Engraftable human neural stem cells respond to developmental cues, replace neurons, and express foreign genes

Emerging Human Pluripotent Stem Cell-Based Human-Animal Brain Chimeras for Advancing Disease Modeling and Cell Therapy for Neurological Disorders

Human pluripotent stem cell (hPSC) models provide unprecedented opportunities to study human neurological disorders by recapitulating human-specific disease mechanisms. In particular, hPSC-based human-animal brain chimeras enable the study of human cell pathophysiology in vivo. In chimeric brains, human neural and immune cells can maintain human-specific features, undergo maturation, and functionally integrate into host brains, allowing scientists to study how human cells impact neural circuits and animal behaviors. The emerging human-animal brain chimeras hold promise for modeling human brain cells and their interactions in health and disease, elucidating the disease mechanism from molecular and cellular to circuit and behavioral levels, and testing the efficacy of cell therapy interventions. Here, we discuss recent advances in the generation and applications of using human-animal chimeric brain models for the study of neurological disorders, including disease modeling and cell therapy.

Stem Cell Therapy for the Treatment of Parkinson's Disease: What Promise Does it Hold?

Parkinson's disease (PD) is a common, progressive neurodegenerative disorder characterized by substantia nigra dopamine cell death and a varied clinical picture that affects older people. Although more than two centuries have passed since the earliest attempts to find a cure for PD, it remains an unresolved problem. With this in mind, cell replacement therapy is a new strategy for treating PD. This novel approach aims to replace degenerated dopaminergic (DAergic) neurons with new ones or provide a new source of cells that can differentiate into DAergic neurons. Induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), neural stem cells (NSCs), and embryonic stem cells (ESCs) are among the cells considered for transplantation therapies. Recently disease-modifying strategies like cell replacement therapies combined with other therapeutic approaches, such as utilizing natural compounds or biomaterials, are proposed to modify the underlying neurodegeneration. In the present review, we discuss the current advances in cell replacement therapy for PD and summarize the existing experimental and clinical evidence supporting this approach.

Dissecting Intra-tumor Heterogeneity in the Glioblastoma Microenvironment Using Fluorescence-Guided Multiple Sampling

The treatment of the most aggressive primary brain tumor in adults, glioblastoma (GBM), is challenging due to its heterogeneous nature, invasive potential, and poor response to chemo- and radiotherapy. As a result, GBM inevitably recurs and only a few patients survive 5 years post-diagnosis. GBM is characterized by extensive phenotypic and genetic heterogeneity, creating a diversified genetic landscape and a network of biological interactions between subclones, ultimately promoting tumor growth and therapeutic resistance. This includes spatial and temporal changes in the tumor microenvironment, which influence cellular and molecular programs in GBM and therapeutic responses. However, dissecting phenotypic and genetic heterogeneity at spatial and temporal levels is extremely challenging, and the dynamics of the GBM microenvironment cannot be captured by analysis of a single tumor sample. In this review, we discuss the current research on GBM heterogeneity, in particular, the utility and potential applications of fluorescence-guided multiple sampling to dissect phenotypic and genetic intra-tumor heterogeneity in the GBM microenvironment, identify tumor and non-tumor cell interactions and novel therapeutic targets in areas that are key for tumor growth and recurrence, and improve the molecular classification of GBM.

Is chimerism associated with cancer across the tree of life?

Chimerism is a widespread phenomenon across the tree of life. It is defined as a multicellular organism composed of cells from other genetically distinct entities. This ability to 'tolerate' non-self cells may be linked to susceptibility to diseases like cancer. Here we test whether chimerism is associated with cancers across obligately multicellular organisms in the tree of life. We classified 12 obligately multicellular taxa from lowest to highest chimerism levels based on the existing literature on the presence of chimerism in these species. We then tested for associations of chimerism with tumour invasiveness, neoplasia (benign or malignant) prevalence and malignancy prevalence in 11 terrestrial mammalian species. We found that taxa with higher levels of chimerism have higher tumour invasiveness, though there was no association between malignancy or neoplasia and chimerism among mammals. This suggests that there may be an important biological relationship between chimerism and susceptibility to tissue invasion by cancerous cells. Studying chimerism might help us identify mechanisms underlying invasive cancers and also could provide insights into the detection and management of emerging transmissible cancers.

Endogenous Neural Stem Cell-induced Neurogenesis after Ischemic Stroke: Processes for Brain Repair and Perspectives

Ischemic stroke is a very common cerebrovascular accident that occurred in adults and causes higher risk of neural deficits. After ischemic stroke, patients are often left with severe neurological deficits. Therapeutic strategies for ischemic stroke might mitigate neuronal loss due to delayed neural cell death in the penumbra or seek to replace dead neural cells in the ischemic core. Currently, stem cell therapy is the most promising approach for inducing neurogenesis for neural repair after ischemic stroke. Stem cell treatments include transplantation of exogenous stem cells but also stimulating endogenous neural stem cells (NSCs) proliferation and differentiation into neural cells. In this review, we will discuss endogenous NSCs-induced neurogenesis after ischemic stroke and provide perspectives for the therapeutic effects of endogenous NSCs in ischemic stroke. Our review would inform future therapeutic development not only for patients with ischemic stroke but also with other neurological deficits.

Established Immortalized Cavernous Endothelial Cells Improve Erectile Dysfunction in Rats with Cavernous Nerve Injury

The main cause of erectile dysfunction (ED) is the damage in penile cavernous endothelial cells (EC). Murine primary ECs have a limited growth potential, and the easy availability of murine ECs will facilitate the study of cavernous endothelial dysfunction in rats. This study was performed to establish immortalized rat penile cavernous ECs (rEC) and investigate how they could repair erectile dysfunction in rats with cavernous nerve injury (CNI). rEC was isolated enzymatically by collagenase digestion and were cultured. An amphotropic replication-incompetent retroviral vector encoding v-myc oncogene was used to transfect rEC for immortalization (vREC). Morphological and immunohistochemical properties of vREC were examined. Eight-week-old male Sprague-Dawley rats were divided into three groups of five rats each, including group 1 = sham operation, group 2 = bilateral CN injury, group 3 = vREC (1 × 106 cells) treatment after CNI. Erectile response was assessed at 2, 4 weeks after transplantation of vREC., Penile tissue were harvested at 4 weeks after transplantation and immune−histochemical examination was performed. vREC showed the expression of CD31, vWF, cell type-specific markers for EC by RT-PCR and flowcytometry. At 2, 4 weeks after transplantation, rats with CNI had significantly lower erectile function than control group (p < 0.05). The group transplanted with vREC showed higher erectile function than the group without vRECs (p < 0.05). vREC was established and repaired erectile dysfunction in rats with CNI. This cell line may be useful for studying mechanisms and drug screening of erectile dysfunction of rats.

Synoviocyte-Derived Extracellular Matrix and bFGF Speed Human Chondrocyte Proliferation While Maintaining Differentiation Potential

Improving the ability of human chondrocytes to proliferate, while maintaining their differentiation potential, has presented a great challenge in cartilage tissue engineering. In this study, human chondrocytes were cultured under four unique growth conditions at physiologic oxygen tension: tissue culture plastic (TCP) only, synoviocyte matrix (SCM)-coated flasks only, SCM-coated flasks with bFGF media supplement, and TCP with bFGF media supplement. The results indicated that, compared to standard TCP, all test conditions showed significantly increased cell expansion rates and an increase in both glycosaminoglycan (GAG) and collagen content during redifferentiation culture. Specifically, the combined SCM + bFGF growth condition showed an additive effect, with an increase of approximately 36% more cells per passage (5-7 days) when compared to the SCM alone. In conclusion, the results of this study demonstrate that bFGF and SCM can be used as supplements to enhance the growth of human chondrocytes both as individual enhancers and as a combined additive.

Targeted mass spectrometry for monitoring of neural differentiation

Human multipotent neural stem cells could effectively be used for the treatment of a variety of neurological disorders. However, a defining signature of neural stem cell lines that would be expandable, non-tumorigenic, and differentiate into desirable neuronal/glial phenotype after in vivo grafting is not yet defined. Employing a mass spectrometry approach, based on selected reaction monitoring, we tested a panel of well-described culture conditions, and measured levels of protein markers routinely used to probe neural differentiation, i.e. POU5F1 (OCT4), SOX2, NES, DCX, TUBB3, MAP2, S100B, GFAP, GALC, and OLIG1. Our multiplexed assay enabled us to simultaneously identify the presence of pluripotent, multipotent, and lineage-committed neural cells, thus representing a powerful tool to optimize novel and highly specific propagation and differentiation protocols. The multiplexing capacity of this method permits the addition of other newly identified cell type-specific markers to further increase the specificity and quantitative accuracy in detecting targeted cell populations. Such an expandable assay may gain the advantage over traditional antibody-based assays, and represents a method of choice for quality control of neural stem cell lines intended for clinical use.

Histological Studies of the Ventricular-Subventricular Zone as Neural Stem Cell and Glioma Stem Cell Niche

The neural stem cell niche of the ventricular-subventricular zone supports the persistence of stem and progenitor cells in the mature brain. This niche has many notable cytoarchitectural features that affect the activity of stem cells and may also support the survival and growth of invading tumor cells. Histochemical studies of the niche have revealed many proteins that, in combination, can help to reveal stem-like cells in the normal or cancer context, although many caveats persist in the quest to consistently identify these cells in the human brain. Here, we explore the complex relationship between the persistent proliferative capacity of the neural stem cell niche and the malignant proliferation of brain tumors, with a special focus on histochemical identification of stem cells and stem-like tumor cells and an eye toward the potential application of high-dimensional imaging approaches to the field.

Global Transcriptional Analyses of the Wnt-Induced Development of Neural Stem Cells from Human Pluripotent Stem Cells

The differentiation of human pluripotent stem cells (hPSCs) to neural stem cells (NSCs) is the key initial event in neurogenesis and is thought to be dependent on the family of Wnt growth factors, their receptors and signaling proteins. The delineation of the transcriptional pathways that mediate Wnt-induced hPSCs to NSCs differentiation is vital for understanding the global genomic mechanisms of the development of NSCs and, potentially, the creation of new protocols in regenerative medicine. To understand the genomic mechanism of Wnt signaling during NSCs development, we treated hPSCs with Wnt activator (CHIR-99021) and leukemia inhibitory factor (LIF) in a chemically defined medium (N2B27) to induce NSCs, referred to as CLNSCs. The CLNSCs were subcultured for more than 40 passages in vitro; were positive for AP staining; expressed neural progenitor markers such as NESTIN, PAX6, SOX2, and SOX1; and were able to differentiate into three neural lineage cells: neurons, astrocytes, and oligodendrocytes in vitro. Our transcriptome analyses revealed that the Wnt and Hedgehog signaling pathways regulate hPSCs cell fate decisions for neural lineages and maintain the self-renewal of CLNSCs. One interesting network could be the deregulation of the Wnt/β-catenin signaling pathway in CLNSCs via the downregulation of c-MYC, which may promote exit from pluripotency and neural differentiation. The Wnt-induced spinal markers HOXA1-4, HOXA7, HOXB1-4, and HOXC4 were increased, however, the brain markers FOXG1 and OTX2, were absent in the CLNSCs, indicating that CLNSCs have partial spinal cord properties. Finally, a CLNSC simple culture condition, when applied to hPSCs, supports the generation of NSCs, and provides a new and efficient cell model with which to untangle the mechanisms during neurogenesis.

A Tool for Accurate Stoichiometric Composition of Cryopreservative Media for Fetal and Induced Pluripotent Stem Cell-Derived Human Neural Stem Cells

Fetal human neural stem cells (fhNSC) are of considerable interest as potential regenerative therapies for neuronal or glial degeneration or destruction resulting from genetic abnormalities, disease, or injury. Realization of this potential requires securing a supply of cells sufficient to meet the needs of transplantation, which are often tens to hundreds of millions of cells per dose. This challenge necessitates the establishment of safe and efficient cell banking protocols. Cryopreservation, involving the slow freezing or vitrification of cells, enables storage of fhNSC for prolonged periods, while maintaining their viability and multipotency required for clinical use. To optimize cryopreservation of fhNSC, attention has become focused on the composition of the medium used to effect cryopreservation by slow freezing/vitrification-i.e., the cryopreservative medium. The cryopreservative medium is typically specified as a dilution of a concentrated cryoprotectant, such as dimethylsulfoxide or glycerol, in cell culture medium that is often combined with serum or another source of necessary growth factors. The present work is devoted to a computational tool for determining the composition of a cryopreservative medium that can be combined with dissociated fhNSC resuspended in a certain volume of culture medium to achieve the criterion of stoichiometric dilution of cryoprotectant favorable to cell viability in the final mixture of cryopreservative medium and cells. © 2021 Wiley Periodicals LLC. Basic Protocol: Culture and passage of fhNSC, counting of enzymatically dissociated fhNSC, and quantitative formulation of cryomedium Alternate Protocol: Procedure when cell medium is not added to the cryomedium.

A Biomarker for Predicting Responsiveness to Stem Cell Therapy Based on Mechanism-of-Action: Evidence from Cerebral Injury

To date, no stem cell therapy has been directed to specific recipients-and, conversely, withheld from others-based on a clinical or molecular profile congruent with that cell's therapeutic mechanism-of-action (MOA) for that condition. We address this challenge preclinically with a prototypical scenario: human neural stem cells (hNSCs) against perinatal/neonatal cerebral hypoxic-ischemic injury (HII). We demonstrate that a clinically translatable magnetic resonance imaging (MRI) algorithm, hierarchical region splitting, provides a rigorous, expeditious, prospective, noninvasive "biomarker" for identifying subjects with lesions bearing a molecular profile indicative of responsiveness to hNSCs' neuroprotective MOA. Implanted hNSCs improve lesional, motor, and/or cognitive outcomes only when there is an MRI-measurable penumbra that can be forestalled from evolving into necrotic core; the core never improves. Unlike the core, a penumbra is characterized by a molecular profile associated with salvageability. Hence, only lesions characterized by penumbral > core volumes should be treated with cells, making such measurements arguably a regenerative medicine selection biomarker.

Stem cells for the treatment of glioblastoma: a 20-year perspective

Glioblastoma, the deadliest form of primary brain tumor, remains a disease without cure. Treatment resistance is in large part attributed to limitations in the delivery and distribution of therapeutic agents. Over the last 20 years, numerous preclinical studies have demonstrated the feasibility and efficacy of stem cells as antiglioma agents, leading to the development of trials to test these therapies in the clinic. In this review we present and analyze these studies, discuss mechanisms underlying their beneficial effect and highlight experimental progress, limitations and the emergence of promising new therapeutic avenues. We hope to increase awareness of the advantages brought by stem cells for the treatment of glioblastoma and inspire further studies that will lead to accelerated implementation of effective therapies.

Glioblastoma is the deadliest and most common form of brain tumor, for which there is no cure. It is very difficult to deliver medicine to the tumor cells, because they spread out widely into the normal brain, and local blood vessels represent a barrier that most medicines cannot cross. It was shown, in many studies over the last 20 years, that stem cells are attracted toward the tumor and that they can deliver many kinds of therapeutic agents directly to brain cancer cells and shrink the tumor. In this review we analyze these studies and present new discoveries that can be used to make stem cell therapies for glioblastoma more effective to prolong the life of patients with brain tumors.

An engineered neurovascular unit for modeling neuroinflammation

The neurovascular unit (NVU) comprises multiple types of brain cells, including brain endothelial cells, astrocytes, pericytes, neurons, microglia, and oligodendrocytes. Each cell type contributes to the maintenance of the molecular transport barrier and brain tissue homeostasis. Several disorders and diseases of the central nervous system, including neuroinflammation, Alzheimer's disease, stroke, and multiple sclerosis, have been associated with dysfunction of the NVU. As a result, there has been increased demand for the development of NVUin vitromodels. Here, we present a three-dimensional (3D) immortalized human cell-based NVU model generated by organizing the brain microvasculature in a collagen matrix embedded with six different types of cells that comprise the NVU. By surrounding a perfusable brain endothelium with six types of NVU-composing cells, we demonstrated a significant impact of the 3D co-culture on the maturation of barrier function, which is supported by cytokines secreted from NVU-composing cells. Furthermore, NVU-composing cells alleviated the inflammatory responses induced by lipopolysaccharides. Our human cell-based NVUin vitromodel could enable elucidation of both physiological and pathological mechanisms in the human brain and evaluation of safety and efficacy in the context of high-content analysis during the process of drug development.

Study on the Safety of Human Oligodendrocyte Precursor Cell Transplantation in Young Animals and Its Efficacy on Myelination

Oligodendrocyte precursor cells (OPCs) can differentiate into myelinating oligodendrocytes during embryonic development, thereby representing an important potential source for myelin repair or regeneration. To the best of our knowledge, there are very few OPCs from human sources (human-derived OPCs [hOPCs]). In this study, we aimed to evaluate the safety and remyelination capacity of hOPCs developed in our laboratory, transplanted into the lateral ventricles of young animals. Several acute and chronic toxicity experiments were conducted in which different doses of hOPCs were transplanted into the lateral ventricles of Sprague–Dawley rats of different ages. The toxicity, biodistribution, and tumor formation ability of the injected hOPCs were examined by evaluating the rats' vital signs, developmental indicators, neural reflexes, as well as by hematology, immunology, and pathology. In addition, the hOPCs were transplanted into the corpus callosum of the shiverer mouse to verify cell myelination efficacy. Overall, our results show that transplanted hOPCs into young mice are nontoxic to their organ function or immune system. The transplanted cells engrafted in the brain and did not appear in other organs, nor did they cause tissue proliferation or tumor formation. In terms of efficacy, the transplanted hOPCs were able to form myelin in the corpus callosum, alleviate the trembling phenotype of shiverer mice, and promote normal development. The transplantation of hOPCs is safe; they can effectively form myelin in the brain, thereby providing a theoretical basis for the future clinical transplantation of hOPCs.

Prenatal transplantation of human amniotic fluid stem cell could improve clinical outcome of type III spinal muscular atrophy in mice

Spinal muscular atrophy (SMA) is a single gene disorder affecting motor function in uterus. Amniotic fluid is an alternative source of stem cell to ameliorate SMA. Therefore, this study aims to examine the therapeutic potential of Human amniotic fluid stem cell (hAFSC) for SMA. Our SMA model mice were generated by deletion of exon 7 of Smn gene and knock-in of human SMN2. A total of 16 SMA model mice were injected with 1 × 10⁵ hAFSC in uterus, and the other 16 mice served as the negative control. Motor function was analyzed by three behavioral tests. Engraftment of hAFSC in organs were assessed by flow cytometry and RNA scope. Frequency of myocytes, neurons and innervated receptors were estimated by staining. With hAFSC transplantation, 15 fetuses survived (93.75% survival) and showed better performance in all motor function tests. Higher engraftment frequency were observed in muscle and liver. Besides, the muscle with hAFSC transplantation expressed much laminin α and PAX-7. Significantly higher frequency of myocytes, neurons and innervated receptors were observed. In our study, hAFSC engrafted on neuromuscular organs and improved cellular and behavioral outcomes of SMA model mice. This fetal therapy could preserve the time window and treat in the uterus.

The role of hippocampal niche exosomes in rat hippocampal neurogenesis after fimbria-fornix transection

Exosomes transfer signaling molecules such as proteins, lipids, and RNAs to facilitate cell–cell communication and play an important role in the stem cell microenvironment. In previous work, we demonstrated that rat fimbria–fornix transection (FFT) enhances neurogenesis from neural stem cells (NSCs) in the subgranular zone (SGZ). However, how neurogenesis is modulated after denervation remains unknown. Here, we investigated whether exosomes in a denervated hippocampal niche may affect neurogenesis. Using the FFT rat model, we extracted hippocampal exosomes and identified them using western blots, transmission electron microscopy (TEM), and nanoparticle size measurement. We also used RNA sequencing and bioinformatic analysis of exosomes to identify noncoding RNA expression profiles and neurogenesis-related miRNAs, respectively. RNA sequencing analysis demonstrated 9 upregulated and 15 downregulated miRNAs. miR-3559-3P and miR-6324 increased gradually after FFT. Thus, we investigated the function of miR-3559-3P and miR-6324 with NSC proliferation and differentiation assays. Transfection of miR-3559-3p and miR-6324 mimics inhibited the proliferation of NSCs and promoted the differentiation of NSCs into neurons, while miR-3559-3p and miR-6324 inhibitors promoted NSC proliferation and inhibited neuronal differentiation. Additionally, the exosome marker molecules CD9, CD63, and Alix were expressed in exosomes extracted from the hippocampal niche. Finally, TEM showed that exosomes were ∼100 nm in diameter and had a “saucer-like” bilayer membrane structure. Taken together, these findings suggest that differentially expressed exosomes and their related miRNAs in the denervated hippocampal niche can promote differentiation of NSCs into neurons.

Chemical mutagenesis of a GPCR ligand: Detoxifying "inflammo-attraction" to direct therapeutic stem cell migration

While inflammatory chemokines, constitutively produced by pathologic regions, are pivotal for attracting reparative stem cells, one would certainly not want to further “inflame” a diseased brain by instilling such molecules. Exploiting the fact that receptors for such cytokines (G protein-coupled receptors [GPCR]) possess two “pockets”—one for binding, the other for signaling—we created a synthetic GPCR-agonist that maximizes interaction with the former and narrows that with the latter. Homing is robust with no inflammation. The peptide successfully directed the integration of human induced pluripotent stem cell derivatives (known to have muted migration) in a model of a prototypical neurodegenerative condition, ameliorating symptomatology.

A transplanted stem cell’s engagement with a pathologic niche is the first step in its restoring homeostasis to that site. Inflammatory chemokines are constitutively produced in such a niche; their binding to receptors on the stem cell helps direct that cell’s “pathotropism.” Neural stem cells (NSCs), which express CXCR4, migrate to sites of CNS injury or degeneration in part because astrocytes and vasculature produce the inflammatory chemokine CXCL12. Binding of CXCL12 to CXCR4 (a G protein-coupled receptor, GPCR) triggers repair processes within the NSC. Although a tool directing NSCs to where needed has been long-sought, one would not inject this chemokine in vivo because undesirable inflammation also follows CXCL12–CXCR4 coupling. Alternatively, we chemically “mutated” CXCL12, creating a CXCR4 agonist that contained a strong pure binding motif linked to a signaling motif devoid of sequences responsible for synthetic functions. This synthetic dual-moity CXCR4 agonist not only elicited more extensive and persistent human NSC migration and distribution than did native CXCL 12, but induced no host inflammation (or other adverse effects); rather, there was predominantly reparative gene expression. When co-administered with transplanted human induced pluripotent stem cell-derived hNSCs in a mouse model of a prototypical neurodegenerative disease, the agonist enhanced migration, dissemination, and integration of donor-derived cells into the diseased cerebral cortex (including as electrophysiologically-active cortical neurons) where their secreted cross-corrective enzyme mediated a therapeutic impact unachieved by cells alone. Such a “designer” cytokine receptor-agonist peptide illustrates that treatments can be controlled and optimized by exploiting fundamental stem cell properties (e.g., “inflammo-attraction”).

Therapeutic Advancement in Neuronal Transdifferentiation of Mesenchymal Stromal Cells for Neurological Disorders

Neurodegenerative disorders have become the leading cause of chronic pain and death. Treatments available are not sufficient to help the patients as they only alleviate the symptoms and not the cause. In this regard, stem cells therapy has emerged as an upcoming option for the replacement of dead and damaged neurons. Stem cells, in general, are characterized as cells exhibiting potency properties, i.e., on being subjected to specific conditions they transform into cells of another lineage. Of all the types, mesenchymal stem cells (MSCs) are known for their pluripotent nature without the obstacle of ethical concern surrounding the procurement of other cell types. Although fibroblasts are quite similar to MSCs morphologically, certain markers like CD73, CD 90 are specific to MSCs, making both the cell types distinguishable from each other. This is implemented while procuring MSCs from a plethora of sources like umbilical cord blood, adipose tissue, bone marrow, etc. Among these, bone marrow MSCs are the most widely used type for neural regeneration. Neural regeneration is achieved via transdifferentiation. Several studies have either transplanted the stem cells into rodent models or have carried out transdifferentiation in vitro. The process involves a combination of growth factors, pre-treatment factors, and neuronal differentiation inducing mediums. The results obtained are characterized by neuron-like morphology, expression of markers, along with electrophysical activity in some. Recent attempts involve exploring biomaterials that may mimic the native ECM and therefore can be directly introduced at the site of interest. The review gives a brief description of MSCs, their sources and markers, and the different attempts that have been made towards achieving the goal of differentiating MSCs into neurons.

Rodent Models of Amyloid-Beta Feature of Alzheimer's Disease: Development and Potential Treatment Implications

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide and causes severe financial and social burdens. Despite much research on the pathogenesis of AD, the neuropathological mechanisms remain obscure and current treatments have proven ineffective. In the past decades, transgenic rodent models have been used to try to unravel this disease, which is crucial for early diagnosis and the assessment of disease-modifying compounds. In this review, we focus on transgenic rodent models used to study amyloid-beta pathology in AD. We also discuss their possible use as promising tools for AD research. There is still no effective treatment for AD and the development of potent therapeutics are urgently needed. Many molecular pathways are susceptible to AD, ranging from neuroinflammation, immune response, and neuroplasticity to neurotrophic factors. Studying these pathways may shed light on AD pathophysiology as well as provide potential targets for the development of more effective treatments. This review discusses the advantages and limitations of these models and their potential therapeutic implications for AD.

Aligned collagen scaffold combination with human spinal cord-derived neural stem cells to improve spinal cord injury repair

Neural stem/progenitor cell (NSPC)-based spinal cord injury (SCI) therapy is expected to bridge the lesion site by transplanting exogenous NSPCs for replacement of lost cells. The transplanted NSPCs produce a microenvironment conducive to neuronal regeneration, and ultimately, functional recovery. Although both human fetal brain- and spinal cord- derived NSPCs (hbNSPCs and hscNSPCs, respectively) have been used for SCI repair, it remains unclear whether hscNSPCs are a more appropriate stem cell source for transplantation than hbNSPCs. Therefore, in this study, we transplanted hbNSPCs or hscNSPCs into rats with complete transection SCI to monitor their differences in SCI treatment. An aligned collagen sponge scaffold (ACSS) was used here for cell retention. Aligned biomaterial scaffolds provide a support platform and favorable morphology for cell growth and differentiation, and guide axial axonal extension. The ACSS fabricated by our group has been previously reported to improve spinal cord repair by promoting neuronal regeneration and remyelination. Compared with the hbNSPC-ACSS, the hscNSPC-ACSS effectively promoted long-term cell survival and neuronal differentiation and improved the SCI microenvironment by reducing inflammation and glial scar formation. Furthermore, the transplanted hscNSPC-ACSS improved recovery of locomotor functions. Therefore, hscNSPCs appear to be a superior cell source to hbNSPCs for SCI cell therapy with greater potential clinical applications.

Full small molecule conversion of human fibroblasts to neuroectodermal cells via a cocktail of Dorsomorphin and Trichostatin A

A revolutionary new approach to produce efficient cells is to induce transdifferentiation to make it conventional in therapeutic strategies. In this paper, we describe a brief cocktail of small molecules including Dorsomorphin (DSM) and Trichostatin A (TSA) to produce safe neuroectodermal cells as a resource to produce various types of nervous system cells for a safe cytotherapy. Furthermore, in order to optimize this strategy, we implemented a cocktail of neurotrophic factors to enhance the viability of the cell. This modification was accompanied by pretreatment of the culture dishes with a combination of poly-l-ornithine and laminin and fibronectin. In order to decrease the length of protocol and transdifferentiation variation concomitantly, TSA was utilized as an epigenetic modulator. Finally, this improved protocol mediated neuroectodermal conversion of human fibroblasts within 12 days with an average efficiency of 24%, promising a fast strategy to produce neuroectodermal cells applicable for therapeutic purposes in neural damages. Here we induce neural cells by a cocktail consists of two small molecules of DSM and TSA. Our protocol is a 12 day protocol with the efficiency of 24% which is a more efficient one in comparison to previous protocols inducing neural cells. Consequently, our protocol shortens the path of in vitro and preclinical studies in the field of neural conversion and neuroregeneration.

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Full small molecule conversion of human fibroblasts to neuroectodermal cells became feasible.

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Application of only 2 small molecules made this conversion possible.

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A 12 day protocol with average efficiency of 24% promises a fast strategy to produce converted human neuroectodermal cells for cytotherapy goals.

Cellular Response of Ventricular-Subventricular Neural Progenitor/Stem Cells to Neonatal Hypoxic-Ischemic Brain Injury and Their Enhanced Neurogenesis

PURPOSE

To elucidate the brain's intrinsic response to injury, we tracked the response of neural stem/progenitor cells (NSPCs) located in ventricular-subventricular zone (V-SVZ) to hypoxic-ischemic brain injury (HI). We also evaluated whether transduction of V-SVZ NSPCs with neurogenic factor NeuroD1 could enhance their neurogenesis in HI.

MATERIALS AND METHODS

Unilateral HI was induced in ICR neonatal mice. To label proliferative V-SVZ NSPCs in response to HI, bromodeoxyuridine (BrdU) and retroviral particles encoding LacZ or NeuroD1/GFP were injected. The cellular responses of NSPCs were analyzed by immunohistochemistry.

RESULTS

Unilateral HI increased the number of BrdU+ newly-born cells in the V-SVZ ipsilateral to the lesion while injury reduced the number of newly-born cells reaching the ipsilateral olfactory bulb, which is the programmed destination of migratory V-SVZ NSPCs in the intact brain. These newly-born cells were directed from this pathway towards the lesions. HI significantly increased the number of newly-born cells in the cortex and striatum by the altered migration of V-SVZ cells. Many of these newly-born cells differentiated into active neurons and glia. LacZ-expressing V-SVZ NSPCs also showed extensive migration towards the non-neurogenic regions ipsilateral to the lesion, and expressed the neuronal marker NeuN. NeuroD1+/GFP+ V-SVZ NSPCs almost differentiated into neurons in the peri-infarct regions.

CONCLUSION

HI promotes the establishment of a substantial number of new neurons in non-neurogenic regions, suggesting intrinsic repair mechanisms of the brain, by controlling the behavior of endogenous NSPCs. The activation of NeuroD1 expression may improve the therapeutic potential of endogenous NSPCs by increasing their neuronal differentiation in HI.

[Effect of the local application of stem cells on repairing facial nerve defects: a systematic review]

OBJECTIVE

To systematically evaluate the repairing effect of stem cells on facial nerve defects.

METHODS

Articles regarding the regenerating effect of stem cells on facial nerves in animals were collected from the databases of Pubmed, Cochrane Library, Web of Science, Embase, Scopus, and CBM. Two professionals independently completed the article screening, data extraction, and bias risk assessment. RevMan 5.3 and random-effects models were used for the statistical analysis, and the results were presented in the form of mean differences (MD) with a 95%CI. The results of functional evaluation (vibrissae movement, facial paralysis) and histological evaluation (density of myelinated fibers, diameter of fibers, thickness of myelin sheath, G ratio) of facial nerve were Meta-analyzed.

RESULTS

A total of 4 614 articles were retrieved from the 6 databases, and 15 of these articles were included in the Meta-analysis. For vibrissae movement and facial paralysis, the stem cell group scored significantly higher than the non-stem cell group (P<0.05). The density of myelinated fibers and thickness of the myelin sheath in the stem cell group were higher than those in the non-stem cell group (P<0.05). The G ratio in the stem cell group was smaller than that in the non-stem cell group (P=0.001). There was no significant difference in fiber diameter (P=0.08).

CONCLUSIONS

Stem cells have potential in promoting facial nerve regeneration.

Piezoelectric Scaffolds as Smart Materials for Neural Tissue Engineering

Injury to the central or peripheral nervous systems leads to the loss of cognitive and/or sensorimotor capabilities, which still lacks an effective treatment. Tissue engineering in the post-injury brain represents a promising option for cellular replacement and rescue, providing a cell scaffold for either transplanted or resident cells. Tissue engineering relies on scaffolds for supporting cell differentiation and growth with recent emphasis on stimuli responsive scaffolds, sometimes called smart scaffolds. One of the representatives of this material group is piezoelectric scaffolds, being able to generate electrical charges under mechanical stimulation, which creates a real prospect for using such scaffolds in non-invasive therapy of neural tissue. This paper summarizes the recent knowledge on piezoelectric materials used for tissue engineering, especially neural tissue engineering. The most used materials for tissue engineering strategies are reported together with the main achievements, challenges, and future needs for research and actual therapies. This review provides thus a compilation of the most relevant results and strategies and serves as a starting point for novel research pathways in the most relevant and challenging open questions.

High-content imaging of 3D-cultured neural stem cells on a 384-pillar plate for the assessment of cytotoxicity

The assessment of neurotoxicity has been performed traditionally with animals. However, in vivo studies are highly expensive and time-consuming, and often do not correlate to human outcomes. Thus, there is a need for cost-effective, high-throughput, highly predictive alternative in vitro test methods based on early markers of mechanisms of toxicity. High-content imaging (HCI) assays performed on three-dimensionally (3D) cultured cells could provide better understanding of the mechanism of toxicity needed to predict neurotoxicity in humans. However, current 3D cell culture systems lack the throughput required for screening neurotoxicity against a large number of chemicals. Therefore, we have developed miniature 3D neural stem cell (NSC) culture on a unique 384-pillar plate, which is complementary to conventional 384-well plates. Mitochondrial membrane impairment, intracellular glutathione level, cell membrane integrity, DNA damage, and apoptosis have been tested against 3D-cultured ReNcell VM on the 384-pillar plate with four model compounds rotenone, 4-aminopyridine, digoxin, and topotecan. The HCI assays performed in 3D-cultured ReNcell VM on the 384-pillar plates were highly robust and reproducible as indicated by the average Z' factor of 0.6 and CV values around 12%. From concentration-response curves and IC₅₀ values, mitochondrial membrane impairment appears to be the early stage marker of cell death by the compounds.

mRNA-Driven Generation of Transgene-Free Neural Stem Cells from Human Urine-Derived Cells

Human neural stem cells (NSCs) hold enormous promise for neurological disorders, typically requiring their expandable and differentiable properties for regeneration of damaged neural tissues. Despite the therapeutic potential of induced NSCs (iNSCs), a major challenge for clinical feasibility is the presence of integrated transgenes in the host genome, contributing to the risk for undesired genotoxicity and tumorigenesis. Here, we describe the advanced transgene-free generation of iNSCs from human urine-derived cells (HUCs) by combining a cocktail of defined small molecules with self-replicable mRNA delivery. The established iNSCs were completely transgene-free in their cytosol and genome and further resembled human embryonic stem cell-derived NSCs in the morphology, biological characteristics, global gene expression, and potential to differentiate into functional neurons, astrocytes, and oligodendrocytes. Moreover, iNSC colonies were observed within eight days under optimized conditions, and no teratomas formed in vivo, implying the absence of pluripotent cells. This study proposes an approach to generate transplantable iNSCs that can be broadly applied for neurological disorders in a safe, efficient, and patient-specific manner.

Derivation of Neural Stem Cells from the Developing and Adult Human Brain

Neural stem cells isolated from the developing and adult brain are an ideal source of cells for use in clinical applications such as cell replacement therapy. The clear advantage of these cells over the more commonly utilised embryonic and pluripotent stem cells is that they are already neurally committed. Of particular importance is the fact that these cells don't require the same level of in vitro culture that can be cost and labour intensive. Foetal neural stem cells can be readily derived from the foetal brain and expand in culture over time. Similarly, adult stem cells have been explored for their potential in vitro and in vivo animal models. In this chapter we identify the progress made in developing these cells as well as the advantages of taking them forward for clinical use.

Choroid plexus-derived miR-204 regulates the number of quiescent neural stem cells in the adult brain

Regulation of adult neural stem cell (NSC) number is critical for lifelong neurogenesis. Here, we identified a post-transcriptional control mechanism, centered around the microRNA 204 (miR-204), to control the maintenance of quiescent (q)NSCs. miR-204 regulates a spectrum of transcripts involved in cell cycle regulation, neuronal migration, and differentiation in qNSCs. Importantly, inhibition of miR-204 function reduced the number of qNSCs in the subependymal zone (SEZ) by inducing pre-mature activation and differentiation of NSCs without changing their neurogenic potential. Strikingly, we identified the choroid plexus of the mouse lateral ventricle as the major source of miR-204 that is released into the cerebrospinal fluid to control number of NSCs within the SEZ. Taken together, our results describe a novel mechanism to maintain adult somatic stem cells by a niche-specific miRNA repressing activation and differentiation of stem cells.

Development of glial restricted human neural stem cells for oligodendrocyte differentiation in vitro and in vivo

In this study, we have developed highly expandable neural stem cells (NSCs) from HESCs and iPSCs that artificially express the oligodendrocyte (OL) specific transcription factor gene Zfp488. This is enough to restrict them to an exclusive oligodendrocyte progenitor cell (OPC) fate during differentiation in vitro and in vivo. During CNS development, Zfp488 is induced during the early stages of OL generation, and then again during terminal differentiation of OLs. Interestingly, the human ortholog Znf488, crucial for OL development in human, has been recently identified to function as a dorsoventral pattering regulator in the ventral spinal cord for the generation of P1, P2/pMN, and P2 neural progenitor domains. Forced expression of Zfp488 gene in human NSCs led to the robust generation of OLs and suppression of neuronal and astrocyte fate in vitro and in vivo. Zfp488 expressing NSC derived oligodendrocytes are functional and can myelinate rat dorsal root ganglion neurons in vitro, and form myelin in Shiverer mice brain in vivo. After transplantation near a site of demyelination, Zfp488 expressing hNSCs migrated to the lesion and differentiated into premyelinating OLs. A certain fraction also homed in the subventricular zone (SVZ). Zfp488-ZsGreen1-hNSC derived OLs formed compact myelin in Shiverer mice brain seen under the electron microscope. Transplanted human neural stem cells (NSC) that have the potential to differentiate into functional oligodendrocytes in response to remyelinating signals can be a powerful therapeutic intervention for disorders where oligodendrocyte (OL) replacement is beneficial.

Concise Review: Human-Animal Neurological Chimeras: Humanized Animals or Human Cells in an Animal?

Blastocyst complementation is an emerging methodology in which human stem cells are transferred into genetically engineered preimplantation animal embryos eventually giving rise to fully developed human tissues and organs within the animal host for use in regenerative medicine. The ethical issues surrounding this method have caused the National Institutes of Health to issue a moratorium on funding for blastocyst complementation citing the potential for human cells to substantially contribute to the brain of the chimeric animal. To address this concern, we performed an in-depth review of the neural transplantation literature to determine how the integration of human cells into the nonhuman neural circuitry has altered the behavior of the host. Despite reports of widespread integration of human cell transplants, our review of 150 transplantation studies found no evidence suggestive of humanization of the animal host, and we thus conclude that, at present, concerns over humanization should not prevent research on blastocyst complementation to continue. We suggest proceeding in a controlled and transparent manner, however, and include recommendations for future research with careful consideration for how human cells may contribute to the animal host nervous system. Stem Cells 2019;37:444-452.

Mary Jane Hogue (1883-1962): A pioneer in human brain tissue culture

The ability to maintain human brain explants in tissue culture was a critical step in the use of these cells for the study of central nervous system disorders. Ross G. Harrison (1870-1959) was the first to successfully maintain frog medullary tissue in culture in 1907, but it took another 38 years before successful culture of human brain tissue was accomplished. One of the pioneers in this achievement was Mary Jane Hogue (1883-1962). Hogue was born into a Quaker family in 1883 in West Chester, Pennsylvania, and received her undergraduate degree from Goucher College in Baltimore, Maryland. Research with the developmental biologist Theodor Boveri (1862-1915) in Würzburg, Germany, resulted in her Ph.D. (1909). Hogue transitioned from studying protozoa to the culture of human brain tissue in the 1940s and 1950s, when she was one of the first to culture cells from human fetal, infant, and adult brain explants. We review Hogue's pioneering contributions to the study of human brain cells in culture, her putative identification of progenitor neuroblast and/or glioblast cells, and her use of the cultures to study the cytopathogenic effects of poliovirus. We also put Hogue's work in perspective by discussing how other women pioneers in tissue culture influenced Hogue and her research.

Identification of characteristic genes distinguishing neural stem cells from astrocytes

BACKGROUND

Neural stem cells (NSCs) have unique biological characteristics such as continuous proliferation and multipotential differentiation, providing a possible method for restoration of central nervous system (CNS) function after injury or disease. NSCs and astrocytes share many similar biological properties including cell morphology and molecular expression and can trans-differentiate into each other under certain conditions. However, characteristic genes specifically expressed by NSCs have not been well described.

METHODS

To provide insights into the characteristic expression of NSCs, bioinformatics analysis of two microarrays of mouse NSCs and astrocytes was performed. Compared to astrocytes, the differentially expressed genes (DEGs) in NSCs were identified and annotated by GO, KEGG and GSEA analysis, respectively. Then key genes were screened by protein-protein interaction (PPI) network and modules analysis, and were verified using multiple high-throughput sequencing resources. Finally, the expression difference between the two cell types was confirmed by Real-time Quantitative PCR (qPCR), western blotting and immunochemical analysis.

RESULTS

In the present study, 282 and 250 NSC-enriched genes from two microarrays were identified and annotated respectively, and the 77 overlapping DEGs were then selected. From the PPI network 24 key genes in three modules were screened out. Importantly, sequencing data of tissues showed that these 24 key genes tended to be highly expressed in NSCs compared with astrocytes. Furthermore, qPCR and western blot analysis of cultured NSCs and astrocytes showed two genes (KIF2C and TOP2A) were not only differentially expressed in RNA level but also at the protein level. Importantly, the NSC-specific genes KIF2C and TOP2A were validated by immunohistochemistry in vivo.

CONCLUSION

In present study, we identified 2 hub genes (KIF2C and TOP2A) that might serve as potential biomarkers for distinguishing NSCs from astrocytes, contributing to our comprehensive understanding of the biological properties and functions of NSCs.

Oligodendrocyte differentiation from human neural stem cells: A novel role for c-Src

Human neural stem cells (hNSCs) can differentiate into an oligodendrocyte lineage to facilitate remyelination in patients. Molecular mechanisms underlying oligodendrocyte fate specification remains unknown, hindering the development of efficient methods to generate oligodendrocytes from hNSCs. We have found that Neurobasal-A medium (NB) is capable of inducing hNSCs to oligodendrocyte progenitor cells (OPCs). We identified several signaling molecules are altered after cultivation in NB medium, including Akt, ERK1/2 and c-Src. While sustained activation of Akt and ERK1/2 during both NB induction and subsequent differentiation was required for OPC differentiation, c-Src phosphorylation was increased temporally during the period of NB induction. Both pharmacological inhibition and RNA interference confirmed that a transient elevation of phospho-c-Src is critical for OPC induction. Furthermore, inactivation of c-Src inhibited phosphorylation of Akt and ERK1/2. In summary, we identified a novel and critical role of c-Src in guiding hNSC differentiation to an oligodendrocyte lineage.

In Vivo Long-Term Tracking of Neural Stem Cells Transplanted into an Acute Ischemic Stroke model with Reporter Gene-Based Bimodal MR and Optical Imaging

Transplantation of neural stem cells (NSCs) is emerging as a new therapeutic approach for stroke. Real-time imaging of transplanted NSCs is essential for successful cell delivery, safety monitoring, tracking cell fate and function, and understanding the interactions of transplanted cells with the host environment. Magnetic resonance imaging (MRI) of magnetic nanoparticle-labeled cells has been the most widely used means to track stem cells in vivo. Nevertheless, it does not allow for the reliable discrimination between live and dead cells. Reporter gene-based MRI was considered as an alternative strategy to overcome this shortcoming. In this work, a class of lentiviral vector-encoding ferritin heavy chain (FTH) and enhanced green fluorescent protein (EGFP) was constructed to deliver reporter genes into NSCs. After these transgenic NSCs were transplanted into the contralateral hemisphere of rats with acute ischemic stroke, MRI and fluorescence imaging (FLI) were performed in vivo for tracking the fate of transplanted cells over a long period of 6 wk. The results demonstrated that the FTH and EGFP can be effectively and safely delivered to NSCs via the designed lentiviral vector. The distribution and migration of grafted stem cells could be monitored by bimodal MRI and FLI. FTH can be used as a robust MRI reporter for reliable reporting of the short-term viability of cell grafts, whereas its capacity for tracking the long-term viability of stem cells remains dependent on several confounding factors such as cell death and the concomitant reactive inflammation.

Bcl-2 Overexpression Improves Survival and Efficacy of Neural Stem Cell-Mediated Enzyme Prodrug Therapy

Tumor-tropic neural stem cells (NSCs) can be engineered to localize gene therapies to invasive brain tumors. However, like other stem cell-based therapies, survival of therapeutic NSCs after transplantation is currently suboptimal. One approach to prolonging cell survival is to transiently overexpress an antiapoptotic protein within the cells prior to transplantation. Here, we investigate the utility and safety of this approach using a clinically tested, v-myc immortalized, human NSC line engineered to contain the suicide gene, cytosine deaminase (CD-NSCs). We demonstrate that both adenoviral- and minicircle-driven expression of the antiapoptotic protein Bcl-2 can partially rescue CD-NSCs from transplant-associated insults. We further demonstrate that the improved CD-NSC survival afforded by transient Bcl-2 overexpression results in decreased tumor burden in an orthotopic xenograft glioma mouse model following administrations of intracerebral CD-NSCs and systemic prodrug. Importantly, no evidence of CD-NSC transformation was observed upon transient overexpression of Bcl-2. This research highlights a critical need to develop clinically relevant strategies to improve survival of therapeutic stem cell posttransplantation. We demonstrate for the first time in this disease setting that improving CD-NSC survival using Bcl-2 overexpression can significantly improve therapeutic outcomes.

Neural stem cell therapy for subacute and chronic ischemic stroke

Neural stem cells (NSCs) play vital roles in brain homeostasis and exhibit a broad repertoire of potentially therapeutic actions following neurovascular injury. One such injury is stroke, a worldwide leading cause of death and disability. Clinically, extensive injury from ischemic stroke results from ischemia-reperfusion (IR), which is accompanied by inflammation, blood-brain barrier (BBB) damage, neural cell death, and extensive tissue loss. Tissue plasminogen activator (tPA) is still the only US Food and Drug Administration-approved clot-lysing agent. Whereas the thrombolytic role of tPA within the vasculature is beneficial, the effects of tPA (in a non-thrombolytic role) within the brain parenchyma have been reported as harmful. Thus, new therapies are needed to reduce the deleterious side effects of tPA and quickly facilitate vascular repair following stroke. The Stroke Treatment Academic Industry Roundtable (STAIR) recommends that stroke therapies "focus on drugs/devices/treatments with multiple mechanisms of action and that target multiple pathways". Thus, based on multifactorial ischemic cascades in various stroke stages, effective stroke therapies need to focus on targeting and ameliorating early IR injury as well as facilitating angiogenesis, neurogenesis, and neurorestorative mechanisms following stroke. This review will discuss the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury and will emphasize both the subacute and chronic phase of ischemic stroke.

Neuronal Cell Sheets of Cortical Motor Neuron Phenotype Derived from Human iPSCs

Transplantation of stem cells that differentiate into more mature neural cells brings about functional improvement in preclinical studies of stroke. Previous transplant approaches in the diseased brain utilized injection of the cells in a cell suspension. In addition, neural stem cells were preferentially used for grafting. However, these cells had no specific relationship to the damaged tissue of stroke and brain injury patients. The injection of cells in a suspension destroyed the cell–cell interactions that are suggested to be important for promoting functional integrity of cortical motor neurons. In order to obtain suitable cell types for grafting in patients with stroke and brain damage, a protocol was modified for differentiating human induced pluripotent stem cells from cells phenotypically related to cortical motor neurons. Moreover, cell sheet technology was applied to neural cell transplantation, as maintaining the cell–cell communications is regarded important for the repair of host brain architecture. Accordingly, neuronal cell sheets that were positive Forebrain Embryonic Zinc Finger (Fez) family zinc finger 2 (FEZF2), COUP-TF-interacting protein 2, insulin-like growth factor–binding protein 4 (IGFBP4), cysteine-rich motor neuron 1 protein precursor (CRIM1), and forkhead box p2 (FOXP2) were developed. These markers are associated with cortical motoneurons that are appropriate for the transplant location in the lesions. The sheets allowed preservation of cell–cell interactions shown by synapsin1 staining after transplantation to damaged mouse brains. The sheet transplantation brought about partial structural restoration and the improvement of motor functions in hemiplegic mice. Collectively, the novel neuronal cell sheets were transplanted into damaged motor cortices; the cell sheets maintained cell–cell interactions and improved the motor functions in the hemiplegic model mice. The motoneuron cell sheets are possibly applicable for stroke patients and patients with brain damage by using patient-specific induced pluripotent stem cells.

Enhancing endogenous capacity to repair a stroke-damaged brain: An evolving field for stroke research

Stroke represents a severe medical condition that causes stroke survivors to suffer from long-term and even lifelong disability. Over the past several decades, a vast majority of stroke research targets neuroprotection in the acute phase, while little work has been done to enhance stroke recovery at the later stage. Through reviewing current understanding of brain plasticity, stroke pathology, and emerging preclinical and clinical restorative approaches, this review aims to provide new insights to advance the research field for stroke recovery. Lifelong brain plasticity offers the long-lasting possibility to repair a stroke-damaged brain. Stroke impairs the structural and functional integrity of entire brain networks; the restorative approaches containing multi-components have great potential to maximize stroke recovery by rebuilding and normalizing the stroke-disrupted entire brain networks and brain functioning. The restorative window for stroke recovery is much longer than previously thought. The optimal time for brain repair appears to be at later stage of stroke rather than the earlier stage. It is expected that these new insights will advance our understanding of stroke recovery and assist in developing the next generation of restorative approaches for enhancing brain repair after stroke.

An open-label proof-of-concept study of intrathecal autologous bone marrow mononuclear cell transplantation in intellectual disability

Background

The underlying pathophysiology in intellectual disability (ID) involves abnormalities in dendritic branching and connectivity of the neuronal network. This limits the ability of the brain to process information. Conceptually, cellular therapy through its neurorestorative and neuroregenerative properties can counteract these pathogenetic mechanisms and improve neuronal connectivity. This improved networking should exhibit as clinical efficacy in patients with ID.

Methods

To assess the safety and efficacy of cellular therapy in patients with ID, we conducted an open-label proof-of-concept study from October 2011 to December 2015. Patients were divided into two groups: intervention group (n = 29) and rehabilitation group (n = 29). The intervention group underwent cellular transplantation consisting of intrathecal administration of autologous bone marrow mononuclear cells and standard neurorehabilitation. The rehabilitation group underwent only standard neurorehabilitation.

The results of the symptomatic outcomes were compared between the two groups. In the intervention group analysis, the outcome measures used were the intelligence quotient (IQ) and the Wee Functional Independence Measure (Wee-FIM). To compare the pre-intervention and post-intervention results, statistical analysis was done using Wilcoxon’s matched-pairs test for Wee-FIM scores and McNemar’s test for symptomatic improvements and IQ. The effect of age and severity of the disorder were assessed for their impact on the outcome of intervention. Positron emission tomography-computed tomography (PET-CT) brain scan was used as a monitoring tool to study effects of the intervention. Adverse events were monitored for the safety of cellular therapy.

Results

On symptomatic analysis, greater improvements were seen in the intervention group as compared to the rehabilitation group. In the intervention group, the symptomatic improvements, IQ and Wee-FIM were statistically significant. A significantly better outcome of the intervention was found in the paediatric age group (<18 years) and patients with milder severity of ID. Repeat PET-CT scan in three patients of the intervention group showed improved metabolism in the frontal, parietal cortex, thalamus, mesial temporal structures and cerebellum. No major adverse events were witnessed.

Conclusions

Cellular transplantation with neurorehabilitation is safe and effective for the treatment of underlying brain deficits in ID.

Trial registration

ClinicalTrials.gov NCT02245724. Registered 12 September 2014.

Tumor-homing cytotoxic human induced neural stem cells for cancer therapy

Engineered neural stem cells (NSCs) are a promising approach to treating glioblastoma (GBM). The ideal NSC drug carrier for clinical use should be easily isolated and autologous to avoid immune rejection. We transdifferentiated (TD) human fibroblasts into tumor-homing early-stage induced NSCs (h-iNSC^TE), engineered them to express optical reporters and different therapeutic gene products, and assessed the tumor-homing migration and therapeutic efficacy of cytotoxic h-iNSC^TE in patient-derived GBM models of surgical and nonsurgical disease. Molecular and functional analysis revealed that our single-factor SOX2 TD strategy converted human skin fibroblasts into h-iNSC^TE that were nestin⁺ and expressed pathways associated with tumor-homing migration in 4 days. Time-lapse motion analysis showed that h-iNSC^TE rapidly migrated to human GBM cells and penetrated human GBM spheroids, a process inhibited by blockade of CXCR4. Serial imaging showed that h-iNSC^TE delivery of the proapoptotic agent tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL) reduced the size of solid human GBM xenografts 250-fold in 3 weeks and prolonged median survival from 22 to 49 days. Additionally, h-iNSC^TE thymidine kinase/ganciclovir enzyme/prodrug therapy (h-iNSC^TE-TK) reduced the size of patient-derived GBM xenografts 20-fold and extended survival from 32 to 62 days. Mimicking clinical NSC therapy, h-iNSC^TE-TK therapy delivered into the postoperative surgical resection cavity delayed the regrowth of residual GBMs threefold and prolonged survival from 46 to 60 days. These results suggest that TD of human skin into h-iNSC^TE is a platform for creating tumor-homing cytotoxic cell therapies for cancer, where the potential to avoid carrier rejection could maximize treatment durability in human trials.

Updates on Human Neural Stem Cells: From Generation, Maintenance, and Differentiation to Applications in Spinal Cord Injury Research

Human neural stem cells (hNSCs) and human induced pluripotent stem cells (hiPSCs) have been the primary focuses in basic science and translational research as well as in investigative clinical applications. Therefore, the capability to perform reliable derivation, effective expansion, and long-term maintenance of uncommitted hNSCs and hiPSCs and their targeted phenotypic differentiations through applying chemically and biologically defined medium in vitro is essential for expanding and enriching the fundamental and technological capacities of stem cell biology and regenerative medicine. In this chapter, we systematically summarized a set of protocols and unique procedures that have been developed in the laboratories of Prof. Teng and his collaborators. These regimens have been, over the years, reproducibly and productively used to derive, propagate, maintain, and differentiate hNSCs, including those derived from hiPSCs. We emphasize the multimodal methodologies that were pioneered and established in our laboratories for characterizing functional multipotency of stem cells and its value in basic science as well as translational biomedical studies.

The state of the art in stem cell biology and regenerative medicine: the end of the beginning

With translational stem cell biology and Regenerative Medicine (the field to which the former gave rise) now over a quarter century old, it is time to take stock of where we have been and where we are going. This editorial overview, which serves as an introduction to this special issue of Pediatric Research dedicated to these fields, reinforces the notion that stem cells are ultimately intrinsic parts of developmental biology, for which Pediatrics represents the clinical face. Although stem cells provide the cellular basis for a great deal of only recently recognized plasticity programmed into the developing and postdevelopmental organism, and although there is enormous promise in harnessing this plasticity for therapeutic advantage, their successful use rests on a deep understanding of their developmental imperatives and the developmental programs in which they engage. The potential uses of stems are ranked and discussed in the order of most readily achievable to those requiring extensively more work. Although that order may not be what was contemplated at the field's birth, we nevertheless retain an optimism for the ultimate positive impact of exploiting this fundamental biology for the well-being of children.

Neural Stem Cells and Its Derivatives as a New Material for Melanin Inhibition

The pigment molecule, melanin, is produced from melanosomes of melanocytes through melanogenesis, which is a complex process involving a combination of chemical and enzymatically catalyzed reactions. The synthesis of melanin is primarily influenced by tyrosinase (TYR), which has attracted interest as a target molecule for the regulation of pigmentation or depigmentation in skin. Thus, direct inhibitors of TYR activity have been sought from various natural and synthetic materials. However, due to issues with these inhibitors, such as weak or permanent ability for depigmentation, allergy, irritant dermatitis and rapid oxidation, in vitro and in vivo, the development of new materials that inhibit melanin production is essential. A conditioned medium (CM) derived from stem cells contains many cell-secreted factors, such as cytokines, chemokines, growth factors and extracellular vesicles including exosomes. In addition, the secreted factors could negatively regulate melanin production through stimulation of a microenvironment of skin tissue in a paracrine manner, which allows the neural stem cell CM to be explored as a new material for skin depigmentation. In this review, we will summarize the current knowledge regulating depigmentation, and discuss the potential of neural stem cells and their derivatives, as a new material for skin depigmentation.

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

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

Role of MEK partner-1 in cancer stemness through MEK/ERK pathway in cancerous neural stem cells, expressing EGFRviii

Background

Glioma stem cells (GSCs) are a major cause of the frequent relapse observed in glioma, due to their high drug resistance and their differentiation potential. Therefore, understanding the molecular mechanisms governing the ‘cancer stemness’ of GSCs will be particularly important for improving the prognosis of glioma patients.

Methods

We previously established cancerous neural stem cells (CNSCs) from immortalized human neural stem cells (F3 cells), using the H-Ras oncogene. In this study, we utilized the EGFRviii mutation, which frequently occurs in brain cancers, to establish another CNSC line (F3.EGFRviii), and characterized its stemness under spheroid culture.

Results

The F3.EGFRviii cell line was highly tumorigenic in vitro and showed high ERK1/2 activity as well as expression of a variety of genes associated with cancer stemness, such as SOX2 and NANOG, under spheroid culture conditions. Through meta-analysis, PCR super-array, and subsequent biochemical assays, the induction of MEK partner-1 (MP1, encoded by the LAMTOR3 gene) was shown to play an important role in maintaining ERK1/2 activity during the acquisition of cancer stemness under spheroid culture conditions. High expression of this gene was also closely associated with poor prognosis in brain cancer.

Conclusion

These data suggest that MP1 contributes to cancer stemness in EGFRviii-expressing glioma cells by driving ERK activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0703-y) contains supplementary material, which is available to authorized users.

Functional Stem Cell Integration into Neural Networks Assessed by Organotypic Slice Cultures

Re-formation or preservation of functional, electrically active neural networks has been proffered as one of the goals of stem cell-mediated neural therapeutics. A primary issue for a cell therapy approach is the formation of functional contacts between the implanted cells and the host tissue. Therefore, it is of fundamental interest to establish protocols that allow us to delineate a detailed time course of grafted stem cell survival, migration, differentiation, integration, and functional interaction with the host. One option for in vitro studies is to examine the integration of exogenous stem cells into an existing active neural network in ex vivo organotypic cultures. Organotypic cultures leave the structural integrity essentially intact while still allowing the microenvironment to be carefully controlled. This allows detailed studies over time of cellular responses and cell-cell interactions, which are not readily performed in vivo. This unit describes procedures for using organotypic slice cultures as ex vivo model systems for studying neural stem cell and embryonic stem cell engraftment and communication with CNS host tissue. © 2017 by John Wiley & Sons, Inc.

Human Umbilical Cord Blood Cells can be Induced to Express Markers for Neurons and Glia

Rare cells are present in human umbilical cord blood that do not express the hematopoietic marker CD45 and in culture do not produce cells of hematopoietic lineage. These umbilical cord multipotent stem cells (UC-MC) behave as multilineage progenitor cells (stem cells) and can be expanded in tissue culture. Exposure to basic fibroblast growth factor (bFGF) and human epidermal growth factor (hEGF) for a minimum of 7 days in culture induces expression of neural and glial markers. Western immunoblots demonstrate expression of both β-tubulin III and glial fibrillary acidic protein (GFAP). Immunocytochemistry of the cells showed intense labeling to both compounds on the intracellular cytoskeleton. The oligodendrocyte cell surface marker galactocerebroside (Gal-C) was present on most cells. Many cells show dual labeling, expressing both neuronal and glial markers.