Induced Pluripotent Stem Cells for Ischemic Stroke Treatment

Grafts of hydrogel-embedded electrically stimulated subventricular stem cells into the stroke cavity improves functional recovery of mice

JOURNAL/nrgr/04.03/01300535-202602000-00039/figure1/v/2025-05-05T160104Z/r/image-tiff The major aim of stroke therapy is to stimulate brain repair and improve behavioral recovery after cerebral ischemia. One option is to stimulate endogenous neurogenesis in the subventricular zone and direct the newly formed neurons to the damaged area. However, only a small percentage of these neurons survive, and many do not reach the damaged area, possibly because the corpus callosum impedes the migration of subventricular zone-derived stem cells into the lesioned cortex. A second major obstacle to stem cell therapy is the strong inflammatory reaction induced by cerebral ischemia, whereby the associated phagocytic activity of brain macrophages removes both therapeutic cells and/or cell-based drug carriers. To address these issues, neurogenesis was electrically stimulated in the subventricular zone, followed by isolation of proliferating cells, including newly formed neurons, which were subsequently mixed with a nutritional hydrogel. This mixture was then transferred to the stroke cavity of day 14 post-stroke mice. We found that the performance of the treated animals improved in behavioral tests, including novel object, open field, hole board, grooming, and "time-to-feel" adhesive tape tests. Furthermore, immunostaining revealed that the stem cell marker nestin, the neuroepithelial marker Mash1, and the immature neuronal marker doublecortin-positive cells survived in the transplanted area for 2 weeks, possibly due to reduced phagocytic activity and supportive angiogenesis. These results clearly indicate that the transplantation of committed subventricular zone stem cells combined with a protective nutritional gel directly into the infarct cavity after the peak of stroke-induced neuroinflammation represents a feasible approach to improve neurorestoration after cerebral ischemia.

Tissue Engineering and Regenerative Medicine: Perspectives and Challenges

From the pioneering days of cell therapy to the achievement of bioprinting organs, tissue engineering, and regenerative medicine have seen tremendous technological advancements, offering solutions for restoring damaged tissues and organs. However, only a few products and technologies have received United States Food and Drug Administration approval. This review highlights significant progress in cell therapy, extracellular vesicle-based therapy, and tissue engineering. Hematopoietic stem cell transplantation is a powerful tool for treating many diseases, especially hematological malignancies. Mesenchymal stem cells have been extensively studied. The discovery of induced pluripotent stem cells has revolutionized disease modeling and regenerative applications, paving the way for personalized medicine. Gene therapy represents an innovative approach to the treatment of genetic disorders. Additionally, extracellular vesicle-based therapies have emerged as rising stars, offering promising solutions in diagnostics, cell-free therapeutics, drug delivery, and targeted therapy. Advances in tissue engineering enable complex tissue constructs, further transforming the field. Despite these advancements, many technical, ethical, and regulatory challenges remain. This review addresses the current bottlenecks, emphasizing novel technologies and interdisciplinary research to overcome these hurdles. Standardizing practices and conducting clinical trials will balance innovation and regulation, improving patient outcomes and quality of life.

Effects of stem cell therapy on preclinical stroke

Stroke, particularly ischemic stroke, is a leading cause of global mortality and disability. It is caused by blood flow obstruction and reduced oxygen delivery to brain tissue. Conventional treatments, such as tissue plasminogen activator (tPA) and mechanical thrombectomy (MT), have limited efficacy in repairing neural damage and carry risks of adverse effects. As a result, stem cell therapies, including mesenchymal stem cells (MSCs), have emerged as promising approaches for enhancing neural recovery and offering neuroprotection in ischemic stroke management. MSCs offer multifaceted benefits, such as reducing inflammation, protecting neurons, and promoting angiogenesis and neurogenesis. Recent evidence highlights the importance of MSC secretomes-extracellular vesicles (EVs) and exosomes rich in neuroprotective factors, such as microRNAs, proteins, and cytokines. These bioactive molecules demonstrated considerable efficacy in preclinical models by reducing neuroinflammation, preserving neurovascular integrity, and promoting cellular repair in ischemic environments. Preclinical in vitro and in vivo studies demonstrate the potential of the MSC secretomes to restore brain function after ischemic stroke. This is achieved by enhancing neuronal survival through mechanisms such as angiogenesis or vascular recovery, neuroprotection including modulation of immune or inflammatory responses, apoptosis, and autophagy, and promoting post-stroke neurogenesis. This review explores the translational challenges and future potential of integrating conventional ischemic stroke therapies with stem cell-based or cell-free approaches. The present study synthesizes current insights into the role of MSC-derived secretomes from both in vitro and in vivo studies.

Exosomes derived from highly scalable and regenerative human progenitor cells promote functional improvement in a rat model of ischemic stroke

Globally, there are 15 million stroke patients each year who have significant neurological deficits. Today, there are no treatments that directly address these deficits. With demographics shifting to an older population, the problem is worsening. Therefore, it is crucial to develop feasible therapeutic treatments for stroke. In this study, we tested exosomes derived from embryonic endothelial progenitor cells (eEPC) to assess their therapeutic efficacy in a rat model of ischemic stroke. Importantly, we have developed purification methods aimed at producing robust and scalable exosomes suitable for manufacturing clinical grade therapeutic exosomes. We characterized exosome cargos including RNA-seq, miRNAs targets, and proteomic mass spectrometry analysis, and we found that eEPC-exosomes were enhanced with angiogenic miRNAs (i.e., miR-126), anti-inflammatory miRNA (i.e., miR-146), and anti-apoptotic miRNAs (i.e., miR-21). The angiogenic activity of diverse eEPC-exosomes sourced from a panel of eEPC production lines was assessed in vitro by live-cell vascular tube formation and scratch wound assays, showing that several eEPC-exosomes promoted the proliferation, tube formation, and migration in endothelial cells. We further applied the exosomes systemically in a rat middle cerebral artery occlusion (MCAO) model of stroke and tested for neurological recovery (mNSS) after injury in ischemic animals. The mNSS scores revealed that recovery of sensorimotor functioning in ischemic MCAO rats increased significantly after intravenous administration of eEPC-exosomes and outpaced recovery obtained through treatment with umbilical cord stem cells. Finally, we investigated the potential mechanism of eEPC-exosomes in mitigating ischemic stroke injury and inflammation by the expression of neuronal, endothelial, and inflammatory markers. Taken together, these data support the finding that eEPCs provide a valuable source of exosomes for developing scalable therapeutic products and therapies for stroke and other ischemic diseases.

Co-transplantation of autologous treg cells: A groundbreaking cell therapy for brain diseases

Cell therapy and regenerative medicine have made remarkable progress in treating neurodegenerative disorders. Induced pluripotent stem cells (iPSCs) offer a promising source for cell replacement therapies, but their practical application faces challenges due to poor survival and integration after transplantation. Park et al. propose a novel therapeutic strategy involving the co-transplantation of regulatory T cells (Tregs) and iPSC-derived dopamine neurons. This combined approach enhances the survival of transplanted cells and protects against neuroinflammation-induced damage. In PD animal models, the co-transplantation approach significantly suppressed the host immune response, resulting in improved behavioral recovery. Additionally, Tregs demonstrate acute neuroprotection and contribute to delayed neuro-restoration in ischemic stroke. This combined approach of cell therapy with immunomodulation offers a promising avenue for advancing our understanding of neurological diseases and promoting the development of novel treatments.

Generation of induced pluripotent stem cells from rat fibroblasts and optimization of its differentiation into mature functional neurons

BACKGROUND

Induced pluripotent stem cells (iPSCs) derived neural stem cells (NSCs) provide a potential for autologous neural transplantation therapy following neurological insults. Thus far, in preclinical studies the donor iPSCs-NSCs are mostly of human or mouse origin with concerns centering around graft rejection when applied to rat brain injury models. For better survival and integration of transplanted cells in the injured brain in rat models, use of rat-iPSC-NSCs and in combination with biomaterials is of advantageous. Herein, we report a detailed method in generating rat iPSCs with improved reprogramming efficiency and differentiation into neurons.

NEW METHOD

Rat fibroblasts were reprogrammed into iPSCs with polybrene and EF1α-STEMCCA-LoxP lentivirus vector. Pluripotency characterization, differentiation into neuronal linage cells were assessed with RT-qPCR, Western blotting, immunostaining and patch-clamp methods. Cells were cultured in a custom-designed integrin array system as well as in a hydrogel-based 3D condition.

RESULTS

We describe a thorough method for the generation of rat-iPSC-NSCs, and identify integrin αvβ8 as a substrate for the optimal growth of rat-iPSC-NSCs. Furthermore, with hydrogel as the supporting biomaterial in the 3-D culture, when combined with integrin αvβ8 binding peptide, it forms a conducive environment for optimal growth and differentiation of iPSC-NSCs into mature neurons.

COMPARISON WITH EXISTING METHODS

Published studies about rat-iPSC-NSCs are rare. This study provides a detailed protocol for the generation of rat iPSC-NSCs and optimal growth conditions for neuronal differentiation. Our method is useable for studies to assess the utility of rat iPSC-NSCs for neural transplantation in rat brain injury models.

Stem cell-based ischemic stroke therapy: Novel modifications and clinical challenges

Ischemic stroke (IS) causes severe disability and high mortality worldwide. Stem cell (SC) therapy exhibits unique therapeutic potential for IS that differs from current treatments. SC's cell homing, differentiation and paracrine abilities give hope for neuroprotection. Recent studies on SC modification have enhanced therapeutic effects for IS, including gene transfection, nanoparticle modification, biomaterial modification and pretreatment. These methods improve survival rate, homing, neural differentiation, and paracrine abilities in ischemic areas. However, many problems must be resolved before SC therapy can be clinically applied. These issues include production quality and quantity, stability during transportation and storage, as well as usage regulations. Herein, we reviewed the brief pathogenesis of IS, the "multi-mechanism" advantages of SCs for treating IS, various SC modification methods, and SC therapy challenges. We aim to uncover the potential and overcome the challenges of using SCs for treating IS and convey innovative ideas for modifying SCs.

Targeting Neurogenesis in Seeking Novel Treatments for Ischemic Stroke

The interruption of cerebral blood flow leads to ischemic cell death and results in ischemic stroke. Although ischemic stroke is one of the most important causes of long-term disability and mortality, limited treatments are available for functional recovery. Therefore, extensive research has been conducted to identify novel treatments. Neurogenesis is regarded as a fundamental mechanism of neural plasticity. Therefore, therapeutic strategies targeting neurogenesis are thought to be promising. Basic research has found that therapeutic intervention including cell therapy, rehabilitation, and pharmacotherapy increased neurogenesis and was accompanied by functional recovery after ischemic stroke. In this review, we consolidated the current knowledge of the relationship between neurogenesis and treatment for ischemic stroke. It revealed that many treatments for ischemic stroke, including clinical and preclinical ones, have enhanced brain repair and functional recovery post-stroke along with neurogenesis. However, the intricate mechanisms of neurogenesis and its impact on stroke recovery remain areas of extensive research, with numerous factors and pathways involved. Understanding neurogenesis will lead to more effective stroke treatments, benefiting not only stroke patients but also those with other neurological disorders. Further research is essential to bridge the gap between preclinical discoveries and clinical implementation.

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.

JAK2/STAT3 pathway mediates neuroprotective and pro-angiogenic treatment effects of adult human neural stem cells in middle cerebral artery occlusion stroke animal models

Mismatches between pre-clinical and clinical results of stem cell therapeutics for ischemic stroke limit their clinical applicability. To overcome these discrepancies, precise planning of pre-clinical experiments that can be translated to clinical trials and the scientific elucidation of treatment mechanisms is important. In this study, adult human neural stem cells (ahNSCs) derived from temporal lobe surgical samples were used (to avoid ethical and safety issues), and their therapeutic effects on ischemic stroke were examined using middle cerebral artery occlusion animal models. 5 × 10⁵ ahNSCs was directly injected into the lateral ventricle of contralateral brain hemispheres of immune suppressed rat stroke models at the subacute phase of stroke. Compared with the mock-treated group, ahNSCs reduced brain tissue atrophy and neurological sensorimotor and memory functional loss. Tissue analysis demonstrated that the significant therapeutic effects were mediated by the neuroprotective and pro-angiogenic activities of ahNSCs, which preserved neurons in ischemic brain areas and decreased reactive astrogliosis and microglial activation. The neuroprotective and pro-angiogenic effects of ahNSCs were validated in in vitro stroke models and were induced by paracrine factors excreted by ahNSCs. When the JAK2/STAT3 signaling pathway was inhibited by a specific inhibitor, AG490, the paracrine neuroprotective and pro-angiogenic effects of ahNSCs were reversed. This pre-clinical study that closely simulated clinical settings and provided treatment mechanisms of ahNSCs for ischemic stroke may aid the development of protocols for subsequent clinical trials of ahNSCs and the realization of clinically available stem cell therapeutics for ischemic stroke.

Xeno-free induced pluripotent stem cell-derived neural progenitor cells for in vivo applications

BACKGROUND

Currently, there is no regenerative therapy for patients with neurological and neurodegenerative disorders. Cell-therapies have emerged as a potential treatment for numerous brain diseases. Despite recent advances in stem cell technology, major concerns have been raised regarding the feasibility and safety of cell therapies for clinical applications.

METHODS

We generated good manufacturing practice (GMP)-compatible neural progenitor cells (NPCs) from transgene- and xeno-free induced pluripotent stem cells (iPSCs) that can be smoothly adapted for clinical applications. NPCs were characterized in vitro for their differentiation potential and in vivo after transplantation into wild type as well as genetically immunosuppressed mice.

RESULTS

Generated NPCs had a stable gene-expression over at least 15 passages and could be scaled for up to 1018 cells per initially seeded 106 cells. After withdrawal of growth factors in vitro, cells adapted a neural fate and mainly differentiated into active neurons. To ensure a pure NPC population for in vivo applications, we reduced the risk of iPSC contamination by applying micro RNA-switch technology as a safety checkpoint. Using lentiviral transduction with a fluorescent and bioluminescent dual-reporter construct, combined with non-invasive in vivo bioluminescent imaging, we longitudinally tracked the grafted cells in healthy wild-type and genetically immunosuppressed mice as well as in a mouse model of ischemic stroke. Long term in-depth characterization revealed that transplanted NPCs have the capability to survive and spontaneously differentiate into functional and mature neurons throughout a time course of a month, while no residual pluripotent cells were detectable.

CONCLUSION

We describe the generation of transgene- and xeno-free NPCs. This simple differentiation protocol combined with the ability of in vivo cell tracking presents a valuable tool to develop safe and effective cell therapies for various brain injuries.

iPSCs in Neurodegenerative Disorders: A Unique Platform for Clinical Research and Personalized Medicine

In the past, several animal disease models were developed to study the molecular mechanism of neurological diseases and discover new therapies, but the lack of equivalent animal models has minimized the success rate. A number of critical issues remain unresolved, such as high costs for developing animal models, ethical issues, and lack of resemblance with human disease. Due to poor initial screening and assessment of the molecules, more than 90% of drugs fail during the final step of the human clinical trial. To overcome these limitations, a new approach has been developed based on induced pluripotent stem cells (iPSCs). The discovery of iPSCs has provided a new roadmap for clinical translation research and regeneration therapy. In this article, we discuss the potential role of patient-derived iPSCs in neurological diseases and their contribution to scientific and clinical research for developing disease models and for developing a roadmap for future medicine. The contribution of humaniPSCs in the most common neurodegenerative diseases (e.g., Parkinson’s disease and Alzheimer’s disease, diabetic neuropathy, stroke, and spinal cord injury) were examined and ranked as per their published literature on PUBMED. We have observed that Parkinson’s disease scored highest, followed by Alzheimer’s disease. Furthermore, we also explored recent advancements in the field of personalized medicine, such as the patient-on-a-chip concept, where iPSCs can be grown on 3D matrices inside microfluidic devices to create an in vitro disease model for personalized medicine.

An ischemia-homing bioengineered nano-scavenger for specifically alleviating multiple pathogeneses in ischemic stroke

BACKGROUND

Ischemic stroke is one of the most serious global public health problems. However, the performance of current therapeutic regimens is limited due to their poor target specificity, narrow therapeutic time window, and compromised therapeutic effect. To overcome these barriers, we designed an ischemia-homing bioengineered nano-scavenger by camouflaging a catalase (CAT)-loaded self-assembled tannic acid (TA) nanoparticle with a M2-type microglia membrane (TPC@M2 NPs) for ischemic stroke treatment.

RESULTS

The TPC@M2 NPs can on-demand release TA molecules to chelate excessive Fe2+, while acid-responsively liberating CAT to synergistically scavenge multiple ROS (·OH, ·O2-, and H2O2). Besides, the M2 microglia membrane not only can be served as bioinspired therapeutic agents to repolarize M1 microglia into M2 phenotype but also endows the nano-scavenger with ischemia-homing and BBB-crossing capabilities.

CONCLUSIONS

The nano-scavenger for specific clearance of multiple pathogenic elements to alleviate inflammation and protect neurons holds great promise for combating ischemic stroke and other inflammation-related diseases.