Intracerebral transplantation of autologous adipose-derived stem cells for chronic ischemic stroke: A phase I study

How neural stem cell therapy promotes brain repair after stroke

The human brain has a very limited capacity for self-repair, presenting significant challenges in recovery following injuries such as ischemic stroke. Stem cell-based therapies have emerged as promising strategies to enhance post-stroke recovery. Building on a large body of preclinical evidence, clinical trials are currently ongoing to prove the efficacy of stem cell therapy in stroke patients. However, the mechanisms through which stem cell grafts promote neural repair remain incompletely understood. Key questions include whether these effects are primarily driven by (1) the secretion of trophic factors that stimulate endogenous repair processes, (2) direct neural cell replacement, or (3) a combination of both mechanisms. This review explores the latest advancements in neural stem cell therapy for stroke, highlighting research insights in brain repair mechanisms. Deciphering the fundamental mechanisms underlying stem cell-mediated brain regeneration holds the potential to refine therapeutic strategies and advance treatments for a range of neurological disorders.

Clinical state and future directions of stem cell therapy in stroke rehabilitation

Despite substantial advances in the acute management of stroke, it remains a leading cause of adult disability and mortality worldwide. Currently, the reperfusion modalities thrombolysis and thrombectomy benefit only a fraction of patients in the hyperacute phase of ischemic stroke. Thus, with the exception of vagal nerve stimulation combined with intensive physical therapy, there are no approved neuroprotective/neurorestorative therapies for stroke survivors. Stem cell therapy is a promising treatment for stroke patients and has been the focus of an increasing number of clinical trials over the past two decades. We provide a comprehensive overview of stem cell therapies available to stroke patients, focusing on the different types and doses of stem cells, timing and route of administration, patient selection, clinical outcomes, translational challenges, and future directions for the field. Information on ongoing and completed studies was retrieved from ClinicalTrials.gov, PubMed, Google Scholar, ICTRP, and Scopus. Autologous bone marrow-derived mononuclear cells (BMMNCs) are the most used, followed by autologous bone marrow stromal cells. IV therapy is typically applied in acute to subacute phases, while IT or IC routes are utilized in chronic phases. Although early-phase trials (Phase I/II) indicate strong safety and tolerability, definitive clinical effectiveness has yet to be unequivocally proven. Cochrane meta-analyses show NIH Stroke Scale improvements, though studies often have high bias and small sample sizes. Larger randomized, double-blind, placebo-controlled trials are ongoing to refine stem cell transplantation protocols, addressing cell type and source, dosage, timing, patient selection, the potential for combination therapies, and clinical efficacy.

Therapeutic Potential of Adipose-Derived Regenerative Cells for Ischemic Diseases

Adipose-derived regenerative cells (ADRCs) are one of the most promising cell sources that possess significant therapeutic effects. They have now become a main source of cell therapy for the treatment of ischemic diseases due to their easy accessibility, expansion, and differentiation. Additionally, ADRCs can release multiple paracrine factors and extracellular vesicles that contribute to tissue regeneration by promoting angiogenesis, regulating inflammation, alleviating apoptosis, and inhibiting fibrosis. However, ADRCs still have some limitations to realize their full therapeutic potential. To address these issues, protective mechanistic studies and bioengineering studies have been carried out. This review focused on the recently studied mechanisms, such as paracrine factors, cell fusion, and mitochondrial transfer, involving the therapeutic potential of ADRCs in ischemic diseases and discussed some modification techniques of ADRCs.

Synergistic Enhancement of Therapeutic Efficacy in Acute Myocardial Infarction via Nanoflower-Like Mn3O4 Nanozymes in Coordination with Adipose-Derived Stem Cell Transplantation

Background

Acute myocardial infarction (AMI) is a leading cause of mortality worldwide. Adipose-derived stem cell (ADSC) transplantation presents a promising therapeutic approach for AMI; however, the harsh microenvironment of the infarcted myocardium, characterized by hypoxia and oxidative stress, limits the survival and efficacy of ADSCs. Nanozymes (NZs), which have robust anti-oxidative enzyme-mimicking activities, have demonstrated potential in combating oxidative stress and improving cell viability.

Methods

Mn3O4 NZs (Mn-Nzs), which have nanoflower-like structures were synthesized and their structure and multi-enzyme mimetic activities (superoxide dismutase, catalase, and glutathione peroxidase) were characterized. Blood biochemical parameters were measured in the heart, liver, spleen, lungs and kidneys of the rats, followed by hematoxylin and eosin (HE) staining. The impact of Mn3O4 NZs on reactive oxygen species (ROS) levels, and viability of ADSCs under oxidative stress was assessed in vitro. In vivo studies were conducted using a rat AMI model to evaluate the therapeutic efficacy of ADSC transplantation, in conjunction with Mn3O4 treatment. In addition, proteomic analysis was performed to elucidate the mechanisms of action underlying the therapeutic effects.

Results

Mn3O4 NZs exhibited multi-enzyme mimetic activities, including superoxide dismutase, catalase, and glutathione peroxidase, reducing reactive oxygen species levels and apoptosis in ADSCs under oxidative stress. In the AMI rat model, Mn-NZs had good biocompatibility and ADSC transplantation or Mn3O4 NZs treatment alone significantly reduced infarct size, fibrosis levels, and improved microvascular density and heart function. Notably, the combination of Mn3O4 NZs with ADSC transplantation enhanced ADSC survival and differentiation, amplifying therapeutic efficacy. Proteomic analysis revealed that Mn3O44 NZs upregulated proteins associated with anti-oxidative damage, anti-inflammation, and anti-fibrosis pathways. In addition, Mn-NZs upregulated MMP8 via AKT pathway phosphorylation.

Conclusion

The findings highlight a novel strategy integrating NZ anti-oxidant properties with stem cell transplantation to improve AMI treatment outcomes.

Mesenchymal stem cells therapy for chronic ischemic stroke-a systematic review

Stroke represents a significant global health issue, primarily in the form of ischemic stroke. Despite the availability of therapeutic interventions, the recovery from chronic stroke, occurring 3 months post-initial stroke, poses substantial challenges. A promising avenue for post-acute stroke patients is mesenchymal stem cells (MSCs) therapy, which is derived from various sources and is globally recognized as the most utilized and extensively studied stem cell therapy. This systematic review, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, aims to synthesize evidence regarding the impact of MSCs therapy on patients with chronic ischemic stroke. Employing an advanced search strategy across databases such as PubMed, PubMed Central, Google Scholar, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrial.gov, a total of 70 studies were identified, with 4studies meeting the inclusion criteria. Although positive outcomes were observed in terms of efficacy and safety, certain limitations, such as small sample sizes, study heterogeneity, and the absence of placebo groups, undermine the overall strength of the evidence. It is crucial to address these limitations in future research, highlighting the importance of larger sample sizes, standardized methodologies, and comparative trials to improve the assessment of MSCs' efficacy and safety. Moving forward, key priorities include exploring underlying mechanisms, determining optimal administration modes and dosages, and conducting comparative trials. By addressing these aspects, we can propel MSCs therapies toward greater efficacy, safety, and applicability across diverse patient populations.

Priming and Combined Strategies for the Application of Mesenchymal Stem Cells in Ischemic Stroke: A Promising Approach

Ischemic stroke (IS) is a leading cause of death and disability worldwide. Tissue plasminogen activator (tPA) administration and mechanical thrombectomy are the main treatments but have a narrow time window. Mesenchymal stem cells (MSCs), which are easily scalable in vitro and lack ethical concerns, possess the potential to differentiate into various types of cells and secrete a great number of growth factors for neuroprotection and regeneration. Moreover, MSCs have low immunogenicity and tumorigenic properties, showing safety and preliminary efficacy both in preclinical studies and clinical trials of IS. However, it is unlikely that MSC treatment alone will be sufficient to maximize recovery due to the low survival rate of transplanted cells and various mechanisms of ischemic brain damage in the different stages of IS. Preconditioning was used to facilitate the homing, survival, and secretion ability of the grafted MSCs in the ischemic region, while combination therapies are alternatives that can maximize the treatment effects, focusing on multiple therapeutic targets to promote stroke recovery. In this case, the combination therapy can yield a synergistic effect. In this review, we summarize the type of MSCs, preconditioning methods, and combined strategies as well as their therapeutic mechanism in the treatment of IS to accelerate the transformation from basic research to clinical application.

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.

Cell Therapy and Functional Recovery of Stroke

Stroke is the most common cause of disability. Brain repair mechanisms are often insufficient to allow a full recovery. Stroke damage involve all brain cell type and extracellular matrix which represent the crucial "glio-neurovascular niche" useful for brain plasticity. Regenerative medicine including cell therapies hold great promise to decrease post-stroke disability of many patients, by promoting both neuroprotection and neural repair through direct effects on brain lesion and/or systemic effects such as immunomodulation. Mechanisms of action vary according to each grafted cell type: "peripheral" stem cells, such as mesenchymal stem cells (MSC), can provide paracrine trophic support, and neural stem/progenitor cells (NSC) or neurons can act as direct cells' replacements. Optimal time window, route, and doses are still debated, and may depend on the chosen medicinal product and its expected mechanism such as neuroprotection, delayed brain repair, systemic effects, or graft survival and integration in host network. MSC, mononuclear cells (MNC), umbilical cord stem cells and NSC are the most investigated. Innovative approaches are implemented concerning combinatorial approaches with growth factors and biomaterials such as injectable hydrogels which could protect a cell graft and/or deliver drugs into the post-stroke cavity at chronic stages. Through main publications of the last two decades, we provide in this review concepts and suggestions to improve future translational researches and larger clinical trials of cell therapy in stroke.

Emerging Roles of Exosomes in Stroke Therapy

Stroke is the number one cause of morbidity in the United States and number two cause of death worldwide. There is a critical unmet medical need for more effective treatments of ischemic stroke, and this need is increasing with the shift in demographics to an older population. Recently, several studies have reported the therapeutic potential of stem cell-derived exosomes as new candidates for cell-free treatment in stoke. This review focuses on the use of stem cell-derived exosomes as a potential treatment tool for stroke patients. Therapy using exosomes can have a clear clinical advantage over stem cell transplantation in terms of safety, cost, and convenience, as well as reducing bench-to-bed latency due to fewer regulatory milestones. In this review article, we focus on (1) the therapeutic potential of exosomes in stroke treatment, (2) the optimization process of upstream and downstream production, and (3) preclinical application in a stroke animal model. Finally, we discuss the limitations and challenges faced by exosome therapy in future clinical applications.

Advanced Progress in the Role of Adipose-Derived Mesenchymal Stromal/Stem Cells in the Application of Central Nervous System Disorders

Currently, adipose-derived mesenchymal stromal/stem cells (ADMSCs) are recognized as a highly promising material for stem cell therapy due to their accessibility and safety. Given the frequently irreversible damage to neural cells associated with CNS disorders, ADMSC-related therapy, which primarily encompasses ADMSC transplantation and injection with exosomes derived from ADMSCs or secretome, has the capability to inhibit inflammatory response and neuronal apoptosis, promote neural regeneration, as well as modulate immune responses, holding potential as a comprehensive approach to treat CNS disorders and improve prognosis. Empirical evidence from both experiments and clinical trials convincingly demonstrates the satisfactory safety and efficacy of ADMSC-related therapies. This review provides a systematic summary of the role of ADMSCs in the treatment of central nervous system (CNS) disorders and explores their therapeutic potential for clinical application. ADMSC-related therapy offers a promising avenue to mitigate damage and enhance neurological function in central nervous system (CNS) disorders. However, further research is necessary to establish the safety and efficacy of clinical ADMSC-based therapy, optimize targeting accuracy, and refine delivery approaches for practical applications.

Evolving Clinical-Translational Investigations of Cerebroprotection in Ischemic Stroke

Ischemic stroke is a highly morbid disease, with over 50% of large vessel stroke (middle cerebral artery or internal carotid artery terminus occlusion) patients suffering disability despite maximal acute reperfusion therapy with thrombolysis and thrombectomy. The discovery of the ischemic penumbra in the 1980s laid the foundation for a salvageable territory in ischemic stroke. Since then, the concept of neuroprotection has been a focus of post-stroke care to (1) minimize the conversion from penumbra to core irreversible infarct, (2) limit secondary damage from ischemia-reperfusion injury, inflammation, and excitotoxicity and (3) to encourage tissue repair. However, despite multiple studies, the preclinical-clinical research enterprise has not yet created an agent that mitigates post-stroke outcomes beyond thrombolysis and mechanical clot retrieval. These translational gaps have not deterred the scientific community as agents are under continuous investigation. The NIH has recently promoted the concept of cerebroprotection to consider the whole brain post-stroke rather than just the neurons. This review will briefly outline the translational science of past, current, and emerging breakthroughs in cerebroprotection and use of these foundational ideas to develop a novel paradigm for optimizing stroke outcomes.

Application of cross-migration theory in limb rehabilitation of stroke patients with hemiplegia

BACKGROUND

Stroke is a common cause of neurological dysfunction, often resulting in hemiplegia. Thus, rehabilitation of limb function in stroke patients is an important step towards accelerating recovery and improving quality of life.

AIM

To investigate whether unilateral strength training in hemiplegic stroke patients could lead to cross-migration, an increase in bilateral muscle strength, and an improvement in lower limb motor function.

METHODS

We randomly divided 120 patients with hemiplegic stroke into two groups: Eexperimental and control groups, with 60 patients in each group. Both groups received routine rehabilitation treatment, while the experimental group additionally received ankle dorsiflexion resistance training on the healthy side for 6 wk. We measured the maximum voluntary contract (MVC), changes in surface electromyography (EMG), and the lower limb motor function using the simplified Fugl Meyer Motor Function Assessment Scale (FMA) before and within 1 wk after training.

RESULTS

The FMA score in the experimental group improved significantly compared to both their pre-training score and the control group's post-training score (P < 0.05). The integrated EMG of the anterior tibialis muscle and pulmonary intestine muscle in the experimental group were significantly different after training than before (P < 0.05). Furthermore, the MVC of the anterior tibialis muscle on both the healthy and affected sides and the MVC of the pulmonary intestine muscle on both sides showed significant improvement compared with before training and the control group (P < 0.05).

CONCLUSION

Our findings suggest that ankle dorsiflexion resistance training on the healthy side in hemiplegic stroke patients can increase strength in the opposite tibialis anterior muscle and antagonist's muscle, indicating a cross-migration phenomenon of strength training. Furthermore, this type of training can also improve lower limb motor function, providing a new exercise method for improving early ankle dorsiflexion dysfunction.

A novel injectable radiopaque hydrogel with potent properties for multicolor CT imaging in the context of brain and cartilage regenerative therapy

Cell therapy is promising to treat many conditions, including neurological and osteoarticular diseases. Encapsulation of cells within hydrogels facilitates cell delivery and can improve therapeutic effects. However, much work remains to be done to align treatment strategies with specific diseases. The development of imaging tools that enable monitoring cells and hydrogel independently is key to achieving this goal. Our objective herein is to longitudinally study an iodine-labeled hydrogel, incorporating gold-labeled stem cells, by bicolor CT imaging after in vivo injection in rodent brains or knees. To this aim, an injectable self-healing hyaluronic acid (HA) hydrogel with long-persistent radiopacity was formed by the covalent grafting of a clinical contrast agent on HA. The labeling conditions were tuned to achieve sufficient X-ray signal and to maintain the mechanical and self-healing properties as well as injectability of the original HA scaffold. The efficient delivery of both cells and hydrogel at the targeted sites was demonstrated by synchrotron K-edge subtraction-CT. The iodine labeling enabled to monitor the hydrogel biodistribution in vivo up to 3 days post-administration, which represents a technological first in the field of molecular CT imaging agents. This tool may foster the translation of combined cell-hydrogel therapies into the clinics.

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.

The role of mesenchymal stem cell transplantation for ischemic stroke and recent research developments

Ischemic stroke is a common cerebrovascular disease that seriously affects human health. However, most patients do not practice self-care and cannot rely on the current clinical treatment for guaranteed functional recovery. Stem cell transplantation is an emerging treatment studied in various central nervous system diseases. More importantly, animal studies show that transplantation of mesenchymal stem cells (MSCs) can alleviate neurological deficits and bring hope to patients suffering from ischemic stroke. This paper reviews the biological characteristics of MSCs and discusses the mechanism and progression of MSC transplantation to provide new therapeutic directions for ischemic stroke.

Neuroinflammation, Stem Cells, and Stroke

Stroke remains a significant unmet clinical need with few treatment options that have a very narrow therapeutic window, thereby causing massive mortality and morbidity in the United States and around the world. Accordingly, finding safe and effective novel treatments with a wider therapeutic window stands as an urgent need in stroke. The progressive inflammation that occurs centrally and peripherally after stroke serves as a unique therapeutic target to retard and even halt the secondary cell death. Stem cell therapy represents a potent approach that can diminish inflammation in both the stroke brain and periphery (eg, spleen), advancing a paradigm shift from a traditionally brain-focused therapy to treating stroke as a neurological disorder with a significant peripheral pathology. The purpose of this review article is to highlight the inflammation-mediated secondary cell death that plagues both brain and spleen in stroke and to evaluate the therapeutic potential of stem cell therapy in dampening these inflammatory responses.

Neurofunctional and neuroimaging readouts for designing a preclinical stem-cell therapy trial in experimental stroke

With the aim of designing a preclinical study evaluating an intracerebral cell-based therapy for stroke, an observational study was performed in the rat suture model of ischemic stroke. Objectives were threefold: (i) to characterize neurofunctional and imaging readouts in the first weeks following transient ischemic stroke, according to lesion subtype (hypothalamic, striatal, corticostriatal); (ii) to confirm that intracerebral administration does not negatively impact these readouts; and (iii) to calculate sample sizes for a future therapeutic trial using these readouts as endpoints. Our results suggested that the most relevant endpoints were side bias (staircase test) and axial diffusivity (AD) (diffusion tensor imaging). Hypothalamic-only lesions did not affect those parameters, which were close to normal. Side bias in striatal lesions reached near-normal levels within 2 weeks, while rats with corticostriatal lesions remained impaired until week 14. AD values were decreased at 4 days and increased at 5 weeks post-surgery, with a subtype gradient: hypothalamic < striatal < corticostriatal. Intracerebral administration did not impact these readouts. After sample size calculation (18-147 rats per group according to the endpoint considered), we conclude that a therapeutic trial based on both readouts would be feasible only in the framework of a multicenter trial.