Transplanted human fetal neural stem cells survive, migrate, and differentiate in ischemic rat cerebral cortex

Regenerative Rehabilitation for Stroke Recovery by Inducing Synergistic Effects of Cell Therapy and Neurorehabilitation on Motor Function: A Narrative Review of Pre-Clinical Studies

Neurological diseases severely affect the quality of life of patients. Although existing treatments including rehabilitative therapy aim to facilitate the recovery of motor function, achieving complete recovery remains a challenge. In recent years, regenerative therapy has been considered as a potential candidate that could yield complete functional recovery. However, to achieve desirable results, integration of transplanted cells into neural networks and generation of appropriate microenvironments are essential. Furthermore, considering the nascent state of research in this area, we must understand certain aspects about regenerative therapy, including specific effects, nature of interaction when administered in combination with rehabilitative therapy (regenerative rehabilitation), and optimal conditions. Herein, we review the current status of research in the field of regenerative therapy, discuss the findings that could hold the key to resolving the challenges associated with regenerative rehabilitation, and outline the challenges to be addressed with future studies. The current state of research emphasizes the importance of determining the independent effect of regenerative and rehabilitative therapies before exploring their combined effects. Furthermore, the current review highlights the progression in the treatment perspective from a state of compensation of lost function to that of a possibility of complete functional recovery.

Evaluation of cell transplant-mediated attenuation of diffuse injury in experimental autoimmune encephalomyelitis using onVDMP CEST MRI

The development and translation of cell therapies have been hindered by an inability to predict and evaluate their efficacy after transplantation. Using an experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS), we studied attenuation of the diffuse injury characteristic of EAE and MS by transplanted glial-restricted precursor cells (GRPs). We assessed the potential of on-resonance variable delay multiple pulse (onVDMP) chemical exchange saturation transfer (CEST) MRI to visualize this attenuation. Allogeneic GRPs transplanted in the motor cortex or lateral ventricles attenuated paralysis in EAE mice and attenuated differences compared to naïve mice in onVDMP CEST signal 5 days after transplantation near the transplantation site. Histological analysis revealed that transplanted GRPs co-localized with attenuated astrogliosis. Hence, diffuse injury-sensitive onVDMP CEST MRI may complement conventional MRI to locate and monitor tissue regions responsive to GRP therapy.

Structural understanding of T cell receptor triggering

The T cell receptor (TCR) is one of the most complicated receptors in mammalian cells, and its triggering mechanism remains mysterious. As an octamer complex, TCR comprises an antigen-binding subunit (TCRαβ) and three CD3 signaling subunits (CD3ζζ, CD3δε, and CD3γε). Engagement of TCRαβ with an antigen peptide presented on the MHC leads to tyrosine phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) in CD3 cytoplasmic domains (CDs), thus translating extracellular binding kinetics to intracellular signaling events. Whether conformational change plays an important role in the transmembrane signal transduction of TCR is under debate. Attracted by the complexity and functional importance of TCR, many groups have been studying TCR structure and triggering for decades using diverse biochemical and biophysical tools. Here, we synthesize these structural studies and discuss the relevance of the conformational change model in TCR triggering.

Parathyroid hormone-producing cells exist in adipose tissues surrounding the parathyroid glands in hemodialysis patients with secondary hyperparathyroidism

Possible ectopic parathyroid hormone (PTH) production in adipose tissues surrounding hyperplastic parathyroid glands was examined in patients with secondary hyperparathyroidism (SHPT). In vitro culture of adipose tissues from 31 patients excised during parathyroidectomy showed PTH secretion in 23 (74.2%) patients. In vitro PTH secretion was detected in adipose tissues adhered to the parathyroid glands from 22 (71.0%) patients, in not-adhered adipose from 11 (35.5%) and in the thymus from four (28.6%) patients. Immunohistochemistry revealed colonies of PTH- and GCM2-positive cells intricately intertwined with adipocytes in excised adipose tissues prior to culture. When pieces of parathyroid parenchyma from SHPT patients were transplanted into the thyroid of immunodeficient nude rats with induced SHPT, the transplants secreted human PTH for one to three-and-half months after transplantation and expressed adipocyte markers, PPARγ2 and perilipin A, that the transplants did not express prior to transplantation. These findings indicate the importance of thoroughly removing adipose tissues surrounding the parathyroid glands when performing parathyroidectomy. We speculate that these ectopic PTH-producing cells are parathyroid parenchymal cells pushed out from the glands along with adipocyte progenitors during nodular growth of hyperplastic parenchymal cells and that these cells proliferate in SHPT, forming colonies PTH-producing cells intricately intertwined with adipocytes.

Translating concepts of neural repair after stroke: Structural and functional targets for recovery

Stroke is among the most common causes of adult disability worldwide, and its disease burden is shifting towards that of a long-term condition. Therefore, the development of approaches to enhance recovery and augment neural repair after stroke will be critical. Recovery after stroke involves complex interrelated systems of neural repair. There are changes in both structure (at the molecular, cellular, and tissue levels) and function (in terms of excitability, cortical maps, and networks) that occur spontaneously within the brain. Several approaches to augment neural repair through enhancing these changes are under study. These include identifying novel drug targets, implementing rehabilitation strategies, and developing new neurotechnologies. Each of these approaches has its own array of different proposed mechanisms. Current investigation has emphasized both cellular and circuit-based targets in both gray and white matter, including axon sprouting, dendritic branching, neurogenesis, axon preservation, remyelination, blood brain barrier integrity, blockade of extracellular inhibitory signals, alteration of excitability, and promotion of new brain cortical maps and networks. Herein, we review for clinicians recovery after stroke, basic elements of spontaneous neural repair, and ongoing work to augment neural repair. Future study requires alignment of basic, translational, and clinical research. The field continues to grow while becoming more clearly defined. As thrombolysis changed stroke care in the 1990 s and thrombectomy in the 2010 s, the augmentation of neural repair and recovery after stroke may revolutionize care for these patients in the coming decade.

Monitoring maturation of neural stem cell grafts within a host microenvironment

Neural stem cells (NSC) act as a versatile tool for neuronal cell replacement strategies to treat neurodegenerative disorders in which functional neurorestorative mechanisms are limited. While the beneficial effects of such cell-based therapy have already been documented in terms of neurodegeneration of various origins, a neurophysiological basis for improvement in the recovery of neurological function is still not completely understood. This overview briefly describes the cumulative evidence from electrophysiological studies of NSC-derived neurons, aimed at establishing the maturation of differentiated neurons within a host microenvironment, and their integration into the host circuits, with a particular focus on the neurogenesis of NSC grafts within the post-ischemic milieu. Overwhelming evidence demonstrates that the host microenvironment largely regulates the lineage of NSC grafts. This regulatory role, as yet underestimated, raises possibilities for the favoured maturation of a subset of neural phenotypes in order to gain timely remodelling of the impaired brain tissue and amplify the therapeutic effects of NSC-based therapy for recovery of neurological function.

Neural stem cell transplantation therapy for brain ischemic stroke: Review and perspectives

Brain ischemic stroke is one of the most common causes of death and disability, currently has no efficient therapeutic strategy in clinic. Due to irreversible functional neurons loss and neural tissue injury, stem cell transplantation may be the most promising treatment approach. Neural stem cells (NSCs) as the special type of stem cells only exist in the nervous system, can differentiate into neurons, astrocytes, and oligodendrocytes, and have the abilities to compensate insufficient endogenous nerve cells and improve the inflammatory microenvironment of cell survival. In this review, we focused on the important role of NSCs therapy for brain ischemic stroke, mainly introduced the methods of optimizing the therapeutic efficacy of NSC transplantation, such as transfection and overexpression of specific genes, pretreatment of NSCs with inflammatory factors, and co-transplantation with cytokines. Next, we discussed the potential problems of NSC transplantation which seriously limited their rapid clinical transformation and application. Finally, we expected a new research topic in the field of stem cell research. Based on the bystander effect, exosomes derived from NSCs can overcome many of the risks and difficulties associated with cell therapy. Thus, as natural seed resource of nervous system, NSCs-based cell-free treatment is a newly therapy strategy, will play more important role in treating ischemic stroke in the future.

A NeuroD1 AAV-Based Gene Therapy for Functional Brain Repair after Ischemic Injury through In Vivo Astrocyte-to-Neuron Conversion

Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 adeno-associated virus (AAV)-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level. Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Anterograde and retrograde tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.

Adult Stem Cells and Induced Pluripotent Stem Cells for Stroke Treatment

Stroke is the main cause of disability and death in the world within neurological diseases. Despite such a huge impact, enzymatic, and mechanical recanalization are the only treatments available so far for ischemic stroke, but only <20% of patients can benefit from them. The use of stem cells as a possible cell therapy in stroke has been tested for years. The results obtained from these studies, although conflicting or controversial in some aspects, are promising. In the last few years, the recent development of the induced pluripotent stem cells has opened new possibilities to find new cell therapies against stroke. In this review, we will provide an overview of the state of the art of cell therapy in stroke. We will describe the current situation of the most employed stem cells and the use of induced pluripotent stem cells in stroke pathology. We will also present a summary of the different clinical trials that are being carried out or that already have results on the use of stem cells as a potential therapeutic intervention for stroke.

Neural regeneration by regionally induced stem cells within post-stroke brains: Novel therapy perspectives for stroke patients

Ischemic stroke is a critical disease which causes serious neurological functional loss such as paresis. Hope for novel therapies is based on the increasing evidence of the presence of stem cell populations in the central nervous system (CNS) and the development of stem-cell-based therapies for stroke patients. Although mesenchymal stem cells (MSCs) represented initially a promising cell source, only a few transplanted MSCs were present near the injured areas of the CNS. Thus, regional stem cells that are present and/or induced in the CNS may be ideal when considering a treatment following ischemic stroke. In this context, we have recently showed that injury/ischemia-induced neural stem/progenitor cells (iNSPCs) and injury/ischemia-induced multipotent stem cells (iSCs) are present within post-stroke human brains and post-stroke mouse brains. This indicates that iNSPCs/iSCs could be developed for clinical applications treating patients with stroke. The present study introduces the traits of mouse and human iNSPCs, with a focus on the future perspective for CNS regenerative therapies using novel iNSPCs/iSCs.

Drug-like delivery methods of stem cells as biologics for stroke

Introduction: Stem cell therapy is an experimental treatment for brain disorders. Although a cellular product, stem cells can be classified as biologics based on the cells' secretion of therapeutic substances. Treatment with stem cell biologics may appeal to stroke because of the secondary cell death mechanisms, especially neuroinflammation, that are rampant from the onset and remain elevated during the progressive phase of the disease requiring multi-pronged biological targets to effectively abrogate the neurodegenerative pathology. However, the optimal delivery methods, among other logistical approaches (i.e. cell doses and timing of intervention), for stem cell therapy will need to be refined before stem cell biologics can be successfully utilized for stroke in large scale clinical trials. Areas covered: In this review, we discuss how the innate qualities of stem cells characterize them as biologics, how stem cell transplantation may be an ideal treatment for stroke, and the various routes of stem cell administration that have been employed in various preclinical and clinical investigations. Expert opinion: There is a need to optimize the delivery of stem cell biologics for stroke in order to guide the safe and effective translation of this therapy from the laboratory to the clinic.

Optochemogenetic Stimulation of Transplanted iPS-NPCs Enhances Neuronal Repair and Functional Recovery after Ischemic Stroke

Cell transplantation therapy provides a regenerative strategy for neural repair. We tested the hypothesis that selective excitation of transplanted induced pluripotent stem cell-derived neural progenitor cells (iPS-NPCs) could recapitulate an activity-enriched microenvironment that confers regenerative benefits for the treatment of stroke. Mouse iPS-NPCs were transduced with a novel optochemogenetics fusion protein, luminopsin 3 (LMO3), which consisted of a bioluminescent luciferase, Gaussia luciferase, and an opsin, Volvox Channelrhodopsin 1. These LMO3-iPS-NPCs can be activated by either photostimulation using light or by the luciferase substrate coelenterazine (CTZ). In vitro stimulations of LMO3-iPS-NPCs increased expression of synapsin-1, postsynaptic density 95, brain derived neurotrophic factor (BDNF), and stromal cell-derived factor 1 and promoted neurite outgrowth. After transplantation into the ischemic cortex of mice, LMO3-iPS-NPCs differentiated into mature neurons. Synapse formation between implanted and host neurons was identified using immunogold electron microscopy and patch-clamp recordings. Stimulation of transplanted cells with daily intranasal administration of CTZ enhanced axonal myelination, synaptic transmission, improved thalamocortical connectivity, and functional recovery. Patch-clamp and multielectrode array recordings in brain slices showed that CTZ or light stimulation facilitated synaptic transmission and induced neuroplasticity mimicking the LTP of EPSPs. Stroke mice received the combined LMO3-iPS-NPC/CTZ treatment, but not cell or CTZ alone, showed enhanced neural network connections in the peri-infarct region, promoted optimal functional recoveries after stroke in male and female, young and aged mice. Thus, excitation of transplanted cells via the noninvasive optochemogenetics treatment provides a novel integrative cell therapy with comprehensive regenerative benefits after stroke.SIGNIFICANCE STATEMENT Neural network reconnection is critical for repairing damaged brain. Strategies that promote this repair are expected to improve functional outcomes. This study pioneers the generation and application of an optochemogenetics approach in stem cell transplantation therapy after stroke for optimal neural repair and functional recovery. Using induced pluripotent stem cell-derived neural progenitor cells (iPS-NPCs) expressing the novel optochemogenetic probe luminopsin (LMO3), and intranasally delivered luciferase substrate coelenterazine, we show enhanced regenerative properties of LMO3-iPS-NPCs in vitro and after transplantation into the ischemic brain of different genders and ages. The noninvasive repeated coelenterazine stimulation of transplanted cells is feasible for clinical applications. The synergetic effects of the combinatorial cell therapy may have significant impacts on regenerative approach for treatments of CNS injuries.

Evaluation of Neurosecretome from Mesenchymal Stem Cells Encapsulated in Silk Fibroin Hydrogels

Physical and cognitive disabilities are hallmarks of a variety of neurological diseases. Stem cell-based therapies are promising solutions to neuroprotect and repair the injured brain and overcome the limited capacity of the central nervous system to recover from damage. It is widely accepted that most benefits of different exogenously transplanted stem cells rely on the secretion of different factors and biomolecules that modulate inflammation, cell death and repair processes in the damaged host tissue. However, few cells survive in cerebral tissue after transplantation, diminishing the therapeutic efficacy. As general rule, cell encapsulation in natural and artificial polymers increases the in vivo engraftment of the transplanted cells. However, we have ignored the consequences of such encapsulation on the secretory activity of these cells. In this study, we investigated the biological compatibility between silk fibroin hydrogels and stem cells of mesenchymal origin, a cell population that has gained increasing attention and popularity in regenerative medicine. Although the survival of mesenchymal stem cells was not affected inside hydrogels, this biomaterial format caused adhesion and proliferation deficits and impaired secretion of several angiogenic, chemoattractant and neurogenic factors while concurrently potentiating the anti-inflammatory capacity of this cell population through a massive release of TGF-Beta-1. Our results set a milestone for the exploration of engineering polymers to modulate the secretory activity of stem cell-based therapies for neurological disorders.

Examining the fundamental biology of a novel population of directly reprogrammed human neural precursor cells

BACKGROUND

Cell reprogramming is a promising avenue for cell-based therapies as it allows for the generation of multipotent, unipotent, or mature somatic cells without going through a pluripotent state. While the use of autologous cells is considered ideal, key challenges for their clinical translation include the ability to reproducibly generate sufficient quantities of cells within a therapeutically relevant time window.

METHODS

We performed transfection of three distinct human somatic starting populations of cells with a non-integrating synthetic plasmid expressing Musashi 1 (MSI1), Neurogenin 2 (NGN2), and Methyl-CpG-Binding Domain 2 (MBD2). The resulting directly reprogrammed neural precursor cells (drNPCs) were examined in vitro using RT-qPCR, karyotype analysis, immunohistochemistry, and FACS at early and late time post-transfection. Electrophysiology (patch clamp) was performed on drNPC-derived neurons to determine their capacity to generate action potentials. In vivo characterization was performed following transplantation of drNPCs into two animal models (Shiverer and SCID/Beige mice), and the numbers, location, and differentiation profile of the transplanted cells were examined using immunohistochemistry.

RESULTS

Human somatic cells can be directly reprogrammed within two weeks to neural precursor cells (drNPCs) by transient exposure to Msi1, Ngn2, and MBD2 using non-viral constructs. The drNPCs generate all three neural cell types (astrocytes, oligodendrocytes, and neurons) and can be passaged in vitro to generate large numbers of cells within four weeks. drNPCs can respond to in vivo differentiation and migration cues as demonstrated by their migration to the olfactory bulb and contribution to neurogenesis in vivo. Differentiation profiles of transplanted cells onto the corpus callosum of myelin-deficient mice reveal the production of oligodendrocytes and astrocytes.

CONCLUSIONS

Human drNPCs can be efficiently and rapidly produced from donor somatic cells and possess all the important characteristics of native neural multipotent cells including differentiation into neurons, astrocytes, and oligodendrocytes, and in vivo neurogenesis and myelination.

Using Dental Pulp Stem Cells for Stroke Therapy

Stroke is a leading cause of permanent disability world-wide, but aside from rehabilitation, there is currently no clinically-proven pharmaceutical or biological agent to improve neurological disability. Cell-based therapies using stem cells, such as dental pulp stem cells, are a promising alternative for treatment of neurological diseases, including stroke. The ischaemic environment in stroke affects multiple cell populations, thus stem cells, which act through cellular and molecular mechanisms, are promising candidates. The most common stem cell population studied in the neurological setting has been mesenchymal stem cells due to their accessibility. However, it is believed that neural stem cells, the resident stem cell of the adult brain, would be most appropriate for brain repair. Using reprogramming strategies, alternative sources of neural stem and progenitor cells have been explored. We postulate that a cell of closer origin to the neural lineage would be a promising candidate for reprogramming and modification towards a neural stem or progenitor cell. One such candidate population is dental pulp stem cells, which reside in the root canal of teeth. This review will focus on the neural potential of dental pulp stem cells and their investigations in the stroke setting to date, and include an overview on the use of different sources of neural stem cells in preclinical studies and clinical trials of stroke.

Overexpression of BRCA1 in Neural Stem Cells Enhances Cell Survival and Functional Recovery after Transplantation into Experimental Ischemic Stroke

Transplantation of neural stem cells (NSCs) is a promising therapy for ischemic stroke. However, the effectiveness of this approach is limited by grafted cell death. Breast cancer susceptibility protein 1 (BRCA1) could suppress apoptosis in neural progenitors and modulate oxidative stress in neurons. In this study, we found that BRCA1 was upregulated by oxygen-glucose deprivation/reoxygenation (OGD/R). Overexpression of BRCA1 in NSCs reduced cell apoptosis and oxidative stress after OGD/R insult. The molecule overexpression also stimulated cellular proliferation in OGD/R NSCs and increased the survival rate of grafted cells. Further, the transplantation of BRCA1-transfected NSCs into mice with ischemic stroke increased brain-derived neurotropic factor and nerve growth factor expression in the brain and elicited neurological function improvement. In addition, we found that RING finger domain and BRCT domain of BRCA1 could physically interact with p53 in NSCs. The cross talk between BRCA1 RING finger domain and p53 was responsible for p53 ubiquitination and degradation. Our findings indicate that modification with BRCA1 could enhance the efficacy of NSCs transplantation in ischemic stroke.

Therapeutic strategy against ischemic stroke with the concept of neurovascular unit

Stroke is one of the leading causes of death and disability globally. Although thrombolytic therapy by t-PA and mechanical thrombectomy have improved outcomes of ischemic stroke patients, both of these approaches are applicable to limited numbers of patients owing to their time constraints. Therefore, development of other treatment approaches such as developing neuroprotective drugs and nerve regeneration therapy is required to overcome ischemic stroke. The concept of the neurovascular unit (NVU) was formalized by the Stroke Progress Review Group of the National Institute of Neurological Disorders and Stroke in 2001. This concept emphasizes the importance not just of neurons but of the interactions between neurons, endothelial cells, astroglia, microglia and associated tissue matrix proteins to investigate the pathological condition of ischemic stroke. Many reports have been published about these interactions. This review focuses on the roles of cells that surround cerebral vasculature, especially endothelial cells, and reports therapeutic strategies against ischemic stroke from four points of view including angiogenesis, neurotrophic effects, protection of NVU components and regenerative therapy.

Neural stem cell therapy for stroke: A multimechanistic approach to restoring neurological function

INTRODUCTION

Neural stem cells (NSCs) have demonstrated multimodal therapeutic function for stroke, which is the leading cause of long-term disability and the second leading cause of death worldwide. In preclinical stroke models, NSCs have been shown to modulate inflammation, foster neuroplasticity and neural reorganization, promote angiogenesis, and act as a cellular replacement by differentiating into mature neural cell types. However, there are several key technical questions to address before NSC therapy can be applied to the clinical setting on a large scale.

PURPOSE OF REVIEW

In this review, we will discuss the various sources of NSCs, their therapeutic modes of action to enhance stroke recovery, and considerations for the clinical translation of NSC therapies. Understanding the key factors involved in NSC-mediated tissue recovery and addressing the current translational barriers may lead to clinical success of NSC therapy and a first-in-class restorative therapy for stroke patients.

Safety and efficacy evaluations of an adeno-associated virus variant for preparing IL10-secreting human neural stem cell-based therapeutics

Gene therapy technologies are inevitably required to boost the therapeutic performance of cell therapies; thus, validating the efficacy of gene carriers specifically used for preparing cellular therapeutics is a prerequisite for evaluating the therapeutic capabilities of gene and cell combinatorial therapies. Herein, the efficacy of a recombinant adeno-associated virus derivative (rAAVr3.45) was examined to evaluate its potential as a gene carrier for genetically manipulating interleukin-10 (IL10)-secreting human neural stem cells (hNSCs) that can potentially treat ischemic injuries or neurological disorders. Safety issues that could arise during the virus preparation or viral infection were investigated; no replication-competent AAVs were detected in the final cell suspensions, transgene expression was mostly transient, and no severe interference on endogenous gene expression by viral infection occurred. IL10 secretion from hNSCs infected by rAAVr3.45 encoding IL10 did not alter the transcriptional profile of any gene by more than threefold, but the exogenously boosted IL10 was sufficient to provoke immunomodulatory effects in an ischemic brain injury animal model, thereby accelerating the recovery of neurological deficits and the reduction of brain infarction volume. This study presents evidence that rAAVr3.45 can be potentially used as a gene carrier to prepare stem cell therapeutics.

Neural Stem Cell Transplantation into a Mouse Model of Stroke

Stroke is the fifth leading cause of death among Americans each year. Current standard-of-care treatment for stroke deploys intravenous tissue-type plasminogen activator (tPA), mechanical thrombolysis, or delivery of fibrinolytics. Although these therapies have reduced stroke-induced damage, therapeutic options still remain limited. Transplantation of patient-specific neural stem (NS) cells represents a promising strategy for the treatment of stroke. Basic science research has shown that transplanted NS cells can differentiate in the brain of rodent models of stroke and promote behavioral recovery. Clinical trials exploring the feasibility of stem cell treatment for stroke are currently being conducted. However, questions remain regarding the optimal means of delivering NS cells, including cell dose, infusion speed, timing of transplantation, anatomic site, and imaging-assisted monitoring and guidance. Of the different available delivery modalities, intravascular NS delivery after stroke represents one practical approach. In this chapter, I provide methods for intravascular delivery of NS cells in a mouse model of stroke. The techniques involved include cell culture of NS cells, flow cytometry of NS cells, modeling stroke via unilateral common carotid artery occlusion, intra-arterial injection of NS cells into the brain, behavior analyses, and immunohistochemistry. Intra-arterial NS cell therapy has the potential to improve functional recovery after ischemic stroke.

[Cell therapy for ischemic stroke. Stem cell types and results of pre-clinical trials]

The literature review addresses the use of stem cells (SC) in ischemic stroke (IS). Part 1 of the paper overviews the results of experimental animal studies. Characteristics of different SC types and results of their studies in experimental models of IS are presented in the first section, the second section considers pros and cons of the methods of SC injection.

Transplantation of Olfactory Stem Cells with Biodegradable Hydrogel Accelerates Facial Nerve Regeneration After Crush Injury

Olfactory mucosa contains neural stem cells, called olfactory stem cells (OSCs), which produce trophic support required for promoting axonal regeneration after nerve injury. However, the local tissue environment can reduce the viability/function of transplanted cells when placed directly on the injury. Although gelatin hydrogels have been shown to aid cell survival during transplantation, such OSC‐hydrogel combinations have not been extensively tested, particularly during recovery from facial nerve palsy. In this study, OSCs were isolated from the olfactory mucosae of newborn mice and were shown to express neural stem cell markers before differentiation, as well as cell‐type specific markers after differentiation, confirming their multipotency. The OSCs also secrete growth factors and various cytokines that promote nerve regeneration. To test the effects of OSC transplantation in vivo, Medgel, a biodegradable hydrogel sponge, was applied to retain OSCs around the injury site and to lessen the detrimental effects of the local environment in an established facial nerve palsy mouse model. When OSCs were transplanted into the injury site, accelerated recovery was observed for 1 week. When OSCs were transplanted with Medgel, a higher level and duration of accelerated recovery was observed. OSCs in Medgel also increased peripheral nerve function and increased the number of regenerated nerve fibers. These results suggest that OSCs implanted with Medgel accelerate and enhance recovery from facial palsy in mice. Because human OSCs can be easily obtained from olfactory mucosa biopsies with limited risk, this OSC‐Medgel combination is a candidate treatment option for accelerating recovery after facial nerve injury. stem cells translational medicine2019;8:169&10

Stem cell therapy in autism: recent insights

Autism spectrum disorders (ASDs) are characterized by core domains: persistent deficits in social communication and interaction; restricted, repetitive patterns of behavior, interests, or activities. ASDs comprise heterogeneous and complex neurodevelopmental pathologies with well-defined inflammatory conditions and immune system dysfunction. Due to neurobiologic changes underlying ASD development, cell-based therapies have been proposed and applied to ASDs. Indeed, stem cells show specific immunologic properties, which make them promising candidates in ASD treatment. This comprehensive up-to-date review focuses on ASD cellular/molecular abnormalities, potentially useful stem cell types, animal models, and current clinical trials on the use of stem cells in treating autism. Limitations are also discussed.

Cortical Reshaping and Functional Recovery Induced by Silk Fibroin Hydrogels-Encapsulated Stem Cells Implanted in Stroke Animals

The restitution of damaged circuitry and functional remodeling of peri-injured areas constitute two main mechanisms for sustaining recovery of the brain after stroke. In this study, a silk fibroin-based biomaterial efficiently supports the survival of intracerebrally implanted mesenchymal stem cells (mSCs) and increases functional outcomes over time in a model of cortical stroke that affects the forepaw sensory and motor representations. We show that the functional mechanisms underlying recovery are related to a substantial preservation of cortical tissue in the first days after mSCs-polymer implantation, followed by delayed cortical plasticity that involved a progressive functional disconnection between the forepaw sensory (FLs₁) and caudal motor (cFLm₁) representations and an emergent sensory activity in peri-lesional areas belonging to cFLm₁. Our results provide evidence that mSCs integrated into silk fibroin hydrogels attenuate the cerebral damage after brain infarction inducing a delayed cortical plasticity in the peri-lesional tissue, this later a functional change described during spontaneous or training rehabilitation-induced recovery. This study shows that brain remapping and sustained recovery were experimentally favored using a stem cell-biomaterial-based approach.

Enhancement of neuronal differentiation by using small molecules modulating Nodal/Smad, Wnt/β-catenin, and FGF signaling

Pluripotent embryonic stem cells are one of the best modalities for the disease treatment due to their potential for self-renewal and differentiation into various cell types. Induction of stem cell differentiation into specific cell lineages has been investigated for decades, especially in vitro neuronal differentiation of embryonic stem cells. However, in vitro differentiation methods do not yield sufficient amounts of neurons for use in the therapeutic treatment of neurological disorders. Here, we provide an improved neuronal differentiation method based on a combination of small regulatory molecules for specific signaling pathways (FGF4 for FGF signaling, SB431542 for Nodal/Smad signaling, and XAV939 and BIO for Wnt signaling) in N2B27 media. We found that FGF4 was required for neural induction, SB431542 accelerated neural precursor differentiation, and treatment with XAV939 and BIO at different periods enhanced neuronal differentiation. These optimized neuronal differentiation conditions may allow a greater neuron cell yield within a shorter time than current methods and be the basis for treatment of neurological dysfunction using stem cells.

Neural stem cell therapies and hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury is a significant cause of morbidity and mortality in the adult as well as in the neonate. Extensive pre-clinical studies have shown promising therapeutic effects of neural stem cell-based treatments for hypoxic-ischemic brain injury. There are two major strategies of neural stem cell-based therapies: transplanting exogenous neural stem cells and boosting self-repair of endogenous neural stem cells. Neural stem cell transplantation has been proved to improve functional recovery after brain injury through multiple by-stander mechanisms (e.g., neuroprotection, immunomodulation), rather than simple cell-replacement. Endogenous neural stem cells reside in certain neurogenic niches of the brain and response to brain injury. Many molecules (e.g., neurotrophic factors) can stimulate or enhance proliferation and differentiation of endogenous neural stem cells after injury. In this review, we first present an overview of neural stem cells during normal brain development and the effect of hypoxic-ischemic injury on the activation and function of endogenous neural stem cells in the brain. We then summarize and discuss the current knowledge of strategies and mechanisms for neural stem cell-based therapies on brain hypoxic-ischemic injury, including neonatal hypoxic-ischemic brain injury and adult ischemic stroke.

Brain and spinal cord injury repair by implantation of human neural progenitor cells seeded onto polymer scaffolds

Hypoxic-ischemic (HI) brain injury and spinal cord injury (SCI) lead to extensive tissue loss and axonal degeneration. The combined application of the polymer scaffold and neural progenitor cells (NPCs) has been reported to enhance neural repair, protection and regeneration through multiple modes of action following neural injury. This study investigated the reparative ability and therapeutic potentials of biological bridges composed of human fetal brain-derived NPCs seeded upon poly(glycolic acid)-based scaffold implanted into the infarction cavity of a neonatal HI brain injury or the hemisection cavity in an adult SCI. Implantation of human NPC (hNPC)–scaffold complex reduced the lesion volume, induced survival, engraftment, and differentiation of grafted cells, increased neovascularization, inhibited glial scar formation, altered the microglial/macrophage response, promoted neurite outgrowth and axonal extension within the lesion site, and facilitated the connection of damaged neural circuits. Tract tracing demonstrated that hNPC–scaffold grafts appear to reform the connections between neurons and their targets in both cerebral hemispheres in HI brain injury and protect some injured corticospinal fibers in SCI. Finally, the hNPC–scaffold complex grafts significantly improved motosensory function and attenuated neuropathic pain over that of the controls. These findings suggest that, with further investigation, this optimized multidisciplinary approach of combining hNPCs with biomaterial scaffolds provides a more versatile treatment for brain injury and SCI.

Biodegradable scaffolds seeded with human fetal brain cells can help repair neurological injuries in rodents. A team led by Kook In Park and Il-Shin Lee from the Yonsei University College of Medicine in Seoul, South Korea, created a mesh of plastic fibers that they bathed in neural progenitor cells. Over the course of several days, these cells differentiated into different types of brain cells, including neurons and glia. The researchers implanted these cell-scaffold complexes into the sites of injury in two rodent models: newborn mice with oxygen deprivation to the brain, and adult rats with severed spinal cords. In both cases, the treatment helped the injured tissues heal and improved the neurological or motor function of the animals. The authors suggest these tissue-engineered structures could also help people with brain or spine injuries.

Delayed and repeated intranasal delivery of bone marrow stromal cells increases regeneration and functional recovery after ischemic stroke in mice

BACKGROUND

Stroke is a leading cause of death and disability worldwide, yet there are limited treatments available. Intranasal administration is a novel non-invasive strategy to deliver cell therapy into the brain. Cells delivered via the intranasal route can migrate from the nasal mucosa to the ischemic infarct and show acute neuroprotection as well as functional benefits. However, there is little information about the regenerative effects of this transplantation method in the delayed phase of stroke. We hypothesized that repeated intranasal deliveries of bone marrow stromal cells (BMSCs) would be feasible and could enhance delayed neurovascular repair and functional recovery after ischemic stroke.

RESULTS

Reverse transcription polymerase chain reaction and immunocytochemistry were performed to analyze the expression of regenerative factors including SDF-1α, CXCR4, VEGF and FAK in BMSCs. Ischemic stroke targeting the somatosensory cortex was induced in adult C57BL/6 mice by permanently occluding the right middle cerebral artery and temporarily occluding both common carotid arteries. Hypoxic preconditioned (HP) BMSCs (HP-BMSCs) with increased expression of surviving factors HIF-1α and Bcl-xl (1 × 106 cells/100 μl per mouse) or cell media were administered intranasally at 3, 4, 5, and 6 days after stroke. Mice received daily BrdU (50 mg/kg) injections until sacrifice. BMSCs were prelabeled with Hoechst 33342 and detected within the peri-infarct area 6 and 24 h after transplantation. In immunohistochemical staining, significant increases in NeuN/BrdU and Glut-1/BrdU double positive cells were seen in stroke mice received HP-BMSCs compared to those received regular BMSCs. HP-BMSC transplantation significantly increased local cerebral blood flow and improved performance in the adhesive removal test.

CONCLUSIONS

This study suggests that delayed and repeated intranasal deliveries of HP-treated BMSCs is an effective treatment to encourage regeneration after stroke.

Sevoflurane preconditioning induced endogenous neurogenesis against ischemic brain injury by promoting microglial activation

Brain ischemia causes irreversible damage to functional neurons in cases of infarct. Promoting endogenous neurogenesis to replace necrotic neurons is a promising therapeutic strategy for ischemia patients. The neuroprotective role of sevoflurane preconditioning implies that it might also enhance endogenous neurogenesis and functional restoration in the infarct region. By using a transient middle cerebral artery occlusion (tMCAO) model, we discovered that endogenous neurogenesis was enhanced by sevoflurane preconditioning. This enhancement process is characterized by the promotion of neuroblast proliferation within the subventricular zone (SVZ), migration and differentiation into neurons, and the presence of astrocytes and oligodendrocytes at the site of infarct. The newborn neurons in the sevoflurane preconditioning group showed miniature excitatory postsynaptic currents (mEPSCs), increased synaptophysin and PSD95 staining density, indicating normal neuronal function. Furthermore, long-term behavioral improvement was observed in the sevoflurane preconditioning group consistent with endogenous neurogenesis. Further histological analyses showed that sevoflurane preconditioning accelerated microglial activation, including migration, phagocytosis and secretion of brain-derived neurotrophic factor (BDNF). Intraperitoneal injection of minocycline, a microglial inhibitor, suppressed microglial activation and reversed neurogenesis. Our data showed that sevoflurane preconditioning promoted microglial activities, created a favorable microenvironment for endogenous neurogenesis and accelerated functional reconstruction in the infarct region.

Sensors of Succinate: Neural Stem Cell Grafts Fight Neuroinflammation

In this issue of Cell Stem Cell, Peruzzotti-Jametti et al. (2018) demonstrate how neural stem cells, transplanted in a mouse model of multiple sclerosis, respond to extracellular succinate and modulate neuroinflammation by releasing anti-inflammatory prostaglandin E2 and scavenging succinate. This mechanism reduces CNS damage and ameliorates motor impairment.

Maturation of neural stem cells and integration into hippocampal circuits - a functional study in an in situ model of cerebral ischemia

The hippocampus is the region of the brain that is most susceptible to ischemic lesion because it contains pyramidal neurons that are highly vulnerable to ischemic cell death. A restricted brain neurogenesis limits the possibility of reversing massive cell death after stroke and, hence, endorses cell-based therapies for neuronal replacement strategies following cerebral ischemia. Neurons differentiated from neural stem/progenitor cells (NSPCs) can mature and integrate into host circuitry, improving recovery after stroke. However, how the host environment regulates the NSPC behavior in post-ischemic tissue remains unknown. Here, we studied functional maturation of NSPCs in control and post-ischemic hippocampal tissue after modelling cerebral ischemia in situ We traced the maturation of electrophysiological properties and integration of the NSPC-derived neurons into the host circuits, with these cells developing appropriate activity 3 weeks or less after engraftment. In the tissue subjected to ischemia, the NSPC-derived neurons exhibited functional deficits, and differentiation of embryonic NSPCs to glial types - oligodendrocytes and astrocytes - was boosted. Our findings of the delayed neuronal maturation in post-ischemic conditions, while the NSPC differentiation was promoted towards glial cell types, provide new insights that could be applicable to stem cell therapy replacement strategies used after cerebral ischemia.

Hydrogels-Assisted Cell Engraftment for Repairing the Stroke-Damaged Brain: Chimera or Reality

The use of advanced biomaterials as a structural and functional support for stem cells-based therapeutic implants has boosted the development of tissue engineering applications in multiple clinical fields. In relation to neurological disorders, we are still far from the clinical reality of restoring normal brain function in neurodegenerative diseases and cerebrovascular disorders. Hydrogel polymers show unique mechanical stiffness properties in the range of living soft tissues such as nervous tissue. Furthermore, the use of these polymers drastically enhances the engraftment of stem cells as well as their capacity to produce and deliver neuroprotective and neuroregenerative factors in the host tissue. Along this article, we review past and current trends in experimental and translational research to understand the opportunities, benefits, and types of tentative hydrogel-based applications for the treatment of cerebral disorders. Although the use of hydrogels for brain disorders has been restricted to the experimental area, the current level of knowledge anticipates an intense development of this field to reach clinics in forthcoming years.

Stem Cell Therapy for Alzheimer's Disease: A Review of Recent Clinical Trials

Stem cell therapy has been noted to be a disease-modifying treatment for Alzheimer's disease (AD). After the failure to develop new drugs for AD, the number of studies on stem cells, such as mesenchymal stem cells (MSCs) and neural stem cells (NSCs), has increased from the early 2000 s. Issues pertaining to stem cells have been investigated in many animal studies in terms of stem cell origin, differentiation potency, method of culture, tumor formation, injection route, and mobility. Since 2010, mainly in East Asia, researchers began clinical trials investigating the use of stem cells for AD. Two phase I trials on moderate AD have been completed; though they revealed no severe acute or long-term side effects, no significant clinical efficacy was observed. Several studies, which involve more sophisticated study designs using different injection routes, well-established scales, and biomarkers such as amyloid positron emission tomography, are planned for mild to moderate AD patients. Here, we review the concept of stem cell therapy for AD and the progress of recent clinical trials.

Stroke promotes survival of nearby transplanted neural stem cells by decreasing their activation of caspase 3 while not affecting their differentiation

Although transplantation of stem cells improves recovery of the nervous tissue, little is known about the influence of different brain regions on transplanted cells. After we confirmed that cells with uniform differentiation potential can be generated in independent experiments, one million of neural stem cells isolated from B6.Cg-Tg(Thy1-YFP)16Jrs/J mouse embryos were transplanted into the brain 24 h after induction of stroke. The lateral ventricles, the corpus callosum and the striatum were tested. Two and four weeks after the transplantation, the cells transplanted in all three regions have been attracted to the ischemic core. The largest number of attracted cells has been observed after transplantation into the striatum. Their differentiation pattern and expression of neuroligin 1, SynCAM 1, postsynaptic density protein 95 and synapsin 1 followed the same pattern observed during in vitro cultivation and it did not differ among the tested regions. Differentiation pattern of the cells transplanted in the stroke-affected and healthy animals was the same. On the other hand, neural stem cells transplanted in the striatum of the animals affected by stroke exhibited significantly increased survival rates reaching 260 ± 19%, when compared to cells transplanted in their wild type controls. Surprisingly, improved survival two and four weeks after transplantation was not due to increased proliferation of the grafted cells and it was accompanied by decreased levels of activity of Casp3 (19.56 ± 3.1% in the stroke-affected vs. 30.14 ± 2.4% in healthy animals after four weeks). We assume that the decreased levels of Casp3 in cells transplanted near the ischemic region was linked to increased vasculogenesis, synaptogenesis, astrocytosis and axonogenesis detected in the host tissue affected by ischemia.

Transplantation of iPS cell-derived neural progenitors overexpressing SDF-1α increases regeneration and functional recovery after ischemic stroke

Ischemic stroke is a leading cause of human death and disability while clinical treatments are limited. The adult brain possesses endogenous regenerative activities that may benefit tissue repair after stroke. Trophic factors such as stromal cell-derived factor 1 alpha (SDF-1α) are upregulated in the ischemic brain, which promote endogenous regeneration. The regenerative response, however, is normally insufficient. Transplantation of exogenous cells has been explored as regenerative therapies. One promising cell type for transplantation is induced pluripotent stem (iPS) cells which are cells genetically reprogrammed from adult somatic cells. We hypothesized that transplanting neural progenitor cells derived from iPS cells (iPS-NPCs) could provide cell replacement and trophic support. The trophic factor SDF-1α was overexpressed in iPS-NPCs by lentiviral transduction to test if SDF-1α could increase regeneration in the ischemic brain. These SDF-1α-iPS-NPCs were differentiated in vitro to express mature neuronal and synaptic markers. Differentiated cells expressed functional Na+ and K+ channels, and fired action potentials. In the oxygen glucose deprivation (OGD) test, SDF-1α-iPS-NPCs survived significantly better compared to control iPS-NPCs. In mice subjected to focal cerebral ischemia in the sensorimotor cortex, iPS-NPCs and SDF-1α-iPS-NPCs were intracranially transplanted into the ischemic cortex 7 days after stroke. Neuronal differentiation of transplanted cells was identified using NeuN 14 days after transplantation. Mice that received SDF-1α-iPS-NPCs had greater numbers of NeuN/BrdU and Glut-1/BrdU co-labeled cells in the peri-infarct area and improved locomotion compared to the control iPS-NPC transplantation. Thus, SDF-1α upregulation in transplanted cells may be a therapeutic strategy to enhance endogenous neurovascular repair after ischemic stroke in adult mice.

Regenerative potential of primary adult human neural stem cells on micropatterned bio-implants boosts motor recovery

Background

The adult brain is unable to regenerate itself sufficiently after large injuries. Therefore, hopes rely on therapies using neural stem cell or biomaterial transplantation to sustain brain reconstruction. The aim of the present study was to evaluate the improvement in sensorimotor recovery brought about by human primary adult neural stem cells (hNSCs) in combination with bio-implants.

Methods

hNSCs were pre-seeded on implants micropatterned for neurite guidance and inserted intracerebrally 2 weeks after a primary motor cortex lesion in rats. Long-term behaviour was significantly improved after hNSC implants versus cell engraftment in the grip strength test. MRI and immunohistological studies were conducted to elucidate the underlying mechanisms of neuro-implant integration.

Results

hNSC implants promoted tissue reconstruction and limited hemispheric atrophy and glial scar expansion. After 3 months, grafted hNSCs were detected on implants and expressed mature neuronal markers (NeuN, MAP2, SMI312). They also migrated over a short distance to the reconstructed tissues and to the peri-lesional tissues, where 26% integrated as mature neurons. Newly formed host neural progenitors (nestin, DCX) colonized the implants, notably in the presence of hNSCs, and participated in tissue reconstruction. The microstructured bio-implants sustained the guided maturation of both grafted hNSCs and endogenous progenitors.

Conclusions

These immunohistological results are coherent with and could explain the late improvement observed in sensorimotor recovery. These findings provide novel insights into the regenerative potential of primary adult hNSCs combined with microstructured implants.

Transplantation of feeder-free human induced pluripotent stem cell-derived cortical neuron progenitors in adult male Wistar rats with focal brain ischemia

The use of human induced pluripotent stem cells (hiPSCs) eliminates the ethical issues associated with fetal or embryonic materials, thus allowing progress in cell therapy research for ischemic stroke. Strict regulation of cell therapy development requires the xeno-free condition to eliminate clinical complications. Maintenance of hiPSCs with feeder-free condition presents a higher degree of spontaneous differentiation in comparison with conventional cultures. Therefore, feeder-free derivation might be not ideal for developing transplantable hiPSC derivatives. We developed the feeder-free condition for differentiation of cortical neurons from hiPSCs. Then, we evaluated the cells' characteristics upon transplantation into the sham and focal brain ischemia on adult male Wistar rats. Grafts in lesioned brains demonstrated polarized reactivity toward the ischemic border, indicated by directional preferences in axonal outgrowth and cellular migration, with no influence on graft survival. Following the transplantation, forelimb asymmetry was better restored compared with controls. Herein, we provide evidence to support the use of the xeno-free condition for the development of cell therapy for ischemic stroke.

Transplantation of bFGF-expressing neural stem cells promotes cell migration and functional recovery in rat brain after transient ischemic stroke

Cerebrovascular disease such as stroke is one of the most common diseases in the aging population, and neural stem cells (NSCs) transplantation may provide an alternative therapy for cerebral ischemia. However, a hostile microenvironment in the ischemic brain offers is challenging for the survival of the transplanted cells. Considering the neuroprotective role of basic fibroblast growth factor (bFGF), the present study investigated whether bFGF gene-modified NSCs could improve the neurological function deficit after transient middle cerebral artery occlusion (MCAO) in adult male Sprague-Dawley rats. These rats were intravenously injected with modified NSCs (5×10⁶/200 μL) or vehicle 24 h after MCAO. Histological analysis was performed on days 7 and 28 after tMCAO. The survival, migration, proliferation, and differentiation of the transplanted modified C17.2 cells in the brain were improved. In addition, the intravenous infusion of NSCs and bFGF gene-modified C17.2 cells improved the functional recovery as compared to the control. Furthermore, bFGF promoted the C17.2 cell growth, survival, and differentiation into mature neurons within the infarct region. These data suggested that bFGF gene-modified NSCs have the potential to be a therapeutic agent in brain ischemia.

Getting Closer to an Effective Intervention of Ischemic Stroke: The Big Promise of Stem Cell

Stem cell therapy for ischemic stroke has widely been explored. Results from both preclinical and clinical studies have immensely supported the judicious use of stem cells as therapy. These provide an attractive means for preserving and replacing the damaged brain tissues following an ischemic attack. Since the past few years, researchers have used various types of stem cells to replenish insulted neuronal and glial cells in neurological disorders. In the present review, we discuss different types of stem cells employed for the treatment of ischemic stroke and mechanisms and challenges these cells face once introduced into the living system. Further, we also present different ways to maneuver and overcome challenges to translate the advances made at the preclinical level to clinics.

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.

Optogenetic Inhibition of Striatal Neuronal Activity Improves the Survival of Transplanted Neural Stem Cells and Neurological Outcomes after Ischemic Stroke in Mice

Neural stem cell (NSC) transplantation is a promising treatment to improve the recovery after brain ischemia. However, how the survival, proliferation, migration, and differentiation of implanted NSC are influenced by endogenous neuronal activity remains unclear. In this work, we used optogenetic techniques to control the activity of striatal neurons and investigated how their activity affected the survival and migration of transplanted NSCs and overall neurological outcome after ischemic stroke. NSCs cultured from transgenic mice expressing fluorescent protein were transplanted into the peri-infarct region of the striatum after transient middle cerebral artery occlusion (tMCAO) surgery. The striatal neurons were excited or inhibited for 15 minutes daily via implanted optical fiber after tMCAO. The results revealed that mice which received NSC transplantation and optogenetic inhibition had smaller brain infarct volume and increased NSC migration compared to the NSC alone or PBS group (p < 0.05). In contrast, mice which received NSC transplantation and optogenetic excitation showed no difference in infarct volume and neurological behavior improvement compared to the PBS control group. In vitro experiments further revealed that the conditioned media from excited GABAergic neurons reduced NSC viability through paracrine mechanisms. Conclusion. Optogenetic inhibition of striatal neuronal activity further improved neurological recovery after NSC transplantation at the subacute phase after brain ischemia.

Induced Pluripotent Stem Cell-Derived Neural Stem Cell Therapy Enhances Recovery in an Ischemic Stroke Pig Model

Induced pluripotent stem cell-derived neural stem cells (iNSCs) have significant potential as an autologous, multifunctional cell therapy for stroke, which is the primary cause of long term disability in the United States and the second leading cause of death worldwide. Here we show that iNSC transplantation improves recovery through neuroprotective, regenerative, and cell replacement mechanisms in a novel ischemic pig stroke model. Longitudinal multiparametric magnetic resonance imaging (MRI) following iNSC therapy demonstrated reduced changes in white matter integrity, cerebral blood perfusion, and brain metabolism in the infarcted tissue. The observed tissue level recovery strongly correlated with decreased immune response, enhanced neuronal protection, and increased neurogenesis. iNSCs differentiated into neurons and oligodendrocytes with indication of long term integration. The robust recovery response to iNSC therapy in a translational pig stroke model with increased predictive potential strongly supports that iNSCs may be the critically needed therapeutic for human stroke patients.

Phase I/II randomized controlled trial of autologous bone marrow-derived mesenchymal stem cell therapy for chronic stroke

AIM

To examine the safety and efficacy of mesenchymal stem cell (MSC) therapy for intracerebral haemorrhage with neurological dysfunctions for a year.

METHODS

MSC were ex vivo expanded from 29 mL (17-42 mL) autologous bone marrow. Patients were randomized to have two intravenous injections of autologous MSC or placebos in four weeks apart. Neurological functions and clinical outcomes were monitored before treatment and at 12^th, 16^th, 24^th, 36^th and 60^th week upon completion of the treatment.

RESULTS

A mean of 4.57 × 10⁷ (range: 1.43 × 10⁷-8.40 × 10⁷) MSC per infusion was administered accounting to 8.54 × 10⁵ (2.65 × 10⁵-1.45 × 10⁶) per kilogram body weight in two occasions. There was neither adverse event at time of administration nor sign of de novo tumour development among patients after monitoring for a year post MSC therapy. Neuro-restoration and clinical improvement in terms of modified Barthel index, functional independence measure and extended Glasgow Outcome Scale were evident among patients having MSC therapy compared to patients receiving placebos.

CONCLUSION

Intravenous administration of autologous bone marrow-derived MSC is safe and has the potential of improving neurological functions in chronic stroke patients with severe disability.