Human embryonic stem cell differentiation toward regional specific neural precursors

Embryoid Body Cells from Human Embryonic Stem Cells Overexpressing Dopaminergic Transcription Factors Survive and Initiate Neurogenesis via Neural Rosettes in the Substantia Nigra

Transplantation of immature dopaminergic neurons or neural precursors derived from embryonic stem cells (ESCs) into the substantia nigra pars compacta (SNpc) is a potential therapeutic approach for functional restitution of the nigrostriatal pathway in Parkinson's disease (PD). However, further studies are needed to understand the effects of the local microenvironment on the transplanted cells to improve survival and specific differentiation in situ. We have previously reported that the adult SNpc sustains a neurogenic microenvironment. Non-neuralized embryoid body cells (EBCs) from mouse ESCs (mESCs) overexpressing the dopaminergic transcription factor Lmx1a gave rise to many tyrosine hydroxylase (Th⁺) cells in the intact and damaged adult SNpc, although only for a short-term period. Here, we extended our study by transplanting EBCs from genetically engineered naive human ESC (hESC), overexpressing the dopaminergic transcription factors LMX1A, FOXA2, and OTX2 (hESC-LFO), in the SNpc. Unexpectedly, no graft survival was observed in wild-type hESC EBCs transplants, whereas hESC-LFO EBCs showed viability in the SNpc. Interestingly, neural rosettes, a developmental hallmark of neuroepithelial tissue, emerged at 7- and 15-days post-transplantation (dpt) from the hESC-LFO EBCs. Neural rosettes expressed specification dopaminergic markers (Lmx1a, Otx2), which gave rise to several Th⁺ cells at 30 dpt. Our results suggest that the SNpc enables the robust initiation of neural differentiation of transplanted human EBCs prompted to differentiate toward the midbrain dopaminergic phenotype.

Efficient Neural Differentiation of Mouse Embryonic Stem Cells by Mastic Gum

Purpose: Promoting neurogenesis is a promising strategy to treat neurodegenerative disorders. In the present study, we aimed to evaluate the effect of mastic gum resin from the Pistacia lentiscus var. Chia (Anacardiaceae family) in proliferation capacity and differentiation of embryonic mesenchymal stem cells into a neural lineage. Methods: For this purpose, mastic gum was applied as a neural inducer for stem cell differentiation into the neuronal lineage. Following treatment of embryonic stem cells (ESCs) with mastic gum, verification differentiation of the ESCs into the neuronal lineage, gene expression analysis, and immunocytochemistry staining approach were performed. Results: Gene expression analysis demonstrated that mastic gum increased the expression level of neuron markers in the ESCs-derived neuron-like cells. Moreover, our immunocytochemistry staining results of two important neural stem cell markers, including Nestin and microtubule-associated protein-2 (Map2) expression confirmed that mastic gum has the potential to promote neuronal differentiation in ESCs. Conclusion: In summary, the use of mastic gum to stimulate the differentiation of ESCs into a neural lineage can be considered as a good candidate in stem cell therapy.

Clinical Practice of Umbilical Cord Blood Stem Cells in Transplantation and Regenerative Medicine - Prodigious Promise for Imminent Times

The umbilical cord blood is usually disposed of as an unwanted material after parturition; however, today, it is viewed as a regenerative medication so as to create the organ tissues. This cord blood gathered from the umbilical cord is made up of mesenchymal stem cells, hematopoietic stem cells, and multipotent non-hematopoietic stem cells having many therapeutic effects as these stem cells are utilized to treat malignancies, hematological ailments, inborn metabolic problem, and immune deficiencies. Presently, numerous clinical applications for human umbilical cord blood inferred stem cells, as stem cell treatment initiate new research. These cells are showing such a boon to stem cell treatment; it is nevertheless characteristic that the prospect of conservation of umbilical cord blood is gaining impetus. Current research works have demonstrated that about 80 diseases, including cancer, can be treated or relieved utilizing umbilical cord blood stem cells, and every year, many transplants have been effectively done around the world. However, in terms of factors, including patient selection, cell preparation, dosing, and delivery process, the treatment procedure for therapy with minimally manipulated stem cells can be patented. It is also worth thinking about how this patent could affect cord blood banks. Meanwhile, the utilization of cord blood cells is controversial and adult-derived cells may not be as successful, so numerous clinicians have begun working with stem cells that are acquired from umbilical cord blood. This review epitomizes a change in outlook from what has been completed with umbilical cord blood cell research and cord blood banking on the grounds that cord blood cells do not require much in the method of handling for cryopreservation or for transplantation in regenerative medicine.

Adult Human Multipotent Neural Cells Could Be Distinguished from Other Cell Types by Proangiogenic Paracrine Effects via MCP-1 and GRO

Adult human multipotent neural cells (ahMNCs) are unique cells derived from adult human temporal lobes. They show multipotent differentiation potentials into neurons and astrocytes. In addition, they possess proangiogenic capacities. The objective of this study was to characterize ahMNCs in terms of expression of cell type-specific markers, in vitro differentiation potentials, and paracrine factors compared with several other cell types including fetal neural stem cells (fNSCs) to provide detailed molecular and functional features of ahMNCs. Interestingly, the expression of cell type-specific markers of ahMNCs could not be differentiated from those of pericytes, mesenchymal stem cells (MSCs), or fNSCs. In contrast, differentiation potentials of ahMNCs and fNSCs into neural cells were higher than those of other cell types. Compared with MSCs, ahMNCs showed lower differentiation capacities into osteogenic and adipogenic cells. Moreover, ahMNCs uniquely expressed higher levels of MCP-1 and GRO family paracrine factors than fNSCs and MSCs. These high levels of MCP-1 and GRO family mediated in vivo proangiogenic effects of ahMNCs. These results indicate that ahMNCs have their own distinct characteristics that could distinguish ahMNCs from other cell types. Characteristics of ahMNCs could be utilized further in the preclinical and clinical development of ahMNCs for regenerative medicine. They could also be used as experimental references for other cell types including fNSCs.

Transcriptomic changes due to early, chronic intermittent alcohol exposure during forebrain development implicate WNT signaling, cell-type specification, and cortical regionalization as primary determinants of fetal alcohol syndrome

BACKGROUND

Fetal alcohol syndrome (FAS) due to gestational alcohol exposure represents one of the most common causes of nonheritable lifelong disability worldwide. In vitro and in vivo models have successfully recapitulated multiple facets of the disorder, including morphological and behavioral deficits, but far less is understood regarding the molecular and genetic mechanisms underlying FAS.

METHODS

In this study, we utilized an in vitro human pluripotent stem cell-based (hPSC) model of corticogenesis to probe the effects of early, chronic intermittent alcohol exposure on the transcriptome of first trimester-equivalent cortical neurons.

RESULTS

We used RNA sequencing of developing hPSC-derived neurons treated for 50 days with 50 mM ethanol and identified a relatively small number of biological pathways significantly altered by alcohol exposure. These included cell-type specification, axon guidance, synaptic function, and regional patterning, with a notable upregulation of WNT signaling-associated transcripts observed in alcohol-exposed cultures relative to alcohol-naïve controls. Importantly, this effect paralleled a shift in gene expression of transcripts associated with regional patterning, such that caudal forebrain-related transcripts were upregulated at the expense of more anterior ones. Results from H9 embryonic stem cells were largely replicated in an induced pluripotent stem cell line (IMR90-4), indicating that these patterning alterations are not cell line-specific.

CONCLUSIONS

We found that a major effect of chronic intermittent alcohol on the developing cerebral cortex is an overall imbalance in regionalization, with enrichment of gene expression related to the production of posterodorsal progenitors and a diminution of anteroventral progenitors. This finding parallels behavioral and morphological phenotypes observed in animal models of high-dose prenatal alcohol exposure, as well as patients with FAS.

Comprehensive Perspectives on Experimental Models for Parkinson's Disease

Parkinson’s disease (PD) ranks second among the most common neurodegenerative diseases, characterized by progressive and selective loss of dopaminergic neurons. Various cross-species preclinical models, including cellular models and animal models, have been established through the decades to study the etiology and mechanism of the disease from cell lines to nonhuman primates. These models are aimed at developing effective therapeutic strategies for the disease. None of the current models can replicate all major pathological and clinical phenotypes of PD. Selection of the model for PD largely relies on our interest of study. In this review, we systemically summarized experimental PD models, including cellular and animal models used in preclinical studies, to understand the pathogenesis of PD. This review is intended to provide current knowledge about the application of these different PD models, with focus on their strengths and limitations with respect to their contributions to the assessment of the molecular pathobiology of PD and identification of the therapeutic strategies for the disease.

Transplanted embryonic retinal stem cells have the potential to repair the injured retina in mice

Background

Stem cell transplantation has been reported as one of the promising strategies to treat retinal degenerative diseases. But, the application and the role of retina stem cells (RSCs) in the treatment of patients with retinal degenerative diseases have not been fully revealed. This study aimed to investigate the potential role of transplantation of the embryo-derived RSCs into the vitreous cavity in repairing the damaged retina in mice.

Methods

RSCs were isolated from Kunming mice E17 embryonic retina and ciliary body tissues, and labeled with 5-bromo-2’-deoxyuridin (BrdU). Retinal optic nerve crush injury was induced in left eyes in male Kunming mice by ring clamping the optic nerve. The 6th -generation of BrdU-labeled RSCs were transplanted into the damaged retina by the intravitreal injection, and saline injected eyes were used as the control. Hematoxylin and eosin histological staining, and BrdU, Nestin and Pax6 immunostaining were performed. Electroretinogram (ERG) was used for assessing the electrical activity of the retina.

Results

Embryo-derived RSCs were identified by the positive stains of Pax6 and Nestin. BrdU incorporation was detected in the majority of RSCs. The damaged retina showed cellular nuclear disintegration and fragmentation in the retinal tissue which progressed over the periods of clamping time, and decreased amplitudes of a and b waves in ERG. In the damaged retina with RSCs transplantation, the positive staining for BrdU, Pax6 and Nestin were revealed on the retinal surface. Notably, RSCs migrated into the retinal ganglion cell layer and inner nuclear. Transplanted RSCs significantly elevated the amplitudes of a waves in retina injured eyes.

Conclusions

Embryonic RSCs have similar characteristics to neural stem cells. Transplantation of RSCs by intravitreal injection would be able to repair the damaged retina.

The quest of cell surface markers for stem cell therapy

Stem cells and their derivatives are novel pharmaceutics that have the potential for use as tissue replacement therapies. However, the heterogeneous characteristics of stem cell cultures have hindered their biomedical applications. In theory and practice, when cell type-specific or stage-specific cell surface proteins are targeted by unique antibodies, they become highly efficient in detecting and isolating specific cell populations. There is a growing demand to identify reliable and actionable cell surface markers that facilitate purification of particular cell types at specific developmental stages for use in research and clinical applications. The identification of these markers as very important members of plasma membrane proteins, ion channels, transporters, and signaling molecules has directly benefited from proteomics and tools for proteomics-derived data analyses. Here, we review the methodologies that have played a role in the discovery of cell surface markers and introduce cutting edge single cell proteomics as an advanced tool. We also discuss currently available specific cell surface markers for stem cells and their lineages, with emphasis on the nervous system, heart, pancreas, and liver. The remaining gaps that pertain to the discovery of these markers and how single cell proteomics and identification of surface markers associated with the progenitor stages of certain terminally differentiated cells may pave the way for their use in regenerative medicine are also discussed.

The functions of long non-coding RNAs in neural stem cell proliferation and differentiation

The capacities for neural stem cells (NSCs) self-renewal with differentiation are need to be precisely regulated for ensuring brain development and homeostasis. Recently, increasing number of studies have highlighted that long non-coding RNAs (lncRNAs) are associated with NSC fate determination during brain development stages. LncRNAs are a class of non-coding RNAs more than 200 nucleotides without protein-coding potential and function as novel critical regulators in multiple biological processes. However, the correlation between lncRNAs and NSC fate decision still need to be explored in-depth. In this review, we will summarize the roles and molecular mechanisms of lncRNAs focusing on NSCs self-renewal, neurogenesis and gliogenesis over the course of neural development, still more, dysregulation of lncRNAs in all stage of neural development have closely relationship with development disorders or glioma. In brief, lncRNAs may be explored as effective modulators in NSCs related neural development and novel biomarkers for diagnosis and prognosis of neurological disorders in the future.

Short Review: Investigating ARSACS: models for understanding cerebellar degeneration

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an early-onset neurodegenerative disease that includes progressive cerebellar dysfunction. ARSACS is caused by an autosomal recessive loss-of-function mutation in the SACS gene, which encodes for SACSIN. Although animal models are still necessary to investigate the role of SACSIN in the pathology of this disease, more reliable human cellular models need to be generated to better understand the cerebellar pathophysiology of ARSACS. The discovery of human induced pluripotent stem cells (hiPSC) has permitted the derivation of patient-specific cells. These cells have an unlimited self-renewing capacity and the ability to differentiate into different neural cell types, allowing studies of disease mechanism, drug discovery and cell replacement therapies. In this study, we discuss how the hiPSC-derived cerebellar organoid culture offers novel strategies for targeting the pathogenic mutations related to ARSACS. We also highlight the advantages and challenges of this 3D cellular model, as well as the questions that still remain unanswered.

Bone marrow mesenchymal stem cell transplantation in acute brain trauma

Aim: This study was performed to evaluate the effects of intravenously transplanted rat bone-marrow derived mesenchymal stem cells (rBMSCs) in an acute brain trauma model using serial 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in rat models. Animals, methods: Trauma models were made using a controlled cortical impact injury device. The stem cell treatment group was treated with intravenous injections of BMSCs, and models without stem cell therapy comprised the control group. Serial 18F-FDG PET images were obtained 1, 7, 14, 21, and 28 days after trauma. The difference in 18F-FDG uptake between day 1 and each time point after trauma was analyzed with SPM2 (uncorrected p < 0.005). Results: The stem cell treatment group demonstrated significantly higher 18F-FDG uptake in the right parietal region at 14 days after trauma than at 1 day after trauma. An increase in glucose metabolism in the right parietal cortex appeared on days 21 and 28 after trauma in the group without stem cell treatment. The 18F-FDG uptake in the brain was improved over a broader area, including the right parietal and right primary somatosensory cortex, on days 21 and 28 after trauma in the stem cell treatment group compared with the group without stem cell treatment. Conclusion: BMSC therapy in trauma models led to improved glucose metabolism. This result might support the therapeutic effect of stem cells in brain trauma.

Neural Stem Cells Derived from Human-Induced Pluripotent Stem Cells and Their Use in Models of CNS Injury

Induced pluripotent stem (iPS) cells are derived from differentiated cells by different reprogramming techniques, by introducing specific transcription factors responsible for pluripotency. Induced pluripotent stem cells can serve as an excellent source for differentiated neural stem/progenitor cells (NSCs/NPs). Several methods and protocols are utilized to create a robust number of NSCs/NPs without jeopardizing the safety issues required for in vivo applications. A variety of disease-specific iPS cells have been used to study nervous system diseases. In this chapter, we will focus on some of the derivation and differentiation approaches and the application of iPS-NPs in the treatment of spinal cord injury and stroke.

Comparison of Nutech Functional Score with European Stroke Scale for Patients with Cerebrovascular Accident Treated with Human Embryonic Stem Cells: NFS for CVA Patients Treated with hESCs

PURPOSE

Stem cell therapy is a promising modality for treatment of patients with chronic cerebrovascular accident (CVA) in whom treatment other than physiotherapy or occupational therapy does not address the repair or recovery of the lost function. In this study, the author aimed at evaluating CVA patients treated with human embryonic stem cell (hESC) therapy and comparing their study outcomes with globally accepted European Stroke Scale (ESS) to that with novel scoring system, Nutech functional score (NFS), a 21-point positional and directional scoring system for assessing patients with CVA.

MATERIALS AND METHODS

Patients diagnosed with CVA were assessed with NFS and ESS before and after hESC therapy. NFS assessed the patients in the direction of 1-5 (bad to good), where 5 was considered as the highest possible grade (HPG). The findings were obtained for the patients who scored HPG, and had shown improvement by at least one grade.

RESULTS

Overall, 66.7% of patients scored HPG level on the NFS scale and about 62.5% of the patients scored HPG according to the ESS scale. Approximately, 52.2% patients showed an improvement of 100% (by at least one grade) on NFS scale. None of the patients showed 100% improvement in the alteration of the score by at least one grade when scored with ESS.

CONCLUSION

NFS and ESS scores show that a large population of CVA patients was benefitted with hESC therapy. NFS was found to give more convincing results than ESS, and overcomes the shortcomings of ESS.

Highly Efficient Neural Conversion of Human Pluripotent Stem Cells in Adherent and Animal-Free Conditions

Neural differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) can produce a valuable and robust source of human neural cell subtypes, holding great promise for the study of neurogenesis and development, and for treating neurological diseases. However, current hESCs and hiPSCs neural differentiation protocols require either animal factors or embryoid body formation, which decreases efficiency and yield, and strongly limits medical applications. Here we develop a simple, animal-free protocol for neural conversion of both hESCs and hiPSCs in adherent culture conditions. A simple medium formula including insulin induces the direct conversion of >98% of hESCs and hiPSCs into expandable, transplantable, and functional neural progenitors with neural rosette characteristics. Further differentiation of neural progenitors into dopaminergic and spinal motoneurons as well as astrocytes and oligodendrocytes indicates that these neural progenitors retain responsiveness to instructive cues revealing the robust applicability of the protocol in the treatment of different neurodegenerative diseases. The fact that this protocol includes animal-free medium and human extracellular matrix components avoiding embryoid bodies makes this protocol suitable for the use in clinic. Stem Cells Translational Medicine 2017;6:1217-1226.

Glycogen synthase kinase 3 (GSK3)-inhibitor SB216763 promotes the conversion of human umbilical cord mesenchymal stem cells into neural precursors in adherent culture

The ability to generate neural progenitor cells from human umbilical cord mesenchymal stem cells (hUC-MSCs) has provided an option to treat neurodegenerative diseases. To establish a method for this purpose, we characterized the early neural markers of hUC-MSCs-derived cells under different conditions. We found that neither the elimination of signals for alternative fate nor N2 supplement was sufficient to differentiate hUC-MSCs into neural precursor cells, but the GSK3 inhibitor SB216763 could promote an efficient neural commitment of hUC-MSCs. The results indicated that Wnt/β-catenin might play an important role during the early neural differentiation of hUC-MSCs. Here, we report a method for hUC-MSCs to commit efficiently into a neural fate within a short period of time. This protocol provides an efficient method for hUC-MSCs-based neural regeneration.

Molecular Analysis of Stromal Cells-Induced Neural Differentiation of Mouse Embryonic Stem Cells

Deriving specific neural cells from embryonic stem cells (ESCs) is a promising approach for cell replacement therapies of neurodegenerative diseases. When co-cultured with certain stromal cells, mouse ESCs (mESCs) differentiate efficiently to neural cells. In this study, a comprehensive gene and protein expression analysis of differentiating mESCs is performed over a two-week culture period to track temporal progression of cells from a pluripotent state to specific terminally-differentiated neural cells such as neurons, astrocytes, and oligodendrocytes. Expression levels of 26 genes consisting of marker genes for pluripotency, neural progenitors, and specific neuronal, astroglial, and oligodendrocytic cells are tracked using real time q-PCR. The time-course gene expression analysis of differentiating mESCs is combined with the hierarchal clustering and functional principal component analysis (FPCA) to elucidate the evolution of specific neural cells from mESCs at a molecular level. These statistical analyses identify three major gene clusters representing distinct phases of transition of stem cells from a pluripotent state to a terminally-differentiated neuronal or glial state. Temporal protein expression studies using immunohistochemistry demonstrate the generation of neural stem/progenitor cells and specific neural lineages and show a close agreement with the gene expression profiles of selected markers. Importantly, parallel gene and protein expression analysis elucidates long-term stability of certain proteins compared to those with a quick turnover. Describing the molecular regulation of neural cells commitment of mESCs due to stromal signaling will help identify major promoters of differentiation into specific cell types for use in cell replacement therapy applications.

The science and ethics of cell-based therapies for Parkinson's disease

Parkinson's Disease (PD) is an age-related, disabling neurodegenerative disorder. Although sufferers usually respond to dopamine agonists for extended periods, the disease remains progressive and adverse drug effects can compromise effective long term treatment. Cell-based therapies have been the subject of much hype and optimism with regard to PD. Proof of principle was provided in the 1980s with fetal tissue transplantation trials demonstrating successful graft survival. Embryonic stem cells and reprogrammed or transdifferentiated somatic cells may provide alternative sources of tissue with the potential to overcome the material shortages and technical difficulties that have hindered fetal neural transplants. This article will review the state of the science for cell based therapies and examine the ethical issues that societies must negotiate regarding their clinical use.

Human Embryonic Stem Cells: A Model for the Study of Neural Development and Neurological Diseases

Although the mechanism of neurogenesis has been well documented in other organisms, there might be fundamental differences between human and those species referring to species-specific context. Based on principles learned from other systems, it is found that the signaling pathways required for neural induction and specification of human embryonic stem cells (hESCs) recapitulated those in the early embryo development in vivo at certain degree. This underscores the usefulness of hESCs in understanding early human neural development and reinforces the need to integrate the principles of developmental biology and hESC biology for an efficient neural differentiation.

Concise review: reactive astrocytes and stem cells in spinal cord injury: good guys or bad guys?

Spinal cord injury (SCI) usually results in long lasting locomotor and sensory neuron degeneration below the injury. Astrocytes normally play a decisive role in mechanical and metabolic support of neurons, but in the spinal cord they cause injury, exerting well-known detrimental effects that contribute to glial scar formation and inhibition of axon outgrowth. Cell transplantation is considered a promising approach for replacing damaged cells and promoting neuroprotective and neuroregenerative repair, but the effects of the grafted cells on local tissue and the regenerative properties of endogenous neural stem cells in the injured spinal cord are largely unknown. During the last 2 decades cumulative evidence from diverse animal models has indicated that reactive astrocytes in synergy with transplanted cells could be beneficial for injury in multiple ways, including neuroprotection and axonal growth. In this review, we specifically focus on the dual opposing roles of reactive astrocytes in SCI and how they contribute to the creation of a permissive environment when combined with transplanted cells as the influential components for a local regenerative niche. Modulation of reactive astrocyte function might represent an extremely attractive new therapy to enhance the functional outcomes in patients.

Pluripotent stem cells for Schwann cell engineering

Tissue engineering of Schwann cells (SCs) can serve a number of purposes, such as in vitro SC-related disease modeling, treatment of peripheral nerve diseases or peripheral nerve injury, and, potentially, treatment of CNS diseases. SCs can be generated from autologous stem cells in vitro by recapitulating the various stages of in vivo neural crest formation and SC differentiation. In this review, we survey the cellular and molecular mechanisms underlying these in vivo processes. We then focus on the current in vitro strategies for generating SCs from two sources of pluripotent stem cells, namely embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Different methods for SC engineering from ESCs and iPSCs are reviewed and suggestions are proposed for optimizing the existing protocols. Potential safety issues regarding the clinical application of iPSC-derived SCs are discussed as well. Lastly, we will address future aspects of SC engineering.

Modification of surface/neuron interfaces for neural cell-type specific responses: a review

Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nano-scale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair.

Combination therapy of stem cell derived neural progenitors and drug delivery of anti-inhibitory molecules for spinal cord injury

Regeneration of lost synaptic connections following spinal cord injury (SCI) is limited by local ischemia, cell death, and an excitotoxic environment, which leads to the development of an inhibitory glial scar surrounding a cystic cavity. While a variety of single therapy interventions provide incremental improvements to functional recovery after SCI, they are limited; a multifactorial approach that combines several single therapies may provide a better chance of overcoming the multitude of obstacles to recovery. To this end, fibrin scaffolds were modified to provide sustained delivery of neurotrophic factors and anti-inhibitory molecules, as well as encapsulation of embryonic stem cell-derived progenitor motor neurons (pMNs). In vitro characterization of this combination scaffold confirmed that pMN viability was unaffected by culture alongside sustained delivery systems. When transplanted into a rat sub-acute SCI model, fibrin scaffolds containing growth factors (GFs), anti-inhibitory molecules without pMNs, or pMNs with GFs had lower chondroitin sulfate proteoglycan levels compared to scaffolds containing anti-inhibitory molecules with pMNs. Scaffolds containing pMNs, but not anti-inhibitory molecules, showed survival, differentiation into neuronal cell types, axonal extension in the transplant area, and the ability to integrate into host tissue. However, the combination of pMNs with sustained-delivery of anti-inhibitory molecules led to reduced cell survival and increased macrophage infiltration. While combination therapies retain potential for effective treatment of SCI, further work is needed to improve cell survival and to limit inflammation.

STATEMENT OF SIGNIFICANCE

Spinal cord injury (SCI) creates a highly complex inhibitory environment with a multitude of obstacles that limit recovery. Many therapeutic options have been developed to overcome single obstacles, but single therapies typically only lead to limited functional improvement. Therefore combination therapies may improve recovery by targeting several inhibitory obstacles simultaneously. The present study used biomaterial scaffolds to combine the sustained release of anti-inhibitory molecules and growth factors with cell transplantation of highly purified progenitor motor neurons. This expands upon previously established biomaterial scaffolds by supporting surviving cells, limiting inhibition from the extracellular environment, and replenishing lost cell populations. We show that while promising, certain combinations may exacerbate negative side-effects instead of augmenting positive features.

A switch from canonical to noncanonical Wnt signaling mediates early differentiation of human neural stem cells

Wnt/β-catenin signaling is essential for neurogenesis but less is known about β-catenin-independent Wnt signals. We show here that Wnt/activator protein-1 (AP-1) signaling drives differentiation of human embryonic stem cell and induced pluripotent stem cell-derived neural progenitor cells. Neuronal differentiation was accompanied by a reduction in β-catenin/Tcf-dependent transcription and target gene expression, increased levels and/or phosphorylation of activating transcription factor 2 (ATF2), cyclic AMP response element-binding protein, and c-Jun, and increased AP-1-dependent transcription. Inhibition of Wnt secretion using the porcupine inhibitors IWP-2 and Wnt-C59 blocked neuronal differentiation, while activation or inhibition of Wnt/β-catenin signaling had no effect. Neuronal differentiation increased expression of several Wnt genes, including WNT3A, silencing of which reduced differentiation. Addition of recombinant Wnt-3a to cells treated with IWP-2 or Wnt-C59 increased AP-1 levels and restored neuronal differentiation. The effects of Wnt-3a could not be blocked by addition of Dkk-1 or IWR-1, suggesting the involvement of noncanonical signaling. Consistent with this, restoration of neuronal differentiation by Wnt-3a was reduced by inhibition of Jun N-terminal kinase (JNK) and by gene silencing of ATF2. Together, these observations suggest that β-catenin-independent Wnt signals promote neural stem/progenitor cell differentiation in a signaling pathway involving Wnt-3a, JNK, and ATF2.

Canonical and noncanonical Wnt signaling in neural stem/progenitor cells

The first mammalian Wnt to be discovered, Wnt-1, was found to be essential for the development of a large part of the mouse brain over 25 years ago. We have since learned that Wnt family secreted glycolipoproteins, of which there are nineteen, which activate a diverse network of signals that are particularly important during embryonic development and tissue regeneration. Wnt signals in the developing and adult brain can drive neural stem cell self-renewal, expansion, asymmetric cell division, maturation and differentiation. The molecular events taking place after a Wnt binds to its cell-surface receptors are complex and, at times, controversial. A deeper understanding of these events is anticipated to lead to improvements in the treatment of neurodegenerative diseases and stem cell-based replacement therapies. Here, we review the roles played by Wnts in neural stem cells in the developing mouse brain, at neurogenic sites of the adult mouse and in neural stem cell culture models.

Human neural stem cell-derived cultures in three-dimensional substrates form spontaneously functional neuronal networks

Differentiated human neural stem cells were cultured in an inert three-dimensional (3D) scaffold and, unlike two-dimensional (2D) but otherwise comparable monolayer cultures, formed spontaneously active, functional neuronal networks that responded reproducibly and predictably to conventional pharmacological treatments to reveal functional, glutamatergic synapses. Immunocytochemical and electron microscopy analysis revealed a neuronal and glial population, where markers of neuronal maturity were observed in the former. Oligonucleotide microarray analysis revealed substantial differences in gene expression conferred by culturing in a 3D vs a 2D environment. Notable and numerous differences were seen in genes coding for neuronal function, the extracellular matrix and cytoskeleton. In addition to producing functional networks, differentiated human neural stem cells grown in inert scaffolds offer several significant advantages over conventional 2D monolayers. These advantages include cost savings and improved physiological relevance, which make them better suited for use in the pharmacological and toxicological assays required for development of stem cell-based treatments and the reduction of animal use in medical research. Copyright © 2015 John Wiley & Sons, Ltd.

Loss of non-coding RNA expression from the DLK1-DIO3 imprinted locus correlates with reduced neural differentiation potential in human embryonic stem cell lines

INTRODUCTION

Pluripotent stem cells are increasingly used to build therapeutic models, including the transplantation of neural progenitors derived from human embryonic stem cells (hESCs). Recently, long non-coding RNAs (lncRNAs), including delta-like homolog 1 gene and the type III iodothyronine deiodinase gene (DLK1-DIO3) imprinted locus-derived maternally expressed gene 3 (MEG3), were found to be expressed during neural development. The deregulation of these lncRNAs is associated with various neurological diseases. The imprinted locus DLK1-DIO3 encodes abundant non-coding RNAs (ncRNAs) that are regulated by differential methylation of the locus. We aim to study the correlation between the DLK1-DIO3-derived ncRNAs and the capacity of hESCs to differentiate into neural lineages.

METHODS

We classified hESC sublines into MEG3-ON and MEG3-OFF based on the expression levels of MEG3 and its downstream microRNAs as detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). A cDNA microarray was used to analyze the gene expression profiles of hESCs. To investigate the capacity of neural differentiation in MEG3-ON and MEG3-OFF hESCs, we performed neural lineage differentiation followed by neural lineage marker expression and neurite formation analyses via qRT-PCR and immunocytochemistry, respectively. MEG3-knockdown via small interfering RNA (siRNA) and small hairpin RNA (shRNA) was used to investigate the potential causative effect of MEG3 in regulating neural lineage-related gene expression.

RESULTS

DLK1-DIO3-derived ncRNAs were repressed in MEG3-OFF hESCs compared with those in the MEG3-ON hESCs. The transcriptome profile indicated that many genes related to nervous system development and neural-type tumors were differentially expressed in MEG3-OFF hESCs. Three independent MEG3-knockdown assays using different siRNA and shRNA constructs consistently resulted in downregulation of some neural lineage genes. Lower expression levels of stage-specific neural lineage markers and reduced neurite formation were observed in neural lineage-like cells derived from MEG3-OFF-associated hESCs compared with those in the MEG3-ON groups at the same time points after differentiation.

CONCLUSIONS

Repression of ncRNAs derived from the DLK1-DIO3 imprinted locus is associated with reduced neural lineage differentiation potential in hESCs.

Therapeutic potential of human embryonic stem cell transplantation in patients with cerebral palsy

Background

The present study evaluated the efficacy and safety of human embryonic stem cell (hESC) therapy in patients with CP.

Materials and methods

This analysis included patients (30 days-18 yr) with documented diagnosis of CP. The study consisted of four treatment phases (T1, T2, T3, T4) separated by gap phases. Efficacy of hESC therapy was evaluated based on Gross Motor Function Classification Scores Expanded and Revised (GMFCS-E & R; 1-good to 5-bad).

Results

Ninety one patients were included and all received hESC therapy in T1, 66 patients returned for T2, 38 patients for T3, and 15 patients for T4. Overall, 30.2% patients achieved GMFCS-E & R score 1 during the study with different number of patients achieving GMFCS score 1 by the end of each treatment phase (T1: 6 [6.6%]; T2: 7 [10.6%]; T3: 11 [28.9%]; and T4: 5 [33.3%]). All patients in up to 2 yr (n = 10), 2-4 yr (n = 10), 4-6 yr (n = 9), and 6-12 yr (n = 8) age groups except one of the 5 patients in the age group of 12-18 yr transitioned from GMFCS-E & R score 5 to lower scores by end of T1. Most patients transitioned to GMFCS-E & R score 2 (n = 34) from higher scores by end of T2. Eleven patients achieved GMFCS-E & R score 1 by end of T3. No serious adverse events were observed.

Conclusion

Use of hESC therapy in patients with CP is effective and safe. hESC therapy has demonstrated significant improvement in GMFCS-E & R scale.

Proteome-wide analysis of neural stem cell differentiation to facilitate transition to cell replacement therapies

Neurodegenerative diseases are devastating disorders and the demands on their treatment are set to rise in connection with higher disease incidence. Knowledge of the spatiotemporal profile of cellular protein expression during neural differentiation and definition of a set of markers highly specific for targeted neural populations is a key challenge. Intracellular proteins may be utilized as a readout for follow-up transplantation and cell surface proteins may facilitate isolation of the cell subpopulations, while secreted proteins could help unravel intercellular communication and immunomodulation. This review summarizes the potential of proteomics in revealing molecular mechanisms underlying neural differentiation of stem cells and presents novel candidate proteins of neural subpopulations, where understanding of their functionality may accelerate transition to cell replacement therapies.

Synergistic contribution of SMAD signaling blockade and high localized cell density in the differentiation of neuroectoderm from H9 cells

Directed neural differentiation of human embryonic stem cells (ESCs) enables researchers to generate diverse neuronal populations for human neural development study and cell replacement therapy. To realize this potential, it is critical to precisely understand the role of various endogenous and exogenous factors involved in neural differentiation. Cell density, one of the endogenous factors, is involved in the differentiation of human ESCs. Seeding cell density can result in variable terminal cell densities or localized cell densities (LCDs), giving rise to various outcomes of differentiation. Thus, understanding how LCD determines the differentiation potential of human ESCs is important. The aim of this study is to highlight the role of LCD in the differentiation of H9 human ESCs into neuroectoderm (NE), the primordium of the nervous system. We found the initially seeded cells form derived cells with variable LCDs and subsequently affect the NE differentiation. Using a newly established method for the quantitative examination of LCD, we demonstrated that in the presence of induction medium supplemented with or without SMAD signaling blockers, high LCD promotes the differentiation of NE. Moreover, SMAD signaling blockade promotes the differentiation of NE but not non-NE germ layers, which is dependent on high LCDs. Taken together, this study highlights the need to develop innovative strategies or techniques based on LCDs for generating neural progenies from human ESCs.

SOX9 as a Predictor for Neurogenesis Potentiality of Amniotic Fluid Stem Cells

Preclinical studies of amniotic fluid-derived cell therapy have been successful in the research of neurodegenerative diseases, peripheral nerve injury, spinal cord injury, and brain ischemia. Transplantation of human amniotic fluid stem cells (AFSCs) into rat brain ventricles has shown improvement in symptoms of Parkinson's disease and also highlighted the minimal immune rejection risk of AFSCs, even between species. Although AFSCs appeared to be a promising resource for cell-based regenerative therapy, AFSCs contain a heterogeneous pool of distinct cell types, rendering each preparation of AFSCs unique. Identification of predictive markers for neuron-prone AFSCs is necessary before such stem cell-based therapeutics can become a reality. In an attempt to identify markers of AFSCs to predict their ability for neurogenesis, we performed a two-phase study. In the discovery phase of 23 AFSCs, we tested ZNF521/Zfp521, OCT6, SOX1, SOX2, SOX3, and SOX9 as predictive markers of AFSCs for neural differentiation. In the validation phase, the efficacy of these predictive markers was tested in independent sets of 18 AFSCs and 14 dental pulp stem cells (DPSCs). We found that high expression of SOX9 in AFSCs is associated with good neurogenetic ability, and these positive correlations were confirmed in independent sets of AFSCs and DPSCs. Furthermore, knockdown of SOX9 in AFSCs inhibited their neuronal differentiation. In conclusion, the discovery of SOX9 as a predictive marker for neuron-prone AFSCs could expedite the selection of useful clones for regenerative medicine, in particular, in neurological diseases and injuries.

Accelerated neuronal differentiation toward motor neuron lineage from human embryonic stem cell line (H9)

Motor neurons loss plays a pivotal role in the pathoetiology of various debilitating diseases such as, but not limited to, amyotrophic lateral sclerosis, primary lateral sclerosis, progressive muscular atrophy, progressive bulbar palsy, pseudobulbar palsy, and spinal muscular atrophy. However, advancement in motor neuron replacement therapy has been significantly constrained by the difficulties in large-scale production at a cost-effective manner. Current methods to derive motor neuron heavily rely on biochemical stimulation, chemical biological screening, and complex physical cues. These existing methods are seriously challenged by extensive time requirements and poor yields. An innovative approach that overcomes prior hurdles and enhances the rate of successful motor neuron transplantation in patients is of critical demand. Iron, a trace element, is indispensable for the normal development and function of the central nervous system. Whether ferric ions promote neuronal differentiation and subsequently promote motor neuron lineage has never been considered. Here, we demonstrate that elevated iron concentration can drastically accelerate the differentiation of human embryonic stem cells (hESCs) toward motor neuron lineage potentially via a transferrin mediated pathway. HB9 expression in 500 nM iron-treated hESCs is approximately twofold higher than the control. Moreover, iron treatment generated more matured and functional motor neuron-like cells that are ∼1.5 times more sensitive to depolarization when compared to the control. Our methodology renders an expedited approach to harvest motor neuron-like cells for disease, traumatic injury regeneration, and drug screening.

A well-refined in vitro model derived from human embryonic stem cell for screening phytochemicals with midbrain dopaminergic differentiation-boosting potential for improving Parkinson's disease

Stimulation of endogenous neurogenesis is a potential approach to compensate for loss of dopaminergic neurons of substantia nigra compacta nigra (SNpc) in patients with Parkinson's disease (PD). This objective was to establish an in vitro model by differentiating pluripotent human embryonic stem cells (hESCs) into midbrain dopaminergic (mDA) neurons for screening phytochemicals with mDA neurogenesis-boosting potentials. Consequently, a five-stage differentiation process was developed. The derived cells expressed many mDA markers including tyrosine hydroxylase (TH), β-III tubulin, and dopamine transporter (DAT). The voltage-gated ion channels and dopamine release were also examined for verifying neuron function, and the dopamine receptor agonists bromocriptine and 7-hydroxy-2-(dipropylamino)tetralin (7-OH-DPAT) were used to validate our model. Then, several potential phytochemicals including green tea catechins and ginsenosides were tested using the model. Finally, ginsenoside Rb1 was identified as the most potent phytochemical which is capable of upregulating neurotrophin expression and inducing mDA differentiation.

Effects of silica and titanium oxide particles on a human neural stem cell line: morphology, mitochondrial activity, and gene expression of differentiation markers

Several in vivo studies suggest that nanoparticles (smaller than 100 nm) have the ability to reach the brain tissue. Moreover, some nanoparticles can penetrate into the brains of murine fetuses through the placenta by intravenous administration to pregnant mice. However, it is not clear whether the penetrated nanoparticles affect neurogenesis or brain function. To evaluate its effects on neural stem cells, we assayed a human neural stem cell (hNSCs) line exposed in vitro to three types of silica particles (30 nm, 70 nm, and <44 μm) and two types of titanium oxide particles (80 nm and < 44 μm). Our results show that hNSCs aggregated and exhibited abnormal morphology when exposed to the particles at concentrations ≥ 0.1 mg/mL for 7 days. Moreover, all the particles affected the gene expression of Nestin (stem cell marker) and neurofilament heavy polypeptide (NF-H, neuron marker) at 0.1 mg/mL. In contrast, only 30-nm silica particles at 1.0 mg/mL significantly reduced mitochondrial activity. Notably, 30-nm silica particles exhibited acute membrane permeability at concentrations ≥62.5 μg/mL in 24 h. Although these concentrations are higher than the expected concentrations of nanoparticles in the brain from in vivo experiments in a short period, these thresholds may indicate the potential toxicity of accumulated particles for long-term usage or continuous exposure.

Phenotypic assays for β-amyloid in mouse embryonic stem cell-derived neurons

Given the complex nature of Alzheimer's disease (AD), a cell-based model that recapitulates the physiological properties of the target neuronal population would be extremely valuable for discovering improved drug candidates and chemical probes to uncover disease mechanisms. We established phenotypic neuronal assays for the biogenesis and synaptic action of amyloid β peptide (Aβ) based on embryonic stem cell-derived neurons (ESNs). ESNs enriched with pyramidal neurons were robust, scalable, and amenable to a small-molecule screening assay, overcoming the apparent limitations of neuronal models derived from human pluripotent cells. Small-molecule screening of clinical compounds identified four compounds capable of reducing Aβ levels in ESNs derived from the Tg2576 mouse model of AD. Our approach is therefore highly suitable for phenotypic screening in AD drug discovery and has the potential to identify therapeutic candidates with improved efficacy and safety potential.

Non-coding RNAs in pluripotency and neural differentiation of human pluripotent stem cells

Several studies have demonstrated the important role of non-coding RNAs as regulators of posttranscriptional processes, including stem cells self-renewal and neural differentiation. Human embryonic stem cells (hESCs) and induced pluripotent stem cells (ihPSCs) show enormous potential in regenerative medicine due to their capacity to differentiate to virtually any type of cells of human body. Deciphering the role of non-coding RNAs in pluripotency, self-renewal and neural differentiation will reveal new molecular mechanisms involved in induction and maintenances of pluripotent state as well as triggering these cells toward clinically relevant cells for transplantation. In this brief review we will summarize recently published studies which reveal the role of non-coding RNAs in pluripotency and neural differentiation of hESCs and ihPSC.

Current concept in neural regeneration research: NSCs isolation, characterization and transplantation in various neurodegenerative diseases and stroke: A review

Since last few years, an impressive amount of data has been generated regarding the basic in vitro and in vivo biology of neural stem cells (NSCs) and there is much far hope for the success in cell replacement therapies for several human neurodegenerative diseases and stroke. The discovery of adult neurogenesis (the endogenous production of new neurons) in the mammalian brain more than 40 years ago has resulted in a wealth of knowledge about stem cells biology in neuroscience research. Various studies have done in search of a suitable source for NSCs which could be used in animal models to understand the basic and transplantation biology before treating to human. The difficulties in isolating pure population of NSCs limit the study of neural stem behavior and factors that regulate them. Several studies on human fetal brain and spinal cord derived NSCs in animal models have shown some interesting results for cell replacement therapies in many neurodegenerative diseases and stroke models. Also the methods and conditions used for in vitro culture of these cells provide an important base for their applicability and specificity in a definite target of the disease. Various important developments and modifications have been made in stem cells research which is needed to be more specified and enrolment in clinical studies using advanced approaches. This review explains about the current perspectives and suitable sources for NSCs isolation, characterization, in vitro proliferation and their use in cell replacement therapies for the treatment of various neurodegenerative diseases and strokes.

TAF4 controls differentiation of human neural progenitor cells through hTAF4-TAFH activity

Expression of general transcription factor and co-activator TAF4 varies during development and in the processes of cell differentiation with suggested connection to neurodegenerative diseases. Here, we show that expression of TAF4 alternative splice variants is different in various regions of the human brain, substantiating the role of alternative splicing of TAF4 in the regulation of neural development and brain function. Most of the described splicing events affect the TAFH homology domain of TAF4 (hTAF4-TAFH). Besides, differentiated towards neural lineages, normal human neural progenitors (NHNPs) lose canonical full-length TAF4 isoform. To study the effects of hTAF4-TAFH splicing on neuronal differentiation, we used RNAi approach to target hTAF4-TAFH-encoding domain in NHNPs. Results show that inactivation of hTAF4-TAFH domain accelerates differentiation of human neural progenitor cells. Conversely, enhanced expression of TAF4 suppresses differentiation and keeps neural progenitor cells in a stem cell-like state. Finally, we provide data on the involvement of TP53 and noncanonical WNT signaling pathways in mediating effects of TAF4 on neuronal differentiation. Overall, our data suggest that specific isoforms of TAF4 may selectively and efficiently control neurogenesis.

Stem cells for brain repair in neonatal hypoxia-ischemia

Neonatal hypoxic-ischemic insults are a significant cause of pediatric encephalopathy, developmental delays, and spastic cerebral palsy. Although the developing brain's plasticity allows for remarkable self-repair, severe disruption of normal myelination and cortical development upon neonatal brain injury are likely to generate life-persisting sensory-motor and cognitive deficits in the growing child. Currently, no treatments are available that can address the long-term consequences. Thus, regenerative medicine appears as a promising avenue to help restore normal developmental processes in affected infants. Stem cell therapy has proven effective in promoting functional recovery in animal models of neonatal hypoxic-ischemic injury and therefore represents a hopeful therapy for this unmet medical condition. Neural stem cells derived from pluripotent stem cells or fetal tissues as well as umbilical cord blood and mesenchymal stem cells have all shown initial success in improving functional outcomes. However, much still remains to be understood about how those stem cells can safely be administered to infants and what their repair mechanisms in the brain are. In this review, we discuss updated research into pathophysiological mechanisms of neonatal brain injury, the types of stem cell therapies currently being tested in this context, and the potential mechanisms through which exogenous stem cells might interact with and influence the developing brain.

New opportunities: harnessing induced pluripotency for discovery in diabetes and metabolism

The landmark discovery of induced pluripotent stem cells (iPSCs) by Shinya Yamanaka has transformed regenerative biology. Previously, insights into the pathogenesis of chronic human diseases have been hindered by the inaccessibility of patient samples. However, scientists are now able to convert patient fibroblasts into iPSCs and differentiate them into disease-relevant cell types. This ability opens new avenues for investigating disease pathogenesis and designing novel treatments. In this review, we highlight the uses of human iPSCs to uncover the underlying causes and pathological consequences of diabetes and metabolic syndromes, multifactorial diseases whose etiologies have been difficult to unravel using traditional methodologies.

Directed differentiation of aged human bone marrow multipotent stem cells effectively generates dopamine neurons

This study aimed to isolate aged human bone marrow multipotent stem cells (hAMSCs) with the potential for multilineage differentiation and to directly induce the cells to generate dopamine neurons, which could be used for Parkinson's disease therapy. We compared different culture methods for stem cells from aged human bone marrow and identified hAMSCs that could proliferate in vitro for at least 60 doubling times. Using RT-PCR and IHC, we found that these hAMSCs expressed pluripotent genes, such as Oct4, Sox2, and Nanog. In vitro studies also proved that hAMSCs could differentiate into three germ layer-derived cell types, such as osteogenic, chondrogenic, adipogenic, and hepatocyte-liked cells. After induction for more than 20 d in vitro with retinoic acid, basic fibroblast growth factor, and sonic hedgehog using a two-step method and withdrawal of serum, hAMSCs could differentiate into dopamine neurons at the positive ratio of 70%, which showed DA secretion function upon depolarization. In conclusion, we suggest that hAMSCs can be used as cell sources to develop medical treatments to prevent the progression of Parkinson's disease, especially in aged persons.

Biomedical and clinical promises of human pluripotent stem cells for neurological disorders

Neurological disorders are characterized by the chronic and progressive loss of neuronal structures and functions. There is a variability of the onsets and causes of clinical manifestations. Cell therapy has brought a new concept to overcome brain diseases, but the advancement of this therapy is limited by the demands of specialized neurons. Human pluripotent stem cells (hPSCs) have been promised as a renewable resource for generating human neurons for both laboratory and clinical purposes. By the modulations of appropriate signalling pathways, desired neuron subtypes can be obtained, and induced pluripotent stem cells (iPSCs) provide genetically matched neurons for treating patients. These hPSC-derived neurons can also be used for disease modeling and drug screening. Since the most urgent problem today in transplantation is the lack of suitable donor organs and tissues, the derivation of neural progenitor cells from hPSCs has opened a new avenue for regenerative medicine. In this review, we summarize the recent reports that show how to generate neural derivatives from hPSCs, and discuss the current evidence of using these cells in animal studies. We also highlight the possibilities and concerns of translating these hPSC-derived neurons for biomedical and clinical uses in order to fight against neurological disorders.

Differentiation of glutamatergic neurons from mouse embryonic stem cells requires raptor S6K signaling

Although the mammalian target of rapamycin complex 1 (mTORC1) functions as an important signaling complex in many cellular processes, the role of mTORC1 in neurons derived from embryonic stem cells (ESCs) has been less explored. Here, using a modified protocol to differentiate mouse ESCs (mESCs) into almost uniform glutamatergic neurons, we explored the importance of raptor/mTORC1 in the differentiation of mESCs. Raptor gene-trap mESCs, and raptor-knockdown mESCs formed smaller-sized embryonic bodies than the wild type and failed to undergo neuronal differentiation. Treatment with 1μM rapamycin starting at the point when neuronal precursors began to differentiate from mESCs caused the gradual loss of neurites, shrinkage of soma, and a decreased ratio of neurite length to cell number over 48 to 72h of treatment. This change was accompanied by activation of caspase-3 and S6 kinase (S6K), but not 4E-binding protein 1 (4EBP1). Knockdown of raptor during neuronal differentiation from mESCs also resulted in gradual loss of neurites and shrinkage of cell bodies. Loss of neurite density resulting from rapamycin treatment could be reversed by overexpression of S6K T389E. Taken together, these data demonstrate that raptor/mTORC1/S6K plays a critical role in the differentiation and survival of neurons derived from mESCs.

Insulin concentration is critical in culturing human neural stem cells and neurons

Cell culture of human-derived neural stem cells (NSCs) is a useful tool that contributes to our understanding of human brain development and allows for the development of therapies for intractable human brain disorders. Human NSC (hNSC) cultures, however, are not commonly used, mainly because of difficulty with consistently maintaining the cells in a healthy state. In this study, we show that hNSC cultures, unlike NSCs of rodent origins, are extremely sensitive to insulin, an indispensable culture supplement, and that the previously reported difficulty in culturing hNSCs is likely because of a lack of understanding of this relationship. Like other neural cell cultures, insulin is required for hNSC growth, as withdrawal of insulin supplementation results in massive cell death and delayed cell growth. However, severe apoptotic cell death was also detected in insulin concentrations optimized to rodent NSC cultures. Thus, healthy hNSC cultures were only produced in a narrow range of relatively low insulin concentrations. Insulin-mediated cell death manifested not only in all human NSCs tested, regardless of origin, but also in differentiated human neurons. The underlying cell death mechanism at high insulin concentrations was similar to insulin resistance, where cells became less responsive to insulin, resulting in a reduction in the activation of the PI3K/Akt pathway critical to cell survival signaling.

Mesenchymal autologous stem cells

The use of cell-based therapies for spinal cord injuries has recently gained prominence as a potential therapy or component of a combination strategy. Experimental and clinical studies have been performed using mesenchymal stem cell therapy to treat spinal cord injuries with encouraging results. However, there have been reports on the adverse effects of these stem cell-based therapies, especially in the context of tumor modulation. This article surveys the literature relevant to the potential of mesenchymal autologous stem cells for spinal cord injuries and their clinical implications.