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

Emerging strategies for nerve repair and regeneration in ischemic stroke: neural stem cell therapy

Ischemic stroke is a major cause of mortality and disability worldwide, with limited treatment options available in clinical practice. The emergence of stem cell therapy has provided new hope to the field of stroke treatment via the restoration of brain neuron function. Exogenous neural stem cells are beneficial not only in cell replacement but also through the bystander effect. Neural stem cells regulate multiple physiological responses, including nerve repair, endogenous regeneration, immune function, and blood-brain barrier permeability, through the secretion of bioactive substances, including extracellular vesicles/exosomes. However, due to the complex microenvironment of ischemic cerebrovascular events and the low survival rate of neural stem cells following transplantation, limitations in the treatment effect remain unresolved. In this paper, we provide a detailed summary of the potential mechanisms of neural stem cell therapy for the treatment of ischemic stroke, review current neural stem cell therapeutic strategies and clinical trial results, and summarize the latest advancements in neural stem cell engineering to improve the survival rate of neural stem cells. We hope that this review could help provide insight into the therapeutic potential of neural stem cells and guide future scientific endeavors on neural stem cells.

Stroke: Evolution of newer treatment modalities for acute ischemic stroke

Acute ischemic stroke is one of the leading causes of morbidity and mortality worldwide. Restoration of cerebral blood flow to affected ischemic areas has been the cornerstone of therapy for patients for eligible patients as early diagnosis and treatment have shown improved outcomes. However, there has been a paradigm shift in the management approach over the last decade, and with the emphasis currently directed toward including newer modalities such as neuroprotection, stem cell treatment, magnetic stimulation, anti-apoptotic drugs, delayed recanalization, and utilization of artificial intelligence for early diagnosis and suggesting algorithm-based management protocols.

Stroke studies in large animals: Prospects of mitochondrial transplantation and enhancing efficiency using hydrogels and nanoparticle-assisted delivery

One of the most frequent reasons for mortality and disability today is acute ischemic stroke, which occurs by an abrupt disruption of cerebral circulation. The intricate damage mechanism involves several factors, such as inflammatory response, disturbance of ion balance, loss of energy production, excessive reactive oxygen species and glutamate release, and finally, neuronal death. Stroke research is now carried out using several experimental models and potential therapeutics. Furthermore, studies are being conducted to address the shortcomings of clinical care. A great deal of research is being done on novel pharmacological drugs, mitochondria targeting compounds, and different approaches including brain cooling and new technologies. Still, there are many unanswered questions about disease modeling and treatment strategies. Before these new approaches may be used in therapeutic settings, they must first be tested on large animals, as most of them have been done on rodents. However, there are several limitations to large animal stroke models used for research. In this review, the damage mechanisms in acute ischemic stroke and experimental acute ischemic stroke models are addressed. The current treatment approaches and promising experimental methods such as mitochondrial transplantation, hydrogel-based interventions, and strategies like mitochondria encapsulation and chemical modification, are also examined in this work.

An update on stem cell therapy for stroke patients: Where are we now?

With a foundation built upon initial work from the 1980s demonstrating graft viability in cerebral ischemia, stem cell transplantation has shown immense promise in promoting survival, enhancing neuroprotection and inducing neuroregeneration, while mitigating both histological and behavioral deficits that frequently accompany ischemic stroke. These findings have led to a number of clinical trials that have thoroughly supported a strong safety profile for stem cell therapy in patients but have generated variable efficacy. As preclinical evidence continues to expand through the investigation of new cell lines and optimization of stem cell delivery, it remains critical for translational models to adhere to the protocols established through basic scientific research. With the recent shift in approach towards utilization of stem cells as a conjunctive therapy alongside standard thrombolytic treatments, key issues including timing, route of administration, and stem cell type must each be appropriately translated from the laboratory in order to resolve the question of stem cell efficacy for cerebral ischemia that ultimately will enhance therapeutics for stroke patients towards improving quality of life.

Transplantation of neural stem cells improves recovery of stroke-affected mice and induces cell-specific changes in GSDMD and MLKL expression

Introduction

Stroke, the second leading cause of death and disability in Europe, is primarily caused by interrupted blood supply, leading to ischemia-reperfusion (IR) injury and subsequent neuronal death. Current treatment options are limited, highlighting the need for novel therapies. Neural stem cells (NSCs) have shown promise in treating various neurological disorders, including stroke. However, the underlying mechanisms of NSC-mediated recovery remain unclear.

Methods

Eighty C57Bl/6-Tyrc-Brd mice underwent ischemic stroke induction and were divided into four groups: sham, stroke-affected, stroke-affected with basal cell medium injection, and stroke-affected with NSCs transplantation. NSCs, isolated from mouse embryos, were stereotaxically transplanted into the stroke-affected brains. Magnetic resonance imaging (MRI) and neurological scoring were used to assess recovery. Immunohistochemical analysis and gene expression assays were performed to evaluate pyroptosis and necroptosis markers.

Results

NSC transplantation significantly improved neurological recovery compared to control groups. In addition, although not statistically significant, NSCs reduced stroke volume. Immunohistochemical analysis revealed upregulation of Gasdermin D (GSDMD) expression post-stroke, predominantly in microglia and astrocytes. However, NSC transplantation led to a reduction in GSDMD signal intensity in astrocytes, suggesting an effect of NSCs on GSDMD activity. Furthermore, NSCs downregulated Mixed Lineage Kinase Domain-Like Protein (Mlkl) expression, indicating a reduction in necroptosis. Immunohistochemistry demonstrated decreased phosphorylated MLKL (pMLKL) signal intensity in neurons while stayed the same in astrocytes following NSC transplantation, along with increased distribution in microglia.

Discussion

NSC transplantation holds therapeutic potential in stroke recovery by targeting pyroptosis and necroptosis pathways. These findings shed light on the mechanisms underlying NSC-mediated neuroprotection and support their further exploration as a promising therapy for stroke patients.

Engineering 3D Scaffold-Free Nanoparticle-Laden Stem Cell Constructs for Piezoelectric Enhancement of Human Neural Tissue Formation and Function

Electrical stimulation (ES) of cellular systems can be utilized for biotechnological applications and electroceuticals (bioelectric medicine). Neural cell stimulation especially has a long history in neuroscience research and is increasingly applied for clinical therapies. Application of ES via conventional electrodes requires external connectors and power sources, hindering scientific and therapeutic applications. Here engineering novel 3D scaffold-free human neural stem cell constructs with integrated piezoelectric nanoparticles for enhanced neural tissue induction and function is described. Tetragonal barium titanate (BaTi03) nanoparticles are employed as piezoelectric stimulators prepared as cytocompatible dispersions, incorporated into 3D self-organizing neural spheroids, and activated wirelessly by ultrasound. Ultrasound delivery (low frequency; 40 kHz) is optimized for cell survival, and nanoparticle activation enabled ES throughout the spheroids during differentiation, tissue formation, and maturation. The resultant human neural tissues represent the first example of direct tissue loading with piezoelectric particles for ensuing 3D ultrasound-mediated piezoelectric enhancement of human neuronal induction from stem cells, including augmented neuritogenesis and synaptogenesis. It is anticipated that the platform described will facilitate advanced tissue engineering and in vitro modeling of human neural (and potentially non-neural) tissues, with modeling including tissue development and pathology, and applicable to preclinical testing and prototyping of both electroceuticals and pharmaceuticals.

Nanotechnology and bioengineering approaches to improve the potency of mesenchymal stem cell as an off-the-shelf versatile tumor delivery vehicle

Targeting actionable mutations in oncogene-driven cancers and the evolution of immuno-oncology are the two prominent revolutions that have influenced cancer treatment paradigms and caused the emergence of precision oncology. However, intertumoral and intratumoral heterogeneity are the main challenges in both fields of precision cancer treatment. In other words, finding a universal marker or pathway in patients suffering from a particular type of cancer is challenging. Therefore, targeting a single hallmark or pathway with a single targeted therapeutic will not be efficient for fighting against tumor heterogeneity. Mesenchymal stem cells (MSCs) possess favorable characteristics for cellular therapy, including their hypoimmune nature, inherent tumor-tropism property, straightforward isolation, and multilineage differentiation potential. MSCs can be loaded with various chemotherapeutics and oncolytic viruses. The combination of these intrinsic features with the possibility of genetic manipulation makes them a versatile tumor delivery vehicle that can be used for in vivo selective tumor delivery of various chemotherapeutic and biological therapeutics. MSCs can be used as biofactory for the local production of chemical or biological anticancer agents at the tumor site. MSC-mediated immunotherapy could facilitate the sustained release of immunotherapeutic agents specifically at the tumor site, and allow for the achievement of therapeutic concentrations without the need for repetitive systemic administration of high therapeutic doses. Despite the enthusiasm evoked by preclinical studies that used MSC in various cancer therapy approaches, the translation of MSCs into clinical applications has faced serious challenges. This manuscript, with a critical viewpoint, reviewed the preclinical and clinical studies that have evaluated MSCs as a selective tumor delivery tool in various cancer therapy approaches, including gene therapy, immunotherapy, and chemotherapy. Then, the novel nanotechnology and bioengineering approaches that can improve the potency of MSC for tumor targeting and overcoming challenges related to their low localization at the tumor sites are discussed.

Selected serum cytokines and vitamin D levels as potential prognostic markers of acute ischemic stroke

Inflammation-derived oxidative stress is postulated to contribute to neuronal damage leading to poor clinical outcomes in Acute Ischemic Stroke (AIS). We aimed to investigate the association between serum levels of selected cytokines (IL-1β, IFN-γ, IL-4), and vitamin D in ischemic stroke progression, and their accuracy in predicting AIS prognosis, among Sri Lankans. We compared 60 AIS patients admitted in 4 phases post-stroke onset (<6 h; 6-24 h; 24-48 h; 48-96 h; n = 15/phase), with 15 age- and sex-matched controls. The 30-day functional outcome (FO) was assessed using the modified Rankin Scale (mRS). Serum cytokine and vitamin D levels were quantified using sandwich ELISAs, and competitive ELISA, respectively. The CombiROC web tool established optimal prognostic biomarker combinations. Serum IL-1β and IFN-γ were elevated in all four phases following stroke onset while IL-4 was elevated exclusively in the recovery phase (48-96 h) (p<0.05). Th1 bias polarization of the Th1:Th2 cytokine (IFN-γ:IL-4) ratio occurred with AIS progression while a Th2 bias occurred during AIS recovery (p<0.05). Lower serum IL-1β and higher IL-4 levels were associated with a good FO (p<0.05), while lower Vitamin D levels were related to a poor FO (p = 0.001). The triple-biomarker panel, IL-4- IFN-γ -Vit D, accurately predicted AIS prognosis (sensitivity = 100%, specificity = 91.9%, area under the curve = 0.98). Serum immunologic mediators IFN-γ, IL-4, and vitamin D may be useful biomarkers of AIS prognosis and may serve as therapeutic targets in improving stroke outcomes. Vitamin D supplementation may improve the prognosis of AIS patients. Furthermore, binary logistic model fitted for FO indicated Th1:Th2 cytokine ratio (IFN-γ:IL-4), vitamin D status, history of stroke, and ischemic heart disease as significant predictors of AIS prognosis.

Pharmacological and stem cell therapy of stroke in animal models: Do they accurately reflect the response of humans?

Cerebrovascular diseases are the second leading cause of death worldwide. Despite significant research investment, the only available therapeutic options are mechanical thrombectomy and tissue plasminogen activator thrombolysis. None of the more than a thousand drugs tested on animal models have proven successful in human clinical trials. Several factors contribute to this poor translation of data from stroke-related animal models to human stroke patients. Firstly, our understanding of the molecular and cellular processes involved in recovering from an ischemic stroke is severely limited. Secondly, although the risk of stroke is particularly high among older patients with comorbidities, most drugs are tested on young, healthy animals in controlled laboratory conditions. Furthermore, in animal models, the tracking of post-stroke recovery typically spans only 3 to 28 days, with occasional extensions to 60 days, whereas human stroke recovery is a more extended and complex process. Thirdly, young animal models often exhibit a considerably higher rate of spontaneous recovery compared to humans following a stroke. Fourth, only a very limited number of animals are utilized for each condition, including control groups. Another contributing factor to the much smaller beneficial effects in humans is that positive outcomes from numerous animal studies are more readily accepted than results reported in human trials that do not show a clear benefit to the patient. Useful recommendations for conducting experiments in animal models, with increased chances of translatability to humans, have been issued by both the STEPS investigative team and the STAIR committee. However, largely, due to economic factors, these recommendations are largely ignored. Furthermore, one might attribute the overall failures in predicting and subsequently developing effective acute stroke therapies beyond thrombolysis to potential design deficiencies in clinical trials.

Intracerebral transplantation of MRI-trackable autologous bone marrow stromal cells for patients with subacute ischemic stroke

BACKGROUND

Ischemic stroke is one of the leading causes of death and neurological disability worldwide, and stem cell therapy is highly expected to reverse the sequelae. This phase 1/2, first-in-human study evaluated the safety, feasibility, and monitoring of an intracerebral-transplanted magnetic resonance imaging (MRI)-trackable autologous bone marrow stromal cell (HUNS001-01) for patients with subacute ischemic stroke.

METHODS

The study included adults with severe disability due to ischemic stroke. HUNS001-01 cultured with human platelet lysates and labeled with superparamagnetic iron oxide was stereotactically transplanted into the peri-infarct area 47-64 days after ischemic stroke onset (dose: 2 or 5 × 107 cells). Neurological and radiographic evaluations were performed throughout 1 year after cell transplantation. The trial was registered at UMIN Clinical Trial Registry (number UMIN000026130).

FINDINGS

All seven patients who met the inclusion criteria successfully achieved cell expansion, underwent intracerebral transplantation, and completed 1 year of follow-up. No product-related adverse events were observed. The median National Institutes of Health Stroke Scale and modified Rankin scale scores before transplantation were 13 and 4, which showed improvements of 1-8 and 0-2, respectively. Cell tracking proved that the engrafted cells migrated toward the infarction border area 1-6 months after transplantation, and the quantitative susceptibility mapping revealed that cell signals at the migrated area constantly increased throughout the follow-up period up to 34% of that of the initial transplanted site.

CONCLUSIONS

Intracerebral transplantation of HUNS001-01 was safe and well tolerated. Cell tracking shed light on the therapeutic mechanisms of intracerebral transplantation.

FUNDING

This work was supported by the Japan Agency for Medical Research and Development (AMED; JP17bk0104045 and JP20bk0104011).

Phase 1 study of safety and preliminary efficacy of intranasal transplantation of human neural stem cells (ANGE-S003) in Parkinson's disease

BACKGROUND

Intranasal transplantation of ANGE-S003 human neural stem cells showed therapeutic effects and were safe in preclinical models of Parkinson's disease (PD). We investigated the safety and tolerability of this treatment in patients with PD and whether these effects would be apparent in a clinical trial.

METHODS

This was a 12-month, single-centre, open-label, dose-escalation phase 1 study of 18 patients with advanced PD assigned to four-time intranasal transplantation of 1 of 3 doses: 1.5 million, 5 million or 15 million of ANGE-S003 human neural stem cells to evaluate their safety and efficacy.

RESULTS

7 patients experienced a total of 14 adverse events in the 12 months of follow-up after treatment. There were no serious adverse events related to ANGE-S003. Safety testing disclosed no safety concerns. Brain MRI revealed no mass formation. In 16 patients who had 12-month Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) data, significant improvement of MDS-UPDRS total score was observed at all time points (p<0.001), starting with month 3 and sustained till month 12. The most substantial improvement was seen at month 6 with a mean reduction of 19.9 points (95% CI, 9.6 to 30.3; p<0.001). There was no association between improvement in clinical outcome measures and cell dose levels.

CONCLUSIONS

Treatment with ANGE-S003 is feasible, generally safe and well tolerated, associated with functional improvement in clinical outcomes with peak efficacy achieved at month 6. Intranasal transplantation of neural stem cells represents a new avenue for the treatment of PD, and a larger, longer-term, randomised, controlled phase 2 trial is warranted for further investigation.

Neural regeneration in the human central nervous system-from understanding the underlying mechanisms to developing treatments. Where do we stand today?

Mature neurons in the human central nervous system (CNS) fail to regenerate after injuries. This is a common denominator across different aetiologies, including multiple sclerosis, spinal cord injury and ischemic stroke. The lack of regeneration leads to permanent functional deficits with a substantial impact on patient quality of life, representing a significant socioeconomic burden worldwide. Great efforts have been made to decipher the responsible mechanisms and we now know that potent intra- and extracellular barriers prevent axonal repair. This knowledge has resulted in numerous clinical trials, aiming to promote neuroregeneration through different approaches. Here, we summarize the current understanding of the causes to the poor regeneration within the human CNS. We also review the results of the treatment attempts that have been translated into clinical trials so far.

Safety and efficacy of bone marrow mononuclear cell therapy for ischemic stroke recovery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Cell-based therapy represents a potential treatment for ischemic stroke (IS). Here, we performed a systematic review and meta-analysis to summarize the evidence provided by randomized controlled trials (RCTs) for the transplantation of bone marrow mononuclear cells (BMMNCs) in patients with IS in any phase after stroke.

METHODS

We searched several databases for relevant articles up to the 10th of March 2023, including MEDLINE, EMBASE, the Cochrane Library, and ClinicalTrials.gov. Subgroup analyses were implemented to evaluate the dose and route of BMMNC administration. Statistical data were analyzed by Review Manager version 5.3 software.

RESULTS

Six RCTs were included in this article, including 177 patients who were treated by the transplantation of BMMNCs and 166 patients who received medical treatment. The three-month National Institutes of Health Stroke Scale (NIHSS) score indicated a favorable outcome for the BMMNC transplantation group (standardized mean difference (SMD), - 0.34; 95% confidence interval (CI), - 0.57 to - 0.11; P = 0.004). There were no significant differences between the two groups at six months post-transplantation with regards to NIHSS score (SMD 0.00; 95% CI - 0.26 to 0.27; P = 0.97), modified Rankin Scale (risk ratio (RR) 1.10; 95% CI 0.75 to 1.63; P = 0.62), Barthel Index change (SMD 0.68; 95% CI - 0.59 to 1.95; P = 0.29), and infarct volume change (SMD - 0.08; 95% CI - 0.42 to 0.26; P = 0.64). In addition, there was no significant difference between the two groups in terms of safety outcome (RR 1.24; 95% CI 0.80 to 1.91; P = 0.33).

CONCLUSION

Our meta-analysis demonstrated that the transplantation of BMMNCs was safe; however, the efficacy of this procedure requires further validation in larger RTCs.

Neuroprotective Approaches for Brain Injury After Cardiac Arrest: Current Trends and Prospective Avenues

With the implementation of improved bystander cardiopulmonary resuscitation techniques and public-access defibrillation, survival after out-of-hospital cardiac arrest (OHCA) has increased significantly over the years. Nevertheless, OHCA survivors have residual anoxia/reperfusion brain damage and associated neurological impairment resulting in poor quality of life. Extracorporeal membrane oxygenation or targeted temperature management has proven effective in improving post-cardiac arrest (CA) neurological outcomes, yet considering the substantial healthcare costs and resources involved, there is an urgent need for alternative treatment strategies that are crucial to alleviate brain injury and promote recovery of neurological function after CA. In this review, we searched PubMed for the latest preclinical or clinical studies (2016-2023) utilizing gas-mediated, pharmacological, or stem cell-based neuroprotective approaches after CA. Preclinical studies utilizing various gases (nitric oxide, hydrogen, hydrogen sulfide, carbon monoxide, argon, and xenon), pharmacological agents targeting specific CA-related pathophysiology, and stem cells have shown promising results in rodent and porcine models of CA. Although inhaled gases and several pharmacological agents have entered clinical trials, most have failed to demonstrate therapeutic effects in CA patients. To date, stem cell therapies have not been reported in clinical trials for CA. A relatively small number of preclinical stem-cell studies with subtle therapeutic benefits and unelucidated mechanistic explanations warrant the need for further preclinical studies including the improvement of their therapeutic potential. The current state of the field is discussed and the exciting potential of stem-cell therapy to abate neurological dysfunction following CA is highlighted.

Human-Induced Pluripotent Stem Cell-Derived Neural Progenitor Cells Showed Neuronal Differentiation, Neurite Extension, and Formation of Synaptic Structures in Rodent Ischemic Stroke Brains

Ischemic stroke is a major cerebrovascular disease with high morbidity and mortality rates; however, effective treatments for ischemic stroke-related neurological dysfunction have yet to be developed. In this study, we generated neural progenitor cells from human leukocyte antigen major loci gene-homozygous-induced pluripotent stem cells (hiPSC-NPCs) and evaluated their therapeutic effects against ischemic stroke. hiPSC-NPCs were intracerebrally transplanted into rat ischemic brains produced by transient middle cerebral artery occlusion at either the subacute or acute stage, and their in vivo survival, differentiation, and efficacy for functional improvement in neurological dysfunction were evaluated. hiPSC-NPCs were histologically identified in host brain tissues and showed neuronal differentiation into vGLUT-positive glutamatergic neurons, extended neurites into both the ipsilateral infarct and contralateral healthy hemispheres, and synaptic structures formed 12 weeks after both acute and subacute stage transplantation. They also improved neurological function when transplanted at the subacute stage with γ-secretase inhibitor pretreatment. However, their effects were modest and not significant and showed a possible risk of cells remaining in their undifferentiated and immature status in acute-stage transplantation. These results suggest that hiPSC-NPCs show cell replacement effects in ischemic stroke-damaged neural tissues, but their efficacy is insufficient for neurological functional improvement after acute or subacute transplantation. Further optimization of cell preparation methods and the timing of transplantation is required to balance the efficacy and safety of hiPSC-NPC transplantation.

Revolutionizing Stroke Recovery: Unveiling the Promise of Stem Cell Therapy

Stem cells, renowned for their unique regenerative capabilities, present significant hope in treating stroke, a major cause of disability globally. This review offers a detailed analysis of stem cell applications in stroke (ischemic and hemorrhagic) recovery. It examines therapies based on autologous (patient-derived), allogeneic (donor-derived), and Granulocyte-Colony Stimulating Factor (G-CSF) based stem cells, focusing on cell types such as Mesenchymal Stem/Stromal Cells (MSCs), Bone Marrow Mononuclear Stem Cells (BMMSCs), and Neural Stem/Progenitor Cells (NSCs). The paper compiles clinical trial data to evaluate their effectiveness and safety and addresses the ethical concerns of these innovative treatments. By explaining the mechanisms of stem cell-induced neurological repair, this review underscores stem cells' potential in revolutionizing stroke rehabilitation and suggests avenues for future research.

Skin derived precursors induced Schwann cells mediated tissue engineering-aided neuroregeneration across sciatic nerve defect

A central question in neural tissue engineering is how the tissue-engineered nerve (TEN) translates detailed transcriptional signals associated with peripheral nerve regeneration into meaningful biological processes. Here, we report a skin-derived precursor-induced Schwann cell (SKP-SC)-mediated chitosan/silk fibroin-fabricated tissue-engineered nerve graft (SKP-SCs-TEN) that can promote sciatic nerve regeneration and functional restoration nearly to the levels achieved by autologous nerve grafts according to behavioral, histological, and electrophysiological evidence. For achieving better effect of neuroregeneration, this is the first time to jointly apply a dynamic perfusion bioreactor and the ascorbic acid to stimulate the SKP-SCs secretion of extracellular matrix (ECM). To overcome the limitation of traditional tissue-engineered nerve grafts, jointly utilizing SKP-SCs and their ECM components were motivated by the thought of prolongating the effect of support cells and their bioactive cues that promote peripheral nerve regeneration. To further explore the regulatory model of gene expression and the related molecular mechanisms involved in tissue engineering-aided peripheral nerve regeneration, we performed a cDNA microarray analysis of gene expression profiling, a comprehensive bioinformatics analysis and a validation study on the grafted segments and dorsal root ganglia tissues. A wealth of transcriptomic and bioinformatics data has revealed complex molecular networks and orchestrated functional regulation that may be responsible for the effects of SKP-SCs-TEN on promoting peripheral nerve regeneration. Our work provides new insights into transcriptomic features and patterns of molecular regulation in nerve functional recovery aided by SKP-SCs-TEN that sheds light on the broader possibilities for novel repair strategies of peripheral nerve injury.

Stem Cell Therapy for Repair of the Injured Brain: Five Principles

Cell therapy holds great promise for regenerative treatment of disease. Despite recent breakthroughs in clinical research, applications of cell therapies to the injured brain have not yielded the desired results. We pinpoint current limitations and suggest five principles to advance stem cell therapies for brain regeneration. While we focus on cell therapy for stroke, all principles also apply for other brain diseases.

Opportunities for developing neural stem cell treatments for acute ischemic stroke: A systematic review and gap analysis

Ischemic stroke is a leading cause of disability and death. Current treatments are limited. Stem cell therapy has been highlighted as a potentially effective treatment to mitigate damage and restore function, but efficacy results are mixed. This study aimed to systematically review the literature on stem cell therapies for early acute ischemic stroke; and identify opportunities for future research to facilitate the development of an effective stem cell-based treatment. Original research published within the last 10 years that focused on the evaluation of a stem cell-based treatment for acute ischemic stroke in adult patients or subjects was included. Risk of bias was assessed using the SYRCLE and Cochrane risk of bias tools for animal and human studies, respectively. 3,396 articles were screened, 58 full-text articles were reviewed and 33 met inclusion criteria. Many studies appeared to be at risk of bias. Study designs and results were heterogeneous. Most studies were preclinical and involved stem cell administration within 24 hours. Seven studies tested the effects of multiple administration timepoints and one investigated repeat dosing. Six studies were conducted in humans and stem cell administration ranged from 24 hours to 90 days post stroke. Most studies employed the use of mesenchymal stem cells. The most appropriate cell delivery method appeared to be intra-arterial. Evidence suggests that stem cell therapy may be associated with beneficial effects. A literature gap analysis identified numerous opportunities for treatment development.

Anti-stroke biologics: from recombinant proteins to stem cells and organoids

The use of biologics in various diseases has dramatically increased in recent years. Stroke, a cerebrovascular disease, is the second most common cause of death, and the leading cause of disability with high morbidity worldwide. For biologics applied in the treatment of acute ischaemic stroke, alteplase is the only thrombolytic agent. Meanwhile, current clinical trials show that two recombinant proteins, tenecteplase and non-immunogenic staphylokinase, are most promising as new thrombolytic agents for acute ischaemic stroke therapy. In addition, stem cell-based therapy, which uses stem cells or organoids for stroke treatment, has shown promising results in preclinical and early clinical studies. These strategies for acute ischaemic stroke mainly rely on the unique properties of undifferentiated cells to facilitate tissue repair and regeneration. However, there is a still considerable journey ahead before these approaches become routine clinical use. This includes optimising cell delivery methods, determining the ideal cell type and dosage, and addressing long-term safety concerns. This review introduces the current or promising recombinant proteins for thrombolysis therapy in ischaemic stroke and highlights the promise and challenges of stem cells and cerebral organoids in stroke therapy.

The Role of Stem Cells as Therapeutics for Ischaemic Stroke

Stroke remains one of the leading causes of death and disability worldwide. Current reperfusion treatments for ischaemic stroke are limited due to their narrow therapeutic window in rescuing ischaemic penumbra. Stem cell therapy offers a promising alternative. As a regenerative medicine, stem cells offer a wider range of treatment strategies, including long-term intervention for chronic patients, through the reparation and replacement of injured cells via mechanisms of differentiation and proliferation. The purpose of this review is to evaluate the therapeutic role of stem cells for ischaemic stroke. This paper discusses the pathology during acute, subacute, and chronic phases of cerebral ischaemic injury, highlights the mechanisms involved in mesenchymal, endothelial, haematopoietic, and neural stem cell-mediated cerebrovascular regeneration, and evaluates the pre-clinical and clinical data concerning the safety and efficacy of stem cell-based treatments. The treatment of stroke patients with different types of stem cells appears to be safe and efficacious even at relatively higher concentrations irrespective of the route and timing of administration. The priming or pre-conditioning of cells prior to administration appears to help augment their therapeutic impact. However, larger patient cohorts and later-phase trials are required to consolidate these findings.

A review and meta-analysis of stem cell therapies in stroke patients: effectiveness and safety evaluation

PURPOSE

Stem cells have been extensively used during the last decade to improve clinical outcomes after stroke. The dramatic increase in trials in this field has led us to perform a systematic review and meta-analysis to understand the safety, effectiveness, and relative limitations of this type of intervention.

METHOD

This review summarizes the current evidence pooled from PubMed (Medline), EMBASE, EBSCOhost, http://clinicaltrials.gov , Scopus (Elsevier), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (Science Citation Index Expanded) databases for the use of stem cell therapies in stroke patients without combinations with other treatment modalities. The National Institutes of Health Stroke, modified Rankin Scales, and Barthel Index scores after external stem cell administration have been evaluated on the 3rd, 6th, and 12th months after treatment. The random effect analysis was performed using the Review Manager 5.4.1. The characteristics of stem cell sources and their adverse effects have been discussed as well.

FINDINGS

Although reasonably safe, the effectiveness evidence fluctuated to a large extent due to the heterogeneity of the clinical trials and the absence of a systematic approach. The stem cell sources and the administration window were not strongly associated with clinical outcomes.

CONCLUSION

Further studies should be conducted to understand the deep discrepancy between preclinical and clinical trials and to execute phase 3 clinical trials with robust control of study characteristics and outcomes.

Blood-Brain Barrier (BBB)-Crossing Strategies for Improved Treatment of CNS Disorders

Blood-brain barrier (BBB) is a special biological property of the brain neurovascular unit (including brain microvessels and capillaries), which facilitates the transport of nutrients into the central nervous system (CNS) and exchanges metabolites but restricts passage of blood-borne neurotoxic substances and drugs/xenobiotics into CNS. BBB plays a crucial role in maintaining the homeostasis and normal physiological functions of CNS but severely impedes the delivery of drugs and biotherapeutics into CNS for treatment of neurological disorders. A variety of technologies have been developed in the past decade for brain drug delivery. Most of these technologies are still in preclinical stage and some are undergoing clinical studies. Only a few have been approved by regulatory agencies for clinical applications. This chapter will overview the strategies and technologies/approaches for brain drug delivery and discuss some of the recent advances in the field.

Ultrasound-Targeted Microbubble Destruction Increases BBB Permeability and Promotes Stem Cell-Induced Regeneration of Stroke by Downregulating MMP8

The objective of this study was to evaluate the feasibility, safety, and effectiveness of intravenous stem cell delivery utilizing ultrasound-targeted microbubble destruction (UTMD) in a rat model of middle cerebral artery occlusion (MCAO), while investigating the underlying mechanisms. Acute cerebral infarction (ACI) was induced surgically in adult rats to create the MCAO rat model. Intravenous injection of SonoVue microbubbles and bone marrow-derived mesenchymal stem cells (BMSC) was performed concurrently, with or without ultrasound targeting the stroke. The animals were divided into four groups: sham-operated group, ACI-MCAO rats treated with phosphate-buffered saline (ACI+PBS), rats receiving intravenous delivery of BMSC expressing green fluorescent protein (GFP-BMSC; ACI+BMSC), and rats receiving intravenous GFP-BMSC with simultaneous UTMD exposure (ACI+BMSC+UTMD). The efficacy of the treatments was assessed by evaluating the animals' neurological function using the Longa score and examining histopathological changes such as cerebral infarct volume, cerebral edema, and cell apoptosis. A rat cytokine array was utilized to identify the potential cytokines that may be responsible for the therapeutic effect of UTMD-mediated BMSC treatment. Optimal UTMD parameters resulted in an increase in blood-brain barrier (BBB) permeability after 30 min, which returned to baseline 72 h later without causing any residual injury. UTMD application significantly increased the homing of intravenously delivered BMSC, resulting in a 2.2-fold increase in GFP-BMSC cell count on day 3 and a 2.6-fold increase on day 7 compared with intravenous delivery alone. This effect persisted for up to 6 weeks after injection. Intravenous BMSC delivery significantly reduced the volume of cerebral infarct and decreased cerebral edema, leading to a lower Longa score. Furthermore, this effect was further enhanced by UTMD. Acute cerebral infarction induced by MCAO led to elevated matrix metalloproteinase 8 (MMP8) levels in the cerebrospinal fluid, which were significantly reduced following UTMD-mediated BMSC treatment. Ultrasound-targeted microbubble destruction facilitates the migration and homing of BMSC into the brain, possibly by transiently increasing blood-brain barrier (BBB) permeability, thereby improving therapeutic outcomes in an ACI rat model. The observed effect may be partly attributed to modulation of MMP8 levels.Advances in knowledge: UTMD-mediated intravenously delivered BMSC transplantation led to a significant increase in cell homing and reduction of MMP8 levels, resulting in increased therapeutic effect in an acute ischemic cerebral infarction model.

Nanosensor Chemical Cytometry: Advances and Opportunities in Cellular Therapy and Precision Medicine

With the definition of therapeutics now encompassing transplanted or engineered cells and their molecular products, there is a growing scientific necessity for analytics to understand this new category of drugs. This Perspective highlights the recent development of new measurement science on label-free single cell analysis, nanosensor chemical cytometry (NCC), and their potential for cellular therapeutics and precision medicine. NCC is based on microfluidics integrated with fluorescent nanosensor arrays utilizing the optical lensing effect of a single cell to real-time extract molecular properties and correlate them with physical attributes of single cells. This new class of cytometry can quantify the heterogeneity of the multivariate physicochemical attributes of the cell populations in a completely label-free and nondestructive way and, thus, suggest the vein-to-vein conditions for the safe therapeutic applications. After the introduction of the NCC technology, we suggest the technological development roadmap for the maturation of the new field: from the sensor/chip design perspective to the system/software development level based on hardware automation and deep learning data analytics. The advancement of this new single cell sensing technology is anticipated to aid rich and multivariate single cell data setting and support safe and reliable cellular therapeutics. This new measurement science can lead to data-driven personalized precision medicine.

Neural Stem Cell Extracellular Vesicles Carrying YBX1 Inhibited Neuronal Pyroptosis Through Increasing m6A-modified GPR30 Stability and Expression in Ischemic Stroke

Neural stem cell-derived extracellular vesicles (NSC-derived EVs) alleviated ischemic stroke (IS) by suppressing the activation of nucleotide-binding domain leucine-rich repeats family protein 3 (NLRP3) inflammasome and neuronal pyroptosis. However, the specific mechanism needs further investigation. qRT-qPCR, Western blotting, and immunofluorescence detected related gene expression. Immunofluorescent analyzed the expression of Ki-67, βIII-Tubulin (Tuj1), and GFAP. Lactate dehydrogenase (LDH) release and IL-1β and IL-18 levels were analyzed by LDH and ELISA kits. TTC staining evaluated the infarction of brain tissues. Flow cytometric analysis measured caspase-1 activity. M6A methylated RNA immunoprecipitation PCR (MeRIP-PCR) measured methylation levels of G protein-coupled receptor 30 (GPR30). RIP and Co-IP analyzed the interactions of Y box binding protein (YBX1)/GPR30, YBX1/IGF2BP1 and NLRP3/speckle-type POZ protein (SPOP), as well as the ubiquitination levels of NLRP3. NSC-derived EVs inhibited the ischemia-reperfusion (I/R) injury of rats and the neuronal pyroptosis induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of EVs carrying YBX1 or GPR30 silencing abolished these inhibiting effects. GPR30 mRNA and IGF2BP1 protein were enriched by YBX1 antibody. YBX1 enhanced the stability of m6A-modified GPR30 by interacting with IGF2BP1 and thus promoting GPR30 expression. Knockdown of IGF2BP1 suppressed the binding between YBX1 and GPR30 mRNA. GPR30 promoted NLRP3 ubiquitination by interacting with SPOP. EVs carrying YBX1 could reduce the infarction of brain tissues and inhibit neuronal pyroptosis in rats with I/R injury. NSC-derived EVs carrying YBX1 increased the stability of m6A-modified GPR30 by interacting with IGF2BP1; the upregulation of GPR30 inhibited the activation of NLRP3 inflammasome through promoting NLRP3 ubiquitination by SPOP, ultimately suppressing the neuronal pyroptosis in IS.

Comparative study of the efficacy of intra-arterial and intravenous transplantation of human induced pluripotent stem cells-derived neural progenitor cells in experimental stroke

Background

Cell therapy using neural progenitor cells (NPCs) is a promising approach for ischemic stroke treatment according to the results of multiple preclinical studies in animal stroke models. In the vast majority of conducted animal studies, the therapeutic efficacy of NPCs was estimated after intracerebral transplantation, while the information of the effectiveness of systemic administration is limited. Nowadays, several clinical trials aimed to estimate the safety and efficacy of NPCs transplantation in stroke patients were also conducted. In these studies, NPCs were transplanted intracerebrally in the subacute/chronic phase of stroke. The results of clinical trials confirmed the safety of the approach, however, the degree of functional improvement (the primary efficacy endpoint) was not sufficient in the majority of the studies. Therefore, more studies are needed in order to investigate the optimal transplantation parameters, especially the timing of cell transplantation after the stroke onset. This study aimed to evaluate the therapeutic effects of intra-arterial (IA) and intravenous (IV) administration of NPCs derived from induced pluripotent stem cells (iNPCs) in the acute phase of experimental stroke in rats. Induced pluripotent stem cells were chosen as the source of NPCs as this technology is perspective, has no ethical concerns and provides the access to personalized medicine.

Methods

Human iNPCs were transplanted IA or IV into male Wistar rats 24 h after the middle cerebral artery occlusion stroke modeling. Therapeutic efficacy was monitored for 14 days and evaluated in comparison with the cell transplantation-free control group. Additionally, cell distribution in the brain was assessed.

Results

The obtained results show that both routes of systemic transplantation (IV and IA) significantly reduced the mortality and improved the neurological deficit of experimental animals compared to the control group. At the same time, according to the MRI data, only IA administration led to faster and prominent reduction of the stroke volume. After IA administration, iNPCs transiently trapped in the brain and were not detected on day 7 after the transplantation. In case of IV injection, transplanted cells were not visualized in the brain. The obtained data demonstrated that the systemic transplantation of human iNPCs in the acute phase of ischemic stroke can be a promising therapeutic strategy.

Stem cells in central nervous system diseases: Promising therapeutic strategies

Central nervous system (CNS) diseases are a leading cause of death and disability. Due to CNS neurons have no self-renewal and regenerative ability as they mature, their loss after injury or disease is irreversible and often leads to functional impairments. Unfortunately, therapeutic options for CNS diseases are still limited, and effective treatments for these notorious diseases are warranted to be explored. At present, stem cell therapy has emerged as a potential therapeutic strategy for improving the prognosis of CNS diseases. Accumulating preclinical and clinical evidences have demonstrated that multiple molecular mechanisms, such as cell replacement, immunoregulation and neurotrophic effect, underlie the use of stem cell therapy for CNS diseases. However, several issues have yet to be addressed to support its clinical application. Thus, this review article aims to summarize the role and underlying mechanisms of stem cell therapy in treating CNS diseases. And it is worthy of further evaluation for the potential therapeutic applications of stem cell treatment in CNS disease.

Neuroprotective potential of intranasally delivered L-myc immortalized human neural stem cells in female rats after a controlled cortical impact injury

Efficacious stem cell-based therapies for traumatic brain injury (TBI) depend on successful delivery, migration, and engraftment of stem cells to induce neuroprotection. L-myc expressing human neural stem cells (LMNSC008) demonstrate an inherent tropism to injury sites after intranasal (IN) administration. We hypothesize that IN delivered LMNSC008 cells migrate to primary and secondary injury sites and modulate biomarkers associated with neuroprotection and tissue regeneration. To test this hypothesis, immunocompetent adult female rats received either controlled cortical impact injury or sham surgery. LMNSC008 cells or a vehicle were administered IN on postoperative days 7, 9, 11, 13, 15, and 17. The distribution and migration of eGFP-expressing LMNSC008 cells were quantified over 1 mm-thick optically cleared (CLARITY) coronal brain sections from TBI and SHAM controls. NSC migration was observed along white matter tracts projecting toward the hippocampus and regions of TBI. ELISA and Nanostring assays revealed a shift in tissue gene expression in LMNSC008 treated rats relative to controls. LMNSC008 treatment reduced expression of genes and pathways involved in inflammatory response, microglial function, and various cytokines and receptors. Our proof-of-concept studies, although preliminary, support the rationale of using intranasal delivery of LMNSC008 cells for functional studies in preclinical models of TBI and provide support for potential translatability in TBI patients.

Evaluating the Feasibility of Hydrogel-Based Neural Cell Sprays

Neurological injuries have poor prognoses with serious clinical sequelae. Stem cell transplantation enhances neural repair but is hampered by low graft survival (ca. 80%) and marker expression/proliferative potential of hydrogel-sprayed astrocytes was retained. Combining a cell spray format with polymer encapsulation technologies could form the basis of a non-invasive graft delivery method, offering potential advantages over current cell delivery approaches.

Mesenchymal stem cell therapy in aqueous deficient dry eye disease

ENGLISH SUMMARY

Dry eye disease (DED) is characterized by ocular dryness, irritation and blurred vision and has a significant impact on the patient's quality of life. This condition can be particularly severe in patients with aqueous deficient dry eye disease (ADDE) due to Sjögren's syndrome (SS), an autoimmune disease that affects the lacrimal and salivary glands. Current treatments for ADDE are often limited to symptomatic relief. A literature review was conducted to explore the current surgical interventions used or tested in humans with ADDE (I). These interventions include procedures involving the eyelids and tear ducts, transplantation of amniotic membrane or salivary glands, injections around the tear ducts and cell-based injections into the lacrimal gland (LG). Each treatment has its advantages and disadvantages; however, treating dry eyes in patients with SS presents a particular challenge due to the systemic nature of the disease. Moreover, there is a need for new therapeutic options. Mesenchymal stem cells (MSCs) are a type of stem cell that have shown promise in regenerating damaged tissue and reducing inflammation in various diseases. Previous studies in animal models have suggested that MSCs could be effective in treating ADDE. Thus, this thesis aims to investigate the safety and efficacy of injecting MSCs into the LG as a treatment option for patients with ADDE secondary to SS. The study also aims to see this treatment in light of existing and novel investigational treatment options. The clinical studies conducted for this thesis are the first of their kind in humans. MSCs derived from healthy donors' adipose tissue (ASCs) were cultured in a laboratory, frozen and thawed ready for use. In the safety study, we performed the first human trial involving the administration of a single injection of ASCs into the LG of one eye in seven patients suffering from severe ADDE (II). The primary objective was to test the safety of this treatment, while the secondary objective was to assess improvements in subjective and objective signs of dry eye. The results of the trial showed no serious side effects within 4 months of follow-up after treatment. On average, there was a 40% reduction in dry eye symptoms assessed with the Ocular Surface Disease Index (OSDI) questionnaire. Additionally, in the treated eye, there was a significant decrease in tear osmolarity, an increase in tear film stability and an increase in tear production. To further investigate the efficacy of this treatment, our research group performed a clinical, randomized study aiming to compare the ASC injection into the LG with the injection of a vehicle (the excipient in which the ASCs are dissolved) and observation (no intervention) (III). The study involved 20 subjects receiving ASC injection, 20 subjects receiving vehicle injection and 14 patients being observed without intervention. The subjects were examined to assess the outcomes with a 12-month follow-up after treatment. Both intervention groups showed a significant reduction in subjective dry eye symptoms of approximately 40%. This improvement was evident at the 1-week follow-up and persisted until the 12-month follow-up. The observation group did not experience any change in OSDI score. The ASCs group exhibited a significant mean increase in non-invasive tear break-up time (NIKBUT) of 6.48 s (149%) at the four-week follow-up, which was significantly higher than that in the vehicle group (p = 0.04). Moreover, the ASCs group showed a significant increase in NIKBUT compared to that in the observation group at the 12-month follow-up (p = 0.004). In both the ASCs and vehicle group, a significant increase in Schirmer test scores at the 4-month follow-up and the 12-month follow-up was observed. In conclusion, this thesis contributes valuable findings with a new treatment option for patients with dry eye disease. Injection of ASCs into the LG was shown to be safe and to improve subjective dry eye symptoms and specifically the tear film stability in patients with ADDE due to SS. Compared to other treatment modalities of ADDE, this treatment has greater potential, as ASCs could potentially be used as an anti-inflammatory therapeutic option for managing DED of other causes as well. RESUMÉ (DANISH SUMMARY): Tørre øjne, karakteriseret ved tørhedsfornemmelse og irritation af øjnene samt sløret syn, har en betydelig indvirkning på patientens livskvalitet. Denne tilstand kan vaere saerligt alvorlig hos patienter med nedsat tåreproduktion (ADDE) som følge af Sjögrens syndrom (SS), en autoimmun sygdom, der påvirker tårekirtlerne og spytkirtlerne. Nuvaerende behandlinger for ADDE er ofte begraenset til symptomlindring. Vi gennemførte en litteraturgennemgang for at undersøge, hvilke nuvaerende kirurgiske behandlingsmetoder, der anvendes eller testes hos patienter med ADDE (I). Disse interventioner inkluderer procedurer, der involverer øjenlåg og tårekanaler, transplantation af amnionhinde eller spytkirtler, injektioner omkring tårekanalerne samt cellebaserede injektioner i tårekirtlen. Hver behandling har sine fordele og ulemper, men behandling af tørre øjne hos patienter med SS udgør en saerlig udfordring på grund af sygdommens systemiske udbredning, og der er behov for nye behandlingsmuligheder. Mesenkymale stamceller (MSCs) er en type stamcelle, der har vist lovende resultater med hensyn til at regenerere beskadiget vaev og reducere inflammation i forskellige sygdomme. Tidligere undersøgelser i dyremodeller har indikeret, at MSCs kan vaere en effektiv behandling af ADDE. Denne afhandling har til formål at undersøge sikkerheden og effekten af injektion af MSCs i tårekirtlen som en mulig behandling til patienter med ADDE som følge af SS. Afhandlingen sigter også mod at sammenligne denne behandling med andre eksisterende, kirurgiske behandlingsmuligheder af ADDE. Som led i dette projekt udførte vi de første kliniske forsøg af sin art i mennesker. MSCs fra raske donorers fedtvaev (ASCs) blev dyrket i et laboratorium, frosset ned og er optøet klar til brug. Det første mål var at teste sikkerheden ved denne behandling og sekundaert at undersøge behandlingens effekt. For at undersøge dette modtog syv forsøgspersoner med svaer ADDE én injektion med ASCs i tårekirtlen på det ene øje (II). Resultaterne af forsøget viste ingen alvorlige bivirkninger inden for fire måneders opfølgning efter behandlingen. I gennemsnit fandt vi yderligere en 40% reduktion i symptomer på tørre øjne vurderet med et spørgeskema, og en markant stigning i tåreproduktionen og af tårefilmens stabilitet i det behandlede øje. For yderligere at undersøge effekten af denne behandling udførte vi et klinisk, randomiseret forsøg med det formål at sammenligne injektion af ASCs i tårekirtlen med injektion af en kontrolopløsning (vaesken, hvor stamcellerne var opløst) og observation (ingen intervention) (III). Studiet omfattede 20 forsøgspersoner, der modtog ASC-injektion, 20 forsøgspersoner, der modtog injektion af kontrolopløsningen, og 14 forsøgspersoner i observationsgruppen. Forsøgspersonerne blev undersøgt med en opfølgningstid på 12 måneder efter behandling. Begge interventionsgrupper viste en betydelig reduktion på ca. 40% i subjektive symptomer på tørre øjne. Denne forbedring var betydelig allerede ved opfølgning efter en uge og varede ved 12 måneder efter behandling. Observationsgruppen oplevede ingen betydelig aendring i symptomer. ASCs gruppen viste desuden en signifikant stigning i tårefilmsstabiliteten (NIKBUT) på 6,48 sekunder (149%) ved opfølgning efter fire uger, hvilket var markant højere end efter injektion af kontrolopløsning (p = 0,04). Desuden viste ASCs gruppen en betydelig stigning i NIKBUT sammenlignet med observationsgruppen ved opfølgning efter 12 måneder (p = 0,004). Både injektion af ASCs og kontrolopløsning medførte en betydelig stigning i tåreproduktionen ved opfølgning fire måneder og 12 måneder efter behandling. Denne afhandling bidrager med vigtige resultater inden for en ny behandlingsmulighed af tørre øjne. Injektion af ASCs i tårekirtlen viste sig at vaere sikker, forbedrede subjektive symptomer på tørre øjne og øgede saerligt tårfilmens stabilitet hos patienter med ADDE på grund af SS. Sammenlignet med andre behandlingsmuligheder for ADDE har denne behandling vist et stort potentiale. ASCs kan muligvis også bruges som en anti-inflammatorisk behandling af tørre øjne af andre årsager i fremtiden.

Neuroprotective potential of intranasally delivered L-myc immortalized human neural stem cells in female rats after a controlled cortical impact injury

Efficacious stem cell-based therapies for traumatic brain injury (TBI) depend on successful delivery, migration, and engraftment of stem cells to induce neuroprotection. L-myc expressing human neural stem cells (LMNSC008) demonstrate an inherent tropism to injury sites after intranasal (IN) administration. We hypothesize that IN delivered LMNSC008 cells migrate to primary and secondary injury sites and modulate biomarkers associated with neuroprotection and tissue regeneration. To test this, immunocompetent adult female rats received a controlled cortical impact injury (CCI) or sham surgery. LMNSC008 cells or a vehicle (VEH) were administered IN on postoperative days 7, 9, 11, 13, 15, and 17. The distribution and migration of eGFP-expressing LMNSC008 cells were quantified over 1 mm-thick optically cleared (CLARITY) coronal brain sections from TBI and SHAM controls. NSC migration was observed along white matter tracts projecting toward the hippocampus and regions of TBI. ELISA and Nanostring assays revealed a shift in tissue gene expression in LMNSC008 treated rats relative to controls. LMNSC008 treatment reduced expression of genes and pathways involved in inflammatory response, microglial function, and various cytokines and receptors. The data demonstrate a robust proof-of-concept for LMNSC008 therapy for TBI and provides a strong rationale for IN delivery for translation in TBI patients.

Non-human primate models of focal cortical ischemia for neuronal replacement therapy

Despite the high prevalence, stroke remains incurable due to the limited regeneration capacity in the central nervous system. Neuronal replacement strategies are highly diverse biomedical fields that attempt to replace lost neurons by utilizing exogenous stem cell transplants, biomaterials, and direct neuronal reprogramming. Although these approaches have achieved encouraging outcomes mostly in the rodent stroke model, further preclinical validation in non-human primates (NHP) is still needed prior to clinical trials. In this paper, we briefly review the recent progress of promising neuronal replacement therapy in NHP stroke studies. Moreover, we summarize the key characteristics of the NHP as highly valuable translational tools and discuss (1) NHP species and their advantages in terms of genetics, physiology, neuroanatomy, immunology, and behavior; (2) various methods for establishing NHP focal ischemic models to study the regenerative and plastic changes associated with motor functional recovery; and (3) a comprehensive analysis of experimentally and clinically accessible outcomes and a potential adaptive mechanism. Our review specifically aims to facilitate the selection of the appropriate NHP cortical ischemic models and efficient prognostic evaluation methods in preclinical stroke research design of neuronal replacement strategies.

Practical Use of Immortalized Cells in Medicine: Current Advances and Future Perspectives

In modern science, immortalized cells are not only a convenient tool in fundamental research, but they are also increasingly used in practical medicine. This happens due to their advantages compared to the primary cells, such as the possibility to produce larger amounts of cells and to use them for longer periods of time, the convenience of genetic modification, the absence of donor-to-donor variability when comparing the results of different experiments, etc. On the other hand, immortalization comes with drawbacks: possibilities of malignant transformation and/or major phenotype change due to genetic modification itself or upon long-term cultivation appear. At first glance, such issues are huge hurdles in the way of immortalized cells translation into medicine. However, there are certain ways to overcome such barriers that we describe in this review. We determined four major areas of usage of immortalized cells for practical medicinal purposes, and each has its own means to negate the drawbacks associated with immortalization. Moreover, here we describe specific fields of application of immortalized cells in which these problems are of much lesser concern, for example, in some cases where the possibility of malignant growth is not there at all. In general, we can conclude that immortalized cells have their niches in certain areas of practical medicine where they can successfully compete with other therapeutic approaches, and more preclinical and clinical trials with them should be expected.

Current state of stem cell research in non-human primates: an overview

The remarkable similarity between non-human primates (NHPs) and humans establishes them as essential models for understanding human biology and diseases, as well as for developing novel therapeutic strategies, thereby providing more comprehensive reference data for clinical treatment. Pluripotent stem cells such as embryonic stem cells and induced pluripotent stem cells provide unprecedented opportunities for cell therapies against intractable diseases and injuries. As continue to harness the potential of these biotechnological therapies, NHPs are increasingly being employed in preclinical trials, serving as a pivotal tool to evaluate the safety and efficacy of these interventions. Here, we review the recent advancements in the fundamental research of stem cells and the progress made in studies involving NHPs.

Functional reconstruction of the impaired cortex and motor function by hMGEOs transplantation in stroke

Stroke is the leading cause of death and long-term disability worldwide. But treatments are not available to promote functional recovery, and efficient therapies need to be investigated. Stem cell-based therapies hold great promise as potential technologies to restore function in brain disorders. Loss of GABAergic interneurons after stroke may result in sensorimotor defects. Here, by transplanting human brain organoids resembling the MGE domain (human MGE organoids, hMGEOs) derived from human induced pluripotent stem cells (hiPSCs) into the infarcted cortex of stroke mice, we found that grafted hMGEOs survived well and primarily differentiated into GABAergic interneurons and significantly restored the sensorimotor deficits of stroke mice for a long time. Our study offers the feasibility of stem cell replacement therapeutics strategy for stroke.

Clinical results of neurorestorative cell therapies and therapeutic indications according to cellular bio-proprieties

Cell therapies have been explored to treat patients with nervous diseases for over 20 years. Even though most kinds of cell therapies demonstrated neurorestorative effects in non-randomized clinical trials; the effects of the majority type cells could not be confirmed by randomized controlled trials. In this review, clinical therapeutic results of neurorestorative cell therapies according to cellular bio-proprieties or cellular functions were introduced. Currently it was demonstrated from analysis of this review that some indications of cell therapies were not appropriate, they might be reasons why their neurorestorative effects could not be proved by multicenter, randomized, double blind, placebo-controlled clinical trials. Theoretically if one kind of cell therapy has neurorestorative effects according to its cellular bio-proprieties, it should have appropriate indications. The cell therapies with special bio-properties is promising if the indication selections are appropriate, such as olfactory ensheathing cells for chronic ischemic stroke, and their neurorestorative effects can be confirmed by higher level clinical trials of evidence-based medicine.

Cerebral organoids transplantation repairs infarcted cortex and restores impaired function after stroke

Stroke usually causes prolonged or lifelong disability, owing to the permanent loss of infarcted tissue. Although a variety of stem cell transplantation has been explored to improve neuronal defect behavior by enhancing neuroplasticity, it remains unknown whether the infarcted tissue can be reconstructed. We here cultured human cerebral organoids derived from human pluripotent stem cells (hPSCs) and transplanted them into the junction of the infarct core and the peri-infarct zone of NOD-SCID mice subjected to stroke. Months later, we found that the grafted organoids survived well in the infarcted core, differentiated into target neurons, repaired infarcted tissue, sent axons to distant brain targets, and integrated into the host neural circuit and thereby eliminated sensorimotor defect behaviors of stroke mice, whereas transplantation of dissociated single cells from organoids failed to repair the infarcted tissue. Our study offers a new strategy for reconstructing infarcted tissue via organoids transplantation thereby reversing stroke-induced disability.

Therapeutic Potential of Chinese Medicine for Endogenous Neurogenesis: A Promising Candidate for Stroke Treatment

Strokes are a leading cause of morbidity and mortality in adults worldwide. Extensive preclinical studies have shown that neural-stem-cell-based treatments have great therapeutic potential for stroke. Several studies have confirmed that the effective components of traditional Chinese medicine can protect and maintain the survival, proliferation, and differentiation of endogenous neural stem cells through different targets and mechanisms. Therefore, the use of Chinese medicines to activate and promote endogenous nerve regeneration and repair is a potential treatment option for stroke patients. Here, we summarize the current knowledge regarding neural stem cell strategies for ischemic strokes and the potential effects of these Chinese medicines on neuronal regeneration.

Immortalization Reversibility in the Context of Cell Therapy Biosafety

Immortalization (genetically induced prevention of replicative senescence) is a promising approach to obtain cellular material for cell therapy or for bio-artificial organs aimed at overcoming the problem of donor material shortage. Immortalization is reversed before cells are used in vivo to allow cell differentiation into the mature phenotype and avoid tumorigenic effects of unlimited cell proliferation. However, there is no certainty that the process of de-immortalization is 100% effective and that it does not cause unwanted changes in the cell. In this review, we discuss various approaches to reversible immortalization, emphasizing their advantages and disadvantages in terms of biosafety. We describe the most promising approaches in improving the biosafety of reversibly immortalized cells: CRISPR/Cas9-mediated immortogene insertion, tamoxifen-mediated self-recombination, tools for selection of successfully immortalized cells, using a decellularized extracellular matrix, and ensuring post-transplant safety with the use of suicide genes. The last process may be used as an add-on for previously existing reversible immortalized cell lines.

Comparison of the Administration Route of Stem Cell Therapy for Ischemic Stroke: A Systematic Review and Meta-Analysis of the Clinical Outcomes and Safety

Stem cell treatment is emerging as an appealing alternative for stroke patients, but there still needs to be an agreement on the protocols in place, including the route of administration. This systematic review aimed to assess the efficacy and safety of the administration routes of stem cell treatment for ischemic stroke. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A comprehensive literature search was undertaken using the PubMed, Scopus, and Cochrane databases. A total of 21 publications on stem cell therapy for ischemic stroke were included. Efficacy outcomes were measured using the National Institutes of Health Stroke Scale (NIHSS), the modified Rankin Scale (mRS), and the Barthel index (BI). Intracerebral administration showed a better outcome than other routes, but a greater number of adverse events followed due to its invasiveness. Adverse events were shown to be related to the natural history of stroke not to the treatment. However, further investigation is required, since studies have yet to compare the different administration methods directly.

Research progress in clinical trials of stem cell therapy for stroke and neurodegenerative diseases

The incidence of stroke and neurodegenerative diseases is gradually increasing in modern society, but there is still no treatment that is effective enough. Stem cells are cells that can reproduce (self-renew) and differentiate into the body, which have shown significance in basic research, while doctors have also taken them into clinical trials to determine their efficacy and safety. Existing clinical trials mainly include middle-aged and elderly patients with stroke or Parkinson's disease (mostly 40-80 years old), mainly involving injection of mesenchymal stem cells and bone marrow mesenchymal stem cells through the veins and the putamen, with a dosage of mostly 106-108 cells. The neural and motor functions of the patients were restored after stem cell therapy, and the safety was found to be good during the follow-up period of 3 months to 5 years. Here, we review all clinical trials and the latest advances in stroke, Alzheimer's disease, and Parkinson's disease, with the hope that stem cell therapy will be used in the clinic in the future to achieve effective treatment rates and benefit patients.

Dying transplanted neural stem cells mediate survival bystander effects in the injured brain

Neural stem and progenitor cell (NSPC) transplants provide neuroprotection in models of acute brain injury, but the underlying mechanisms are not fully understood. Here, we provide evidence that caspase-dependent apoptotic cell death of NSPCs is required for sending survival signals to the injured brain. The secretome of dying NSPCs contains heat-stable proteins, which protect neurons against glutamate-induced toxicity and trophic factor withdrawal in vitro, and from ischemic brain damage in vivo. Our findings support a new concept suggesting a bystander effect of apoptotic NSPCs, which actively promote neuronal survival through the release of a protective "farewell" secretome. Similar protective effects by the secretome of apoptotic NSPC were also confirmed in human neural progenitor cells and neural stem cells but not in mouse embryonic fibroblasts (MEF) or human dopaminergic neurons, suggesting that the observed effects are cell type specific and exist for neural progenitor/stem cells across species.

Neuroprotective Strategies for Ischemic Stroke-Future Perspectives

Ischemic stroke is the main cause of death and the most common cause of acquired physical disability worldwide. Recent demographic changes increase the relevance of stroke and its sequelae. The acute treatment for stroke is restricted to causative recanalization and restoration of cerebral blood flow, including both intravenous thrombolysis and mechanical thrombectomy. Still, only a limited number of patients are eligible for these time-sensitive treatments. Hence, new neuroprotective approaches are urgently needed. Neuroprotection is thus defined as an intervention resulting in the preservation, recovery, and/or regeneration of the nervous system by interfering with the ischemic-triggered stroke cascade. Despite numerous preclinical studies generating promising data for several neuroprotective agents, successful bench-to-bedside translations are still lacking. The present study provides an overview of current approaches in the research field of neuroprotective stroke treatment. Aside from "traditional" neuroprotective drugs focusing on inflammation, cell death, and excitotoxicity, stem-cell-based treatment methods are also considered. Furthermore, an overview of a prospective neuroprotective method using extracellular vesicles that are secreted from various stem cell sources, including neural stem cells and bone marrow stem cells, is also given. The review concludes with a short discussion on the microbiota-gut-brain axis that may serve as a potential target for future neuroprotective therapies.

Exosomal miR-128-3p reversed fibrinogen-mediated inhibition of oligodendrocyte progenitor cell differentiation and remyelination after cerebral ischemia

AIMS

To investigate the role of exosomal miR-128-3p in promoting fibrinogen-mediated inhibition of oligodendrocyte progenitor cell (OPC) differentiation and the therapeutic potential of exosomal miR-128-3p in cerebral ischemia.

METHODS

Mouse models of middle cerebral artery occlusion (MCAO) were established as described previously. MCAO was treated with fibrinogen and exosomes by stereotactically injecting into the left stratum. Mouse cortical OPCs were used for mRNA and miRNA sequencing analysis. Exosomes were isolated from neural stem cells (NSCs) of mice.

RESULTS

Fibrinogen deposition suppressed remyelination after MCAO and inhibited OPC differentiation by activating ACVR1, the bone morphogenetic protein (BMP) signaling type I receptor. In vitro, miR-sequencing and verification studies revealed that miR-128-3p is associated with BMP signaling mediated by ACVR1. Additionally, transfer of NSC-derived exosomal miR-128-3p to OPCs significantly increased myelin basic protein expression and inhibited BMP signaling. Furthermore, NSC-derived exosomal miR-128-3p protected against fibrinogen-induced demyelination related to BMP signaling, reduced the infarct volume, and improved neurological function after MCAO.

CONCLUSIONS

Fibrinogen deposition inhibits remyelination after ischemic damage and NSC-derived exosomal miR-128-3p promotes OPC differentiation into OLs by suppressing BMP signaling, indicating that NSC-derived exosomal miR-128-3p represents a potential therapeutic target for ischemic stroke.

Neural stem/progenitor cell-derived extracellular vesicles: A novel therapy for neurological diseases and beyond

As bilayer lipid membrane vesicles secreted by neural stem/progenitor cells (NSCs), NSC-derived extracellular vesicles (NSC-EVs) have attracted growing attention for their promising potential to serve as novel therapeutic agents in treatment of neurological diseases due to their unique physicochemical characteristics and biological functions. NSC-EVs exhibit advantages such as stable physical and chemical properties, low immunogenicity, and high penetration capacity to cross blood-brain barrier to avoid predicaments of the clinical applications of NSCs that include autoimmune responses, ethical/religious concerns, and the problematic logistics of acquiring fetal tissues. More importantly, NSC-EVs inherit excellent neuroprotective and neuroregenerative potential and immunomodulatory capabilities from parent cells, and display outstanding therapeutic effects on mitigating behavioral alterations and pathological phenotypes of patients or animals with neurological diseases. In this review, we first comprehensively summarize the progress in functional research and application of NSC-EVs in different neurological diseases, including neurodegenerative diseases, acute neurological diseases, dementia/cognitive dysfunction, and peripheral diseases. Next, we provide our thoughts on current limitations/concerns as well as tremendous potential of NSC-EVs in clinical applications. Last, we discuss future directions of further investigations on NSC-EVs and their probable applications in both basic and clinical research.

Safety and efficacy of intra-arterial bone marrow mononuclear cell transplantation in patients with acute ischaemic stroke in Spain (IBIS trial): a phase 2, randomised, open-label, standard-of-care controlled, multicentre trial

BACKGROUND

Pilot clinical trials have shown the safety of intra-arterial bone marrow mononuclear cells (BMMNCs) in stroke. However, the efficacy of different doses of intra-arterial BMMNCs in patients with acute stroke has not been tested in a randomised clinical trial. We aimed to show safety and efficacy of two different doses of autologous intra-arterial BMMNC transplantation in patients with acute stroke.

METHODS

The IBIS trial was a multicentre phase 2, randomised, controlled, investigator-initiated, assessor-blinded, clinical trial, in four stroke centres in Spain. We included patients (aged 18-80 years) with a non-lacunar, middle cerebral artery ischaemic stroke within 1-7 days from stroke onset and with a National Institutes of Health Stroke Scale score of 6-20. We randomly assigned patients (2:1:1) with a computer-generated randomisation sequence to standard of care (control group) or intra-arterial injection of autologous BMMNCs at one of two different doses (2 × 106 BMMNCs/kg or 5 × 106 BMMNCs/kg). The primary efficacy outcome was the proportion of patients with modified Rankin Scale scores of 0-2 at 180 days in the intention-to-treat population, comparing each BMMNC dose group and the pooled BMMNC group versus the control group. The primary safety endpoint was the proportion of serious adverse events. This trial was registered at ClinicalTrials.gov, NCT02178657 and is completed.

FINDINGS

Between April 1, 2015, and May 20, 2021, we assessed 114 patients for eligibility. We randomly assigned 77 (68%) patients: 38 (49%) to the control group, 20 (26%) to the low-dose BMMNC group, and 19 (25%) the high-dose BMMNC group. The mean age of participants was 62·4 years (SD 12·7), 46 (60%) were men, 31 (40%) were women, all were White, and 63 (82%) received thrombectomy. The median NIHSS score before randomisation was 12 (IQR 9-15), with intra-arterial BMMNC injection done a median of 6 days (4-7) after stroke onset. The primary efficacy outcome occurred in 14 (39%) patients in the control group versus ten (50%) in the low-dose group (adjusted odds ratio 2·08 [95% CI 0·55-7·85]; p=0·28), eight (44%) in the high-dose group (1·89 [0·52-6·96]; p=0·33), and 18 (47%) in the pooled BMMNC group (2·22 [0·72-6·85]; p=0·16). We found no differences in the proportion of patients who had adverse events or dose-related events, but two patients had a groin haematoma after cell injection in the low-dose BMMNC group.

INTERPRETATION

Intra-arterial BMMNCs were safe in patients with acute ischaemic stroke, but we found no significant improvement at 180 days on the mRS. Further clinical trials are warranted to investigate whether improvements might be possible at different timepoints.

FUNDING

Instituto de Salud Carlos III co-funded by the European Regional Development Fund/European Social Fund, Mutua Madrileña, and the Regional Ministry of Health of Andalusia.

Comparative Analysis of the Results of Stroke Treatment With Multiple Administrations of Wharton's Jelly Mesenchymal Stem Cells-Derived HE-ATMP and Standard Conservative Treatment: Case Series Study

Stroke remains still the leading cause of long-term disability worldwide. Although interventions such as early reperfusion, intravenous thrombolysis, and endovascular revascularization have shown neurological benefit in stroke patients, there is still lack of effective treatment enabling regeneration of nervous tissue after cerebral ischemic episodes. Cell therapy is an evolving opportunity for stroke survivors with residual neurological deficits. The purpose of this study was to evaluate safety and potential efficacy of multiple administration of Hospital Exemption-Advanced Therapy Medicinal Product (HE-ATMP) comprising 3 × 107 Wharton's jelly mesenchymal stem cells (WJMSCs). A study group was composed of six patients-three women and three men. The patients were qualified to the treatment with diagnosis of chronic stroke (2-24 months after cerebral ischemic episode), during 2 years. All the patients undergone repeated rounds of HE-ATMP administration to the CSF (cerebrospinal fluid) via lumbar puncture. The control group consisted of six patients (two women and four men) who experienced stroke, treated at the same time (follow-up period: 24 months) using standard treatment methods, without endovascular treatment. To evaluate the results of the therapy, we used both impairment scales [National Institutes of Health Stroke Score (NIHSS)] and functional outcomes scales [Modified Rankin Scale (MRS) and Barthel Index (BI)]. In four patients, who received at least three repeated rounds of HE-ATMP, we reported neurological improvement and reduction of functional neurodeficiency. The biggest improvement concerned the reduction of speech disorders in two cases; significant improvement in the field of motor skills in three patients and reduction of apraxia and improvement of logical communication skills in two patients were also reported. All the patients became more independent. Significant improvement of the neurological condition using the same scales was registered only in two patients from the control group. We did not report any adverse events in the treated group during follow-up. At 1-year follow-up, we demonstrate safety and beneficial effect of WJMSC transplantation including neurological improvement and reduction of functional neurodeficiency. We are aware that the samples size of this study is relatively small. The treatment regimen needs to be further tested in larger group of patients.

Nanoparticle and Stem Cell Combination Therapy for the Management of Stroke

Stroke is currently one of the primary causes of morbidity and mortality worldwide. Unfortunately, the available treatments for stroke are still extremely limited. Indeed, stem cell (SC) therapy is a new option for the treatment of stroke that could significantly expand the therapeutic time window of stroke. Some proposed mechanisms for stroke-based SC therapy are the incorporation of SCs into the host brain to replace dead or damaged cells/tissues. Moreover, acute cell delivery can inhibit apoptosis and decrease lesion size, providing immunomudolatory and neuroprotection effects. However, several major SC problems related to SCs such as homing, viability, uncontrolled differentiation, and possible immune response, have limited SC therapy. A combination of SC therapy with nanoparticles (NPs) can be a solution to address these challenges. NPs have received considerable attention in regulating and controlling the behavior of SCs because of their unique physicochemical properties. By reviewing the pathophysiology of stroke and the therapeutic benefits of SCs and NPs, we hypothesize that combined therapy will offer a promising future in the field of stroke management. In this work, we discuss recent literature in SC research combined with NP-based strategies that may have a synergistic outcome after stroke incidence.

Research hotspots and frotiers of stem cells in stroke: A bibliometric analysis from 2004 to 2022

Background: Stroke is one of the leading causes of mortality and permanent disability worldwide. However, the current stroke treatment has a limited effect. Therefore, a new treatment is urgently needed. Stem cell therapy is a cutting-edge treatment for stroke patients. This study aimed to gain better understanding of global stem cell trends in stroke via a bibliometric analysis. Methods: We used the Web of Science Core Collection to search pertinent articles about stem cells in stroke published between 2004 and 2022. Analysis was conducted using CiteSpace, VOSviewer, and the R package "bibliometrix" to identify publication outputs, countries/regions, institutions, authors/co-cited authors, journals/co-cited journals, co-cited references, and keywords. Results: A total of 6,703 publications were included in the bibliometric analysis. The total number of citations significantly and rapidly increased between 2004 and 2022, with the most pronounced growth pattern observed in the period of 2008-2009. In terms of authoritarian countries, the USA had the most publications among the countries. As for institutions and authors, the most prolific institution was the University of South Florida, followed by Oakland University and then Shanghai Jiao Tong University, and Chopp, M. and Borlongan, Cesario V, had the most output among the authors. Regarding the journals, Cell Transplantation had the highest publication, followed by Brain Research. As for references, "Mesenchymal stem cells as trophic mediators" was the most frequently cited (2,082), and the article entitled Neuronal replacement from endogenous precursors in the adult brain after stroke had the strongest burstiness (strength = 81.35). Emerging hot words in the past decade included "adhesion molecule," "mesenchymal stromal cell," "extracellular vesicle," "pluripotent stem cells," "signaling pathway," "plasticity," and "exosomes." Conclusion: Between 2004 and 2022, the terms "neurogenesis," "angiogenesis," "mesenchymal stem cells," "extracellular vesicle," "exosomes," "inflammation," and "oxidative stress" have emerged as the hot research areas for research on stem cells in stroke. Although stem cells exert a number of positive effects, the main mechanisms for mitigating the damage caused by stroke are still unknown. Clinical challenges may include complicating factors that can affect the efficacy of stem cell therapy, which are worth a deep exploration.