brain contusion and analyzed the donor and host MHC antigen expression and the effect of a short-term immunosuppression with cyclosporine. In vitro human neural stem cells expressed only MHC-II antigens. This expression was down-regulated 6 weeks after transplantation. The host response was characterized by an increased MHC-II expression which was down-regulated by a longer term of immunosuppression. These findings are novel and necessary in order to understand the immunogenicity of human neural stem cell grafts.

Differentiation of rhesus embryonic stem cells to neural progenitors and neurons

Embryonic stem (ES) cells are pluripotent cells capable of differentiating into cell lineages derived from all primary germ layers including neural cells. In this study we describe an efficient method for differentiating rhesus monkey ES cells to neural lineages and the subsequent isolation of an enriched population of Nestin and Musashi positive neural progenitor (NP) cells. Upon differentiation, these cells exhibit electrophysiological characteristics resembling cultured primary neurons. Embryoid bodies (EBs) were formed in ES growth medium supplemented with 50% MEDII. After 7 days in suspension culture, EBs were transferred to adherent culture and either differentiated in serum containing medium or expanded in serum free medium. Immunocytochemistry on differentiating cells derived from EBs revealed large networks of MAP-2 and NF200 positive neurons. DAPI staining showed that the center of the MEDII-treated EBs was filled with rosettes. NPs isolated from adherent EB cultures expanded in serum free medium were passaged and maintained in an undifferentiated state by culture in serum free N2 with 50% MEDII and bFGF. Differentiating neurons derived from NPs fired action potentials in response to depolarizing current injection and expressed functional ionotropic receptors for the neurotransmitters glutamate and gamma-aminobutyric acid (GABA). NPs derived in this way could serve as models for cellular replacement therapy in primate models of neurodegenerative disease, a source of neural cells for toxicity and drug testing, and as a model of the developing primate nervous system.

Human umbilical cord blood (HUCB) cells for central nervous system repair

Cellular therapy is a compelling and potential treatment for certain neurological and neurodegenerative diseases as well as a viable treatment for acute injury to the spinal cord and brain. The hematopoietic system offers alternative sources for stem cells compared to those of fetal or embryonic origin. Bone marrow stromal and umbilical cord cells have been used in pre-clinical models of brain injury, directed to differentiate into neural phenotypes, and have been related to functional recovery after engraftment in central nervous system (CNS) injury models. This paper reviews the advantages, utilization and progress of human umbilical cord blood (HUCB) cells in the neural cell transplantation and repair field.

D1 dopamine receptor regulation of cell cycle in FGF- and EGF-supported primary cultures of embryonic cerebral cortical precursor cells

In the mammalian fetus, proliferation of the majority of cells destined for the cerebral cortex takes place within the transient proliferative zones of the cerebral wall. Recent investigations have demonstrated that cell of these zones express high levels of D1 dopamine receptors (D1Rs). However, the specific roles of these receptors have not been investigated. The present study tests the hypothesis that D1Rs are capable of regulating the cell cycle of cerebral cortical precursor cells. For this purpose, primary cultures of cells of the proliferative zones from the cerebral wall of 14-day-old mouse fetuses were generated and maintained in the presence of either fibroblast growth factor-2 (FGF2) or epidermal growth factor (EGF). These growth factors were chosen as supporting two distinct populations of precursor cells in the fetal cortical proliferative matrix. The involvement of D1Rs in the regulation of proliferative activity was examined by the addition of a range of concentrations of the D1R-specific agonist, SKF82958, to the culture media. Bromodeoxyuridine incorporation assays demonstrated that exposure to this agonist led to a dose-dependent reduction of DNA synthesis in both FGF2- and EGF-supported cultures. Flow cytometric cell cycle assays further revealed that this was due to prevention of the transition of cells from the G1 phase to the S phase of the cell cycle. The D1R specificity of the effects of SKF82958 was supported in that they were blocked by the addition of the D1R antagonists, SCH23390 or NNC010756. We also found that D1R stimulation induced stronger suppression of proliferative activity in EGF-supported than in FGF2-supported cultures. Our observations suggest that D1Rs are capable of regulating the cell cycle during corticogenesis. Furthermore, they raise a possibility that these receptors may display different efficacies in affecting proliferative activity in FGF2-supported versus EGF-supported cerebral cortical precursor cells.