Preconditioning Strategies to Enhance Neural Stem Cell-Based Therapy for Ischemic Stroke

Advances in clinical translation of stem cell-based therapy in neurological diseases

Stem cell-based therapies have raised considerable interest to develop regenerative treatment for neurological disorders with high disability. In this review, we focus on recent preclinical and clinical evidence of stem cell therapy in the treatment of degenerative neurological diseases and discuss different cell types, delivery routes and biodistribution of stem cell therapy. In addition, recent advances of mechanistic insights of stem cell therapy, including functional replacement by exogenous cells, immunomodulation and paracrine effects of stem cell therapies are also demonstrated. Finally, we also highlight the adjunction approaches that has been implemented to augment their reparative function, survival and migration to target specific tissue, including stem cell preconditioning, genetical engineering, co-transplantation and combined therapy.

Regulation and Pharmacology of the Cyclic GMP and Nitric Oxide Pathway in Embryonic and Adult Stem Cells

This review summarizes recent advances in understanding the role of the nitric oxide (NO) and cyclic GMP (cGMP) pathway in stem cells. The levels of expression of various components of the pathway are changed during the differentiation of pluripotent embryonic stem cells. In undifferentiated stem cells, NO regulates self-renewal and survival predominantly through cGMP-independent mechanisms. Natriuretic peptides influence the growth of undifferentiated stem cells by activating particulate isoforms of guanylyl cyclases in a cGMP-mediated manner. The differentiation, recruitment, survival, migration, and homing of partially differentiated precursor cells of various types are sensitive to regulation by endogenous levels of NO and natriuretic peptides produced by stem cells, within surrounding tissues, and by the application of various pharmacological agents known to influence the cGMP pathway. Numerous drugs and formulations target various components of the cGMP pathway to influence the therapeutic efficacy of stem cell-based therapies. Thus, pharmacological manipulation of the cGMP pathway in stem cells can be potentially used to develop novel strategies in regenerative medicine.

Human neural stem cells transplanted during the sequelae phase alleviate motor deficits in a rat model of cerebral palsy

AIMS

Cerebral palsy (CP) is the most common physical disability in children, yet lacks an ideal animal model or effective treatment. This study aimed to develop a reliable CP model in neonatal rats and explore the effectiveness and underlying mechanisms of human neural stem cells (hNSCs) transplantation during the sequelae phase of CP.

METHODS

Vasoconstrictor endothelin-1 (ET-1) was administered intracranially to the motor cortex and striatum of rats on postnatal day 5 to establish a CP model. hNSCs (5 × 105/5 μL) pretreated with hypoxia (5% O2 for 24 h) were transplanted near the infarct 3 weeks after ET-1 injury (the sequelae phase). The distribution and differentiation of hNSCs were observed after transplantation. Changes in neurotrophic factors, neurogenesis, angiogenesis, axonal plasticity, and motor function were analyzed.

RESULTS

Neurobehavioral tests showed poor muscle strength and postural control in young ET-1 rats. Motor deficits of the left forelimb and gait abnormalities persisted into adulthood. Histopathological findings and MRI indicated the atrophy of the cortex, striatum, and adjacent corpus callosum in ET-1 rats. At 56 days after transplantation, hNSCs were widely distributed in the ipsilateral hemisphere, and differentiated into neurons, oligodendrocytes and astrocytes. Transplantation of hNSCs increased BDNF and VEGF expression, EdU+ cell number in the SVZ area, RECA-1+ vessel density and GAP-43 intensity around the lesion in ET-1 rats. The cylinder test revealed a significant increase in the left forelimb motor function from 28 days after transplantation, and the staircase and CatWalk tests showed improvements in fine motor function and gait parameters.

CONCLUSIONS

Intracerebral injection of ET-1 modelled key functional and histopathological features of CP. hNSCs transplanted during the sequelae phase of CP resulted in long-term improvement in motor performance, possibly attributed to its capacity to stimulate neurotrophic factors, facilitate neurogenesis, angiogenesis, and promote axonal plasticity.

Circumferential Esophageal Reconstruction Using a Tissue-engineered Decellularized Tunica Vaginalis Graft in a Rabbit Model

BACKGROUND

Pediatric surgeons have faced esophageal reconstruction challenges for decades owing to a variety of congenital and acquired conditions. This work aimed to introduce a reproducible and efficient approach for creating tissue-engineered esophageal tissue using bone marrow mesenchymal stem cells (BMSCs) cultured in preconditioned mediums seeded on a sheep decellularized tunica vaginalis (DTV) scaffold for partial reconstruction of a rabbit's esophagus.

METHODS

DTV was performed using SDS and Triton X-100 solutions. The decellularized grafts were employed alone (DTV group) or after recellularization with BMSCs cultured for 10 days in preconditioned mediums (RTV group) for reconstructing a 3 cm segmental defect in the cervical esophagus of rabbits (n = 20) after the decellularization process was confirmed. Rabbits were observed for one month, after which they were euthanized, and the reconstructed esophagi were harvested for histological analysis.

RESULTS

Six rabbits in the DTV group and eight rabbits in the RTV group survived until the end of the one-month study period. Despite histological examination demonstrating that both grafts completely repaired the esophageal defect, the RTV graft demonstrated a histological structure similar to that of the normal esophagus. The reconstructed esophagi in the RTV group revealed the arrangement of the different layers of the esophageal wall with the formation of newly formed blood vessels and Schwann-like cells.

CONCLUSION

DTV xenograft is a novel scaffold that promotes cell adhesion and differentiation and might be effectively utilized for regenerating esophageal tissue, paving the way for future clinical trials in pediatric patients.

High-frequency repetitive transcranial magnetic stimulation promotes neural stem cell proliferation after ischemic stroke

JOURNAL/nrgr/04.03/01300535-202408000-00031/figure1/v/2023-12-16T180322Z/r/image-tiff Proliferation of neural stem cells is crucial for promoting neuronal regeneration and repairing cerebral infarction damage. Transcranial magnetic stimulation (TMS) has recently emerged as a tool for inducing endogenous neural stem cell regeneration, but its underlying mechanisms remain unclear. In this study, we found that repetitive TMS effectively promotes the proliferation of oxygen-glucose deprived neural stem cells. Additionally, repetitive TMS reduced the volume of cerebral infarction in a rat model of ischemic stroke caused by middle cerebral artery occlusion, improved rat cognitive function, and promoted the proliferation of neural stem cells in the ischemic penumbra. RNA-sequencing found that repetitive TMS activated the Wnt signaling pathway in the ischemic penumbra of rats with cerebral ischemia. Furthermore, PCR analysis revealed that repetitive TMS promoted AKT phosphorylation, leading to an increase in mRNA levels of cell cycle-related proteins such as Cdk2 and Cdk4. This effect was also associated with activation of the glycogen synthase kinase 3β/β-catenin signaling pathway, which ultimately promotes the proliferation of neural stem cells. Subsequently, we validated the effect of repetitive TMS on AKT phosphorylation. We found that repetitive TMS promoted Ca2+ influx into neural stem cells by activating the P2 calcium channel/calmodulin pathway, thereby promoting AKT phosphorylation and activating the glycogen synthase kinase 3β/β-catenin pathway. These findings indicate that repetitive TMS can promote the proliferation of endogenous neural stem cells through a Ca2+ influx-dependent phosphorylated AKT/glycogen synthase kinase 3β/β-catenin signaling pathway. This study has produced pioneering results on the intrinsic mechanism of repetitive TMS to promote neural function recovery after ischemic stroke. These results provide a strong scientific foundation for the clinical application of repetitive TMS. Moreover, repetitive TMS treatment may not only be an efficient and potential approach to support neurogenesis for further therapeutic applications, but also provide an effective platform for the expansion of neural stem cells.

Hypoxic Preconditioning Prevents Oxidative Stress-Induced Cell Death in Human Hair Follicle Stem Cells

Objectives

This study investigated the impact of hypoxic preconditioning on the survival and oxidative stress tolerance of nestin-expressing hair follicle stem cells (hHFSCs) and SH-SY5Y neuroblastoma cells, two crucial cell types for central nervous system therapies. The study also examined the relative expression of three key genes, HIF1α, BDNF, and VEGF following hypoxic preconditioning.

Materials and Methods

hHFSCs were isolated from human hair follicles, characterized, and subjected to hypoxia for up to 72 hours. SH-SY5Y cells were similarly preconditioned for up to 72 hours. Cell viability under hypoxic conditions and oxidative stress was assessed. The relative expression of key genes was evaluated using qRT-PCR.

Results

hHFSCs exhibited remarkable resilience to hypoxic conditions, while SH-SY5Y cells displayed lower tolerance. Hypoxic preconditioning improved the viability of both cell types under oxidative stress. HIF1α mRNA was significantly downregulated, and VEGF transcripts increased after preconditioning, suggesting adaptations to prolonged hypoxia.

Conclusion

Hypoxic preconditioning enhances the survival and oxidative stress resilience of hHFSCs and SH-SY5Y cells, offering potential benefits for central nervous system cell therapy. The differential responses observed emphasize the need for tailored preconditioning strategies for specific cell types. These findings underscore the importance of hypoxic preconditioning and warrant further research into the underlying mechanisms, bringing us closer to effective neurological disorder treatments.

Artesunate Exerts Organ- and Tissue-Protective Effects by Regulating Oxidative Stress, Inflammation, Autophagy, Apoptosis, and Fibrosis: A Review of Evidence and Mechanisms

The human body comprises numerous organs and tissues operating in synchrony, it facilitates metabolism, circulation, and overall organismal function. Consequently, the well-being of our organs and tissues significantly influences our overall health. In recent years, research on the protective effects of artesunate (AS) on various organ functions, including the heart, liver, brain, lungs, kidneys, gastrointestinal tract, bones, and others has witnessed significant advancements. Findings from in vivo and in vitro studies suggest that AS may emerge as a newfound guardian against organ damage. Its protective mechanisms primarily entail the inhibition of inflammatory factors and affect anti-fibrotic, anti-aging, immune-enhancing, modulation of stem cells, apoptosis, metabolic homeostasis, and autophagy properties. Moreover, AS is attracting a high level of interest because of its obvious antioxidant activities, including the activation of Nrf2 and HO-1 signaling pathways, inhibiting the release of reactive oxygen species, and interfering with the expression of genes and proteins associated with oxidative stress. This review comprehensively outlines the recent strides made by AS in alleviating organismal injuries stemming from various causes and protecting organs, aiming to serve as a reference for further in-depth research and utilization of AS.

Mechanism of action and neuroprotective role of nicorandil in ischemic stroke

Nicorandil is a dual mechanism anti-anginal agent that acts as a nitric oxide (NO) donor and a potassium (K+) channel opener. Recent studies have evaluated the effect of nicorandil on ischemic stroke. Neurons have a low tolerance to hypoxia and therefore the brain tissue is significantly vulnerable to ischemia. Current approved treatments for ischemic stroke are tissue plasminogen activators and clot retrieval methods. The narrow therapeutic time window and lack of efficacy in restoring the dying neurons urge researchers to develop an alternative approach. In the terminal stages of anoxia, K+ channels induce hyperpolarization in various types of neuronal cells, leading to decreased neuronal activity and the preservation of the brain's energy. Nicorandil can open these K+ channels and sustain the hyperpolarization phase, which may have a neuroprotective effect during hypoxia. Additionally, we review how nicorandil can improve overall stroke outcomes through its anti-inflammatory, anti-oxidative, and edema-reducing effects. One of the major components evaluated in stroke patients is blood pressure. Studies have demonstrated that the effect of nicorandil on blood pressure is related to both its K+ channel opening and NO donating mechanisms. Since both hypertension and hypotension need correction before stroke intervention, it's crucial to consider the role of nicorandil and its impact on blood pressure. Previously published studies indicate that the right dosage of nicorandil can improve cerebral blood flow without significant changes in hemodynamic profiles. In this review, we discuss how nicorandil may contribute to better stroke outcomes based on previously published literature and laboratory findings.

Valproic acid and/or rapamycin preconditioning protects hair follicle stem cells from oxygen glucose serum deprivation-induced oxidative injury via activating Nrf2 pathway

Among leading causes of the ischemic stroke pathogenesis, oxidative stress strongly declines rate of stem cell engraftment at the injury site, and disables stem cell-based therapy as a key treatment for ischemia stroke. To overcome this therapeutic limitation, preconditioning has been represented a possible approach to augment the adaptation and viability of stem cells to oxidative stress. Here, we illustrated protective impacts of valproic acid (VPA) and/or rapamycin (RAPA) preconditioning unto oxygen glucose and serum deprivation (OGSD)-stimulated cell damage in hair follicle-derived stem cells (HFSCs) and surveyed the plausible inducement mechanisms. OGSD, as an in vitro cell injury model, was established and HFSCs viability was observed using MTT assay after VPA, RAPA, and VPA-RAPA preconditioning under OGSD. ROS and MDA production was assessed to reflect oxidative stress. Real-time PCR and western blotting were employed to investigate Nrf2 expression. The activity of Nrf2-related antioxidant enzymes including NQO1, GPx and GSH level were examined. VEGF and BDNF mRNA expression levels were analyzed. Our results showed that VPA and/or RAPA preconditioning ameliorated OGSD-induced decline in HFSCs viability. In addition, they considerably prohibited ROS and MDA generation in the OGSD-treated HFSCs. Furthermore, VPA and/or RAPA preconditioning stimulated Nrf2 nuclear repositioning and NQO1 and GPx activity and GSH amount, as well as expression of paracrine factors VEGF and BDNF in OGSD-treated HFSCs. Thus, the protective effects afforded by VPA and/or RAPA preconditioning, which involved Nrf2-modulated oxidant stress and regulation of VEGF and BDNF expression, display a simple strategy to augment cell-transplantation efficiency for ischemic stroke.

Potential injectable hydrogels as biomaterials for central nervous system injury: A narrative review

Numerous modalities exist through which the central nervous system (CNS) may sustain injury or impairment, encompassing traumatic incidents, stroke occurrences, and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Presently available pharmacological and therapeutic interventions are incapable of restoring or regenerating damaged CNS tissue, leading to substantial unmet clinical needs among patients with CNS ailments or injuries. To address and facilitate the recovery of the impaired CNS, cell-based repair strategies encompass multiple mechanisms, such as neuronal replacement, therapeutic factor secretion, and the promotion of host brain plasticity. Despite the progression of cell-based CNS reparation as a therapeutic strategy throughout the years, substantial barriers have impeded its widespread implementation in clinical settings. The integration of cell technologies with advancements in regenerative medicine utilizing biomaterials and tissue engineering has recently facilitated the surmounting of several of these impediments. This comprehensive review presents an overview of distinct CNS conditions necessitating cell reparation, in addition to exploring potential biomaterial methodologies that enhance the efficacy of treating brain injuries.

Preconditioning Concepts for the Therapeutic Use of Extracellular Vesicles Against Stroke

Various preclinical stroke models have demonstrated the neuroprotective effects of extracellular vesicles (EVs) obtained from several types of cells, including neurons, astrocytes, microglia, neuronal progenitor cells, bone marrow stem cells, and mesenchymal stem cells. EVs interfere with key mechanisms in stroke pathophysiology such as cell death, neuroinflammation, autophagy, and angiogenesis. The mode of action and efficacy depend on the specific EV content, including miRNAs, proteins, and lipids, which can be modified through (I) bioengineering methods, (II) choice of source cells, and (III) modification of the source cell environment. Indeed, modifying the environment by preconditioning the EV-secreting cells with oxygen-glucose deprivation or medium modification revealed superior neuroprotective effects in stroke models. Although the concept of preconditioned EVs is relatively novel, it holds promise for the future treatment of ischemic stroke. Here, we give a brief overview about the main mechanisms of EV-induced neuroprotection and discuss the current status of preconditioning concepts for EV-treatment of ischemic stroke.

The role of cGAS-STING signaling in ischemic stroke: From immune response to therapeutic targeting

Stroke, a debilitating condition with limited treatment options, presents a significant therapeutic challenge. A comprehensive grasp of stroke pathophysiology is imperative for designing newer and more effective therapeutic approaches. Notably, the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a central orchestrator of the poststroke immune response. It regulates pivotal processes, including immune cell activation, cytokine production, neuroinflammation, apoptosis, and tissue regeneration. Modulating this pathway shows immense potential in improving stroke outcomes, necessitating the development of selective inhibitors and activators. This review provides an overview of the cGAS-STING pathway's role in ischemic stroke and explores emerging therapies, including cGAS and STING inhibitors and STING agonist preconditioning. It also addresses challenges like specificity, timing, and off-target effects.

A Tale of Two: When Neural Stem Cells Encounter Hypoxia

Normoxia is defined as an oxygen concentration of 20.9%, as in room air, whereas hypoxia refers to any oxygen concentration less than this. Any physiological oxygen deficiency or tissue oxygen deficiency relative to demand is called hypoxia. Neural stem cells (NSCs) are multipotent stem cells that can differentiate into multiple cell lines such as neurons, oligodendrocytes, and astrocytes. Under hypoxic conditions, the apoptosis rate of NSCs increases remarkably in vitro or in vivo. However, some hypoxia promotes the proliferation and differentiation of NSCs. The difference is related to the oxygen concentration, the duration of hypoxia, the hypoxia tolerance threshold of the NSCs, and the tissue source of the NSCs. The main mechanism of hypoxia-induced proliferation and differentiation involves an increase in cyclin and erythropoietin concentrations, and hypoxia-inducible factors play a key role. Multiple molecular pathways are activated during hypoxia, including Notch, Wnt/β-catenin, PI3K/Akt, and altered microRNA expression. In addition, we review the protective effect of exogenous NSCs transplantation on ischemic or anoxic organs, the therapeutic potential of hypoxic preconditioning on exogenous NSCs and clinical application of NSCs.

3D-Printed Microinjection Needle Arrays via a Hybrid DLP-Direct Laser Writing Strategy

Microinjection protocols are ubiquitous throughout biomedical fields, with hollow microneedle arrays (MNAs) offering distinctive benefits in both research and clinical settings. Unfortunately, manufacturing-associated barriers remain a critical impediment to emerging applications that demand high-density arrays of hollow, high-aspect-ratio microneedles. To address such challenges, here, a hybrid additive manufacturing approach that combines digital light processing (DLP) 3D printing with "ex situ direct laser writing (esDLW)" is presented to enable new classes of MNAs for fluidic microinjections. Experimental results for esDLW-based 3D printing of arrays of high-aspect-ratio microneedles-with 30 μm inner diameters, 50 μm outer diameters, and 550 μm heights, and arrayed with 100 μm needle-to-needle spacing-directly onto DLP-printed capillaries reveal uncompromised fluidic integrity at the MNA-capillary interface during microfluidic cyclic burst-pressure testing for input pressures in excess of 250 kPa (n = 100 cycles). Ex vivo experiments perform using excised mouse brains reveal that the MNAs not only physically withstand penetration into and retraction from brain tissue but also yield effective and distributed microinjection of surrogate fluids and nanoparticle suspensions directly into the brains. In combination, the results suggest that the presented strategy for fabricating high-aspect-ratio, high-density, hollow MNAs could hold unique promise for biomedical microinjection applications.

Artesunate regulates the proliferation and differentiation of neural stem cells by activating the JAK‑2/STAT‑3 signaling pathway in ischemic stroke

Ischemic stroke is one of the most common causes of disability and death globally; therefore, the repair and reconstruction of the central nervous system (CNS) after stroke is very important. Neural stem/progenitor cells (NSPCs) may be the key to cell replacement therapy to treat CNS damage. It has previously been reported that artesunate (ART) is involved in the regulation of the biological functions of NSPCs; however, the mechanism of action of ART remains unclear. In the present study, different concentrations of ART were used to treat NSPCs following oxygen-glucose deprivation (OGD). Cell viability and apoptosis were analyzed using Cell Counting Kit-8 assay and flow cytometry, respectively, whereas immunofluorescence analysis was used to measure the expression levels of the differentiation-related molecule doublecortin (DCX) and proliferating cell nuclear antigen (PCNA). Western blotting was performed to analyze the expression levels of molecules related to the JAK-2/STAT-3 signaling pathway. The present results indicated that treatment with ART following OGD significantly promoted the viability of NSPCs, inhibited the apoptosis of NSPCs, and promoted the expression of PCNA and DCX. Moreover, ART significantly downregulated the protein expression levels of phosphorylated (p)-JAK-2 and p-STAT-3. Furthermore, activation of the JAK-2/STAT-3 signaling pathway and treatment with ART reversed the effects of ART on the proliferation, apoptosis and differentiation of NSPCs. In conclusion, the present data suggested that ART may promote the proliferation and differentiation of NSPCs, and reduce the apoptosis of NSPCs, by inhibiting the JAK-2/STAT-3 signaling pathway. ART may potentially be used for the treatment of ischemic stroke.

Stem-Cell-Based Therapy: The Celestial Weapon against Neurological Disorders

Stem cells are a versatile source for cell therapy. Their use is particularly significant for the treatment of neurological disorders for which no definitive conventional medical treatment is available. Neurological disorders are of diverse etiology and pathogenesis. Alzheimer's disease (AD) is caused by abnormal protein deposits, leading to progressive dementia. Parkinson's disease (PD) is due to the specific degeneration of the dopaminergic neurons causing motor and sensory impairment. Huntington's disease (HD) includes a transmittable gene mutation, and any treatment should involve gene modulation of the transplanted cells. Multiple sclerosis (MS) is an autoimmune disorder affecting multiple neurons sporadically but induces progressive neuronal dysfunction. Amyotrophic lateral sclerosis (ALS) impacts upper and lower motor neurons, leading to progressive muscle degeneration. This shows the need to try to tailor different types of cells to repair the specific defect characteristic of each disease. In recent years, several types of stem cells were used in different animal models, including transgenic animals of various neurologic disorders. Based on some of the successful animal studies, some clinical trials were designed and approved. Some studies were successful, others were terminated and, still, a few are ongoing. In this manuscript, we aim to review the current information on both the experimental and clinical trials of stem cell therapy in neurological disorders of various disease mechanisms. The different types of cells used, their mode of transplantation and the molecular and physiologic effects are discussed. Recommendations for future use and hopes are highlighted.

Neural Stem Cells Therapy for Ischemic Stroke: Progress and Challenges

Ischemic stroke, with its high morbidity and mortality, is the most common cerebrovascular accident and results in severe neurological deficits. Despite advances in medical and surgical intervention, post-stroke therapies remain scarce, which seriously affects the quality of life of patients. Over the past decades, stem cell transplantation has been recognized as very promising therapy for neurological diseases. Neural stem cell (NSC) transplantation is the optimal choice for ischemic stroke as NSCs inherently reside in the brain and can potentially differentiate into a variety of cell types within the central nervous system. Recent research has demonstrated that NSC transplantation can facilitate neural recovery after ischemic stroke, but the mechanisms still remain unclear, and basic/clinical studies of NSC transplantation for ischemic stroke have not yet been thoroughly elucidated. We thus, in this review, provide a futher understanding of the therapeutic role of NSCs for ischemic stroke, and evaluate their prospects for future application in clinical patients of ischemic stroke.

Upregulating microRNA‐210 to Inhibit Apoptosis of Neural Stem Cells with an MRI–Visible Nanomedicine for Stroke Therapy

Transplantation of neural stem cells (NSCs) is a promising paradigm for treating stroke. However, the poor survival of transplanted NSCs greatly limits the therapeutic potential. microRNA‐210 (miR‐210), a key hypoxia‐regulated miRNA, can enhance cell survival by targeting the expression of multiple apoptosis‐related genes, such as caspase‐8‐associated protein‐2 (casp8ap2), Bax, and Bcl‐2. Meanwhile, a noninvasive cell‐tracking method is also indispensable for monitoring the in vivo cell‐based therapy. Herein, an MRI–visible nanomedicine is developed to codeliver superparamagnetic iron oxide (SPIO) nanoparticles and miR‐210 into NSCs. This therapeutic nanomedicine not only promotes the survival of NSCs via upregulating miR‐210 to inhibit NSCs apoptosis but also allows an in vivo tracking of transplanted NSCs with MRI. The enhanced NSCs survivability significantly promotes the structural and functional recovery after stroke onset, which highlights the great potential of the multifunctional nanomedicine to improve the therapeutic efficacy of NSCs for stroke treatment.

Stem cell therapy for central nervous system disorders: Metabolic interactions between transplanted cells and local microenvironments

Stem cell therapy is a promising and rapidly advancing treatment strategy for a multitude of neurologic disorders. Yet, while early phase clinical trials are being pursued in many disorders, the mechanism of action often remains unclear. One important potential mechanism by which stem cells provide neuroprotection is through metabolic signaling with diseased neurons, glia, and other cell types in the nervous system microenvironment. Early studies exploring such interactions report normalization of glucose metabolism, induction of protective mitochondrial genes, and even interactions with supportive neurovasculature. Local metabolic conditions also impact stem cell biology, which can have a large impact on transplant viability and efficacy. Epigenetic changes that occur in the donor prior to collection of stem cells, and even during in vitro culture conditions, may have effects on stem cell biology that are carried into the host upon stem cell transplantation. Transplanted stem cells also face potentially toxic metabolic microenvironments at the targeted transplant site. Novel approaches for metabolically "preconditioning" stem cells prior to transplant harness metabolic machinery to optimize stem cell survival upon transplant. Ultimately, an improved understanding of the metabolic cross-talk between implanted stem cells and the local nervous system environment, in both disease and injury states, will increase the likelihood of success in translating stem cell therapy to early trials in neurological disease.

Effect of Heat Shock Preconditioning on Pressure Injury Prevention via Hsp27 Upregulation in Rat Models

Pressure injury (PI) prevention is a huge industry and involves various interventions. Temperature and moisture are important factors for wound healing; however, the active mechanism by which “moist heat” affects PI prevention has not yet been clarified. Thus, we explored the protective and therapeutic effects of hydrotherapy on PI based on the preconditioning (PC) principle, which might be useful for clinical practice. This study aimed to investigate the preventive mechanisms of heat shock preconditioning on PIs in rat models. The experiment was performed in the basic medical laboratory of Nagano College of Nursing in Japan. Ten rats were divided into two groups, with five rats in each group. Rats in the control group were not bathed. Rats in the preconditioning group (PC group) were bathed with hot tap-water. Bathing was conducted thrice a week. After bathing for 4 weeks, the PI model was constructed on the rats’ dorsal skin. The skin temperature, skin moisture, and area of ulcers were compared between the two groups. In vitro, we investigated the expression of heat shock protein 27 (Hsp27) in 6, 12, and 24 h after the PI model was constructed through Western blot analysis. Ulcers occurred in the control group 24 h after the PI model constructed, wheras the PC group exhibited ulcers after 36 h. The ulcer area was larger in the control group than that in the PC group after 24 h (all p < 0.05). The temperatures of PI wounds in the control group decreased and were lower than those in the PC group after 1, 6, 12, 36, and 48 h (all p < 0.05). However, the skin moisture levels of PI wounds increased in the control group and were higher than those in the PC group at the same time (all p < 0.05). Using Western blot analysis, hydrotherapy preconditioning showed the potential to increase Hsp27 expression after pressure was released (p < 0.05). We determine that heat shock preconditioning had a preventive effect on PIs in rat models, a result that may be associated with their actions in the upregulation of Hsp27.

The Role of Concomitant Nrf2 Targeting and Stem Cell Therapy in Cerebrovascular Disease

Despite the reality that a death from cerebrovascular accident occurs every 3.5 min in the United States, there are few therapeutic options which are typically limited to a narrow window of opportunity in time for damage mitigation and recovery. Novel therapies have targeted pathological processes secondary to the initial insult, such as oxidative damage and peripheral inflammation. One of the greatest challenges to therapy is the frequently permanent damage within the CNS, attributed to a lack of sufficient neurogenesis. Thus, recent use of cell-based therapies for stroke have shown promising results. Unfortunately, stroke-induced inflammatory and oxidative damage limit the therapeutic potential of these stem cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been implicated in endogenous antioxidant and anti-inflammatory activity, thus presenting an attractive target for novel therapeutics to enhance stem cell therapy and promote neurogenesis. This review assesses the current literature on the concomitant use of stem cell therapy and Nrf2 targeting via pharmaceutical and natural agents, highlighting the need to elucidate both upstream and downstream pathways in optimizing Nrf2 treatments in the setting of cerebrovascular disease.

Carbon Monoxide Protects Neural Stem Cells Against Iron Overload by Modulating the Crosstalk Between Nrf2 and NF-κB Signaling

Although accumulating evidences have demonstrated pro-survival effects of CO against various insults, the precise mechanism explaining how neural stem cells (NSCs) are protected by CO also remains largely unknown. Here we report CO pro-survival effect on NSCs against iron overload was comparable to that obtained with pharmacological inhibitors of reactive oxygen species (ROS). Its pro-survival effect was accompanied by the inhibition of ROS and subsequent inhibition of NF-κB which is mediated through nuclear factor erythroid 2-related factor 2 (Nrf2), in that activation of Nrf2 by CO inhibited ROS via up-regulation of NQO-1 while down-regulation of Nrf2 reversed the pro-survival effect of CO both in vitro and in vivo. CO-mediated preconditioning results in Nrf2 up-regulation and NF-κB inhibition, suggesting that these two pathways act in an inverse manner to maintain redox homeostasis. Our findings revealed CO preconditioning as a promising treatment strategy to improve efficacy of NSCs transplantation after hemorrhagic stroke.

Preconditioning with secretome of neural crest-derived stem cells enhanced neurotrophic expression in mesenchymal stem cells

During the last 20 years, stem cell therapy has been considered as an effective approach for regenerative medicine. Due to poor ability of stem cells to survive following transplantation, it has been proposed that beneficial effects of stem cells mainly depend on paracrine function. Therefore, the present study was designed to reinforce mesenchymal stem cells (MSCs) to express higher levels of trophic factors especially the ones with the neurotrophic properties. Here, bone marrow (BM)-MSCs and adipose-MSCs were treated with conditioned medium (CM) of dental pulp stem cells (DPSCs) or hair follicle stem cells (HFSCs) for up to three days. The relative expression of five key trophic factors that have critical effects on the central nervous system regeneration were evaluated using qRT-PCR technique. Furthermore, to assess the impacts of conditioned mediums on the fate of MSCs, expression of seven neuronal/glial markers were evaluated 3 days after the treatments. The obtained data revealed priming of BM-MSCs with HFSC-CM or DPSC-CM increases the BDNF expression over time. Such effect was also observed in adipose-MSCs following DPSC-CM treatment. Secretome preconditioning remarkably increased NGF expression in the adipose-MSCs. In addition, although priming of adipose-MSCs with HFSC-CM increased GDNF expression one day after the treatment, DPSC-CM enhanced GDNF mRNA in BM-MSCs at a later time point. It seemed priming of BM-MSCs with HFSC-CM, promoted differentiation into the glial lineage. Our findings showed that MSCs preconditioning with secretome of neural crest-derived stem cells could be a promising approach to enhance the neurotrophic potential of these stem cells.

Association of Interleukin-6-174G/C Polymorphism With Ischemic Stroke: An Updated Meta-Analysis

Background: Although numerous epidemiological studies have investigated the association between -174G/C(rs1800795) polymorphism in the interleukin-6 (IL-6) gene-stimulatory region and the risk of ischemic stroke (IS), they failed to reach a unified conclusion. The true relationship between -174G/C(rs1800795) polymorphism and IS remains controversial and unclear. Therefore, in this meta-analysis, we aimed to analyze more precisely the association between -174G/C(rs1800795) single-nucleotide polymorphism (SNP) of IL-6 gene and IS in a larger pooled population. Methods: A comprehensive literature search was performed in PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials until June 30, 2021. A fixed or random-effects model was utilized based on heterogeneity between studies. The odds ratios (ORs) and 95% confidence intervals (Cis) were calculated in the models of allele comparison (G vs. C), homozygote comparison (GG vs. CC) and (GC vs. CC), dominant (GG vs. GC + CC), hyper dominant (GG + CC vs. GC), and recessive (GG + GC vs. CC) to determine the strength of associations. Results: This meta-analysis included 13 case-control studies in 35 articles with 5,548 individuals. Overall, no significant associations between IL-6 -174G/C(rs1800795) and IS were identified (G vs. C:OR [95% CI] = 0.99 [0.81, 1.21], P = 0.91; GG + CC vs. GC:0.97 [0.85, 1.11], P = 0.66; GG vs. GC + CC: 1.01 [0.81, 1.25], P = 0.94; GC vs. CC: OR [95% CI] = 1.01 [0.68, 1.5], P = 0.96; GG vs. CC:0.93 [0.57, 1.51], P = 0.76; GG + GC vs. CC:0.97 [0.64, 1.47], P = 0.89). In the subgroup analyses by ethnicity or HWE P-value, there was a statistically significant association between IL-6 -174G/C(rs1800795) polymorphisms and IS in the alleles model; (G vs. C: LogOR [95% CI] = 0.14 [-0.16,.45], P = 0.00), homozygote model (GG vs. CC: LogOR [95% CI] = 0.18 [-0.58,.95], P = 0.00) and (GC vs. CC: LogOR [95% CI] = 0.2 [-0.46,.85], P = 0.00), dominant model (GG vs. GC + CC: OR [95% CI] = 0.02 [-0.72, 0.77], P = 0.00), and recessive model (GG + GC vs. CC: OR [95% CI]= -0.17 [-0.86,.52], P = 0.00) of the European population and in the dominant model (GG vs. GC + CC: OR [95% CI] = -0.13 [-0.51, 0.24]) of the Asian population. No statistical significance was identified in both six models of HWE p ≥ 0.2 group (both P ≥ 0.05). Conclusion: This meta-analysis revealed no correlation between IL-6 -174G/C(rs1800795) polymorphism and IS, whereas the subgroup analysis indicated that the relationship between IL-6 -174G/C(rs1800795) polymorphism and IS susceptibility varied significantly according to ethnicity and geography.

Neural stem cell therapy for brain disease

Brain diseases, including brain tumors, neurodegenerative disorders, cerebrovascular diseases, and traumatic brain injuries, are among the major disorders influencing human health, currently with no effective therapy. Due to the low regeneration capacity of neurons, insufficient secretion of neurotrophic factors, and the aggravation of ischemia and hypoxia after nerve injury, irreversible loss of functional neurons and nerve tissue damage occurs. This damage is difficult to repair and regenerate the central nervous system after injury. Neural stem cells (NSCs) are pluripotent stem cells that only exist in the central nervous system. They have good self-renewal potential and ability to differentiate into neurons, astrocytes, and oligodendrocytes and improve the cellular microenvironment. NSC transplantation approaches have been made for various neurodegenerative disorders based on their regenerative potential. This review summarizes and discusses the characteristics of NSCs, and the advantages and effects of NSCs in the treatment of brain diseases and limitations of NSC transplantation that need to be addressed for the treatment of brain diseases in the future.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.

Effect of nicorandil on the spatial arrangement of primary motor cortical neurons in the sub-acute phase of stroke in a rat model

INTRODUCTION

Ischemic stroke remains a major cause of disability and death worldwide. The density and the spatial distribution of the primary motor (M1) cortical neurons are important in signal transmission and control the movement-related functions. Recently, the neuroprotective effect of nicorandil in cerebral ischemia was described through its anti-apoptosis, antioxidant and anti-inflammatory properties. This study aimed to determine the effects of nicorandil on the neurobehavioral outcome, infarct size, and density, and spatial distribution of M1 cortical neurons after cerebral ischemia.

METHODS

Thirty Sprague-Dawley rats were randomly divided into three groups. Sham underwent surgery without middle cerebral artery occlusion (MCAO) and drug. The MCAO and treatment groups after MCAO received saline or nicorandil 2, 24, 48, and 72 h after the induction of brain ischemia. Neurobehavioral tests were performed, brains removed, sectioned, and stained by 2,3,5-triphenyltetrazolium chloride (TTC) to estimate the size of the infarction and Nissl staining to evaluate the numerical density, mean area, and the distribution pattern of M1 cortical neurons, using Voronoi spatial tessellation.

RESULTS

Although nicorandil treatment significantly decreased the neurological deficits and density of neuronal neighbors, it could not preserve the normal regular spatial distributions of M1 cortical neurons after MCAO. It also could not significantly improve motor function or reduce ischemic lesion size.

CONCLUSIONS

Treatment using the present dose of nicorandil during sub-acute ischemic stroke could not increase neuronal density or preserve the normal regular spatial distributions after MCAO. However, it had beneficial effects on neurobehavioral and motor function and somewhat reduced ischemic lesion size.

Programmed cell death in stem cell-based therapy: Mechanisms and clinical applications

Stem cell-based therapy raises hopes for a better approach to promoting tissue repair and functional recovery. However, transplanted stem cells show a high death percentage, creating challenges to successful transplantation and prognosis. Thus, it is necessary to investigate the mechanisms underlying stem cell death, such as apoptotic cascade activation, excessive autophagy, inflammatory response, reactive oxygen species, excitotoxicity, and ischemia/hypoxia. Targeting the molecular pathways involved may be an efficient strategy to enhance stem cell viability and maximize transplantation success. Notably, a more complex network of cell death receives more attention than one crucial pathway in determining stem cell fate, highlighting the challenges in exploring mechanisms and therapeutic targets. In this review, we focus on programmed cell death in transplanted stem cells. We also discuss some promising strategies and challenges in promoting survival for further study.

The Implementation of Preconditioned Epidermal Neural Crest Stem Cells to Combat Ischemic Stroke. Comment on Othman, F.A.; Tan, S.C. Preconditioning Strategies to Enhance Neural Stem Cell-Based Therapy for Ischemic Stroke. Brain Sci. 2020, 10, 893

In the recent review published in Brain Sciences, Othman and Tan suggested several preconditioning strategies to improve stem cell therapy after ischemic brain injury [...].

The KATP channel opener, nicorandil, ameliorates brain damage by modulating synaptogenesis after ischemic stroke

With population growth and aging, more and more patients with cerebral infarction have varying degrees of disability. ATP-sensitive potassium (KATP) channels regulate many cellular functions by coupling metabolic status with cell membrane electrical activity. Nicorandil (N-(2-hydroxyethyl)-nicotinamide nitrate) is the first KATP channel opener approved for clinical use. It has been reported that it might exert protective effects on the cerebral infarction by increasing cerebral blood flow and reducing inflammation. However, only a few studies explored its role in synaptogenesis. We made the rat model of middle cerebral artery occlusion (MCAO). Nicorandil was administered to rats via oral administration immediately after the surgery at a dose of 7.5 mg/kg and then daily for the next days. Infarct volume, cerebral edema, neurological deficits, cognitive impairment, and the level of Synaptophysin (SYP)、Growth associated protein-43 (GAP43) and neuronal nuclear antigen (NeuN) levels were measured to evaluate the effect of nicorandil. Our data showed that nicorandil treatment could decrease brain damage, improve learning and memory, and increase SYP、GAP43 and NeuN level. Taken together, we propose that nicorandil, as an opener of the KATP channel, provides a neuroprotective role in MCAO by promoting synaptic connections.