Clinical Trials of Stem Cell Therapy for Cerebral Ischemic Stroke

Therapeutic potential of stem cells in subarachnoid hemorrhage

Aneurysm rupture can result in subarachnoid hemorrhage, a condition with potentially severe consequences, such as disability and death. In the acute stage, early brain injury manifests as intracranial pressure elevation, global cerebral ischemia, acute hydrocephalus, and direct blood-brain contact due to aneurysm rupture. This may subsequently cause delayed cerebral infarction, often with cerebral vasospasm, significantly affecting patient outcomes. Chronic complications such as brain volume loss and chronic hydrocephalus can further impact outcomes. Investigating the mechanisms of subarachnoid hemorrhage-induced brain injury is paramount for identifying effective treatments. Stem cell therapy, with its multipotent differentiation capacity and anti-inflammatory effects, has emerged as a promising approach for treating previously deemed incurable conditions. This review focuses on the potential application of stem cells in subarachnoid hemorrhage pathology and explores their role in neurogenesis and as a therapeutic intervention in preclinical and clinical subarachnoid hemorrhage studies.

Intranasal administration of stem cell-derived exosome alleviates cognitive impairment against subarachnoid hemorrhage

INTRODUCTION

Brain damage caused by subarachnoid hemorrhage (SAH) currently lacks effective treatment, leading to stagnation in the improvement of functional outcomes for decades. Recent studies have demonstrated the therapeutic potential of exosomes released from mesenchymal stem cells (MSC), which effectively attenuate neuronal apoptosis and inflammation in neurological diseases. Due to the challenge of systemic dilution associated with intravenous administration, intranasal delivery has emerged as a novel approach for targeting the brain. In this study, we investigate the effects of intranasally administered MSC-derived exosomes in a SAH animal model and elucidate their mode of action.

METHODS

Exosomes were isolated from the cell supernatants of amnion-derived MSC. SAH was induced in 8-week-old Sprague-Dawley rats using an autologous blood prechiasmatic cistern injection model. A total of 1.2 × 1010 particles of exosomes in 200 μL of PBS or PBS alone were intranasally administered immediately and 24 h post-injury. Neurological function was assessed up to 7 days after injury, and histological analysis was performed to evaluate their anti-apoptotic and anti-inflammatory effects. The biodistribution of exosomes was assessed using PET/CT imaging of 64Cu labeled exosome. In vitro analyses were performed using primary glial cells and cell lines to evaluate the anti-inflammatory effects of the exosomes.

RESULTS

Animals treated with exosomes exhibited significant improvement in cognitive function compared with PBS treated animal. Apoptotic cells and inflammation were reduced for the exosome group in the hippocampal CA1 area and in cortex, resulting in better neuronal cell survival. Blood brain barrier permeability was also preserved in the exosome group. Nuclear imaging revealed that exosomes were primarily transferred to the olfactory nerve and cerebrum; furthermore, exosomes were also observed in the trigeminal nerve and brainstem, where exosomes were co-localized with microglia and with endothelial cells. In vitro assessment showed that exosome administration ameliorated inflammation and prevented the death of glial cells.

CONCLUSIONS

MSC-derived exosomes were successfully transferred into the brain through intranasal administration and alleviated brain damage following SAH.

Neuroplasticity therapy using glia-like cells derived from human mesenchymal stem cells for the recovery of cerebral infarction sequelae

Despite a dramatic increase in ischemic stroke incidence worldwide, effective therapies for attenuating sequelae of cerebral infarction are lacking. This study investigates the use of human mesenchymal stem cells (hMSCs) induced toward glia-like cells (ghMSCs) to ameliorate chronic sequelae resulting from cerebral infarction. Transcriptome analysis demonstrated that ghMSCs exhibited astrocytic characteristics, and assessments conducted ex vivo using organotypic brain slice cultures demonstrated that ghMSCs exhibited superior neuroregenerative and neuroprotective activity against ischemic damage compared to hMSCs. The observed beneficial effects of ghMSCs were diminished by pre-treatment with a CXCR2 antagonist, indicating a direct role for CXCR2 signaling. Studies conducted in rats subjected to cerebral infarction demonstrated that ghMSCs restored neurobehavioral functions and reduced chronic brain infarction in a dose-dependent manner when transplanted at the subacute-to-chronic phase. These beneficial impacts were also inhibited by a CXCR2 antagonist. Molecular analyses confirmed that increased neuroplasticity contributed to ghMSCs' neuroregenerative effects. These data indicate that ghMSCs hold promise for treating refractory sequelae resulting from cerebral infarction by enhancing neuroplasticity and identify CXCR2 signaling as an important mediator of ghMSCs' mechanism of action.

Mechanism of inflammatory response and therapeutic effects of stem cells in ischemic stroke: current evidence and future perspectives

Ischemic stroke is a leading cause of death and disability worldwide, with an increasing trend and tendency for onset at a younger age. China, in particular, bears a high burden of stroke cases. In recent years, the inflammatory response after stroke has become a research hotspot: understanding the role of inflammatory response in tissue damage and repair following ischemic stroke is an important direction for its treatment. This review summarizes several major cells involved in the inflammatory response following ischemic stroke, including microglia, neutrophils, monocytes, lymphocytes, and astrocytes. Additionally, we have also highlighted the recent progress in various treatments for ischemic stroke, particularly in the field of stem cell therapy. Overall, understanding the complex interactions between inflammation and ischemic stroke can provide valuable insights for developing treatment strategies and improving patient outcomes. Stem cell therapy may potentially become an important component of ischemic stroke treatment.

Phase I/II trial of intracerebral transplantation of autologous bone marrow stem cells combined with recombinant peptide scaffold for patients with chronic intracerebral haemorrhage: a study protocol

INTRODUCTION

Intracerebral haemorrhage (ICH) stands as a leading global cause of death and disability, posing a significant challenge with limited treatment options, especially for chronic patients. Recent advances in stem cell therapies have opened new avenues for therapeutic potential. Our previous preclinical research has demonstrated that intracerebral transplantation of bone marrow stromal cells (BMSCs) combined with a recombinant human collagen type I scaffold enables higher cell survival and engraftment and holds promising potential. In this article, we present the protocol for a novel clinical trial, named 'Research on Advanced Intervention using Novel Bone MarrOW stem cells for chronic intracerebral haemorrhage' (RAINBOW-Hx).

METHODS AND ANALYSIS

RAINBOW-Hx is a phase I/II, open-label, uncontrolled study with the primary objective of assessing the safety and efficacy of intracerebral transplantation of autologous BMSCs combined with the scaffold (HUFF-01) in patients with chronic ICH. Eight patients, experiencing moderate to severe neurological deficits for 12 months or longer, will be enrolled. The haemorrhage location will be limited to the basal ganglia and thalamus. Approximately 50 mL of bone marrow will be extracted from the iliac bone of each patient, and BMSCs will be cultured using autologous platelet lysate. 3 days before transplantation, BMSCs will be combined with the scaffold to generate HUFF-01. Each patient will receive a 50 000 HUFF-01 dose, containing approximately 50 million BMSCs, through stereotactic transplantation into the haemorrhagic cavity. Neurological assessments, MRI, 18F-fluorodeoxyglucose positron emission tomography and 123I-Iomazenil single-photon emission CT will be performed for 1 year after administration.

ETHICS AND DISSEMINATION

The trial protocols were reviewed and approved by the Institutional Review Board of the Hokkaido University Hospital (R5-11), and this study is conducted according to Good Clinical Practice guidelines and the principles of the Declaration of Helsinki. The results of this trial will be submitted for publication in a peer-reviewed scientific journal.

TRIAL REGISTRATION NUMBER

jRCT2013230053, Japan Registry of Clinical Trials.

Secretome from hypoxic mesenchymal stem cells as a potential therapy for ischemic stroke: Investigations on VEGF and GFAP expression

Ischemic stroke is a sudden onset of neurological deficit resulting from a blockage in cerebral blood vessels, which can lead to brain tissue damage, chronic disability, and increased risk of mortality. Secretome from hypoxic mesenchymal stem cells (SH-MSC) is a potential therapy to improve neurological deficit by increasing the expression of vascular endothelial growth factor (VEGF) and reducing glial fibrillary acidic protein (GFAP). These effects can reduce the infarction area of ischemic stroke. Therefore, the aim of this study was to analyze the effect of 150 μL and 300 μL SH-MSC injection on VEGF and GFAP expression as well as the improvement of infarction area in ischemic stroke animal model. A post-test-only experimental design with consecutive sampling was used, with Rattus norvegicus as subjects. Stromal mesenchymal stem cells (S-MSCs) were isolated from the umbilical cords of rats at 21 days of gestation. Secretome production by the S- MSCs was induced under a hypoxic condition, and subsequently isolated. The resultant secretome was administered to rats subjected to middle cerebral artery occlusion (MCAO) at doses of 150 μL (P1 group) and 300 μL (P2 group). The results showed that the infarction area was reduced in P1 (p<0.001) and P2 groups (p<0.001). SH-MSC at a dose of 300 μL increased the expression of VEGF (p=0.028) and reduced the expression of GFAP (p=0.001). In conclusion, secretome from hypoxic S-MSC could potentially improve ischemic stroke by upregulating VEGF expression and downregulating GFAP expression.

Unveiling Smyd-2's Role in Cytoplasmic Nrf-2 Sequestration and Ferroptosis Induction in Hippocampal Neurons After Cerebral Ischemia/Reperfusion

SET and MYND Domain-Containing 2 (Smyd-2), a specific protein lysine methyltransferase (PKMT), influences both histones and non-histones. Its role in cerebral ischemia/reperfusion (CIR), particularly in ferroptosis-a regulated form of cell death driven by lipid peroxidation-remains poorly understood. This study identifies the expression of Smyd-2 in the brain and investigates its relationship with neuronal programmed cell death (PCD). We specifically investigated how Smyd-2 regulates ferroptosis in CIR through its interaction with the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway. Smyd-2 knockout protects HT-22 cells from Erastin-induced ferroptosis but not TNF-α + Smac-mimetic-induced apoptosis/necroptosis. This neuroprotective effect of Smyd-2 knockout in HT-22 cells after Oxygen-Glucose Deprivation/Reperfusion (OGD/R) was reversed by Erastin. Smyd-2 knockout in HT-22 cells shows neuroprotection primarily via the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway, despite the concurrent upregulation of Smyd-2 and Nrf-2 observed in both the middle cerebral artery occlusion (MCAO) and OGD/R models. Interestingly, vivo experiments demonstrated that Smyd-2 knockout significantly reduced ferroptosis and lipid peroxidation in hippocampal neurons following CIR. Moreover, the Nrf-2 inhibitor ML-385 abolished the neuroprotective effects of Smyd-2 knockout, confirming the pivotal role of Nrf-2 in ferroptosis regulation. Cycloheximide (CHX) fails to reduce Nrf-2 expression in Smyd-2 knockout HT-22 cells. Smyd-2 knockout suppresses Nrf-2 lysine methylation, thereby promoting the Nrf-2/Keap-1 pathway without affecting the PKC-δ/Nrf-2 pathway. Conversely, Smyd-2 overexpression disrupts Nrf-2 nuclear translocation, exacerbating ferroptosis and oxidative stress, highlighting its dual regulatory role. This study underscores Smyd-2's potential for ischemic stroke treatment by disrupting the Smyd-2/Nrf-2-driven antioxidant capacity, leading to hippocampal neuronal ferroptosis. By clarifying the intricate interplay between ferroptosis and oxidative stress via the Nrf-2/Keap-1 pathway, our findings provide new insights into the molecular mechanisms of CIR and identify Smyd-2 as a promising therapeutic target.

2-Acetylacteoside improves recovery after ischemic stroke by promoting neurogenesis via the PI3K/Akt pathway

Ischemic stroke induces adult neurogenesis in the subventricular zone (SVZ), even in elderly patients. Harnessing of this neuroregenerative response presents the therapeutic potential for post-stroke recovery. We found that phenylethanoid glycosides (PhGs) derived from Cistanche deserticola aid neural repair after stroke by promoting neurogenesis. Among these, 2-acetylacteoside had the most potent on the proliferation of neural stem cells (NSCs) in vitro. Furthermore, 2-acetylacteoside was shown to alleviate neural dysfunction by increase neurogenesis both in vivo and in vitro. RNA-sequencing analysis highlighted differentially expressed genes within the PI3K/Akt signaling pathway. The candidate target Akt was validated as being regulated by 2-acetylacteoside, which, in turn, enhanced the proliferation and differentiation of cultured NSCs after oxygen-glucose deprivation/reoxygenation (OGD/R), as evidenced by Western blot analysis. Subsequent analysis using cultured NSCs from adult subventricular zones (SVZ) confirmed that 2-acetylacteoside enhanced the expression of phosphorylated Akt (p-Akt), and its effect on NSC neurogenesis was shown to be dependent on the PI3K/Akt pathway. In summary, our findings elucidate for the first time the role of 2-acetylacteoside in enhancing neurological recovery, primarily by promoting neurogenesis via Akt activation following ischemic brain injury, which offers a novel strategy for long-term cerebrological recovery in ischemic stroke.

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.

Intranasal delivery of engineered extracellular vesicles loaded with miR-206-3p antagomir ameliorates Alzheimer's disease phenotypes

Rationale: The level of miR-206-3p in the plasma and temporal cortex is increased in Alzheimer's disease (AD) patients. miR-206-3p antagomir injected into hippocampus ameliorates cognitive deficits by enhancing the level of BDNF. However, the trauma caused by brain injection and susceptibility to degradation limit its application. Methods: To overcome these challenges, we constructed engineered extracellular vesicles derived from mesenchymal stem cell (MSC-EVs) loaded with miR-206-3p antagomir (MSC-EVs-anta) by electroporation technology, and explored the therapeutic effects of MSC-EVs-anta delivered by intranasal administration on AD mice. Transcriptome sequencing and LC-MS/MS proteomic analysis were employed to disclose the mechanism underlying the attenuation of AD phenotypes by MSC-EVs-anta. Results: MSC-EVs-anta had favorable neuroprotection by promoting neurite outgrowth in vitro. Following intranasal administration, MSC-EVs-anta improved learning and memory deficits, promoted hippocampal neurogenesis and synaptic plasticity, and alleviated Aβ deposition. Compared with MSC-EVs or miR-206-3p antagomir alone, MSC-EVs-anta showed superior therapeutic effects. Mechanistically, MSC-EVs-anta significantly upregulated brain-derived neurotrophic factor (BDNF) in AD mice, and activated the BDNF/TrkB signaling pathway. The data from two-omics analyses demonstrated that the differentially expressed proteins and genes significantly regulated by MSC-EVs-anta were primarily enriched in the pathways involved in neurogenesis and synapse. Conclusions: Our findings highlight the intranasal administration of MSC-EVs-anta as a promising strategy for the treatment of AD.

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.

Brain repair mechanisms after cell therapy for stroke

Cell-based therapies hold great promise for brain repair after stroke. While accumulating evidence confirms the preclinical and clinical benefits of cell therapies, the underlying mechanisms by which they promote brain repair remain unclear. Here, we briefly review endogenous mechanisms of brain repair after ischaemic stroke and then focus on how different stem and progenitor cell sources can promote brain repair. Specifically, we examine how transplanted cell grafts contribute to improved functional recovery either through direct cell replacement or by stimulating endogenous repair pathways. Additionally, we discuss recently implemented preclinical refinement methods, such as preconditioning, microcarriers, genetic safety switches and universal (immune evasive) cell transplants, as well as the therapeutic potential of these pharmacologic and genetic manipulations to further enhance the efficacy and safety of cell therapies. By gaining a deeper understanding of post-ischaemic repair mechanisms, prospective clinical trials may be further refined to advance post-stroke cell therapy to the clinic.

The Aging Immune System: A Critical Attack on Ischemic Stroke

Ischemic stroke caused by cerebrovascular embolism is an age-related disease with high rates of disability and mortality. Although the mechanisms of immune and inflammatory development after stroke have been of great interest, most studies have neglected the critical and unavoidable factor of age. As the global aging trend intensifies, the number of stroke patients is constantly increasing, emphasizing the urgency of finding effective measures to address the needs of elderly stroke patients. The concept of "immunosenescence" appears to explain the worse stroke outcomes in older individuals. Immune remodeling due to aging involves dynamic changes at all levels of the immune system, and the overall consequences of central (brain-resident) and peripheral (non-brain-resident) immune cells in stroke vary according to the age of the individual. Lastly, the review outlines recent strategies aimed at immunosenescence to improve stroke prognosis.

Three-dimensional cultured human umbilical cord mesenchymal stem cells attenuate pulmonary fibrosis by improving the balance of mitochondrial fusion and fission

Pulmonary fibrosis is a kind of fibrotic interstitial pneumonia with poor prognosis. Aging, environmental pollution, and coronavirus disease 2019 are considered as independent risk factors for pulmonary fibrogenesis. Consequently, the morbidity and mortality striking continues to rise in recent years. However, the clinical therapeutic efficacy is very limited and unsatisfactory. So it is necessary to develop a new effective therapeutic approach for pulmonary fibrosis. Human umbilical cord mesenchymal stem cells (hucMSCs) are considered as a promising treatment for various diseases because of their multiple differentiation and immunomodulatory function. The key bottleneck in the clinical application of hucMSCs therapy is the high-quality and large-scale production. This study used FloTrix miniSpin bioreactor, a three-dimensional (3D) cell culture system, for large-scale expansion of hucMSCs in vitro, and proved 3D cultured hucMSCs inhibited the differentiation of fibroblasts into myofibroblasts and myofibroblasts proliferation and migration, leading to slow down the development of pulmonary fibrosis. Further mechanistic studies clarified that hucMSCs reduced the amount of binding between circELP2 and miR-630, resulting in blocking YAP/TAZ translocation from cytoplasm to nucleus. This condition inhibited mitochondrial fusion and promoted mitochondrial fission, and ultimately improved fusion/fission balance and cellular homeostasis. To sum up, this work clarified the anti-fibrosis and mechanism of hucMSCs cultured from the 3D FloTrix miniSpin bioreactor. We hope to provide new ideas and new methods for the clinical transformation and industrialization of hucMSCs therapy.

The impact of ischemic stroke on bone marrow microenvironment and extracellular vesicles: A study on inflammatory and molecular changes

An ischemic stroke (IS) is caused due to the lack of blood flow to cerebral tissue. Most of the studies have focused on how stroke affects the localized tissue, but it has been observed that a stroke can cause secondary complications in distant organs, such as Bone Marrow (BM). Our study focused on the effect of ischemic strokes on the bone marrow microenvironment. Bone marrow (BM) is a vital organ that maintains inflammatory homeostasis and aids in the repair of damaged tissue after injury/IS. We used the middle cerebral artery occlusion (MCAO) model of ischemic stroke on adult mice (6 months) and investigated the changes in the BM environment. BM cells were used for western blot and RT-PCR, and the BM supernatant was used for cytokine analysis and extracellular vesicle (EVs) isolation. We observed a significant increase in the total cell number within the BM and an increase in TNF-alpha and MCP-1, which are known for inducing a pro-inflammatory environment. Western blots analysis on the whole BM cell lysate demonstrated elevated levels of inflammatory factors (IL-6, TNF-alpha, and TLR-4) and senescence markers (p21 p16). EVs isolated from the BM supernatant showed no change in size or concentration; however, we found that the EVs carried increased miRNA-141-3p and miRNA-34a. Proteomic analysis on BM-derived EVs showed an alteration in the protein cargo of IS. We observed an increase in FgB, C3, Fn1, and Tra2b levels. The signaling pathway analysis showed mitochondrial function is most affected within the bone marrow. Our study demonstrated that IS induces changes in the BM environment and EVs secreted in the BM.

The advantages of multi-level omics research on stem cell-based therapies for ischemic stroke

Stem cell transplantation is a potential therapeutic strategy for ischemic stroke. However, despite many years of preclinical research, the application of stem cells is still limited to the clinical trial stage. Although stem cell therapy can be highly beneficial in promoting functional recovery, the precise mechanisms of action that are responsible for this effect have yet to be fully elucidated. Omics analysis provides us with a new perspective to investigate the physiological mechanisms and multiple functions of stem cells in ischemic stroke. Transcriptomic, proteomic, and metabolomic analyses have become important tools for discovering biomarkers and analyzing molecular changes under pathological conditions. Omics analysis could help us to identify new pathways mediated by stem cells for the treatment of ischemic stroke via stem cell therapy, thereby facilitating the translation of stem cell therapies into clinical use. In this review, we summarize the pathophysiology of ischemic stroke and discuss recent progress in the development of stem cell therapies for the treatment of ischemic stroke by applying multi-level omics. We also discuss changes in RNAs, proteins, and metabolites in the cerebral tissues and body fluids under stroke conditions and following stem cell treatment, and summarize the regulatory factors that play a key role in stem cell therapy. The exploration of stem cell therapy at the molecular level will facilitate the clinical application of stem cells and provide new treatment possibilities for the complete recovery of neurological function in patients with ischemic stroke.

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.

Role of intracranial bone marrow mesenchymal stem cells in stroke recovery: A focus on post-stroke inflammation and mitochondrial transfer

Stem cell therapy has become a hot research topic in the medical field in recent years, with enormous potential for treating a variety of diseases. In particular, bone marrow mesenchymal stem cells (BMSCs) have wide-ranging applications in the treatment of ischemic stroke, autoimmune diseases, tissue repair, and difficult-to-treat diseases. BMSCs can differentiate into multiple cell types and exhibit strong immunomodulatory properties. Although BMSCs can regulate the inflammatory response activated after stroke, the mechanism by which BMSCs regulate inflammation remains unclear and requires further study. Recently, stem cell therapy has emerged as a potentially effective approach for enhancing the recovery process following an ischemic stroke. For example, by regulating post-stroke inflammation and by transferring mitochondria to exert therapeutic effects. Therefore, this article reviews the therapeutic effects of intracranial BMSCs in regulating post-stroke inflammation and mitochondrial transfer in the treatment of stroke, providing a basis for further research.

Stem cell therapy: a new hope for stroke and traumatic brain injury recovery and the challenge for rural minorities in South Carolina

Stroke and traumatic brain injury (TBI) are a significant cause of death and disability nationwide. Both are considered public health concerns in rural communities in the state of South Carolina (SC), particularly affecting the African American population resulting in considerable morbidity, mortality, and economic burden. Stem cell therapy (SCT) has emerged as a potential intervention for both diseases with increasing research trials showing promising results. In this perspective article, the authors aim to discuss the current research in the field of SCT, the results of early phase trials, and the utilization of outcome measures and biomarkers of recovery. We searched PubMed from inception to December 2023 for articles on stem cell therapy in stroke and traumatic brain injury and its impact on rural communities, particularly in SC. Early phase trials of SCT in Stroke and Traumatic Brain injury yield promising safety profile and efficacy results, but the findings have not yet been consistently replicated. Early trials using mesenchymal stem cells for stroke survivors showed safety, feasibility, and improved functional outcomes using broad and domain-specific outcome measures. Neuroimaging markers of recovery such as Functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG) combined with neuromodulation, although not widely used in SCT research, could represent a breakthrough when evaluating brain injury and its functional consequences. This article highlights the role of SCT as a promising intervention while addressing the underlying social determinants of health that affect therapeutic outcomes in relation to rural communities such as SC. It also addresses the challenges ethical concerns of stem cell sourcing, the high cost of autologous cell therapies, and the technical difficulties in ensuring transplanted cell survival and strategies to overcome barriers to clinical trial enrollment such as the ethical concerns of stem cell sourcing, the high cost of autologous cell therapies, and the technical difficulties in ensuring transplanted cell survival and equitable healthcare.

The hybrid operation based on microsurgery assisted by intraoperative spinal angiography in patients with spinal dural arteriovenous fistula: a series of 45 cases from multicenter research

BACKGROUND

To assess the clinical effects of hybrid surgery, which includes spinal angiography-assisted microsurgery, in the treatment of spinal dural arteriovenous fistulas (SDAVF).

METHODS

We retrospectively reviewed 45 patients who underwent hybrid Spinal dural arteriovenous fistula (SDAVF) resection between September 2019 and June 2022. The hybrid surgery involved intraoperative digital subtraction angiography (DSA) of the spinal vessels to determine the source of the blood-supplying artery, location of the fistula and draining vein, indocyanine green fluorescence (ICG)-assisted microsurgical resection of the fistula, and postoperative DSA to verify therapeutic efficacy. The Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD), Visual Analog Scale (VAS), Barthel score, modified Rankin Scale (mRS) and modified Aminoff-Logue score (key indicator) were used to assess the clinical effects of SDAVF resection.

RESULTS

A series of 45 patients with SDAVF were successfully treated with hybrid surgery without fistula recurrence. There were no intraoperative complications related to spinal angiography, and none of the patients died. Postoperatively, two patients experienced clinical deterioration of spinal cord function, which manifested as bilateral lower extremity paralysis and bladder sphincter dysfunction. Postoperatively, improvement in mALS scores was observed in 16 cases (35.6%) within 1-2 days, 12 cases (26.7%) at 1 week, and 7 cases (15.6%) at 6 months. No SDAVF recurrence was detected in the spinal MRA examination 6 months after surgery. When compared with preoperative mALS scores, 35 cases (77.8%) showed significant improvement in symptoms, 8 cases (17.8%), remained unchanged, and 2 cases (4.4%) deteriorated. Compared with the preoperative scores, the postoperative mALS score was significantly decreased [postoperative vs. preoperative: 2(1,3) vs. 3(2,4)], HAMD score [(12.2 ± 5.5) vs. (19.6 ± 6.3)], HAMA score [(15.6 ± 5.5) vs. (20.5 ± 6.5)], and VAS score [3(2,5) vs. 5(4,8)]. Conversely, Barthel scoresshowed significant increase [(74.6 ± 8.7) vs. (67.8 ± 9.2)] (P < 0.05). However, the mRS scores were lower than preoperatively [1(1,2) vs. 2(1,2.5)], but the difference was not statistically significant (P > 0.05). There was a significant increase in "good" neurological outcomes at follow-up compared with preoperative function (62.2% vs. 33.3%) (P = 0.023).

CONCLUSION

Hybrid surgery is a safe and effective treatment for patients with SAVF, which is beneficial for improving anxiety, depression, spinal cord, and neurological function, and relieving pain. However, the treatment of patients with SDAVF is a complex, long-term process requiring further multidisciplinary interventions, including clinical care, psychosocial interventions, and neurorehabilitation.

A taurine-based hydrogel with the neuroprotective effect and the ability to promote neural stem cell proliferation

Ischemic stroke, a cerebrovascular disease caused by arterial occlusion in the brain, can lead to brain impairment and even death. Stem cell therapies have shown positive advantages to treat ischemic stroke because of their extended time window, but the cell viability is poor when transplanted into the brain directly. Therefore, a new hydrogel GelMA-T was developed by introducing taurine on GelMA to transplant neural stem cells. The GelMA-T displayed the desired photocuring ability, micropore structure, and cytocompatibility. Its compressive modulus was more similar to neural tissue compared to that of GelMA. The GelMA-T could protect SH-SY5Y cells from injury induced by OGD/R. Furthermore, the NE-4C cells showed better proliferation performance in GelMA-T than that in GelMA during both 2D and 3D cultures. All results demonstrate that GelMA-T possesses a neuroprotective effect for ischemia/reperfusion injury against ischemic stroke and plays a positive role in promoting NSC proliferation. The novel hydrogel is anticipated to function as cell vehicles for the transplantation of neural stem cells into the stroke cavity, aiming to treat ischemic stroke.

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.

The therapeutic role of SSEA3(+) human umbilical cord blood mononuclear cells in ischemic stroke model

Numerous evidences showed that human umbilical cord blood (UCB) mononuclear cells were a promising approach for the therapy of ischemic stroke(IS). The effect of stage-specific embryonic antigen 3 (SSEA3）positive subpopulation in UCB was not investigated in IS. In this study, we isolated SSEA3 positive cells from healthy UCB mononuclear cells, which comprised about 7.01% of the total UCB-mononuclear cells. Flow cytometry analysis revealed that SSEA3(+)UCB cells were almost positive for CD44 and CD45, and negative for CD73, CD90 and CD105. The expression of Oct3/4 in SSEA3(+)UCB cells were higher than that in UCB. SSEA3(+)UCB cells sorted by magnetic cell sorting were intravenously injected into the middle cerebral arterial occlusion(MCAO) rat model. Neurological score showed that SSEA3(+)UCB transplantation group exhibited significant improvements in the functional outcome of MCAO rats than UCB transplantation group. Nissl staining and microtubule association protein-2(MAP2) immunofluorescence staining showed that the SSEA3(+)UCB transplantation group decreased neuronal loss. SSEA3(+)UCB transplantation group reduced neuronal apoptosis, inhibited caspase3 expression, and decreased tumor necrosis factor α(TNF-α). These results indicate that SSEA3 positive cells are a novel subpopulation of UCB cells, which exhibit great potential for the treatment of ischemic stroke.

Peripheral nerve transfers for dysfunctions in central nervous system injuries: a systematic review

BACKGROUND

The review highlights recent advancements and innovative uses of nerve transfer surgery in treating dysfunctions caused by central nervous system (CNS) injuries, with a particular focus on spinal cord injury (SCI), stroke, traumatic brain injury, and cerebral palsy.

METHODS

A comprehensive literature search was conducted regarding nerve transfer for restoring sensorimotor functions and bladder control following injuries of spinal cord and brain, across PubMed and Web of Science from January 1920 to May 2023. Two independent reviewers undertook article selection, data extraction, and risk of bias assessment with several appraisal tools, including the Cochrane Risk of Bias Tool, the JBI Critical Appraisal Checklist, and SYRCLE's ROB tool. The study protocol has been registered and reported following PRISMA and AMSTAR guidelines.

RESULTS

Nine hundred six articles were retrieved, of which 35 studies were included (20 on SCI and 15 on brain injury), with 371 participants included in the surgery group and 192 in the control group. These articles were mostly low-risk, with methodological concerns in study types, highlighting the complexity and diversity. For SCI, the strength of target muscle increased by 3.13 of Medical Research Council grade, and the residual urine volume reduced by more than 100 ml in 15 of 20 patients. For unilateral brain injury, the Fugl-Myer motor assessment (FMA) improved 15.14-26 score in upper extremity compared to 2.35-26 in the control group. The overall reduction in Modified Ashworth score was 0.76-2 compared to 0-1 in the control group. Range of motion (ROM) increased 18.4-80° in elbow, 20.4-110° in wrist and 18.8-130° in forearm, while ROM changed -4.03°-20° in elbow, -2.08°-10° in wrist, -2.26°-20° in forearm in the control group. The improvement of FMA in lower extremity was 9 score compared to the presurgery.

CONCLUSION

Nerve transfer generally improves sensorimotor functions in paralyzed limbs and bladder control following CNS injury. The technique effectively creates a 'bypass' for signals and facilitates functional recovery by leveraging neural plasticity. It suggested a future of surgery, neurorehabilitation and robotic-assistants converge to improve outcomes for CNS.

Intranasal administration of stem cell-derived exosomes for central nervous system diseases

ABSTRACT

Exosomes, lipid bilayer-enclosed small cellular vesicles, are actively secreted by various cells and play crucial roles in intercellular communication. These nanosized vesicles transport internalized proteins, mRNA, miRNA, and other bioactive molecules. Recent findings have provided compelling evidence that exosomes derived from stem cells hold great promise as a therapeutic modality for central nervous system disorders. These exosomes exhibit multifaceted properties including anti-apoptotic, anti-inflammatory, neurogenic, and vasculogenic effects. Furthermore, exosomes offer several advantages over stem cell therapy, such as high preservation capacity, low immunogenicity, the ability to traverse the blood-brain barrier, and the potential for drug encapsulation. Consequently, researchers have turned their attention to exosomes as a novel therapeutic avenue. Nonetheless, akin to the limitations of stem cell treatment, the limited accumulation of exosomes in the injured brain poses a challenge to their clinical application. To overcome this hurdle, intranasal administration has emerged as a non-invasive and efficacious route for delivering drugs to the central nervous system. By exploiting the olfactory and trigeminal nerve axons, this approach enables the direct transport of therapeutics to the brain while bypassing the blood-brain barrier. Notably, exosomes, owing to their small size, can readily access the nerve pathways using this method. As a result, intranasal administration has gained increasing recognition as an optimal therapeutic strategy for exosome-based treatments. In this comprehensive review, we aim to provide an overview of both basic and clinical research studies investigating the intranasal administration of exosomes for the treatment of central nervous system diseases. Furthermore, we elucidate the underlying therapeutic mechanisms and offer insights into the prospect of this approach.

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).

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.

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.

Versatile strategies for adult neurogenesis: avenues to repair the injured brain

Brain injuries due to trauma or stroke are major causes of adult death and disability. Unfortunately, few interventions are effective for post-injury repair of brain tissue. After a long debate on whether endogenous neurogenesis actually happens in the adult human brain, there is now substantial evidence to support its occurrence. Although neurogenesis is usually significantly stimulated by injury, the reparative potential of endogenous differentiation from neural stem/progenitor cells is usually insufficient. Alternatively, exogenous stem cell transplantation has shown promising results in animal models, but limitations such as poor long-term survival and inefficient neuronal differentiation make it still challenging for clinical use. Recently, a high focus was placed on glia-to-neuron conversion under single-factor regulation. Despite some inspiring results, the validity of this strategy is still controversial. In this review, we summarize historical findings and recent advances on neurogenesis strategies for neurorepair after brain injury. We also discuss their advantages and drawbacks, as to provide a comprehensive account of their potentials for further studies.

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.

Bioorthogonal microglia-inspired mesenchymal stem cell bioengineering system creates livable niches for enhancing ischemic stroke recovery via the hormesis

Mesenchymal stem cells (MSCs) experience substantial viability issues in the stroke infarct region, limiting their therapeutic efficacy and clinical translation. High levels of deadly reactive oxygen radicals (ROS) and proinflammatory cytokines (PC) in the infarct milieu kill transplanted MSCs, whereas low levels of beneficial ROS and PC stimulate and improve engrafted MSCs' viability. Based on the intrinsic hormesis effects in cellular biology, we built a microglia-inspired MSC bioengineering system to transform detrimental high-level ROS and PC into vitality enhancers for strengthening MSC therapy. This system is achieved by bioorthogonally arming metabolic glycoengineered MSCs with microglial membrane-coated nanoparticles and an antioxidative extracellular protective layer. In this system, extracellular ROS-scavenging and PC-absorbing layers effectively buffer the deleterious effects and establish a micro-livable niche at the level of a single MSC for transplantation. Meanwhile, the infarct's inanimate milieu is transformed at the tissue level into a new living niche to facilitate healing. The engineered MSCs achieved viability five times higher than natural MSCs at seven days after transplantation and exhibited a superior therapeutic effect for stroke recovery up to 28 days. This vitality-augmented system demonstrates the potential to accelerate the clinical translation of MSC treatment and boost stroke recovery.

Estimation of the Ischemic Lesion in the Experimental Stroke Studies Using Magnetic Resonance Imaging (Review)

In translational animal study aimed at evaluation of the effectiveness of innovative methods for treating cerebral stroke, including regenerative cell technologies, of particular importance is evaluation of the dynamics of changes in the volume of the cerebral infarction in response to therapy. Among the methods for assessing the focus of infarction, MRI is the most effective and convenient tool for use in preclinical studies. This review provides a description of MR pulse sequences used to visualize cerebral ischemia at various stages of its development, and a detailed description of the MR semiotics of cerebral infarction. A comparison of various methods for morphometric analysis of the focus of a cerebral infarction, including systems based on artificial intelligence for a more objective measurement of the volume of the lesion, is also presented.

Molecular mechanism underlying miR-204-5p regulation of adipose-derived stem cells differentiation into cells from three germ layers

The limited differentiation ability of adipose-derived stem cells (ADSCs) limits their application in stem cell therapy and regenerative medicine. Here, we explore the molecular mechanism by which miR-204-5p regulates ADSCs differentiation into cells derived from the three germ layers (i.e., adipocytes, neurocytes, and hepatocytes). Although miR-204-5p overexpression inhibited ADSCs differentiation into adipocytes, neurocyte and hepatocyte differentiation were promoted. Mechanistically, miR-204-5p inhibited the expression of PPARG by regulating the AMPK signaling pathway, thereby inhibiting ADSCs differentiation into adipocytes. Further, miR-204-5p regulated JAG1/NOTCH3 axis for the inhibition of differentiation into adipocytes and promotion of differentiation into neurocytes. miR-204-5p might also promote ADSCs differentiation into hepatocytes by upregulating E2F8. The findings of this study provide novel insights into the regulatory mechanisms underlying early embryonic development and will help to facilitate the application of ADSCs in stem cell therapy and regenerative medicine.

A Randomized, Placebo-Controlled, Phase II Trial of Intravenous Allogeneic Non-HLA Matched, Unrelated Donor, Cord Blood Infusion for Ischemic Stroke

Stroke remains a leading cause of death and disability in the US, and time-limited reperfusion strategies remain the only approved treatment options. To address this unmet clinical need, we conducted a phase II randomized clinical trial to determine whether intravenous infusion of banked, non-HLA matched unrelated donor umbilical cord blood (UCB) improved functional outcome after stroke. Participants were randomized 2:1 to UCB or placebo within strata of National Institutes of Health Stroke Scale Score (NIHSS) and study center. Study product was infused 3-10 days following index stroke. The primary endpoint was change in modified Rankin Scale (mRS) from baseline to day 90. Key secondary outcomes included functional independence, NIHSS, the Barthel Index, and assessment of adverse events. The trial was terminated early due to slow accrual and logistical concerns associated with the COVID-19 pandemic, and a total of 73 of a planned 100 participants were included in primary analyses. The median (range) of the change in mRS was 1 point (-2, 3) in UCB and 1 point (-1,4) in Placebo (P = 0.72). A shift analysis comparing the mRS at day 90 utilizing proportional odds modeling showed a common odds ratio of 0.9 (95% CI: 0.4, 2.3) after adjustment for baseline NIHSS and randomization strata. The distribution of adverse events was similar between arms. Although this study did not suggest any safety concerns related to UCB in ischemic stroke, we did not show a clinical benefit in the reduced sample size evaluated.

Extracellular Vesicles Maintain Blood-Brain Barrier Integrity by the Suppression of Caveolin-1/CD147/VEGFR2/MMP Pathway After Ischemic Stroke

Background

Ischemic stroke (IS) causes tragic death and disability worldwide. However, effective therapeutic interventions are finite. After IS, blood-brain barrier (BBB) integrity is disrupted, resulting in deteriorating neurological function. As a novel therapeutic, extracellular vesicles (EVs) have shown ideal restorative effects on BBB integrity post-stroke; however, the definite mechanisms remain ambiguous. In the present study, we investigated the curative effects and the mechanisms of EVs derived from bone marrow mesenchymal stem cells and brain endothelial cells (BMSC-EVs and BEC-EVs) on BBB integrity after acute IS.

Methods

EVs were isolated from BMSCs and BECs, and we investigated the therapeutic effect in vitro oxygen-glucose deprivation (OGD) insulted BECs model and in vivo rat middle cerebral artery occlusion (MCAo) model. The cell monolayer leakage, tight junction expression, and metalloproteinase (MMP) activity were evaluated, and rat brain infarct volume and neurological function were also analyzed.

Results

The administration of two kinds of EVs not only enhanced ZO-1 and Occludin expressions but also reduced the permeability and the activity of MMP-2/9 in OGD-insulted BECs. The amelioration of the cerebral infarction, BBB leakage, neurological function deficits, and the increasing ZO-1 and Occludin levels, as well as MMP activity inhibition was observed in MCAo rats. Additionally, the increased levels of Caveolin-1, CD147, vascular endothelial growth factor receptor 2 (VEGFR2), and vascular endothelial growth factor A (VEGFA) in isolated brain microvessels were downregulated after EVs treatment. In vitro, the employment of Caveolin-1 and CD147 siRNA partly suppressed the expressions of VEGFR2, VEGFA and MMP-2/9 activity and reduced the leakage of OGD insulted BECs and enhanced ZO-1 and Occludin expressions.

Conclusion

Our study firstly demonstrates that BEC and BMSC-EVs administrations maintain BBB integrity via the suppression of Caveolin-1/CD147/VEGFR2/MMP pathway after IS, and the efficacy of BMSC-EVs is superior to that of BEC-EVs.

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.

Transcription Factors in Brain Regeneration: A Potential Novel Therapeutic Target

Transcription factors play a crucial role in providing identity to each cell population. To maintain cell identity, it is essential to balance the expression of activator and inhibitor transcription factors. Cell plasticity and reprogramming offer great potential for future therapeutic applications, as they can regenerate damaged tissue. Specific niche factors can modify gene expression and differentiate or transdifferentiate the target cell to the required fate. Ongoing research is being carried out on the possibilities of transcription factors in regenerating neurons, with neural stem cells (NSCs) being considered the preferred cells for generating new neurons due to their epigenomic and transcriptome memory. NEUROD1/ASCL1, BRN2, MYTL1, and other transcription factors can induce direct reprogramming of somatic cells, such as fibroblasts, into neurons. However, the molecular biology of transcription factors in reprogramming and differentiation still needs to be fully understood.

Hematopoietic Endothelial Progenitor cells enhance motor function and cortical motor map integrity following cerebral ischemia

Background

Hematopoietic stem cells (HSC) are recruited to ischemic areas in the brain and contribute to improved functional outcome in animals. However, little is known regarding the mechanisms of improvement following HSC administration post cerebral ischemia. To better understand how HSC effect post-stroke improvement, we examined the effect of HSC in ameliorating motor impairment and cortical dysfunction following cerebral ischemia.

Methods

Baseline motor performance of male adult rats was established on validated motor tests. Animals were assigned to one of three experimental cohorts: control, stroke, stroke + HSC. One, three and five weeks following a unilateral stroke all animals were tested on motor skills after which intracortical microstimulation was used to derive maps of forelimb movement representations within the motor cortex ipsilateral to the ischemic injury.

Results

Stroke + HSC animals significantly outperformed stroke animals on single pellet reaching at weeks 3 and 5 (28±3% and 33±3% versus 11±4% and 17±3%, respectively, p < 0.05 at both time points). Control animals scored 44±1% and 47±1%, respectively. Sunflower seed opening task was significantly improved in the stroke + HSC cohort versus the stroke cohort at week five-post stroke (79±4 and 48±5, respectively, p < 0.05). Furthermore, Stroke + HSC animals had significantly larger forelimb motor maps than animals in the stroke cohort. Overall infarct size did not significantly differ between the two stroked cohorts.

Conclusion

These data suggest that post stroke treatment of HSC enhances the functional integrity of residual cortical tissue, which in turn supports improved behavioral outcome, despite no observed reduction in infarct size.

Efficacy and Safety of Bone Marrow Derived Stem Cell Therapy for Ischemic Stroke: Evidence from Network Meta-analysis

BACKGROUND

Several types of stem cells are available for the treatment of stroke patients. However, the optimal type of stem cell remains unclear.

OBJECTIVE

To analyze the effects of bone marrow-derived stem cell therapy in patients with ischemic stroke by integrating all available direct and indirect evidence in network meta-analyses.

METHODS

We searched several databases to identify randomized clinical trials comparing clinical outcomes of bone marrow-derived stem cell therapy vs. conventional treatment in stroke patients. Pooled relative risks (RRs) and mean differences (MDs) were reported. The surface under the cumulative ranking (SUCRA) was used to rank the probabilities of each agent regarding different outcomes.

RESULTS

Overall, 11 trials with 576 patients were eligible for analysis. Three different therapies, including mesenchymal stem cells (MSCs), mononuclear stem cells (MNCs), and multipotent adult progenitor cells (MAPCs), were assessed. The direct analysis demonstrated that stem cell therapy was associated with significantly reduced all-cause mortality rates (RR 0.55, 95% CI 0.33 to 0.93; I2=0%). Network analysis demonstrated MSCs ranked first in reducing mortality (RR 0.42, 95% CrI 0.15 to 0.86) and improving modified Rankin Scale score (MD -0.59 95% CI -1.09 to -0.09), with SUCRA values 80%, and 98%, respectively. Subgroup analysis showed intravenous transplantation was superior to conventional therapy in reducing all-cause mortality (RR 0.53, 95% CrI 0.29 to 0.88).

CONCLUSION

Using stem cell transplantation was associated with reduced risk of death and improved functional outcomes in patients with ischemic stroke. Additional large trials are warranted to provide more conclusive evidence.

Recent advances in tissue repair of the blood-brain barrier after stroke

The selective permeability of the blood-brain barrier (BBB) enables the necessary exchange of substances between the brain parenchyma and circulating blood and is important for the normal functioning of the central nervous system. Ischemic stroke inflicts damage upon the BBB, triggering adverse stroke outcomes such as cerebral edema, hemorrhagic transformation, and aggravated neuroinflammation. Therefore, effective repair of the damaged BBB after stroke and neovascularization that allows for the unique selective transfer of substances from the BBB after stroke is necessary and important for the recovery of brain function. This review focuses on four important therapies that have effects of BBB tissue repair after stroke in the last seven years. Most of these new therapies show increased expression of BBB tight-junction proteins, and some show beneficial results in terms of enhanced pericyte coverage at the injured vessels. This review also briefly outlines three effective classes of approaches and their mechanisms for promoting neoangiogenesis following a stroke.

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.

PDGFR-beta signaling mediates endogenous neurogenesis after postischemic neural stem/progenitor cell transplantation in mice

OBJECTIVE

Although platelet-derived growth factor receptor (PDGFR)-β mediates the self-renewal and multipotency of neural stem/progenitor cells (NSPCs) in vitro and in vivo, its mechanisms of activating endogenous NSPCs following ischemic stroke still remain unproven.

METHODS

The exogenous NSPCs were transplanted into the ischemic striatum of PDGFR-β conditionally neuroepithelial knockout (KO) mice at 24 h after transient middle cerebral artery occlusion (tMCAO). 5-Bromo-2'-deoxyuridine (BrdU) was intraperitoneally injected to label the newly formed endogenous NSPCs. Infarction volume was measured, and behavioral tests were performed. In the subventricular zone (SVZ), proliferation of endogenous NSPCs was tested, and synapse formation and expression of nutritional factors were measured.

RESULTS

Compared with control mice, KO mice showed larger infarction volume, delayed neurological recovery, reduced numbers of BrdU positive cells, decreased expression of neurogenic factors (including neurofilament, synaptophysin, and brain-derived neurotrophic factor), and decreased synaptic regeneration in SVZ after tMCAO. Moreover, exogenous NSPC transplantation significantly alleviated neurologic dysfunction, promoted neurogenesis, increased expression of neurologic factors, and diminished synaptic deformation in SVZ of FL mice after tMCAO but had no beneficial effect in KO mice.

CONCLUSION

PDGFR-β signaling may promote activation of endogenous NSPCs after postischemic NSPC transplantation, and thus represents a novel potential regeneration-based therapeutic target.

Randomized placebo-controlled trial of CL2020, an allogenic muse cell-based product, in subacute ischemic stroke

Effective treatments for stroke after the acute phase remain elusive. Muse cells are endogenous, pluripotent, immune-privileged stem cells capable of selectively homing to damaged tissue after intravenous injection and replacing damaged/lost cells via differentiation. This randomized, double-blind, placebo-controlled trial enrolled ischemic stroke patients with modified Rankin Scale (mRS) ≥3. Randomized patients received a single intravenous injection of an allogenic Muse cell-based product, CL2020 (n = 25), or placebo (n = 10), without immunosuppressant, 14-28 days after stroke onset. Safety (primary endpoint: week 12) and efficacy (mRS, other stroke-specific measures) were assessed up to 52 weeks. Key efficacy endpoint was response rate (percentage of patients with mRS ≤2 at week 12). To week 12, 96% of patients in the CL2020 group experienced adverse events and 28% experienced adverse reactions (including one Grade 4 status epilepticus), compared with 100% and 10%, respectively, in the placebo group. Response rate was 40.0% (95% CI, 21.1-61.3) in the CL2020 group and 10.0% (0.3-44.5) in the placebo group; the lower CI in the CL2020 group exceeded the preset efficacy threshold (8.7% from registry data). This randomized placebo-controlled trial demonstrated CL2020 is a possible effective treatment for subacute ischemic stroke.Registry information: JAPIC Clinical Trials Information site (JapicCTI-184103, URL: https://www.clinicaltrials.jp/cti-user/trial/ShowDirect.jsp?japicId=JapicCTI-184103).

Mesenchymal stem cell-derived exosomes: Shaping the next era of stroke treatment

Exosome-based treatments are gaining traction as a viable approach to addressing the various issues faced by an ischemic stroke. These extracellular vesicles, mainly produced by Mesenchymal Stem Cells (MSCs), exhibit many properties with substantial therapeutic potential. Exosomes are particularly appealing for stroke therapy because of their low immunogenicity, effective cargo transport, and ability to cross the blood-brain barrier. Their diverse effects include neuroprotection, angiogenesis stimulation, inflammatory response modulation, and cell death pathway attenuation, synergistically promoting neuronal survival, tissue regeneration, and functional recovery. Exosomes also show potential as diagnostic indicators for early stroke identification and customized treatment options. Despite these promising qualities, current exosome-based therapeutics have some limitations. The heterogeneity of exosome release among cell types, difficulty in standardization and isolation techniques, and complications linked to dosage and targeted administration necessitates extensive investigation. It is critical to thoroughly understand exosomal processes and their complicated interactions within the cellular milieu. To improve the practicality and efficacy of exosome-based medicines, research efforts must focus on improving production processes, developing robust evaluation criteria, and developing large-scale isolation techniques. Altogether, exosomes' multifunctional properties offer a new route for transforming stroke treatment and significantly improving patient outcomes.

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.

Damage mechanism and therapy progress of the blood-brain barrier after ischemic stroke

The blood-brain barrier (BBB) serves as a defensive line protecting the central nervous system, while also maintaining micro-environment homeostasis and inhibiting harmful materials from the peripheral blood. However, the BBB's unique physiological functions and properties make drug delivery challenging for patients with central nervous system diseases. In this article, we briefly describe the cell structure basis and mechanism of action of the BBB, as well as related functional proteins involved. Additionally, we discuss the various mechanisms of BBB damage following the onset of an ischemic stroke, and lastly, we mention several therapeutic strategies accounting for impairment mechanisms. We hope to provide innovative ideas for drug delivery research via the BBB.

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.

Bone marrow-derived mononuclear cells ameliorate neurological function in chronic cerebral infarction model mice via improvement of cerebral blood flow

BACKGROUND AIMS

Stroke is a frequently observed neurological disorder that might lead to permanent and severe disability. Recently, various regenerative therapies have been developed, some of which have already been applied clinically. However, their outcomes have not been fully satisfactory. In particular, the development of regenerative therapies for chronic ischemic stroke is greatly needed. Herein intracerebral administration of bone marrow-derived mononuclear cells (BM-MNCs) was assessed as a potential treatment for chronic ischemic stroke using a severe combined immunodeficiency mouse model characterized by minimal vascular variation unrelated to immunodeficiency.

METHODS

A reproducible model of permanent middle cerebral artery occlusion was prepared, and intracerebral BM-MNC transplantation was performed 14 days after stroke induction in the infarcted brain.

RESULTS

Sensorimotor behavioral function and cerebral blood flow were significantly improved upon treatment with BM-MNCs compared to control medium injection. The transplanted cells exhibited characteristics of the vascular endothelium and microglia/macrophages. Significant angiogenesis and suppression of astrogliosis and microgliosis were observed in the affected brain. Messenger RNA expression analysis showed significant increases in anti-inflammatory cytokines, A2 astrocyte/anti-inflammatory microglia markers and vascular endothelial markers such as vascular endothelial growth factor and significant decreases in pro-inflammatory cytokines and A1 astrocyte/pro-inflammatory microglia markers following BM-MNC transplantation.

CONCLUSIONS

These results suggest that intracerebral administration of BM-MNCs should be considered an effective cell therapy for chronic stroke.

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.