Neuroprotective Effects of Stem Cells in Ischemic Stroke

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.

The mechanisms of Huangqi Guizhi Wuwu decoction in treating ischaemic stroke based on network pharmacology and experiment verification

CONTEXT

Huangqi Guizhi Wuwu Decoction (HGWD) is effective in treating ischaemic stroke (IS). However, its mechanism of action is still unclear.

OBJECTIVE

Network pharmacology integrated with in vivo experiments were used to clarify the underlying mechanisms of HGWD for treating IS.

MATERIALS AND METHODS

TCMSP, GeneCards, OMIM and STRING were used to retrieve and construct visual protein interaction networks for the key targets. The AutoDock tool was used for molecular docking between key targets and active compounds. The neuroprotective effect of HGWD were verified in a middle cerebral artery occlusion (MCAO) model rat. The Sprague-Dawley (SD) rats were divided into sham, model, low-dose (5 g/kg, i.g.), high-dose (20 g/kg, i.g.), and nimodipine (20 mg/kg, i.g.) groups once daily for 7 days. The neurological scores, brain infarct volumes, lipid peroxidation, inflammatory cytokines, Nissl bodies, apoptotic neurons, and signalling pathways were all investigated and evaluated in vivo.

RESULTS

Network pharmacology identified 117 HGWD targets related to IS and 36 candidate compounds. GO and KEGG analyses showed that HGWD anti-IS effects were mainly associated with PI3K-Akt and HIF-1 signalling pathways. HGWD effectively reduced the cerebral infarct volumes (19.19%), the number of apoptotic neurons (16.78%), and the release of inflammatory cytokines, etc. in MCAO rats. Furthermore, HGWD decreased the levels of HIF-1A, VEGFA, Bax, cleaved caspase-3, p-MAPK1, and p-c-Jun while increasing the expression of p-PI3K, p-AKT1, and Bcl-2.

DISCUSSION AND CONCLUSION

This study initially elucidated the mechanism of HGWD anti-IS, which contributed to the further promotion and secondary development of HGWD in clinical practice.

Role of Autophagy Mediated by AMPK/DDiT4/mTOR Axis in HT22 Cells Under Oxygen and Glucose Deprivation/Reoxygenation

Background: cerebral ischemia/reperfusion (I/R) injury is an important complication of ischemic stroke, and autophagy is one of the mechanisms of it. In this study, we aimed to determine the role and mechanism of autophagy in cerebral I/R injury. Methods: the oxygen and glucose deprivation/reoxygenation (OGD/R) method was used to model cerebral I/R injury in HT22 cells. CCK-8 and LDH were conducted to detect viability and damage of the cells, respectively. Apoptosis was measured by flow cytometry and Tunel staining. Autophagic vesicles of HT22 cells were assessed by transmission electron microscopy. Western blotting analysis was used to examine the protein expression involving AMPK/DDiT4/mTOR axis and autophagy-related proteins. 3-Methyladenine and rapamycin were, respectively, used to inhibit and activate autophagy, compound C and AICAR acted as AMPK inhibitor and activator, respectively, and were used to control the starting link of AMPK/DDiT4/mTOR axis. Results: autophagy was activated in HT22 cells after OGD/R was characterized by an increased number of autophagic vesicles, the expression of Beclin1 and LC3II/LC3I, and a decrease in the expression of P62. Rapamycin could increase the viability, reduce LDH leakage rate, and alleviate cell apoptosis in OGD/R cells by activating autophagy. 3-Methyladenine played an opposite role to rapamycin in OGD/R cells. The expression of DDiT4 and the ratio of p-AMPK/AMPK were increased after OGD/R in HT22 cells. While the ratio of p-mTOR/mTOR was reduced by OGD/R, AICAR effectively increased the number of autophagic vesicles, improved viability, reduced LDH leakage rate, and alleviated apoptosis in HT22 cells which suffered OGD/R. However, the effects of compound C in OGD/R HT22 cells were opposite to that of AICAR. Conclusions: autophagy is activated after OGD/R; autophagy activator rapamycin significantly enhanced the protective effect of autophagy on cells of OGD/R. AMPK/DDiT4/mTOR axis is an important pathway to activate autophagy, and AMPK/DDiT4/mTOR-mediated autophagy significantly alleviates cell damage caused by OGD/R.

Long non-coding RNA SNHG7 upregulates FGF9 to alleviate oxygen and glucose deprivation-induced neuron cell injury in a miR-134-5p-dependent manner

Long non-coding RNA small nucleolar RNA host gene 7 (SNHG7) was reported to regulate the pathogenesis of ischemic stroke. The study aimed to disclose SNHG7 role in oxygen and glucose deprivation (OGD)-induced Neuro-2a (N2a) cell disorders. An OGD injury cell model was established using N2a cells. The expression of SNHG7, microRNA-134-5p (miR-134-5p) and fibroblast growth factor 9 (FGF9) was determined by quantitative real-time polymerase chain reaction. Protein expression was detected by western blot. Cell viability and Lactate Dehydrogenase (LDH) leakage were determined by cell counting kit-8 and LDH activity detection assays. Oxidative stress was investigated by Superoxide Dismutase and Catalase activity assays as well as Malondialdehyde and Reactive Oxygen Species detection kits. Cell apoptosis and caspase-3 activity were severally demonstrated by flow cytometry and caspase-3 activity assays. The interaction between miR-134-5p and SNHG7 or FGF9 was predicted by online databases, and identified by mechanism assays. OGD treatment decreased SNHG7 and FGF9 expression, but increased miR-134-5p expression. OGD treatment repressed cell viability, promoted LDH leakage and induced oxidative stress and apoptosis in N2a cells, which was rescued by SNHG7 overexpression. SNHG7 acted as a sponge for miR-134-5p, and regulated OGD-triggered cell damage by associating with miR-134-5p. Additionally, miR-134-5p depletion protected N2a cells from OGD-induced injury by targeting FGF9. Ectopic SNHG7 expression protected against OGD-induced neuronal cell injury by inducing FGF9 through sponging miR-134-5p, providing a novel therapeutic target for ischemic stroke.

Endovascular Stem Cell Therapy Post Stroke Rescues Neurons from Endoplasmic Reticulum Stress-Induced Apoptosis by Modulating Brain-Derived Neurotrophic Factor/Tropomyosin Receptor Kinase B Signaling

Ischemic stroke is devastating, with serious long-term disabilities affecting millions of people worldwide. Growing evidence has shown that mesenchymal stem cells (MSCs) administration after stroke provides neuroprotection and enhances the quality of life in stroke patients. Previous studies from our lab have shown that 1 × 10⁵ MSCs administered intra-arterially (IA) at 6 h post stroke provide neuroprotection through the modulation of inflammasome and calcineurin signaling. Ischemic stroke induces endoplasmic reticulum (ER) stress, which exacerbates the pathology. The current study intends to understand the involvement of brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling in preventing apoptosis induced by ER stress post stroke following IA MSCs administration. Ischemic stroke was induced in ovariectomized female Sprague Dawley rats. The MSCs were administered IA, and animals were sacrificed at 24 h post stroke. Infarct area, neurological deficit score, motor coordination, and biochemical parameters were evaluated. The expression of various genes and proteins was assessed. An inhibition study was also carried out to confirm the involvement of BDNF/TrkB signaling in ER stress-induced apoptosis. IA-administered MSCs improved functional outcomes, reduced infarct area, increased neuronal survival, and normalized biochemical parameters. mRNA and protein expression of ER stress markers were reduced, while those of BDNF and TrkB were increased. Reduction in ER stress-mediated apoptosis was also observed. The present study shows that IA MSCs administration post stroke provides neuroprotection and can modulate ER stress-mediated apoptosis via the BDNF/TrkB signaling pathway.

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.

Neuroprotective Therapies for Spontaneous Intracerebral Hemorrhage

Patients who survive the initial ictus of spontaneous intracerebral hemorrhage (ICH) remain vulnerable to subsequent injury of the perilesional parenchyma by molecular and cellular responses to the hematoma. Secondary brain injury after ICH, which contributes to long-term functional impairment and mortality, has emerged as an attractive therapeutic target. This review summarizes preclinical and clinical evidence for neuroprotective therapies targeting secondary injury pathways following ICH. A focus on therapies with pleiotropic antiinflammatory effects that target thrombin-mediated chemotaxis and inflammatory cell migration has led to studies investigating statins, anticholinergics, sphingosine-1-phosphate receptor modulators, peroxisome proliferator activated receptor gamma agonists, and magnesium. Attempts to modulate ICH-induced blood-brain barrier breakdown and perihematomal edema formation has prompted studies of nonsteroidal antiinflammatory agents, matrix metalloproteinase inhibitors, and complement inhibitors. Iron chelators, such as deferoxamine and albumin, have been used to reduce the free radical injury that ensues from erythrocyte lysis. Stem cell transplantation has been assessed for its potential to enhance subacute neurogenesis and functional recovery. Despite promising preclinical results of numerous agents, their outcomes have not yet translated into positive clinical trials in patients with ICH. Further studies are necessary to improve our understanding of the molecular events that promote damage and inflammation of the perihematomal parenchyma after ICH. Elucidating the temporal and pathophysiologic features of this secondary brain injury could enhance the clinical efficacy of neuroprotective therapies for ICH.

Systematic Investigation of the Effect of Powerful Tianma Eucommia Capsule on Ischemic Stroke Using Network Pharmacology

Background

Ischemic stroke (IS) is a serious disease with a high rate of death and disability, and a growing number of people are becoming victims. Existing drugs not only have limited therapeutic effects but also have obvious side effects. Most importantly, drug resistance due to long-term or improper use of drugs is detrimental to patients. Therefore, it is urgent to find some alternative or supplementary medicines to alleviate the current embarrassment. Powerful Tianma Eucommia Capsule (PTEC) is mainly used to treat IS in China for thousands of years; however, the molecular mechanism is not clear.

Methods

Pharmacology ingredients and target genes were filtered and downloaded from websites. A pharmacology ingredient-target gene network was constructed to predict the molecular interactions between ingredients and target genes. Enrichment analysis was performed to explore the possible signal pathways. LeDock was used to simulate the interaction form between proteins and main active ingredients and to deduce key amino acid positions.

Results

Two hundred eighty-nine target genes and seventy-four pharmacological ingredients were obtained from public databases. Several key ingredients (quercetin, kaempferol, and stigmasterol) and primary core target genes (PTGS1, NCOA2, and PRSS1) were detected through ingredient-target gene network analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis demonstrated that ingredients affect networks mainly in nuclear receptor activity and G protein-coupled amine receptor activity; besides, fluid shear stress and atherosclerosis, human cytomegalovirus infection, and hepatitis B signaling pathways might be the principal therapy ways. A series of presumed key amino acid sites (189ASP, 190SER, 192GLN, 57HIS, and 99TYE) were calculated in PRSS1. Six of the target genes were differentially expressed between male and female patients.

Conclusions

Seven new putative target genes (ACHE, ADRA1A, AR, CHRM3, F7, GABRA1, and PRSS1) were observed in this work. Based on the result of GO and KEGG analysis, this work will be helpful to further demonstrate the molecular mechanism of PTEC treatment of IS.

Transplantation of rat dental pulp stem cells facilities post-lesion recovery in the somatosensory whisker cortex of male Wistar rats

Damage to somatosensory "barrel" cortex reduces the rats' behavioral sensitivity in discrimination of tactile stimuli. Here, we examined how transplantation of stem cells into the lesioned barrel cortex can help in recovery of sensory capacities. We induced mechanical lesions in the right barrel cortex area of male rats. Three days after lesioning, rats received one of three transplantation types: un-differentiated dental pulp stem cells (U-DPSCs) or differentiated dental pulp stem cells (D-DPSCs), or cell medium (vehicle). A fourth group of rats were control without any Surgery. For 4 consecutive weeks, starting one week after transplantation, we evaluated the rats' preference to explore novel textures as a measure of sensory discrimination ability, also measured the expression of glial fibrillary acidic protein (GFAP), Olig 2, nestin, neuronal nuclei (NeuN), brain-derived neurotrophic factor (BDNF) and neuroligin1 by immunohistochemistry and western blotting. Unilateral mechanical lesion decreased the rats' preferential exploration of novel textures compared to the control group across the 4-week behavioral tests. Following stem cell therapy, the rats' performance significantly improved at week 2-4 compared to the vehicle group. Compared to the control group, there was a significant decrease in the expression of nestin, NeuN, Olig 2, BDNF, neuroligin1 and a significant increase in the expression of GFAP in the vehicle group. The expression of the neural markers was significantly higher in DPSCs compared with the vehicle group whereas GFAP level was lower in DPSCs compared to vehicle. We found that DPSCs therapy affected a range of neuronal markers in the barrel cortex post lesion, and improved the rats' recovery for sensory discrimination.

Mechanism of Action of Xiaoyao San in Treatment of Ischemic Stroke is Related to Anti-Apoptosis and Activation of PI3K/Akt Pathway

OBJECTIVE

The traditional Chinese medicine (TCM) formulation Xiaoyao San (XYS) has a good clinical effect in treating ischemic stroke (IS). We explored the mechanism and material basis of XYS in IS treatment.

METHODS

Network pharmacology was used to construct a network of XYS components and IS targets. R software was used to analyze the biological process and pathway analysis of the targets of XYS in IS treatment. In vitro, a model of apoptosis of PC12 cells induced by oxygen-glucose deprivation/reperfusion (OGD/R) was established to evaluate the neuroprotective effect of XYS and its influence on the expression of apoptotic protein-related genes. The affinity between the potentially active compounds in XYS and apoptotic proteins was evaluated by molecular docking.

RESULTS

XYS was shown to have 136 chemical components that exert potential anti-IS activity by acting on 175 proteins. Bioinformatics analysis showed that apoptosis and the phosphoinositide 3-kinase/protein kinase B (PI3K-Akt) signaling pathway were the main signaling pathways of XYS. In vitro experiments showed that XYS could improve the effect of OGD/R on PC12-cell activity (EC50 = 0.43 mg/mL) and inhibit apoptosis. The main mechanisms were related to the improvement of oxidative stress and regulation of apoptosis-related gene expression. Molecular docking showed that C22, C102 and other components in XYS had a strong affinity with apoptosis-related proteins.

CONCLUSION

Network pharmacology, in vitro experiments, and molecular docking were used, for the first time, to study the material basis and molecular mechanism of XYS in IS treatment from the perspective of multiple targets and multiple pathways. We provided a new approach for the future study of TCM formulations in the treatment of complex diseases.

Human Mesenchymal Stem Cells for Spinal Cord Injury

Spinal Cord Injury (SCI), as a devastating and life-altering neurological disorder, is one of the most serious health issues. Currently, the management of acute SCI includes pharmacotherapy and surgical decompression. Both the approaches have been observed to have adverse physiological effects on SCI patients. Therefore, novel therapeutic targets for the management of SCI are urgently required for developing cell-based therapies. Multipotent stem cells, as a novel strategy for the treatment of tissue injury, may provide an effective therapeutic option against many neurological disorders. Mesenchymal stem cells (MSCs) or multipotent stromal cells can typically self-renew and generate various cell types. These cells are often isolated from bone marrow (BM-MSCs), adipose tissues (AD-MSCs), umbilical cord blood (UCB-MSCs), and placenta (PMSCs). MSCs have remarkable potential for the development of regenerative therapies in animal models and humans with SCI. Herein, we summarize the therapeutic potential of human MSCs in the treatment of SCI.

Emerging paradigms in treating cerebral infarction with nanotheranostics: opportunities and clinical challenges

Interest is increasing in the use of nanotheranostics as diagnosis, imaging and therapeutic tools for stroke management, but movement to the clinic remains challenging.

Effect of Wnt signaling pathway on neurogenesis after cerebral ischemia and its therapeutic potential

Neurogenesis process in the chronic phase of ischemic stroke has become the focus of research on stroke treatment recently, mainly through the activation of related pathways to increase the differentiation of neural stem cells (NSCs) in the brain sub-ventricular zone (SVZ) and subgranular zone (SGZ) of hippocampal dentate gyrus (DG) areas into neurons, promoting neurogenesis. While there is still debate about the longevity of active adult neurogenesis in humans, the SVZ and SGZ have the capacity to upregulate neurogenesis in response to cerebral ischemia, which opens discussion about potential treatment strategies to harness this neuronal regenerative response. Wnt signaling pathway is one of the most important approaches potentially targeting on neurogenesis after cerebral ischemia, appropriate activation of which in NSCs may help to improve the sequelae of cerebral ischemia. Various therapeutic approaches are explored on preclinical stage to target endogenous neurogenesis induced by Wnt signaling after stroke onset. This article describes the composition of Wnt signaling pathway and the process of neurogenesis after cerebral ischemia, and emphatically introduces the recent studies on the mechanisms of this pathway for post-stroke neurogenesis and the therapeutic possibility of activating the pathway to improve neurogenesis after stroke.

miR-339 Promotes Hypoxia-Induced Neuronal Apoptosis and Impairs Cell Viability by Targeting FGF9/CACNG2 and Mediating MAPK Pathway in Ischemic Stroke

Ischemic stroke (IS) is a common cerebrovascular disease characterized by insufficient blood blow to the brain and the second leading cause of death as well as disability worldwide. Recent literatures have indicated that abnormal expression of miR-339 is closely related to IS. In this study, we attempted to assess the biological function of miR-339 and its underlying mechanism in IS. By accessing the GEO repository, the expression of miR-339, FGF9, and CACNG2 in middle cerebral artery occlusion (MCAO) and non-MCAO was evaluated. PC12 cells after oxygen-glucose deprivation/reoxygenation (OGD/R) treatment were prepared to mimic in vitro the IS model. The levels of miR-339, FGF9, CACNG2, and MAPK-related markers were quantitatively measured by qRT-PCR and Western blot. CCK-8 and flow cytometry analyses were performed to examine cell viability and apoptosis, respectively. IS-related potential pathways were identified using KEGG enrichment analysis and GO annotations. Bioinformatics analysis and dual-luciferase reporter assay were used to predict and verify the possible target of miR-339. Our results showed that miR-339 expression was significantly increased in MCAO and OGD/R-treated PC12 cells. Overexpression of miR-339 inhibited cell viability of PC12 cells subjected to OGD/R treatment. FGF9 and CACMG2 are direct targets of miR-339 and can reverse the aggressive effect of miR-339 on the proliferation and apoptosis of OGD/R-treated PC12 cells. Moreover, miR-339 mediated the activation of the MAPK pathway, which was inhibited by the FGF9/CACNG2 axis in PC12 cells treated by OGD/R stimulation. In summary, these findings suggested that miR-339 might act as a disruptive molecule to accelerate the IS progression via targeting the FGF9/CACNG2 axis and mediating the MAPK pathway.

Potential of stem cell therapy in intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is a common disease associated with high mortality and morbidity. The treatment of patients with ICH includes medical and surgical interventions. New areas of surgical intervention have been focused on the evacuation of hematoma through minimally invasive neurosurgery. In contrast, there have been no significant advances in the development of medical interventions for functional recovery after ICH. Stem cells exert multiple therapeutic functions and have emerged as a promising treatment strategy. Herein, we summarized the pathophysiology of ICH and its treatment targets, and we introduced the therapeutic mechanisms of stem cells (e.g. neutrotrophy and neuroregeneration). Moreover, we reviewed and summarized the experimental designs of the preclinical studies, including the types of cells and the timing and routes of stem cell administration. We further listed and reviewed the completed/published and ongoing clinical trials supporting the safety and efficacy of stem cell therapy in ICH. The limitations of translating preclinical studies into clinical trials and the objectives of future studies were discussed. In conclusion, current literatures showed that stem cell therapy is a promising treatment in ICH and further translation research on judiciously selected group of patients is warranted before it can be extensively applied in clinical practice.

Neurorestoration Approach by Biomaterials in Ischemic Stroke

Ischemic stroke (IS) is the leading cause of disability in the western world, assuming a high socio-economic cost. One of the most used strategies in the last decade has been biomaterials, which have been initially used with a structural support function. They have been perfected, different compounds have been combined, and they have been used together with cell therapy or controlled release chemical compounds. This double function has driven them as potential candidates for the chronic treatment of IS. In fact, the most developed are in different phases of clinical trial. In this review, we will show the ischemic scenario and address the most important criteria to achieve a successful neuroreparation from the point of view of biomaterials. The spontaneous processes that are activated and how to enhance them is one of the keys that contribute to the success of the therapeutic approach. In addition, the different routes of administration and how they affect the design of biomaterials are analyzed. Future perspectives show where this broad scientific field is heading, which advances every day with the help of technology and advanced therapies.

The effect of magnetic stimulation on differentiation of human induced pluripotent stem cells into neuron

The effect of stem cell transplantation in the treatment of neural lesions is so far not satisfactory. Magnetic stimulation is a feasible exogenous interference to improve transplantation outcome. However, the effect of magnetic stimulation on the differentiation of induced pluripotent stem cells (iPSCs) into neuron has not been studied. In this experiment, an in vitro neuron differentiation system from human iPSCs were established and confirmed. Three magnetic stimuli (high frequency [HF], low frequency [LF], intermittent theta-burst stimulation [iTBS]) were applied twice a day during the differentiation process. Immunofluorescence and quantitative polymerase chain reaction (Q-PCR) were performed to analyze the effect of magnetic stimulation. Neural stem cells were obtained on day 12, manifested as floating neurospheres expressing neural precursor markers. All groups can differentiate into neurons while glial cell markers were not detected. Both Immunofluorescence and PCR results showed LF and iTBS increased the transcription and expression of neuronal nuclei (NeuN). HF significantly increased vesicular glutamate transporters2 transcription while iTBS promoted transcription of both synaptophysin and postsynaptic density protein 95. These results indicate that LF and iTBS can promote the generation of mature neurons from human iPSCs; HF may promote differentiate into glutamatergic neurons while iTBS may promote synapse formation during the differentiation.

Trends in clinical trials for stroke by cell therapy: data mining ClinicalTrials.gov and the ICTRP portal site

Definitive treatment of stroke constitutes an important thesis of regenerative medicine in the cerebrovascular field. However, to date, no cell therapy products for stroke are yet on the market. In this study, we examined the clinical research trends related to cell therapy products in the stroke field based on data obtained from the ClinicalTrials.gov website and International Clinical Trials Research Platform (ICTRP) portal site. These data do not offer results of clinical trials comprehensively but provide information regarding various attributes of planned clinical trials including work in progress. We selected 78 cell therapy studies related to the field of stroke treatment from ClinicalTrial.gov and ICTRP. These were analyzed according to, e.g., the reporting countries, origin (autologous or allogeneic), of cell used, cell types and source organs, the progress of translational phases, target phase of the disease (acute or chronic stroke), and route of administration. This analysis revealed a trend whereby in the acute phase, mesenchymal stem cells were administered intravenously at a relatively higher dose, whereas in the chronic phase a small number of cells were administered intracranially. Only two randomized controlled Phase III studies with over 100 patients are registered, but none of them has been completed. Thus, cell therapy against stroke appears to constitute a premature area compared with cartilage repair as assessed in our previous report. In addition, tracking by means of the ID number of each trial via PubMed revealed that 44% of clinical studies in this field have corresponding published results, which was also discussed.

The interrelationship between cerebral ischemic stroke and glioma: a comprehensive study of recent reports

Glioma and cerebral ischemic stroke are two major events that lead to patient death worldwide. Although these conditions have different physiological incidences, ~10% of ischemic stroke patients develop cerebral cancer, especially glioma, in the postischemic stages. Additionally, the high proliferation, venous thrombosis and hypercoagulability of the glioma mass increase the significant risk of thromboembolism, including ischemic stroke. Surprisingly, these events share several common pathways, viz. hypoxia, cerebral inflammation, angiogenesis, etc., but the proper mechanism behind this co-occurrence has yet to be discovered. The hypercoagulability and presence of the D-dimer level in stroke are different in cancer patients than in the noncancerous population. Other factors such as atherosclerosis and coagulopathy involved in the pathogenesis of stroke are partially responsible for cancer, and the reverse is also partially true. Based on clinical and neurosurgical experience, the neuronal structures and functions in the brain and spine are observed to change after a progressive attack of ischemia that leads to hypoxia and atrophy. The major population of cancer cells cannot survive in an adverse ischemic environment that excludes cancer stem cells (CSCs). Cancer cells in stroke patients have already metastasized, but early-stage cancer patients also suffer stroke for multiple reasons. Therefore, stroke is an early manifestation of cancer. Stroke and cancer share many factors that result in an increased risk of stroke in cancer patients, and vice-versa. The intricate mechanisms for stroke with and without cancer are different. This review summarizes the current clinical reports, pathophysiology, probable causes of co-occurrence, prognoses, and treatment possibilities.

Drug-like delivery methods of stem cells as biologics for stroke

Introduction: Stem cell therapy is an experimental treatment for brain disorders. Although a cellular product, stem cells can be classified as biologics based on the cells' secretion of therapeutic substances. Treatment with stem cell biologics may appeal to stroke because of the secondary cell death mechanisms, especially neuroinflammation, that are rampant from the onset and remain elevated during the progressive phase of the disease requiring multi-pronged biological targets to effectively abrogate the neurodegenerative pathology. However, the optimal delivery methods, among other logistical approaches (i.e. cell doses and timing of intervention), for stem cell therapy will need to be refined before stem cell biologics can be successfully utilized for stroke in large scale clinical trials. Areas covered: In this review, we discuss how the innate qualities of stem cells characterize them as biologics, how stem cell transplantation may be an ideal treatment for stroke, and the various routes of stem cell administration that have been employed in various preclinical and clinical investigations. Expert opinion: There is a need to optimize the delivery of stem cell biologics for stroke in order to guide the safe and effective translation of this therapy from the laboratory to the clinic.

Conductive polymers to modulate the post-stroke neural environment

Despite the prevalence of stroke, therapies to augment recovery remain limited. Here we focus on the use of conductive polymers for cell delivery, drug release, and electrical stimulation to optimize the post-stroke environment for neural recovery. Conductive polymers and their interactions with in vitro and in vivo neural systems are explored. The ability to continuously modify the neural environment utilizing conductive polymers provides applications in directing stem cell differentiation and increasing neural repair. This exciting class of polymers offers new approaches to optimizing the post-stroke brain to improve functional recovery.

[Cell therapy for ischemic stroke. Stem cell types and results of pre-clinical trials]

The literature review addresses the use of stem cells (SC) in ischemic stroke (IS). Part 1 of the paper overviews the results of experimental animal studies. Characteristics of different SC types and results of their studies in experimental models of IS are presented in the first section, the second section considers pros and cons of the methods of SC injection.

Rotary jet-spun porous microfibers as scaffolds for stem cells delivery to central nervous system injury

Stem cell transplantation is a promising strategy to treat brain injuries. However, cell-based therapies are limited because poor local cell engraftment. Here, we present a polylactic acid (PLA) scaffold to support mesenchymal stem cells (MSCs) delivery in stroke. We isolated bone marrow MSCs from adult C57/Bl6 mice, cultured them on PLA polymeric rough microfibrous (PRM) scaffolds obtained by rotary jet spinning, and transplanted over the brains of adult C57/Bl6 mice, carrying thermocoagulation-induced cortical stroke. No inflammatory response to PRM was found. MSCs transplantation significantly reduced the area of the lesion and PRM delivery increased MSCs retention at the injury site. In addition, PRM upregulated α6-integrin and CXCL12 production, which may be the cause for greater cell retention at the lesion site and may provide additional benefit to MSCs transplantation procedures. We conclude that PRM scaffolds offer a promising new system to deliver stem cells to injured areas of the brain.

Sex Steroids, Adult Neurogenesis, and Inflammation in CNS Homeostasis, Degeneration, and Repair

Sex steroidal hormones coordinate the development and maintenance of tissue architecture in many organs, including the central nervous systems (CNS). Within the CNS, sex steroids regulate the morphology, physiology, and behavior of a wide variety of neural cells including, but not limited to, neurons, glia, endothelial cells, and immune cells. Sex steroids spatially and temporally control distinct molecular networks, that, in turn modulate neural activity, synaptic plasticity, growth factor expression and function, nutrient exchange, cellular proliferation, and apoptosis. Over the last several decades, it has become increasingly evident that sex steroids, often in conjunction with neuroinflammation, have profound impact on the occurrence and severity of neuropsychiatric and neurodegenerative disorders. Here, I review the foundational discoveries that established the regulatory role of sex steroids in the CNS and highlight recent advances toward elucidating the complex interaction between sex steroids, neuroinflammation, and CNS regeneration through adult neurogenesis. The majority of recent work has focused on neuroinflammatory responses following acute physical damage, chronic degeneration, or pharmacological insult. Few studies directly assess the role of immune cells in regulating adult neurogenesis under healthy, homeostatic conditions. As such, I also introduce tractable, non-traditional models for examining the role of neuroimmune cells in natural neuronal turnover, seasonal plasticity of neural circuits, and extreme CNS regeneration.

Adjudin-preconditioned neural stem cells enhance neuroprotection after ischemia reperfusion in mice

BACKGROUND

Transplantation of neural stem cells (NSCs) has been proposed as a promising therapeutic strategy for the treatment of ischemia/reperfusion (I/R)-induced brain injury. However, existing evidence has also challenged this therapy on its limitations, such as the difficulty for stem cells to survive after transplantation due to the unfavorable microenvironment in the ischemic brain. Herein, we have investigated whether preconditioning of NSCs with adjudin, a small molecule compound, could enhance their survivability and further improve the therapeutic effect for NSC-based stroke therapy.

METHOD

We aimed to examine the effect of adjudin pretreatment on NSCs by measuring a panel of parameters after their transplantation into the infarct area of ipsilateral striatum 24 hours after I/R in mice.

RESULTS

We found that pretreatment of NSCs with adjudin could enhance the viability of NSCs after their transplantation into the stroke-induced infarct area. Compared with the untreated NSC group, the adjudin-preconditioned group showed decreased infarct volume and neurobehavioral deficiency through ameliorating blood-brain barrier disruption and promoting the expression and secretion of brain-derived neurotrophic factor. We also employed H2O2-induced cell death model in vitro and found that adjudin preconditioning could promote NSC survival through inhibition of oxidative stress and activation of Akt signaling pathway.

CONCLUSION

This study showed that adjudin could be used to precondition NSCs to enhance their survivability and improve recovery in the stroke model, unveiling the value of adjudin for stem cell-based stroke therapy.