Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Human neural stem cell-derived extracellular vesicles protect against ischemic stroke by activating the PI3K/AKT/mTOR pathway

JOURNAL/nrgr/04.03/01300535-202511000-00028/figure1/v/2024-12-20T164640Z/r/image-tiff Human neural stem cell-derived extracellular vesicles exhibit analogous functions to their parental cells, and can thus be used as substitutes for stem cells in stem cell therapy, thereby mitigating the risks of stem cell therapy and advancing the frontiers of stem cell-derived treatments. This lays a foundation for the development of potentially potent new treatment modalities for ischemic stroke. However, the precise mechanisms underlying the efficacy and safety of human neural stem cell-derived extracellular vesicles remain unclear, presenting challenges for clinical translation. To promote the translation of therapy based on human neural stem cell-derived extracellular vesicles from the bench to the bedside, we conducted a comprehensive preclinical study to evaluate the efficacy and safety of human neural stem cell-derived extracellular vesicles in the treatment of ischemic stroke. We found that administration of human neural stem cell-derived extracellular vesicles to an ischemic stroke rat model reduced the volume of cerebral infarction and promoted functional recovery by alleviating neuronal apoptosis. The human neural stem cell-derived extracellular vesicles reduced neuronal apoptosis by enhancing phosphorylation of phosphoinositide 3-kinase, mammalian target of rapamycin, and protein kinase B, and these effects were reversed by treatment with a phosphoinositide 3-kinase inhibitor. These findings suggest that human neural stem cell-derived extracellular vesicles play a neuroprotective role in ischemic stroke through activation of phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway. Finally, we showed that human neural stem cell-derived extracellular vesicles have a good in vivo safety profile. Therefore, human neural stem cell-derived extracellular vesicles are a promising potential agent for the treatment of ischemic stroke.

Current advancements in nanotechnology for stem cells

Stem cell therapy has emerged as a promising approach for regenerative medicine, offering potential treatments for a wide range of diseases and injuries. Although stem cell therapy has great promise, several obstacles have prevented its broad clinical adoption. The effectiveness of therapy has been inhibited by problems such as ineffective stem cell differentiation, low post-transplantation survival rates, and restricted control over stem cell behavior. Furthermore, the implementation of stem cell therapies is further complicated by the possibility of immunological rejection and cancer. Innovative strategies that provide precise control over stem cell characteristics and maximize their therapeutic potential are desperately needed to overcome these obstacles. Recent studies have shown that the effectiveness of stem cell treatments can be greatly increased by nanoscale advances. By establishing an ideal microenvironment and precisely offering growth factors, nanomaterials such as nanoparticles, nanocomposites, and quantum dots have been demonstrated to improve stem cell differentiation and proliferation. This article provides an overview of the recent trends and applications of nanoscale innovations in the context of stem cell therapy. The recent development of precision medicine has been facilitated by the incorporation of nanotechnology into stem cell therapy. The ability to manipulate stem cells at the nanoscale offers unprecedented control over their behavior and function, opening up exciting possibilities for personalized and highly effective therapeutic interventions. This review paper highlights the recent trends and applications of nanotechnology in advancing stem cell therapy, showcasing its potential to revolutionize regenerative medicine.

Investigation of Persistent Photoconductivity of Gallium Nitride Semiconductor and Differentiation of Primary Neural Stem Cells

A gallium nitride (GaN) semiconductor is one of the most promising materials integrated into biomedical devices to play the roles of connecting, monitoring, and manipulating the activity of biological components, due to its excellent photoelectric properties, chemical stability, and biocompatibility. In this work, it was found that the photogenerated free charge carriers of the GaN substrate, as an exogenous stimulus, served to promote neural stem cells (NSCs) to differentiate into neurons. This was observed through the systematic investigation of the effect of the persistent photoconductivity (PPC) of GaN on the differentiation of primary NSCs from the embryonic rat cerebral cortex. NSCs were directly cultured on the GaN surface with and without ultraviolet (UV) irradiation, with a control sample consisting of tissue culture polystyrene (TCPS) in the presence of fetal bovine serum (FBS) medium. Through optical microscopy, the morphology showed a greater number of neurons with the branching structures of axons and dendrites on GaN with UV irradiation. The immunocytochemical results demonstrated that GaN with UV irradiation could promote the NSCs to differentiate into neurons. Western blot analysis showed that GaN with UV irradiation significantly upregulated the expression of two neuron-related markers, βIII-tubulin (Tuj-1) and microtubule-associated protein 2 (MAP-2), suggesting that neurite formation and the proliferation of NSCs during differentiation were enhanced by GaN with UV irradiation. Finally, the results of the Kelvin probe force microscope (KPFM) experiments showed that the NSCs cultured on GaN with UV irradiation displayed about 50 mV higher potential than those cultured on GaN without irradiation. The increase in cell membrane potential may have been due to the larger number of photogenerated free charges on the GaN surface with UV irradiation. These results could benefit topical research and the application of GaN as a biomedical material integrated into neural interface systems or other bioelectronic devices.

Advancements in the mechanisms of Naotai formula in treating stroke: A multi-target strategy

Stroke represents a significant global health challenge, characterized by high incidence, mortality, disability, and recurrence rates, leading to substantial socioeconomic burdens. Despite advancements in acute management and prevention, effective post-stroke recovery strategies remain limited. Naotai Formula (NTF), a traditional Chinese medicine compound, has garnered attention for its potential in stroke treatment, encompassing both ischemic and hemorrhagic types. This review synthesizes recent advancements in basic and clinical research on NTF, focusing on its mechanisms of action in stroke therapy. The formula's multifaceted effects include promoting neuronal regeneration, combating oxidative stress, regulating lipid metabolism, and modulating iron homeostasis. Through a multi-target approach, NTF addresses the complex pathophysiology of stroke, suggesting a promising complementary strategy for stroke recovery. Despite promising findings, further research is required to elucidate its active components, potential side effects, and optimized therapeutic protocols. The integration of traditional Chinese medicine, like NTF, with conventional treatments may enhance stroke management strategies, urging the need for high-quality clinical trials and evidence-based guidelines.

Stem cell grafts enhance endogenous extracellular vesicle expression in the stroke brain

Endogenous brain repair occurs following an ischemic stroke but is transient, thus unable to fully mount a neuroprotective response against the evolving secondary cell death. Finding a treatment strategy that may render robust and long-lasting therapeutic effects stands as a clinically relevant therapy for stroke. Extracellular vesicles appear to be upregulated after stroke, which may represent a candidate target for neuroprotection. In this study, we probed whether transplanted stem cells could enhance the expression of extracellular vesicles to afford stable tissue remodeling in the ischemic stroke brain. Aged rats were initially exposed to the established ischemic stroke model of middle cerebral artery occlusion then received intravenous delivery of either bone marrow-derived mesenchymal stem cell transplantation or vehicle. A year later, the animals were assayed for brain damage, inflammation, and extracellular vesicle expression. Our findings revealed that while core infarction was not reduced, the stroke animals transplanted with stem cells displayed a significant reduction in peri-infarct cell loss that coincided with downregulated Iba1-labeled inflammatory cells and upregulated CD63-positive extracellular vesicles that appeared to be co-localized with GFAP-positive astrocytes. Interestingly, grafted stem cells were not detected at one year post-transplantation period, suggesting that the extracellular vesicles likely originated within the host brain. That long-lasting functional benefits persisted in the absence of surviving transplanted stem cells, but with upregulation of endogenous extracellular vesicles, advances the concept that transplantation of stem cells acutely after stroke propels host extracellular vesicles to the ischemic brain, altogether promoting chronic brain remodeling.

Moxibustion Promoted Axonal Regeneration and Improved Learning and Memory of Post-stroke Cognitive Impairment by Regulating PI3K/AKt and TACC3

BACKGROUND

This study aimed to investigate whether moxibustion could affect PI3K/Akt pathway to regulate Transforming acidic coiled-coil containing protein 3 (TACC3) and promote axonal regeneration to improve learning and memory function in middle cerebral artery occlusion (MCAO) rats.

METHODS

Sixty SD rats were randomly divided into 4 groups: sham-operated control group (SC), model control group (MC), model + moxibustion group (MM), and model + inhibitor + moxibustion group (MIM). The rats in MC, MM, and MIM groups were made into MCAO models, and PI3K inhibitor LY294002 was injected into the rats in MIM group before modeling; while the rats in SC group were only treated with artery separation without monofilament inserting. After that, the rats in MM and MIM groups were intervented with moxibustion. We used the Zea-Longa scale, micro-Magnetic Resonance Imaging (micro-MRI), Morris water maze (MWM), TUNEL, western blot (WB), immunofluorescence and immunohistochemistry to evaluate the neurological deficits, cerebral infarct volume, learning and memory, apoptotic cell percentage in the hippocampal, the expression level of axonal regeneration and PI3K/AKt related proteins, the expression level of TACC3. The detection of 2 h after surgery showed the result before moxibustion and 7 days after the intervention showed the results after moxibustion.

RESULTS

After 7 d of intervention, the scores of Zea-Longa and the cerebral infarct volume, the escape latency, the percentage of apoptosis cells of MM group were lower than that of MC and MIM groups; the frequency of rats crossed the previous platform location, PI3K, p-Akt/t-Akt and TACC3, the level of GAP-43 in MM group was more than MC and MIM groups (P < 0.05). While no statistical difference existed between MIM group and MC group (P > 0.05).

CONCLUSION

Moxibustion can promote axonal regeneration and improve learning and memory of Post-stroke cognitive impairment via activating the PI3K/AKT signaling pathway and TACC3.

Innovation at the Intersection: Emerging Translational Research in Neurology and Psychiatry

Translational research in neurological and psychiatric diseases is a rapidly advancing field that promises to redefine our approach to these complex conditions [...].

Activation of cerebral Ras-related C3 botulinum toxin substrate (Rac) 1 promotes post-ischemic stroke functional recovery in aged mice

Brain functional impairment after stroke is common; however, the molecular mechanisms of post-stroke recovery remain unclear. It is well-recognized that age is the most important independent predictor of poor outcomes after stroke as older patients show poorer functional outcomes following stroke. Mounting evidence suggests that axonal regeneration and angiogenesis, the major forms of brain plasticity responsible for post-stroke recovery, diminished with advanced age. Previous studies suggest that Ras-related C3 botulinum toxin substrate (Rac) 1 enhances stroke recovery as activation of Rac1 improved behavior recovery in a young mice stroke model. Here, we investigated the role of Rac1 signaling in long-term functional recovery and brain plasticity in an aged (male, 18 to 22 months old C57BL/6J) brain after ischemic stroke. We found that as mice aged, Rac1 expression declined in the brain. Delayed overexpression of Rac1, using lentivirus encoding Rac1 injected day 1 after ischemic stroke, promoted cognitive (assessed using novel object recognition test) and sensorimotor (assessed using adhesive removal tests) recovery on days 14-28. This was accompanied by the increase of neurite and proliferative endothelial cells in the peri-infarct zone assessed by immunostaining. In a reverse approach, pharmacological inhibition of Rac1 by intraperitoneal injection of Rac1 inhibitor NSC23766 for 14 successive days after ischemic stroke worsened the outcome with the reduction of neurite and proliferative endothelial cells. Furthermore, Rac1 inhibition reduced the activation of p21-activated kinase 1, the protein level of brain-derived neurotrophic factor, and increased the protein level of glial fibrillary acidic protein in the ischemic brain on day 28 after stroke. Our work provided insight into the mechanisms behind the diminished plasticity after cerebral ischemia in aged brains and identified Rac1 as a potential therapeutic target for improving functional recovery in the older adults after stroke.

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.

Phenylethanoid glycosides derived from Cistanche deserticola promote neurological functions and the proliferation of neural stem cells for improving ischemic stroke

Phenylethanoid glycosides derived from Cistanche deserticola (PhGs) are plant-derived natural medicinal compounds that occur in many medicinal plants. This study aims to investigate whether PhGs treatment improves the stroke and its potential mechanisms. Adult male C57BL/6 J mice were administrated PhGs once daily for 7 days after MCAO surgery. The neurological score, and catwalk were evaluated on Day 1, 3 and 7 after ischemic stroke. Furthermore, triphenyl-2,3,5-tetrazoliumchloride (TTC) and hematoxylin-eosin (H&E) staining were used for evaluating the infarct volume and neuronal restoration. The effects of PhGs on NSCs proliferation were investigated in vitro and in vivo. Western blot was used to detect the proteins of Wnt/β-catenin signaling pathway. This study found that PhGs effectively improved the neurological functions in ischemic stroke mice. TTC and H&E staining demonstrated that PhGs not only reduced infarct volume, but also improved neuronal restoration. The immunohistochemistry and 5-Ethynyl-2-deoxyuridine (EdU) incorporation assays revealed that PhGs promoted the proliferation of neural stem cells (NSCs) in subventricular zone (SVZ). In addition, transcriptome analysis of NSCs showed that the Wnt/β-catenin signaling pathway was involved in the PhGs induced NSCs proliferation. Importantly, the related proteins in the Wnt/β-catenin signaling pathway were changed after PhGs treatment, including β-catenin, Wnt3a, GSK-3β, c-Myc. PhGs treatment improved the stroke through enhancing endogenous NSCs proliferation via activating Wnt/β-catenin signaling pathway. Due to its effect on the proliferation of NSCs, PhGs are a potential adjuvant therapeutic drug for post-stroke treatment.

Quantifying innervation facilitated by deep learning in wound healing

The peripheral nerves (PNs) innervate the dermis and epidermis, and are suggested to play an important role in wound healing. Several methods to quantify skin innervation during wound healing have been reported. Those usually require multiple observers, are complex and labor-intensive, and the noise/background associated with the immunohistochemistry (IHC) images could cause quantification errors/user bias. In this study, we employed the state-of-the-art deep neural network, Denoising Convolutional Neural Network (DnCNN), to perform pre-processing and effectively reduce the noise in the IHC images. Additionally, we utilized an automated image analysis tool, assisted by Matlab, to accurately determine the extent of skin innervation during various stages of wound healing. The 8 mm wound is generated using a circular biopsy punch in the wild-type mouse. Skin samples were collected on days 3, 7, 10 and 15, and sections from paraffin-embedded tissues were stained against pan-neuronal marker- protein-gene-product 9.5 (PGP 9.5) antibody. On day 3 and day 7, negligible nerve fibers were present throughout the wound with few only on the lateral boundaries of the wound. On day 10, a slight increase in nerve fiber density appeared, which significantly increased on day 15. Importantly, we found a positive correlation (R2 = 0.926) between nerve fiber density and re-epithelization, suggesting an association between re-innervation and re-epithelization. These results established a quantitative time course of re-innervation in wound healing, and the automated image analysis method offers a novel and useful tool to facilitate the quantification of innervation in the skin and other tissues.

Quantifying innervation facilitated by deep learning in wound healing

The peripheral nerves (PNs) innervate the dermis and epidermis, which have been suggested to play an important role in wound healing. Several methods to quantify skin innervation during wound healing have been reported. Those usually require multiple observers, are complex and labor-intensive, and noise/background associated with the Immunohistochemistry (IHC) images could cause quantification errors/user bias. In this study, we employed the state-of-the-art deep neural network, DnCNN, to perform pre-processing and effectively reduce the noise in the IHC images. Additionally, we utilized an automated image analysis tool, assisted by Matlab, to accurately determine the extent of skin innervation during various stages of wound healing. The 8mm wound is generated using a circular biopsy punch in the wild-type mouse. Skin samples were collected on days 3,7,10 and 15, and sections from paraffin-embedded tissues were stained against pan-neuronal marker- protein-gene-product 9.5 (PGP 9.5) antibody. On day 3 and day 7, negligible nerve fibers were present throughout the wound with few only on the lateral boundaries of the wound. On day 10, a slight increase in nerve fiber density appeared, which significantly increased on day 15. Importantly we found a positive correlation (R 2  = 0.933) between nerve fiber density and re-epithelization, suggesting an association between re-innervation and re-epithelization. These results established a quantitative time course of re-innervation in wound healing, and the automated image analysis method offers a novel and useful tool to facilitate the quantification of innervation in the skin and other tissues.

Quantifying innervation facilitated by deep learning in wound healing

The peripheral nerves (PNs) innervate the dermis and epidermis, which have been suggested to play an important role in wound healing. Several methods to quantify skin innervation during wound healing have been reported. Those usually require multiple observers, are complex and labor-intensive, and noise/background associated with the Immunohistochemistry (IHC) images could cause quantification errors/user bias. In this study, we employed the state-of-the-art deep neural network, DnCNN, to perform pre-processing and effectively reduce the noise in the IHC images. Additionally, we utilized an automated image analysis tool, assisted by Matlab, to accurately determine the extent of skin innervation during various stages of wound healing. The 8mm wound is generated using a circular biopsy punch in the wild-type mouse. Skin samples were collected on days 3,7,10 and 15, and sections from paraffin-embedded tissues were stained against pan-neuronal marker- protein-gene-product 9.5 (PGP 9.5) antibody. On day 3 and day 7, negligible nerve fibers were present throughout the wound with few only on the lateral boundaries of the wound. On day 10, a slight increase in nerve fiber density appeared, which significantly increased on day 15. Importantly we found a positive correlation (R- 2 = 0.933) between nerve fiber density and re-epithelization, suggesting an association between re-innervation and re-epithelization. These results established a quantitative time course of re-innervation in wound healing, and the automated image analysis method offers a novel and useful tool to facilitate the quantification of innervation in the skin and other tissues.

Three-dimensional-cultured MSC-derived exosome with hydrogel for cerebral ischemia repair

Microglia-mediated neuroinflammatory response, one of the most essential pathological processes of cerebral ischemia-reperfusion (I/R) injury, is acknowledged as the main factors leading to poor prognosis of cerebral ischemia. Exosome derived from mesenchymal stem cell (MSC-Exo) exhibits neuroprotective functions by reducing cerebral ischemia-induced neuroinflammatory response and promoting angiogenesis. However, MSC-Exo has disadvantages such as insufficient targeting capability and low production, which limits their clinical applications. Here, we fabricated gelatin methacryloyl (GelMA) hydrogel for three-dimensional (3D) culture of MSCs. It is indicated that 3D environment could simulate the biological niches of MSCs, thereby significantly increasing the cell stemness of MSCs and improving the yield of MSCs-derived exosomes (3D-Exo). In this study, we utilized the modified Longa method to induce middle cerebral artery occlusion (MCAO) model. Additionally, in vitro and in vivo studies were conducted to interrogate the mechanism of the stronger neuroprotective effect of 3D-Exo. Furthermore, the administration of 3D-Exo in MCAO model could promote neovascularization in infarct region and result in a significant suppression of inflammatory response. This study proposed an exosome-based targeting delivery system for cerebral ischemia and provided a promising strategy for efficient and large-scale production of MSC-Exo.

Smuggling on the Nanoscale-Fusogenic Liposomes Enable Efficient RNA-Transfer with Negligible Immune Response In Vitro and In Vivo

The efficient and biocompatible transfer of nucleic acids into mammalian cells for research applications or medical purposes is a long-standing, challenging task. Viral transduction is the most efficient transfer system, but often entails high safety levels for research and potential health impairments for patients in medical applications. Lipo- or polyplexes are commonly used transfer systems but result in comparably low transfer efficiencies. Moreover, inflammatory responses caused by cytotoxic side effects were reported for these transfer methods. Often accountable for these effects are various recognition mechanisms for transferred nucleic acids. Using commercially available fusogenic liposomes (Fuse-It-mRNA), we established highly efficient and fully biocompatible transfer of RNA molecules for in vitro as well as in vivo applications. We demonstrated bypassing of endosomal uptake routes and, therefore, of pattern recognition receptors that recognize nucleic acids with high efficiency. This may underlie the observed almost complete abolishment of inflammatory cytokine responses. RNA transfer experiments into zebrafish embryos and adult animals fully confirmed the functional mechanism and the wide range of applications from single cells to organisms.

Harnessing nanobiotechnology for cerebral ischemic stroke management

Cerebral ischemic stroke remains one of the most serious neurological disorders that pose threats to human health, causing a large amount of long-term disability or even death throughout the world. Based on its physiologic and pathological features, there are limited available therapeutic options for effective ischemic stroke management. Encouragingly, a rapid advancement of nanobiotechnology is bringing new insights into exploring more alternative strategies against cerebral ischemic stroke, which can cleverly overcome the limitations related to conventional treatment methods. Therefore, this review focuses on the recent achievements of nanobiotechnology for ischemic stroke management, which emphasizes diverse targeted delivery strategies using various nanoplatforms including liposomes, micelles, polymeric nanoparticles, nanogels, inorganic nanomaterials, and cell-derived nano-vectors based on the pathophysiological features of ischemic stroke. Moreover, different therapeutic approaches against ischemic stroke such as neuroprotection, anti-inflammation, thrombolysis, increased blood-brain barrier penetration and reactive oxygen species scavenging are highlighted. Meanwhile, this review discusses how these versatile nanoplatforms were designed to assist in the treatment of ischemic stroke. Based on this, challenges, opportunities, and future perspectives using nanobiotechnology through rational design for effective ischemic stroke management are revealed.

Pathogenomic Signature and Aberrant Neurogenic Events in Experimental Cerebral Ischemic Stroke: A Neurotranscriptomic-Based Implication for Dementia

BACKGROUND

Cerebral ischemic stroke is caused due to neurovascular damage or thrombosis, leading to neuronal dysfunction, neuroinflammation, neurodegeneration, and regenerative failure responsible for neurological deficits and dementia. The valid therapeutic targets against cerebral stroke remain obscure. Thus, insight into neuropathomechanisms resulting from the aberrant expression of genes appears to be crucial.

OBJECTIVE

In this study, we have elucidated how neurogenesis-related genes are altered in experimental stroke brains from the available transcriptome profiles in correlation with transcriptome profiles of human postmortem stroke brain tissues.

METHODS

The transcriptome datasets available on the middle cerebral artery occlusion (MCAo) rat brains were obtained from the Gene Expression Omnibus, National Center for Biotechnology Information. Of the available datasets, 97 samples were subjected to the meta-analysis using the network analyst tool followed by Cytoscape-based enrichment mapping analysis. The key differentially expressed genes (DEGs) were validated and compared with transcriptome profiling of human stroke brains.

RESULTS

Results revealed 939 genes are differently expressed in the brains of the MCAo rat model of stroke, in which 30 genes are key markers of neural stem cells, and regulators of neurogenic processes. Its convergence with DEGs from human stroke brains has revealed common targets.

CONCLUSION

This study has established a panel of highly important DEGs to signify the potential therapeutic targets for neuroregenerative strategy against pathogenic events associated with cerebral stroke. The outcome of the findings can be translated to mitigate neuroregeneration failure seen in various neurological and metabolic disease manifestations with neurocognitive impairments.

Stem Cell- and Cell-Based Therapies for Ischemic Stroke

Stroke is the second cause of disability worldwide as it is expected to increase its incidence and prevalence. Despite efforts to increase the number of patients eligible for recanalization therapies, a significant proportion of stroke survivors remain permanently disabled. This outcome boosted the search for efficient neurorestorative methods. Stem cells act through multiple pathways: cell replacement, the secretion of growth factors, promoting endogenous reparative pathways, angiogenesis, and the modulation of neuroinflammation. Although neural stem cells are difficult to obtain, pose a series of ethical issues, and require intracerebral delivery, mesenchymal stem cells are less immunogenic, are easy to obtain, and can be transplanted via intravenous, intra-arterial, or intranasal routes. Extracellular vesicles and exosomes have similar actions and are easier to obtain, also allowing for engineering to deliver specific molecules or RNAs and to promote the desired effects. Appropriate timing, dosing, and delivery protocols must be established, and the possibility of tumorigenesis must be settled. Nonetheless, stem cell- and cell-based therapies for stroke have already entered clinical trials. Although safe, the evidence for efficacy is less impressive so far. Hopefully, the STEP guidelines and the SPAN program will improve the success rate. As such, stem cell- and cell-based therapy for ischemic stroke holds great promise.

Human umbilical cord-derived mesenchymal stem cells promote repair of neonatal brain injury caused by hypoxia/ischemia in rats

Administration of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) is believed to be an effective method for treating neurodevelopmental disorders. In this study, we investigated the possibility of hUC-MSCs treatment of neonatal hypoxic/ischemic brain injury associated with maternal immune activation and the underlying mechanism. We established neonatal rat models of hypoxic/ischemic brain injury by exposing pregnant rats to lipopolysaccharide on day 16 or 17 of pregnancy. Rat offspring were intranasally administered hUC-MSCs on postnatal day 14. We found that polypyrimidine tract-binding protein-1 (PTBP-1) participated in the regulation of lipopolysaccharide-induced maternal immune activation, which led to neonatal hypoxic/ischemic brain injury. Intranasal delivery of hUC-MSCs inhibited PTBP-1 expression, alleviated neonatal brain injury-related inflammation, and regulated the number and function of glial fibrillary acidic protein-positive astrocytes, thereby promoting plastic regeneration of neurons and improving brain function. These findings suggest that hUC-MSCs can effectively promote the repair of neonatal hypoxic/ischemic brain injury related to maternal immune activation through inhibition of PTBP-1 expression and astrocyte activation.

Optimal therapeutic conditions for the neural stem cell-based management of ischemic stroke: a systematic review and network meta-analysis based on animal studies

BACKGROUND

In order to promote the clinical translation of preclinical findings, it is imperative to identify the most optimal therapeutic conditions and adopt them for further animal and human studies. This study aimed to fully explore the optimal conditions for neural stem cell (NSC)-based ischemic stroke treatment based on animal studies.

METHODS

The PubMed, Ovid-Embase, and Web of Science databases were searched in December 2021. The screening of search results, extraction of relevant data, and evaluation of study quality were performed independently by two reviewers.

RESULTS

In total, 52 studies were included for data analysis. Traditional meta-analysis showed that NSCs significantly reduced the modified neurological severity score (mNSS) and volume of cerebral infarct in animal models of ischemic stroke. Network meta-analysis showed that allogeneic embryonic tissue was the best source of NSCs. Further, intracerebral transplantation was the most optimal route of NSC transplantation, and the acute phase was the most suitable stage for intervention. The optimal number of NSCs for transplantation was 1-5×10⁵ in mouse models and 1×10⁶ or 1.8×10⁶ in rat models.

CONCLUSIONS

We systematically explored the therapeutic strategy of NSCs in ischemic stroke, but additional research is required to develop optimal therapeutic strategies based on NSCs. Moreover, it is necessary to further improve and standardize the design, implementation, measuring standards, and reporting of animal-based studies to promote the development of better animal experiments and clinical research.

Neuromotor prosthetic to treat stroke-related paresis: N-of-1 trial

Background

Functional recovery of arm movement typically plateaus following a stroke, leaving chronic motor deficits. Brain-computer interfaces (BCI) may be a potential treatment for post-stroke deficits

Methods

In this n-of-1 trial (NCT03913286), a person with chronic subcortical stroke with upper-limb motor impairment used a powered elbow-wrist-hand orthosis that opened and closed the affected hand using cortical activity, recorded from a percutaneous BCI comprised of four microelectrode arrays implanted in the ipsilesional precentral gyrus, based on decoding of spiking patterns and high frequency field potentials generated by imagined hand movements. The system was evaluated in a home setting for 12 weeks

Results

Robust single unit activity, modulating with attempted or imagined movement, was present throughout the precentral gyrus. The participant acquired voluntary control over a hand-orthosis, achieving 10 points on the Action Research Arm Test using the BCI, compared to 0 without any device, and 5 using myoelectric control. Strength, spasticity, the Fugl-Meyer scores improved.

Conclusions

We demonstrate in a human being that ensembles of individual neurons in the cortex overlying a chronic supratentorial, subcortical stroke remain active and engaged in motor representation and planning and can be used to electrically bypass the stroke and promote limb function. The participant’s ability to rapidly acquire control over otherwise paralyzed hand opening, more than 18 months after a stroke, may justify development of a fully implanted movement restoration system to expand the utility of fully implantable BCI to a clinical population that numbers in the tens of millions worldwide.

Stroke is a restriction of blood flow to part of the brain and can lead to chronic issues with a person’s ability to control the limbs. The aim of this study was to see if a new type of device could restore movement in a person with arm weakness due to a stroke that occurred a year earlier. In our trial, a sensor was implanted into the surface of the brain, near the site of the stroke, and was connected to a computer that generated a command to open and close the hand with a motorized brace worn on the hand. This person was able to use their own brain activity to trigger the brace and pick up and move objects. This research could support the development of similar medical devices to restore movement in people who have had strokes.

Serruya et al. test in an N-of-1 trial whether a wearable, powered exoskeletal orthosis, driven by a percutaneous, implanted brain–computer interface can restore voluntary upper extremity function following chronic hemiparesis subsequent to a cerebral subcortical stroke. Using this approach, voluntary opening of the paralyzed hand is restored.

The Genetic Basis of Strokes in Pediatric Populations and Insight into New Therapeutic Options

Strokes within pediatric populations are considered to be the 10th leading cause of death in the United States of America, with over half of such events occurring in children younger than one year of life. The multifactorial etiopathology that has an influence on stroke development and occurrence signify the importance of the timely recognition of both modifiable and non-modifiable factors for adequate diagnostic and treatment approaches. The early recognition of a stroke and stroke risk in children has the potential to advance the application of neuroprotective, thrombolytic, and antithrombotic interventions and rehabilitation strategies to the earliest possible timepoints after the onset of a stroke, improving the outcomes and quality of life for affected children and their families. The recent development of molecular genetic methods has greatly facilitated the analysis and diagnosis of single-gene disorders. In this review, the most significant single gene disorders associated with pediatric stroke are presented, along with specific therapeutic options whenever they exist. Besides monogenic disorders that may present with stroke as a first symptom, genetic polymorphisms may contribute to the risk of pediatric and perinatal stroke. The most frequently studied genetic risk factors are several common polymorphisms in genes associated with thrombophilia; these genes code for proteins that are part of the coagulation cascade, fibrolysis, homocystein metabolism, lipid metabolism, or platelets. Single polymorphism frequencies may not be sufficient to completely explain the stroke causality and an analysis of several genotype combinations is a more promising approach. The recent steps forward in our understanding of the disorders underlying strokes has given us a next generation of therapeutics and therapeutic targets by which to improve stroke survival, protect or rebuild neuronal connections in the brain, and enhance neural function. Advances in DNA sequencing and the development of new tools to correct human gene mutations have brought genetic analysis and gene therapy into the focus of investigations for new therapeutic options for stroke patients.

Combination of Stem Cells and Rehabilitation Therapies for Ischemic Stroke

Stem cell transplantation with rehabilitation therapy presents an effective stroke treatment. Here, we discuss current breakthroughs in stem cell research along with rehabilitation strategies that may have a synergistic outcome when combined together after stroke. Indeed, stem cell transplantation offers a promising new approach and may add to current rehabilitation therapies. By reviewing the pathophysiology of stroke and the mechanisms by which stem cells and rehabilitation attenuate this inflammatory process, we hypothesize that a combined therapy will provide better functional outcomes for patients. Using current preclinical data, we explore the prominent types of stem cells, the existing theories for stem cell repair, rehabilitation treatments inside the brain, rehabilitation modalities outside the brain, and evidence pertaining to the benefits of combined therapy. In this review article, we assess the advantages and disadvantages of using stem cell transplantation with rehabilitation to mitigate the devastating effects of stroke.

Modulating poststroke inflammatory mechanisms: Novel aspects of mesenchymal stem cells, extracellular vesicles and microglia

Inflammation plays an important role in the pathological process of ischemic stroke, and systemic inflammation affects patient prognosis. As resident immune cells in the brain, microglia are significantly involved in immune defense and tissue repair under various pathological conditions, including cerebral ischemia. Although the differentiation of M1 and M2 microglia is certainly oversimplified, changing the activation state of microglia appears to be an intriguing therapeutic strategy for cerebral ischemia. Recent evidence indicates that both mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) regulate inflammation and modify tissue repair under preclinical stroke conditions. However, the precise mechanisms of these signaling pathways, especially in the context of the mutual interaction between MSCs or MSC-derived EVs and resident microglia, have not been sufficiently unveiled. Hence, this review summarizes the state-of-the-art knowledge on MSC- and MSC-EV-mediated regulation of microglial activity under ischemic stroke conditions with respect to various signaling pathways, including cytokines, neurotrophic factors, transcription factors, and microRNAs.

Neural Stem Cell-Based Therapies and Glioblastoma Management: Current Evidence and Clinical Challenges

Gliomas, which account for nearly a quarter of all primary CNS tumors, present significant contemporary therapeutic challenges, particularly the highest-grade variant (glioblastoma multiforme), which has an especially poor prognosis. These difficulties are due to the tumor's aggressiveness and the adverse effects of radio/chemotherapy on the brain. Stem cell therapy is an exciting area of research being explored for several medical issues. Neural stem cells, normally present in the subventricular zone and the hippocampus, preferentially migrate to tumor masses. Thus, they have two main advantages: They can minimize the side effects associated with systemic radio/chemotherapy while simultaneously maximizing drug delivery to the tumor site. Another feature of stem cell therapy is the variety of treatment approaches it allows. Stem cells can be genetically engineered into expressing a wide variety of immunomodulatory substances that can inhibit tumor growth. They can also be used as delivery vehicles for oncolytic viral vectors, which can then be used to combat the tumorous mass. An alternative approach would be to combine stem cells with prodrugs, which can subsequently convert them into the active form upon migration to the tumor mass. As with any therapeutic modality still in its infancy, much of the research regarding their use is primarily based upon knowledge gained from animal studies, and a number of ongoing clinical trials are currently investigating their effectiveness in humans. The aim of this review is to highlight the current state of stem cell therapy in the treatment of gliomas, exploring the different mechanistic approaches, clinical applicability, and the existing limitations.