Human neural stem cells in patients with chronic ischaemic stroke (PISCES): a phase 1, first-in-man study

Tracking Neural Progenitor Cell Migration in the Rodent Brain Using Magnetic Resonance Imaging

The study of neurogenesis and neural progenitor cells (NPCs) is important across the biomedical spectrum, from learning about normal brain development and studying disease to engineering new strategies in regenerative medicine. In adult mammals, NPCs proliferate in two main areas of the brain, the subventricular zone (SVZ) and the subgranular zone, and continue to migrate even after neurogenesis has ceased within the rest of the brain. In healthy animals, NPCs migrate along the rostral migratory stream (RMS) from the SVZ to the olfactory bulb, and in diseased animals, NPCs migrate toward lesions such as stroke and tumors. Here we review how MRI-based cell tracking using iron oxide particles can be used to monitor and quantify NPC migration in the intact rodent brain, in a serial and relatively non-invasive fashion. NPCs can either be labeled directly in situ by injecting particles into the lateral ventricle or RMS, where NPCs can take up particles, or cells can be harvested and labeled in vitro, then injected into the brain. For in situ labeling experiments, the particle type, injection site, and image analysis methods have been optimized and cell migration toward stroke and multiple sclerosis lesions has been investigated. Delivery of labeled exogenous NPCs has allowed imaging of cell migration toward more sites of neuropathology, which may enable new diagnostic and therapeutic opportunities for as-of-yet untreatable neurological diseases.

Self-assembling injectable peptide hydrogels for emerging treatment of ischemic stroke

Ischaemic stroke remains one of the leading causes of death and disability worldwide, without any long-term effective treatments targeted at regeneration. This has led to developments of novel, biomaterial-based strategies using self-assembling peptide hydrogels.

MicroRNA-132 directs human periodontal ligament-derived neural crest stem cell neural differentiation

Neurogenesis is the basis of stem cell tissue engineering and regenerative medicine for central nervous system (CNS) disorders. We have established differentiation protocols to direct human periodontal ligament-derived stem cells (PDLSCs) into neuronal lineage, and we recently isolated the neural crest subpopulation from PDLSCs, which are pluripotent in nature. Here, we report the neural differentiation potential of these periodontal ligament-derived neural crest stem cells (NCSCs) as well as its microRNA (miRNA) regulatory mechanism and function in NCSC neural differentiation. NCSCs, treated with basic fibroblast growth factor and epidermal growth factor-based differentiation medium for 24 days, expressed neuronal and glial markers (βIII-tubulin, neurofilament, NeuN, neuron-specific enolase, GFAP, and S100) and exhibited glutamate-induced calcium responses. The global miRNA expression profiling identified 60 upregulated and 19 downregulated human miRNAs after neural differentiation, and the gene ontology analysis of the miRNA target genes confirmed the neuronal differentiation-related biological functions. In addition, overexpression of miR-132 in NCSCs promoted the expression of neuronal markers and downregulated ZEB2 protein expression. Our results suggested that the pluripotent NCSCs from human periodontal ligament can be directed into neural lineage, which demonstrate its potential in tissue engineering and regenerative medicine for CNS disorders.

Stem cells technology: a powerful tool behind new brain treatments

Stem cell research has recently become a hot research topic in biomedical research due to the foreseen unlimited potential of stem cells in tissue engineering and regenerative medicine. For many years, medicine has been facing intense challenges, such as an insufficient number of organ donations that is preventing clinicians to fulfill the increasing needs. To try and overcome this regrettable matter, research has been aiming at developing strategies to facilitate the in vitro culture and study of stem cells as a tool for tissue regeneration. Meanwhile, new developments in the microfluidics technology brought forward emerging cell culture applications that are currently allowing for a better chemical and physical control of cellular microenvironment. This review presents the latest developments in stem cell research that brought new therapies to the clinics and how the convergence of the microfluidics technology with stem cell research can have positive outcomes on the fields of regenerative medicine and high-throughput screening. These advances will bring new translational solutions for drug discovery and will upgrade in vitro cell culture to a new level of accuracy and performance. We hope this review will provide new insights into the understanding of new brain treatments from the perspective of stem cell technology especially regarding regenerative medicine and tissue engineering.

Stand alone or join forces? Stem cell therapy for stroke

INTRODUCTION

Stroke is a major cause of mortality and disability with a narrow therapeutic window. Stem cell therapy may enhance the stroke recovery.

AREAS COVERE

Regenerative medicine via stem cells stands as a novel therapy for stroke. In particular, bone marrow-derived mesenchymal stem cells (MSCs) have neuroprotective and anti-inflammatory properties that improve brain function after stroke. Here, we discuss the safety, efficacy, and mechanism of action underlying the therapeutic effects of bone marrow-derived MSCs. We also examine the discrepant transplant protocols between preclinical studies and clinical trials. Laboratory studies show the safety and efficacy of bone marrow-derived MSCs in stroke models. However, while safe, MSCs remain to be fully evaluated as effective in clinical trials. Furthermore, recognizing the multiple cell death processes associated with stroke, we next discuss the potential therapeutic benefits of a combination therapy. With preliminary results and on-going clinical trials, a careful assessment of dosing, timing, and delivery route regimens will further direct the future of stem cell therapy for neurological disorders, including stroke.

EXPERT OPINION

Bone marrow-derived MSCs appear to be the optimal stem cell source for stroke therapy. Optimizing dosing, timing, and delivery route should guide the clinical application of bone marrow-derived MSCs.

Stem cell-based cell therapy for neuroprotection in stroke: A review

Neurological disorders, such as stroke, are triggered by a loss of neurons and glial cells. Ischemic stroke remains a substantial problem for industrialized countries. Over the previous few decades our understanding about the pathophysiology of stroke has enhanced, nevertheless, more awareness is required to advance the field of stroke recovery. Existing therapies are incapable to adequately relief the disease outcome and are not appropriate to all patients. Meanwhile, the majority of patients continue to show neurological deficits even subsequent effective thrombolysis, recuperative therapies are immediately required that stimulate brain remodeling and repair once stroke damage has happened. Cell therapy is emergent as a hopeful new modality for increasing neurological recovery in ischemic stroke. Numerous types of stem cells from various sources have been identified and their possibility and efficiency for the treatment of stroke have been investigated. Stem cell therapy in patients with stroke using adult stem cells have been first practiced in clinical trials since 15 years ago. Even though stem cells have revealed a hopeful role in ischemic stroke in investigational studies besides early clinical pilot studies, cellular therapy in human is still at a primary stage. In this review, we summarize the types of stem cells, various delivery routes, and clinical application of stem cell-based therapy for stroke treatment.

Mesenchymal Stem Cell Therapy in Stroke: A Systematic Review of Literature in Pre-Clinical and Clinical Research

Exogenous stem cell therapy (SCT) has been recognized recently as a promising neuroregenerative strategy to augment recovery in stroke survivors. Mesenchymal stem cells (MSCs) are the primary source of stem cells used in the majority of both pre-clinical and clinical studies in stroke. In the absence of evidence-based guidelines on the use of SCT in stroke patients, understanding the progress of MSC research across published studies will assist researchers and clinicians in better achieving success in translating research. We conducted a systematic review on published literature using MSCs in both pre-clinical studies and clinical trials between 2008 and 2017 using the public databases PubMed and Ovid Medline, and the clinical trial registry ( www.clinicaltrials.gov ). A total of 78 pre-clinical studies and eight clinical studies were identified. While majority of the pre-clinical and clinical studies demonstrated statistically significant effects, the clinical significance of these findings was still unclear. Effect sizes could not be measured mainly due to reporting issues in pre-clinical studies, thus limiting our ability to compare results across studies quantitatively. The overall quality of both pre-clinical and clinical studies was sub-optimal. By conducting a systematic review of both pre-clinical and clinical studies on MSCs therapy in stroke, we assessed the quality of current evidence and identified several issues and gaps in translating animal studies to human trials. Addressing these issues and incorporating changes into future animal studies and human trials may lead to better success of stem cells-based therapeutics in the near future.

Stroke: The past, present and future

Since the inception of the British Neuroscience Association, there have been major advances in our knowledge of the mechanistic basis for stroke-induced brain damage. Identification of the ischaemic cascade led to the development of hundreds of new drugs, many showing efficacy in preclinical (animal-based) studies. None of these drugs has yet translated to a successful stroke treatment, current therapy being limited to thrombolysis/thrombectomy. However, this translational failure has led to significant improvements in the quality of animal-based stroke research, with the refinement of rodent models, introduction of new technologies (e.g. transgenics, in vivo brain imaging) and improvements in study design (e.g. STAIR, ARRIVE and IMPROVE guidelines). This has run in parallel with advances in clinical diagnostic imaging for detection of ischaemic versus haemorrhagic stroke, differentiating penumbra from ischaemic core, and improved clinical trial design. These preclinical and clinical advances represent the foundation for successful translation from the bench to the bedside in the near future.

Therapeutic Potential of Human Turbinate-Derived Mesenchymal Stem Cells in Experimental Acute Ischemic Stroke

Purpose

Mesenchymal stem cells (MSCs) have demonstrated great promises for the treatment of ischemic stroke. Previously, we identified a new source of MSCs located in the inferior turbinate. We investigated therapeutic potentials of human turbinate- derived mesenchymal stem cells (hTMSCs) in ischemic stroke.

Methods

Ischemic stroke was induced by the intraluminal occlusion of middle cerebral artery (MCAo) for 50 minutes in rats. At one day after MCAo, hTMSCs, adipose tissue-derived MSCs (AdMSCs), or phosphate buffered saline (PBS) were transplanted into the striatum. Functional recovery was assessed by repeating behavioral tests including modified neurologic severity score and corner test. At 14 days after MCAo, brains were stained with hematoxylin and eosin (H&E) for measuring infarct volume. The survival of grafted MSCs was evaluated by immunohistochemistry to human nuclei (hNU). Immunohistochemistry with anti-doublecortin (anti-DCX) was performed to assess hippocampal neurogenesis.

Results

Transplantation of hTMSCs following MCAo showed improvements of neurologic function, which was comparable with that of AdMSCs. H&E staining showed no difference in infarct volume among 3 groups. Regarding the survival of grafted MSCs, the number of hNU-expressing cells was not different between hTMSCs- and AdMSCs-treated groups. Finally, hTMSCs increased the number of subgranular DCX-positive cells compared to PBS-treated controls, without affecting hilar ectopic migration of newborn neurons.

Conclusions

hTMSCs could improve functional recovery following ischemic stroke, of which efficacy was similar to AdMSCs. Although hTMSCs showed comparable infarct size and survival of grafted MSCs, transplantation of hTMSCs could upregulate subgranular neurogenesis with no impact on ectopically migrating newborn neurons.

Optimized Clump Culture Methods for Adult Human Multipotent Neural Cells

Adult human multipotent neural cell (ahMNC) is a candidate for regeneration therapy for neurodegenerative diseases. Here, we developed a primary clump culture method for ahMNCs to increase the efficiency of isolation and in vitro expansion. The same amount of human temporal lobe (1 g) was partially digested and then filtered through strainers with various pore sizes, resulting in four types of clumps: Clump I > 100 µm, 70 µm < Clump II < 100 µm, 40 µm < Clump III < 70 µm, and Clump IV < 40 µm. At 3 and 6 days after culture, Clump II showed significantly higher number of colonies than the other Clumps. Moreover, ahMNCs derived from Clump II (ahMNCs-Clump II) showed stable proliferation, and shortened the time to first passage from 19 to 15 days, and the time to 1 × 10⁹ cells from 42 to 34 days compared with the previous single-cell method. ahMNCs-Clump II had neural differentiation and pro-angiogenic potentials, which are the characteristics of ahMNCs. In conclusion, the novel clump culture method for ahMNCs has significantly higher efficiency than previous techniques. Considering the small amount of available human brain tissue, the clump culture method would promote further clinical applications of ahMNCs.

Stem Cell Therapy in Cerebrovascular Disease

PURPOSE OF REVIEW

The purpose of this article is to provide a review of state-of-the-art cellular therapy in cerebrovascular diseases by discussing published and ongoing clinical trials.

RECENT FINDINGS

In spite of the challenge in translating the success of cellular therapy in acute strokes from preclinical models to clinical trials, early phase clinical trial have recently shown promise in overcoming these challenges. Various stem cell types and doses are being studied, different routes of administration are under investigation, as well as defining the optimal time window to intervene. In addition, experimental methods to enhance cellular therapy, such as ischemic preconditioning, are evolving. After the failure of neuroprotectants in cerebrovascular diseases, researchers have been keen to provide a way of replacement of damaged brain tissue and to promote recovery in order to achieve better outcomes. The field has progressed from intravenous delivery in the 24- to 36-h time window to later intracerebral administration in chronic stroke in clinical trials. New optimism in acute stroke care fostered by the success of mechanical thrombectomy will hopefully extend into cell therapy to promote recovery.

Human neural stem cell transplantation improves cognition in a murine model of Alzheimer's disease

Stem cell transplantation offers a potentially transformative approach to treating neurodegenerative disorders. The safety of cellular therapies is established in multiple clinical trials, including our own in amyotrophic lateral sclerosis. To initiate similar trials in Alzheimer's disease, efficacious cell lines must be identified. Here, we completed a preclinical proof-of-concept study in the APP/PS1 murine model of Alzheimer's disease. Human neural stem cell transplantation targeted to the fimbria fornix significantly improved cognition in two hippocampal-dependent memory tasks at 4 and 16 weeks post-transplantation. While levels of synapse-related proteins and cholinergic neurons were unaffected, amyloid plaque load was significantly reduced in stem cell transplanted mice and associated with increased recruitment of activated microglia. In vitro, these same neural stem cells induced microglial activation and amyloid phagocytosis, suggesting an immunomodulatory capacity. Although long-term transplantation resulted in significant functional and pathological improvements in APP/PS1 mice, stem cells were not identified by immunohistochemistry or PCR at the study endpoint. These data suggest integration into native tissue or the idea that transient engraftment may be adequate for therapeutic efficacy, reducing the need for continued immunosuppression. Overall, our results support further preclinical development of human neural stem cells as a safe and effective therapy for Alzheimer's disease.

In vitro studies on space-conforming self-assembling silk hydrogels as a mesenchymal stem cell-support matrix suitable for minimally invasive brain application

Advanced cell therapies require robust delivery materials and silk is a promising contender with a long clinical track record. Our aim was to optimise self-assembling silk hydrogels as a mesenchymal stem cell (MSC)-support matrix that would allow future minimally invasive brain application. We used sonication energy to programme the transition of silk (1-5% w/v) secondary structure from a random coil to a stable β-sheet configuration. This allowed fine tuning of self-assembling silk hydrogels to achieve space conformity in the absence of any silk hydrogel swelling and to support uniform cell distribution as well as cell viability. Embedded cells underwent significant proliferation over 14 days in vitro, with the best proliferation achieved with 2% w/v hydrogels. Embedded MSCs showed significantly better viability in vitro after injection through a 30G needle when the gels were in the pre-gelled versus post-gelled state. Silk hydrogels (4% w/v) with physical characteristics matching brain tissue were visualised in preliminary in vivo experiments to exhibit good space conformity in an ischemic cavity (intraluminal thread middle cerebral artery occlusion model) in adult male Sprague-Dawley rats (n = 3). This study informs on optimal MSC-hydrogel matrix conditions for minimally invasive application as a platform for future experiments targeting brain repair.

Adult Stem Cells for Regenerative Therapy

Cell therapy has been identified as an effective method to regenerate damaged tissue. Adult stem cells, also known as somatic stem cells or resident stem cells, are a rare population of undifferentiated cells, located within a differentiated organ, in a specialized structure, called a niche, which maintains the microenvironments that regulate the growth and development of adult stem cells. The adult stem cells are self-renewing, clonogenic, and multipotent in nature, and their main role is to maintain the tissue homeostasis. They can be activated to proliferate and differentiate into the required type of cells, upon the loss of cells or injury to the tissue. Adult stem cells have been identified in many tissues including blood, intestine, skin, muscle, brain, and heart. Extensive preclinical and clinical studies have demonstrated the structural and functional regeneration capabilities of these adult stem cells, such as bone marrow-derived mononuclear cells, hematopoietic stem cells, mesenchymal stromal/stem cells, resident adult stem cells, induced pluripotent stem cells, and umbilical cord stem cells. In this review, we focus on the human therapies, utilizing adult stem cells for their regenerative capabilities in the treatment of cardiac, brain, pancreatic, and eye disorders.

Hydrogel-Based Bioprocess for Scalable Manufacturing of Human Pluripotent Stem Cell-Derived Neural Stem Cells

Neural stem cells derived from human pluripotent stem cells (hPSC-NSCs) are of great value for modeling diseases, developing drugs, and treating neurological disorders. However, manufacturing high-quantity and -quality hPSC-NSCs, especially for clinical applications, remains a challenge. Here, we report a chemically defined, high-yield, and scalable bioprocess for manufacturing hPSC-NSCs. hPSCs are expanded and differentiated into NSCs in microscale tubes made with alginate hydrogels. The tubes are used to isolate cells from the hydrodynamic stresses in the culture vessel and limit the radial diameter of the cell mass to less than 400 μm to ensure efficient mass transport during the culture. The hydrogel tubes provide uniform, reproducible, and cell-friendly microspaces and microenvironments for cells. With this new technology, we showed that hPSC-NSCs could be produced in 12 days with high viability (∼95%), high purity (>90%), and high yield (∼5 × 10⁸ cells/mL of microspace). The volumetric yield is about 250 times more than the current state-of-the-art. Whole transcriptome analysis and quantitative real-time polymerase chain reaction showed that hPSC-NSCs made by this process had a similar gene expression to hPSC-NSCs made by the conventional culture technology. The produced hPSC-NSCs could mature into both neurons and glial cells in vitro and in vivo. The process developed in this paper can be used to produce large numbers of hPSC-NSCs for various biomedical applications in the future.

Regenerative Medicine Therapies for Targeting Neuroinflammation After Stroke

Inflammation is a major pathological event following ischemic stroke that contributes to secondary brain tissue damage leading to poor functional recovery. Following the initial ischemic insult, post-stroke inflammatory damage is driven by initiation of a central and peripheral innate immune response and disruption of the blood-brain barrier (BBB), both of which are triggered by the release of pro-inflammatory cytokines and infiltration of circulating immune cells. Stroke therapies are limited to early cerebral blood flow reperfusion, and whilst current strategies aim at targeting neurodegeneration and/or neuroinflammation, innovative research in the field of regenerative medicine aims at developing effective treatments that target both the acute and chronic phase of inflammation. Anti-inflammatory regenerative strategies include the use of nanoparticles and hydrogels, proposed as therapeutic agents and as a delivery vehicle for encapsulated therapeutic biological factors, anti-inflammatory drugs, stem cells, and gene therapies. Biomaterial strategies-through nanoparticles and hydrogels-enable the administration of treatments that can more effectively cross the BBB when injected systemically, can be injected directly into the brain, and can be 3D-bioprinted to create bespoke implants within the site of ischemic injury. In this review, these emerging regenerative and anti-inflammatory approaches will be discussed in relation to ischemic stroke, with a perspective on the future of stroke therapies.

Fourth European stroke science workshop

Lake Eibsee, Garmisch-Partenkirchen, 16 to 18 November, 2017: The European Stroke Organisation convened >120 stroke experts from 21 countries to discuss latest results and hot topics in clinical, translational and basic stroke research. Since its inception in 2011, the European Stroke Science Workshop has become a cornerstone of European Stroke Organisation's academic activities and a major highlight for researchers in the field. Participants include stroke researchers at all career stages and with different backgrounds, who convene for plenary lectures and discussions. The workshop was organised in seven scientific sessions focusing on the following topics: (1) acute stroke treatment and endovascular therapy; (2) small vessel disease; (3) opportunities for stroke research in the omics era; (4) vascular cognitive impairment; (5) intracerebral and subarachnoid haemorrhage; (6) alternative treatment concepts and (7) neural circuits, recovery and rehabilitation. All sessions started with a keynote lecture providing an overview on current developments, followed by focused talks on a timely topic with the most recent findings, including unpublished data. In the following, we summarise the key contents of the meeting. The program is provided in the online only Data Supplement. The workshop started with a key note lecture on how to improve the efficiency of clinical trial endpoints in stroke, which was delivered by Craig Anderson (Sydney, Australia) and set the scene for the following discussions.

Autologous Endothelial Progenitor Cells Transplantation for Acute Ischemic Stroke: A 4-Year Follow-Up Study

Transplantation of endothelial progenitor cells (EPCs) is a proven safe and effective method for treatment of cerebral ischemia in animal experiments. However, safety and efficacy need to be determined in clinical trials. We performed a two‐center, randomized, placebo‐controlled phase I/IIa trial with blinded outcome assessment on 18 patients with acute cerebral infarct within the middle cerebral artery territory, and followed for up to 4 years. Autologous ex vivo expanded EPCs were injected intravenously in the EPC group, and patients who received saline or autologous bone marrow stromal cells served as control groups. Mortality of any cause, adverse events, and new‐onset comorbidities were monitored. Changes in neurological deficits were assessed at different time points. We found no toxicity events or infusional or allergic reactions in any treated group. Three patients in the placebo group died during the 4‐year follow‐up. We found that the EPC group had fewer serious adverse events compared with the placebo‐controlled group, although there were no statistical differences in mortality among the three groups. Furthermore, there was no significant difference in neurological or functional improvement observed among the three groups, except for the Scandinavia Stroke Scale score at 3 months between the EPC group and placebo‐controlled group. Autologous transplantation of EPCs appears to improve long‐term safety in acute cerebral infarct patients, supporting the feasibility of this novel method for treatment of ischemic stroke (ClinicalTrials.gov: NCT01468064). Stem Cells Translational Medicine2019;8:14–21

On the Viability and Potential Value of Stem Cells for Repair and Treatment of Central Neurotrauma: Overview and Speculations

Central neurotrauma, such as spinal cord injury or traumatic brain injury, can damage critical axonal pathways and neurons and lead to partial to complete loss of neural function that is difficult to address in the mature central nervous system. Improvement and innovation in the development, manufacture, and delivery of stem-cell based therapies, as well as the continued exploration of newer forms of stem cells, have allowed the professional and public spheres to resolve technical and ethical questions that previously hindered stem cell research for central nervous system injury. Recent in vitro and in vivo models have demonstrated the potential that reprogrammed autologous stem cells, in particular, have to restore functionality and induce regeneration-while potentially mitigating technical issues of immunogenicity, rejection, and ethical issues of embryonic derivation. These newer stem-cell based approaches are not, however, without concerns and problems of safety, efficacy, use and distribution. This review is an assessment of the current state of the science, the potential solutions that have been and are currently being explored, and the problems and questions that arise from what appears to be a promising way forward (i.e., autologous stem cell-based therapies)-for the purpose of advancing the research for much-needed therapeutic interventions for central neurotrauma.

Long-term stability and computational analysis of migration patterns of L-MYC immortalized neural stem cells in the brain

Background

Preclinical studies indicate that neural stem cells (NSCs) can limit or reverse central nervous system (CNS) damage through delivery of therapeutic agents for cell regeneration. Clinical translation of cell-based therapies raises concerns about long-term stability, differentiation and fate, and absence of tumorigenicity of these cells, as well as manufacturing time required to produce therapeutic cells in quantities sufficient for clinical use. Allogeneic NSC lines are in growing demand due to challenges inherent in using autologous stem cells, including production costs that limit availability to patients.

Methods/Principal findings

We demonstrate the long-term stability of L-MYC immortalized human NSCs (LM-NSC008) cells in vivo, including engraftment, migration, and absence of tumorigenicity in mouse brains for up to nine months. We also examined the distributions of engrafted LM-NSC008 cells within brain, and present computational techniques to analyze NSC migration characteristics in relation to intrinsic brain structures.

Conclusions/Significance

This computational analysis of NSC distributions following implantation provides proof-of-concept for the development of computational models that can be used clinically to predict NSC migration paths in patients. Previously, models of preferential migration of malignant tumor cells along white matter tracts have been used to predict their final distributions. We suggest that quantitative measures of tissue orientation and white matter tracts determined from MR images can be used in a diffusion tensor imaging tractography-like approach to describe the most likely migration routes and final distributions of NSCs administered in a clinical setting. Such a model could be very useful in choosing the optimal anatomical locations for NSC administration to patients to achieve maximum therapeutic effects.

An update on intracerebral stem cell grafts

INTRODUCTION

Primary neurological disorders are notoriously debilitating and deadly, and over the past four decades stem cell therapy has emerged as a promising treatment. Translation of stem cell therapies from the bench to the clinic requires a better understanding of delivery protocols, safety profile, and efficacy in each disease. Areas covered: In this review, benefits and risks of intracerebral stem cell transplantation are presented for consideration. Milestone discoveries in stem cell applications are reviewed to examine the efficacy and safety of intracerebral stem cell transplant therapy for disorders of the central nervous system and inform design of translatable protocols for clinically feasible stem cell-based treatments. Expert commentary: Intracerebral administration, compared to peripheral delivery, is more invasive and carries the risk of open brain surgery. However, direct cell implantation bypasses the blood-brain barrier and reduces the first-pass effect, effectively increasing the therapeutic cell deposition at its intended site of action. These benefits must be weighed with the risk of graft-versus-host immune response. Rigorous clinical trials are underway to assess the safety and efficacy of intracerebral transplants, and if successful will lead to widely available stem cell therapies for neurologic diseases in the coming years.

Activated protein C, protease activated receptor 1, and neuroprotection

Protein C is a plasma serine protease zymogen whose active form, activated protein C (APC), exerts potent anticoagulant activity. In addition to its antithrombotic role as a plasma protease, pharmacologic APC is a pleiotropic protease that activates diverse homeostatic cell signaling pathways via multiple receptors on many cells. Engineering of APC by site-directed mutagenesis provided a signaling selective APC mutant with 3 Lys residues replaced by 3 Ala residues, 3K3A-APC, that lacks >90% anticoagulant activity but retains normal cell signaling activities. This 3K3A-APC mutant exerts multiple potent neuroprotective activities, which require the G-protein-coupled receptor, protease activated receptor 1. Potent neuroprotection in murine ischemic stroke models is linked to 3K3A-APC-induced signaling that arises due to APC's cleavage in protease activated receptor 1 at a noncanonical Arg46 site. This cleavage causes biased signaling that provides a major explanation for APC's in vivo mechanism of action for neuroprotective activities. 3K3A-APC appeared to be safe in ischemic stroke patients and reduced bleeding in the brain after tissue plasminogen activator therapy in a recent phase 2 clinical trial. Hence, it merits further clinical testing for its efficacy in ischemic stroke patients. Recent studies using human fetal neural stem and progenitor cells show that 3K3A-APC promotes neurogenesis in vitro as well as in vivo in the murine middle cerebral artery occlusion stroke model. These recent advances should encourage translational research centered on signaling selective APC's for both single-agent therapies and multiagent combination therapies for ischemic stroke and other neuropathologies.

Ex vivo biomechanical characterization of syringe-needle ejections for intracerebral cell delivery

Intracerebral implantation of cell suspensions is finding its clinical translation with encouraging results in patients with stroke. However, the survival of cells in the brain remains poor. Although the biological potential of neural stem cells (NSCs) is widely documented, the biomechanical effects of delivering cells through a syringe-needle remain poorly understood. We here detailed the biomechanical forces (pressure, shear stress) that cells are exposed to during ejection through different sized needles (20G, 26G, 32G) and syringes (10, 50, 250 µL) at relevant flow rates (1, 5, 10 µL/min). A comparison of 3 vehicles, Phosphate Buffered Saline (PBS), Hypothermosol (HTS), and Pluronic, indicated that less viscous vehicles are favorable for suspension with a high cell volume fraction to minimize sedimentation. Higher suspension viscosity was associated with greater shear stress. Higher flow rates with viscous vehicle, such as HTS reduced viability by ~10% and also produced more apoptotic cells (28%). At 5 µL/min ejection using a 26G needle increased neuronal differentiation for PBS and HTS suspensions. These results reveal the biological impact of biomechanical forces in the cell delivery process. Appropriate engineering strategies can be considered to mitigate these effects to ensure the efficacious translation of this promising therapy.

Engineered stem cell mimics to enhance stroke recovery

Currently, no medical therapies exist to augment stroke recovery. Stem cells are an intriguing treatment option being evaluated, but cell-based therapies have several challenges including developing a stable cell product with long term reproducibility. Since much of the improvement observed from cellular therapeutics is believed to result from trophic factors the stem cells release over time, biomaterials are well-positioned to deliver these important molecules in a similar fashion. Here we show that essential trophic factors secreted from stem cells can be effectively released from a multi-component hydrogel system into the post-stroke environment. Using our polymeric system to deliver VEGF-A and MMP-9, we improved recovery after stroke to an equivalent degree as observed with traditional stem cell treatment in a rodent model. While VEGF-A and MMP-9 have many unique mechanisms of action, connective tissue growth factor (CTGF) interacts with both VEGF-A and MMP-9. With our hydrogel system as well as with stem cell delivery, the CTGF pathway is shown to be downregulated with improved stroke recovery.

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.

Phase 1 Trial of Amnion Cell Therapy for Ischemic Stroke

Background

There is increasing interest in stem cell therapy as another treatment modality in stroke, particularly for patients who are unable to receive endovascular clot retrieval or thrombolysis therapies, or for whom standard treatment has failed. We have recently shown that human amniotic epithelial cells (hAECs) are effective in reducing infarct volume in different animal models of ischemic stroke, including in non-human primates. hAEC therapy attenuated infarct growth and/or promoted functional recovery, even when administered 1–3 days after the onset of stroke.

Methods

We now propose an open label Phase 1 dose escalation trial to assess the safety of allogeneic hAECs in stroke patients with a view to providing an evidence platform for future Phase 2 efficacy trials. We propose a modified 3 + 3 dose escalation study design with additional components for measuring magnetic resonance signal of efficacy as well as the effect of hAECs on immunosuppression after stroke.

Result

The trial will commence in 2018. The findings will be published in a peer-reviewed journal.

Conclusion

The trial is registered with ANZCTR (ACTRN12618000076279p).

Stem Cells Engineered During Different Stages of Reprogramming Reveal Varying Therapeutic Efficacies

Stem cells are emerging as promising treatment strategies for several brain disorders and pathologies. In this study, we explored the potential of creating induced pluripotent stem cell-derived neural stem cells (ipNSC) by using either unmodified or gene-modified somatic cells and tested their fate and therapeutic efficacies in vitro and in vivo. We show that cells engineered in somatic state lose transgene-expression during the neural induction process, which is partially restored by histone deacetylase inhibitor treatment whereas cells engineered at the ipNSC state have sustained expression of transgenes. In vivo, bimodal mouse and human ipNSCs engineered to express tumor specific death-receptor ligand and suicide-inducing therapeutic proteins have profound anti-tumor efficacy when encapsulated in synthetic extracellular matrix and transplanted in mouse models of resected-glioblastoma. This study provides insights into using somatic cells for treating CNS disorders and presents a receptor-targeted cancer therapeutic approach for brain tumors. Stem Cells 2018;36:932-942.

Mesenchymal stem cell transplantation as an effective treatment strategy for ischemic stroke in Asia: a meta-analysis of controlled trials

Objective

The aim of this study was to evaluate the efficacy and safety of the mesenchymal stem cell (MSC) therapy in patients with ischemic stroke (IS).

Materials and methods

Clinical trials involved in this research were searched from PubMed, Web of Science, Cochrane Library, Embase, Wanfang and CNKI database. Therapeutic effects of MSC therapy were assessed according to National Institutes of Health Stroke Scale (NIHSS), Barthel index (BI), Fugl-Meyer Assessment (FMA) and Functional Independence Measure (FIM), and its safety was evaluated based on adverse events.

Results

This research covered 23 trials including 1,279 IS patients. Based on our analysis, the overall condition of IS patients significantly improved after MSC therapy, indicated by decreased NIHSS and increased BI, FMA and FIM scores. Our analysis also showed that the treatment effects in the MSC transplantation group were superior to those in the control group (routine medication therapy) with statistical significance for NIHSS (1 month after therapy: odds ratio [OR]=-1.92, CI=-3.49 to -0.34, P=0.02; 3 months after therapy: OR=-2.65, CI=-3.40 to -1.90, P<0.00001), BI (1 month after therapy: OR=0.99, CI=0.19-1.79, P=0.02; 6 months after therapy: OR=10.10, CI=3.07-17.14, P=0.005), FMA (3 months after therapy: OR=10.20, CI=3.70-16.70, P=0.002; 6 months after therapy: OR=10.82, CI=6.45-15.18, P<0.00001) and FIM (1 month after therapy: OR=15.61, CI=-0.02 to 31.24, P=0.05; 6 months after therapy: OR=16.56, CI=9.06-24.06, P<0.0001). No serious adverse events were reported during MSC therapy.

Conclusion

MSC therapy is safe and effective in treating IS by improving the neurological deficits, motor function and daily life quality of patients.

Allogeneic Umbilical Cord Blood Infusion for Adults with Ischemic Stroke: Clinical Outcomes from a Phase I Safety Study

Stroke is a major cause of death and long‐term disability, affecting one in six people worldwide. The only currently available approved pharmacological treatment for ischemic stroke is tissue plasminogen activator; however, relatively few patients are eligible for this therapy. We hypothesized that intravenous (IV) infusion of banked unrelated allogeneic umbilical cord blood (UCB) would improve functional outcomes in patients with ischemic stroke. To investigate this, we conducted a phase I open‐label trial to assess the safety and feasibility of a single IV infusion of non‐human leukocyte antigen (HLA) matched, ABO matched, unrelated allogeneic UCB into adult stroke patients. Ten participants with acute middle cerebral artery ischemic stroke were enrolled. UCB units were matched for blood group antigens and race but not HLA, and infused 3–9 days post‐stroke. The adverse event (AE) profile over a 12 month postinfusion period indicated that the treatment was well‐tolerated in these stroke patients, with no serious AEs directly related to the study product. Study participants were also assessed using neurological and functional evaluations, including the modified Rankin Score (mRS) and National Institute of Health Stroke Scale (NIHSS). At 3 months post‐treatment, all participants had improved by at least one grade in mRS (mean 2.8 ± 0.9) and by at least 4 points in NIHSS (mean 5.9 ± 1.4), relative to baseline. Together, these data suggest that a single i.v. dose of allogeneic non‐HLA matched human UCB cells is safe in adults with ischemic stroke, and support the conduct of a randomized, placebo‐controlled phase 2 study. stemcellstranslationalmedicine2018;7:521–529

STROKE34 Study Protocol: A Randomized Controlled Phase IIa Trial of Intra-Arterial CD34+ Cells in Acute Ischemic Stroke

Rationale/aim

Despite the increasing efficacy of recanalization therapies for acute ischemic stroke, a large number of patients are left with long-term functional impairment, devoid of efficacious treatments. CD34+ cells comprise a subset of bone marrow-derived mononuclear cells with the capacity to promote angiogenesis in ischemic lesions and have shown promising results in observational and in vitro studies. In this study, we aim to assess the efficacy of an autotransplant of CD34+ cells in acute ischemic stroke.

Sample size estimates

30 patients will be randomized for a power of 90% and alpha of 0.05 to detect a difference in 3 months infarct volume.

Methods and design

We will screen 18–80 years old patients with acute ischemic stroke due to occlusion of a middle cerebral artery (MCA) for randomization. Persistent arterial occlusions, contra-indications to magnetic resonance imaging (MRI), premorbid dependency, or other severe diseases will be excluded. Treatment will involve bone marrow aspiration, selection of CD34+ cells, and their administration intra-arterially in the symptomatic MCA by angiography. Patients will be randomized for treatment at 7 (±2) days, 20 (±5 days) or sham procedure, 10 in each group.

Study outcomes

The primary outcome will be infarct volume in MRI performed at 3 months. Secondary outcomes will include adverse events and multidimensional functional and neurological measures.

Discussion/conclusion

STROKE34 is a PROBE design phase IIa clinical trial to assess the efficacy of intra-arterial administration of CD34+ cells 7 and 20 days after acute ischemic stroke.

Trial registration (EU Clinical Trials Register)

2017-002456-88.

Pharmacological approaches promoting stem cell-based therapy following ischemic stroke insults

Stroke can lead to long-term neurological deficits. Adult neurogenesis, the continuous generation of newborn neurons in distinct regions of the brain throughout life, has been considered as one of the appoaches to restore the neurological function following ischemic stroke. However, ischemia-induced spontaneous neurogenesis is not suffcient, thus cell-based therapy, including infusing exogenous stem cells or stimulating endogenous stem cells to help repair of injured brain, has been studied in numerous animal experiments and some pilot clinical trials. While the effects of cell-based therapy on neurological function during recovery remains unproven in randomized controlled trials, pharmacological agents have been administrated to assist the cell-based therapy. In this review, we summarized the limitations of ischemia-induced neurogenesis and stem-cell transplantation, as well as the potential proneuroregenerative effects of drugs that may enhance efficacy of cell-based therapies. Specifically, we discussed drugs that enhance proliferation, migration, differentiation, survival and function connectivity of newborn neurons, which may restore neurobehavioral function and improve outcomes in stroke patients.

Robust Revascularization in Models of Limb Ischemia Using a Clinically Translatable Human Stem Cell-Derived Endothelial Cell Product

Pluripotent stem cell-derived differentiated endothelial cells offer high potential in regenerative medicine in the cardiovascular system. With the aim of translating the use of a human stem cell-derived endothelial cell product (hESC-ECP) for treatment of critical limb ischemia (CLI) in man, we report a good manufacturing practice (GMP)-compatible protocol and detailed cell tracking and efficacy data in multiple preclinical models. The clinical-grade cell line RC11 was used to generate hESC-ECP, which was identified as mostly endothelial (60% CD31⁺/CD144⁺), with the remainder of the subset expressing various pericyte/mesenchymal stem cell markers. Cell tracking using MRI, PET, and qPCR in a murine model of limb ischemia demonstrated that hESC-ECP was detectable up to day 7 following injection. Efficacy in several murine models of limb ischemia (immunocompromised/immunocompetent mice and mice with either type I/II diabetes mellitus) demonstrated significantly increased blood perfusion and capillary density. Overall, we demonstrate a GMP-compatible hESC-ECP that improved ischemic limb perfusion and increased local angiogenesis without engraftment, paving the way for translation of this therapy.

A biomaterials approach to influence stem cell fate in injectable cell-based therapies

Background

Numerous stem cell therapies use injection-based administration to deliver high-density cell preparations. However, cell retention rates as low as 1% have been observed within days of transplantation. This study investigated the effects of varying administration and formulation parameters of injection-based administration on cell dose recovery and differentiation fate choice of human mesenchymal stem cells.

Methods

The impact of ejection rate via clinically relevant Hamilton micro-syringes and biomaterial-assisted delivery was investigated. Cell viability, the percentage of cell dose delivered as viable cells, proliferation capacity as well as differentiation behaviour in bipotential media were assessed. Characterisation of the biomaterial-based cell carriers was also carried out.

Results

A significant improvement of in-vitro dose recovery in cells co-ejected with natural biomaterials was observed, with ejections within 2% (w/v) gelatin resulting in 87.5 ± 14% of the cell dose being delivered as viable cells, compared to 32.2 ± 19% of the dose ejected in the commonly used saline vehicle at 10 μl/min. Improvement in cell recovery was not associated with the rheological properties of biomaterials utilised, as suggested by previous studies. The extent of osteogenic differentiation was shown to be substantially altered by choice of ejection rate and cell carrier, despite limited contact time with cells during ejection. Collagen type I and bone-derived extracellular matrix cell carriers yielded significant increases in mineralised matrix deposited at day 21 relative to PBS.

Conclusions

An enhanced understanding of how administration protocols and biomaterials influence cell recovery, differentiation capacity and choice of fate will facilitate the development of improved administration and formulation approaches to achieve higher efficacy in stem cell transplantation.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0789-1) contains supplementary material, which is available to authorized users.

Interferon-γ Promotes Neuronal Repair by Transplanted Neural Stem Cells in Ischemic Rats

Ischemic stroke represents the leading cause of adult neurological disability, with no effective therapeutic strategy. Stem cell transplantation promises a new promising for treating stroke, through cell replacement and cytokine paracrine. However, due to the effect of hostile immune microenvironment, the survival and differentiation of stem cells are limited in vivo. Furthermore, the delayed inflammatory response to stroke induced secondary neurological injury. IFN-γ as pro-inflammatory cytokine has the potential to protect stem cell population during inflammatory response, as well as stimulates neurogenesis of stem cells. The purpose of this study was to investigate whether co-injection of neural stem cells and IFN-γ can improve therapeutic outcomes in ischemic stroke model. In this study, we found that IFN-γ did not interfere with the proliferation of neural stem cells (NSCs) in vitro and induced levels of subsequent neuronal differentiation significantly superior to those of other four cytokines BDNF, VEGF, TGF-β, and IGF-1. Co-delivery of IFN-γ (concentration: 50 ng) enhanced the effectiveness of NSC transplantation therapy in ischemic rats. And combined IFN-γ treatment significantly increased neurogenesis in vivo, with more BrdU/DCX dual-positive cells found in ischemic areas. Moreover, co-treatment with IFN-γ and NSCs exerted additional neurological benefits compared with NSC transplantation alone. In conclusion, low concentration of IFN-γ can promote the functions of transplanted NSCs and facilitate their ability of neurological repair. Thus, our findings suggest that co-delivery of NSCs and IFN-γ without genetic modification may be an effective, simple, and novel approach for the treatment of ischemic stroke.

An allogeneic 'off the shelf' therapeutic strategy for peripheral nerve tissue engineering using clinical grade human neural stem cells

Artificial tissues constructed from therapeutic cells offer a promising approach for improving the treatment of severe peripheral nerve injuries. In this study the effectiveness of using CTX0E03, a conditionally immortalised human neural stem cell line, as a source of allogeneic cells for constructing living artificial nerve repair tissue was tested. CTX0E03 cells were differentiated then combined with collagen to form engineered neural tissue (EngNT-CTX), stable aligned sheets of cellular hydrogel. EngNT-CTX sheets were delivered within collagen tubes to repair a 12 mm sciatic nerve injury model in athymic nude rats. Autologous nerve grafts (autografts) and empty tubes were used for comparison. After 8 weeks functional repair was assessed using electrophysiology. Further, detailed histological and electron microscopic analysis of the repaired nerves was performed. Results indicated that EngNT-CTX supported growth of neurites and vasculature through the injury site and facilitated reinnervation of the target muscle. These findings indicate for the first time that a clinically validated allogeneic neural stem cell line can be used to construct EngNT. This provides a potential 'off the shelf' tissue engineering solution for the treatment of nerve injury, overcoming the limitations associated with nerve autografts or the reliance on autologous cells for populating repair constructs.

Potential of Stem Cell-Based Therapy for Ischemic Stroke

Ischemic stroke is one of the major health problems worldwide. The only FDA approved anti-thrombotic drug for acute ischemic stroke is the tissue plasminogen activator. Several studies have been devoted to assessing the therapeutic potential of different types of stem cells such as neural stem cells (NSCs), mesenchymal stem cells, embryonic stem cells, and human induced pluripotent stem cell-derived NSCs as treatments for ischemic stroke. The results of these studies are intriguing but many of them have presented conflicting results. Additionally, the mechanism(s) by which engrafted stem/progenitor cells exert their actions are to a large extent unknown. In this review, we will provide a synopsis of different preclinical and clinical studies related to the use of stem cell-based stroke therapy, and explore possible beneficial/detrimental outcomes associated with the use of different types of stem cells. Due to limited/short time window implemented in most of the recorded clinical trials about the use of stem cells as potential therapeutic intervention for stroke, further clinical trials evaluating the efficacy of the intervention in a longer time window after cellular engraftments are still needed.

Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)

Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.

[Cell therapy for ischemic stroke. Results of clinical trials and perspectives of clinical application in the Russian Federation]

The first part of the review summarized the results of preclinical animal studies using stroke models that demonstrated the efficacy of cell therapy. The second part presents the proposed mechanisms of action of stem cells, optimal therapeutic window for cell transplantation, the results of completed clinical trials on humans in the period from 2010 to 2017, as well as the legal aspects of the use of cell technologies in the Russian Federation.

Treatments to Promote Neural Repair after Stroke

Stroke remains a major cause of human disability worldwide. In parallel with advances in acute stroke interventions, new therapies are under development that target restorative processes. Such therapies have a treatment time window measured in days, weeks, or longer and so have the advantage that they may be accessible by a majority of patients. Several categories of restorative therapy have been studied and are reviewed herein, including drugs, growth factors, monoclonal antibodies, activity-related therapies including telerehabilitation, and a host of devices such as those related to brain stimulation or robotics. Many patients with stroke do not receive acute stroke therapies or receive them and do not derive benefit, often surviving for years thereafter. Therapies based on neural repair hold the promise of providing additional treatment options to a majority of patients with stroke.

Human Neural Stem Cells for Ischemic Stroke Treatment

Ischemic stroke is the second most common cause of death worldwide and a major cause of disability. It takes place when the brain does not receive sufficient blood supply due to the blood clot in the vessels or narrowing of vessels' inner space due to accumulation of fat products. Apart from thrombolysis (dissolving of blood clot) and thrombectomy (surgical removal of blood clot or widening of vessel inner area) during the first hours after an ischemic stroke, no effective treatment to improve functional recovery exists in the post-ischemic phase. Due to their narrow therapeutic time window, thrombolysis and thrombectomy are unavailable to more than 80% of stroke patients.Many experimental studies carried out in animal models of stroke have demonstrated that stem cell transplantation may become a new therapeutic strategy in stroke. Transplantation of stem cells of different origin and stage of development has been shown to lead to improvement in experimental models of stroke through several mechanisms including neuronal replacement, modulation of cellular and synaptic plasticity and inflammation, neuroprotection and stimulation of angiogenesis. Several clinical studies and trials based on stem cell delivery in stroke patients are in progress with goal of improvements of functional recovery through mechanisms other than neuronal replacement. These approaches may provide therapeutic benefit, but generation of specific neurons for reconstruction of stroke-injured neural circuitry remains ultimate challenge. For this purpose, neural stem cells could be developed from multiple sources and fated to adopt required neuronal phenotype.

Stem Cell Therapy: Repurposing Cell-Based Regenerative Medicine Beyond Cell Replacement

Stem cells exhibit simple and naive cellular features, yet their exact purpose for regenerative medicine continues to elude even the most elegantly designed research paradigms from developmental biology to clinical therapeutics. Based on their capacity to divide indefinitely and their dynamic differentiation into any type of tissue, the advent of transplantable stem cells has offered a potential treatment for aging-related and injury-mediated diseases. Recent laboratory evidence has demonstrated that transplanted human neural stem cells facilitate endogenous reparative mechanisms by initiating multiple regenerative processes in the brain neurogenic areas. Within these highly proliferative niches reside a myriad of potent regenerative molecules, including anti-inflammatory cytokines, proteomes, and neurotrophic factors, altogether representing a biochemical cocktail vital for restoring brain function in the aging and diseased brain. Here, we advance the concept of therapeutically repurposing stem cells not towards cell replacement per se, but rather exploiting the cells' intrinsic properties to serve as the host brain regenerative catalysts.

Neurorestorative effect of olfactory ensheathing cells and Schwann cells by intranasal delivery for patients with ischemic stroke: design of a multicenter randomized double-blinded placebo-controlled clinical study

Introduction:

There have been many clinical studies or trials for patients with ischemic stroke by cell therapy, which includes olfactory ensheathing cell (OEC), mononuclear cell, mesenchymal stromal cell, fetal neural cell or products of varying stem cells, etc. Those cells through different transplanting ways have showed moderate neurorestorative effect in patients with ischemic stroke, but majority were not multicenter randomized, double-blinded, placebo-controlled studies or trials. OEC transplantation has shown a more effective to restore neurological damage in central nervous system (CNS). We hypothesize that OEC through intra-olfactory mucosa transplantation can migrate into the ischemic stroke area around and restore neurological deficit caused from this disaster.

Objective of the study:

This is a multicenter, randomized, double-blinded, placebo- controlled 12 month clinical study of OECs and Schwann cells (SCs) for patients with sub-acute ischemic stroke and chronic ischemic stroke, to test which kind of cell has more neurorestorative effect for patients with ischemic stroke relative to placebo.

Design of the study:

This study is involved two groups of patients with sub-acute ischemic stroke and chronic ischemic stroke. Each group enrolls 30 patients. The experimental intervention consists in using OECs and SCs through intra-olfactory mucosa transplantation in participating patients. This will be compared with using placebo (injecting cell culture medium). Participating patients in groups of sub-acute ischemic stroke and chronic ischemic stroke are randomized in natural order to divide into A, B, or C groups and get one of experimental treatment procedures. Patients, operating physicians, and assessing physicians are left unaware of what cells or medium will be injected to participating patients. All patients will be assessed before treatment and after one month, three months, six months, and one year.

Ethics and dissemination:

The clinical study protocol and consent form were approved by Chinese Association of Neurorestoratology and the ethics committees of the hospitals which joined this clinical study. Findings will be published in peer-reviewed journals.

Enhancing Plasticity of the Central Nervous System: Drugs, Stem Cell Therapy, and Neuro-Implants

Stroke represents the first cause of adult acquired disability. Spontaneous recovery, dependent on endogenous neurogenesis, allows for limited recovery in 50% of patients who remain functionally dependent despite physiotherapy. Here, we propose a review of novel drug therapies with strong potential in the clinic. We will also discuss new avenues of stem cell therapy in patients with a cerebral lesion. A promising future for the development of efficient drugs to enhance functional recovery after stroke seems evident. These drugs will have to prove their efficacy also in severely affected patients. The efficacy of stem cell engraftment has been demonstrated but will have to prove its potential in restoring tissue function for the massive brain lesions that are most debilitating. New answers may lay in biomaterials, a steadily growing field. Biomaterials should ideally resemble lesioned brain structures in architecture and must be proven to increase functional reconnections within host tissue before clinical testing.