Small extracellular vesicles secreted by human iPSC-derived MSC enhance angiogenesis through inhibiting STAT3-dependent autophagy in ischemic stroke

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

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

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

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

Argon neuroprotection in ischemic stroke and its underlying mechanism

Ischemic stroke (IS), primarily caused by cerebrovascular obstruction, results in severe neurological deficits and has emerged as a leading cause of death and disability worldwide. Recently, there has been increasing exploration of the neuroprotective properties of the inert gas argon. Argon has exhibited impressive neuroprotection in many in vivo and ex vivo experiments without signs of adverse effects, coupled with the advantages of being inexpensive and easily available. However, the efficient administration strategy and underlying mechanisms of neuroprotection by argon in IS are still unclear. This review summarizes current research on the neuroprotective effects of argon in IS with the goal to provide effective guidance for argon application and to elucidate the potential mechanisms of argon neuroprotection. Early and appropriate argon administration at as high a concentration as possible offers favorable neuroprotection in IS. Argon inhalation has been shown to provide some long-term protection benefits. Argon provides the anti-oxidative stress, anti-inflammatory and anti-apoptotic cytoprotective effects mainly around Toll-like receptor 2/4 (TLR2/4), mediated by extracellular signal-regulated kinase 1/2 (ERK1/2), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), nuclear factor kappa-B (NF-ĸB) and B-cell leukemia/lymphoma 2 (Bcl-2). Therefore, argon holds significant promise as a novel clinical neuroprotective gas agent for ischemic stroke after further researches to identify the optimal application strategy and elucidate the underlying mechanism.

Extracellular vesicles promote autophagy in human microglia through lipid raft-dependent mechanisms

Autophagy dysfunction has been closely related with pathogenesis of many neurodegenerative diseases and therefore represents a potential therapeutic target. Extracellular vesicles (EVs) may act as potent anti-inflammatory agents and also modulators of autophagy in target cells. However, the molecular mechanisms by which EVs modulate autophagy flux in human microglia remain largely unexplored. In the present study, we investigated the effects of EVs derived from human oral mucosa stem cells on the autophagy in human microglia. We demonstrate that EVs promoted autophagy and autophagic flux in human microglia and that this process was dependent on the integrity of lipid rafts. Lipopolysaccharide (LPS) also activated autophagy, but combined treatment with EVs and LPS suppressed autophagy response, indicating interference between these signaling pathways. Blockage of Toll-like receptor 4 (TLR4) with anti-TLR4 antibody suppressed EV-induced autophagy. Furthermore, inhibition of the EV-associated heat shock protein (HSP70) chaperone which is one of the endogenous ligands of the TLR4 also suppressed EV-induced lipid raft formation and autophagy. Pre-treatment of microglia with a selective inhibitor of αvβ3/αvβ5 integrins cilengitide inhibited EV-induced autophagy. Finally, blockage of purinergic P2X4 receptor (P2X4R) with selective inhibitor 5-BDBD also suppressed EV-induced autophagy. In conclusion, we demonstrate that EVs activate autophagy in human microglia through interaction with HSP70/TLR4, αVβ3/αVβ5, and P2X4R signaling pathways and that these effects depend on the integrity of lipid rafts. Our findings could be used to develop new therapeutic strategies targeting disease-associated microglia.

Pharmacological and stem cell therapy of stroke in animal models: Do they accurately reflect the response of humans?

Cerebrovascular diseases are the second leading cause of death worldwide. Despite significant research investment, the only available therapeutic options are mechanical thrombectomy and tissue plasminogen activator thrombolysis. None of the more than a thousand drugs tested on animal models have proven successful in human clinical trials. Several factors contribute to this poor translation of data from stroke-related animal models to human stroke patients. Firstly, our understanding of the molecular and cellular processes involved in recovering from an ischemic stroke is severely limited. Secondly, although the risk of stroke is particularly high among older patients with comorbidities, most drugs are tested on young, healthy animals in controlled laboratory conditions. Furthermore, in animal models, the tracking of post-stroke recovery typically spans only 3 to 28 days, with occasional extensions to 60 days, whereas human stroke recovery is a more extended and complex process. Thirdly, young animal models often exhibit a considerably higher rate of spontaneous recovery compared to humans following a stroke. Fourth, only a very limited number of animals are utilized for each condition, including control groups. Another contributing factor to the much smaller beneficial effects in humans is that positive outcomes from numerous animal studies are more readily accepted than results reported in human trials that do not show a clear benefit to the patient. Useful recommendations for conducting experiments in animal models, with increased chances of translatability to humans, have been issued by both the STEPS investigative team and the STAIR committee. However, largely, due to economic factors, these recommendations are largely ignored. Furthermore, one might attribute the overall failures in predicting and subsequently developing effective acute stroke therapies beyond thrombolysis to potential design deficiencies in clinical trials.

BMSC-Exosomes attenuate ALP dysfunction by restoring lysosomal function via the mTOR/TFEB Axis to reduce cerebral ischemia-reperfusion injury

BACKGROUND

The complex pathophysiological changes following cerebral ischemia-reperfusion injury (CIRI) include the accumulation of defective proteins and damaged organelles, which cause massive neuron demise. To preserve cellular homeostasis, the autophagy-lysosomal pathway (ALP) is crucial for neurons to dispose of these substances. Many studies have shown that bone mesenchymal stem cell exosomes (BMSC-Exos) can reduce CIRI. However, the specific mechanisms have not been well elucidated, a fact that limits its widespread clinical use. This study aimed to clarify whether BMSC-Exos could attenuate ALP dysfunction by restoring lysosomal function after CIRI via inhibiting mTOR and then activating TFEB nucleus translocation.

METHODS

In this study, Flow cytometry, Nanoparticle tracking analysis (NTA), Transmission electron microscope (TEM), and Western blot were used to identify the BMSCs and BMSC-Exos used in this experiment as conforming to the requirements. In vivo experiments, SD rats were modeled with temporary middle cerebral artery occlusion (tMCAO), and BMSC-Exos was injected into the tail vein 2 h after modeling. Triphenyl tetrazolium chloride (TTC) staining, modified neurological severity scores (mNSS), corner turn test, and rotating rod test were used to detect neurological deficits in rats after BMSC-Exos intervention. Western blot and Immunofluorescence were used to detect ALP, transcription factor EB(TFEB) nucleus translocation, and mammalian target of rapamycin (mTOR) change at different time points after modeling and after BMSC-Exos intervention. In vitro experiments, pheochromocytoma cells (PC12) cells were subjected to oxygen-glucose deprivation and reperfusion (OGD/R) modeling to mimic CIRI, and were respectively intervened with BMSC-Exos, BMSC-Exos + MHY 1485 (the mTOR agonist), Rapamycin (the mTOR inhibitor). CCK8, Western blot, and Immunofluorescence were used to detect PC12 cell survival, TFEB nucleus translocation, and cathepsin B(CTSB) Immunofluorescence intensity.

RESULTS

We found that ALP dysfunction occurred 72 h after tMCAO, and BMSC-Exos can attenuate ALP dysfunction by restoring lysosomal function. Next, we examined TFEB nucleus translocation and the expression of mTOR, a key regulator of translocation. We found that BMSC-Exos could inhibit mTOR and activate TFEB nucleus translocation. Additional in vitro tests revealed that BMSC-Exos could increase PC12 cell survival after OGD/R, activating TFEB nucleus translocation and enhancing the fluorescence intensity of CTSB, which in turn could be reversed by the mTOR agonist, MHY1485. This effect was similar to another mTOR inhibitor, Rapamycin.

CONCLUSION

BMSC-Exos could attenuate ALP dysfunction by restoring lysosomal function after CIRI by inhibiting mTOR and then promoting TFEB nucleus translocation.

Lineage-Specific Mesenchymal Stromal Cells Derived from Human iPSCs Showed Distinct Patterns in Transcriptomic Profile and Extracellular Vesicle Production

Over the past decades, mesenchymal stromal cells (MSCs) have been extensively investigated as a potential therapeutic cell source for the treatment of various disorders. Differentiation of MSCs from human induced pluripotent stem cells (iMSCs) has provided a scalable approach for the biomanufacturing of MSCs and related biological products. Although iMSCs shared typical MSC markers and functions as primary MSCs (pMSCs), there is a lack of lineage specificity in many iMSC differentiation protocols. Here, a stepwise hiPSC-to-iMSC differentiation method is employed via intermediate cell stages of neural crest and cytotrophoblast to generate lineage-specific MSCs with varying differentiation efficiencies and gene expression. Through a comprehensive comparison between early developmental cell types (hiPSCs, neural crest, and cytotrophoblast), two lineage-specific iMSCs, and six source-specific pMSCs, are able to not only distinguish the transcriptomic differences between MSCs and early developmental cells, but also determine the transcriptomic similarities of iMSC subtypes to postnatal or perinatal pMSCs. Additionally, it is demonstrated that different iMSC subtypes and priming conditions affected EV production, exosomal protein expression, and cytokine cargo.

Advances in Engineered Nanoparticles for the Treatment of Ischemic Stroke by Enhancing Angiogenesis

Angiogenesis, or the formation of new blood vessels, is a natural defensive mechanism that aids in the restoration of oxygen and nutrition delivery to injured brain tissue after an ischemic stroke. Angiogenesis, by increasing vessel development, may maintain brain perfusion, enabling neuronal survival, brain plasticity, and neurologic recovery. Induction of angiogenesis and the formation of new vessels aid in neurorepair processes such as neurogenesis and synaptogenesis. Advanced nano drug delivery systems hold promise for treatment stroke by facilitating efficient transportation across the the blood-brain barrier and maintaining optimal drug concentrations. Nanoparticle has recently been shown to greatly boost angiogenesis and decrease vascular permeability, as well as improve neuroplasticity and neurological recovery after ischemic stroke. We describe current breakthroughs in the development of nanoparticle-based treatments for better angiogenesis therapy for ischemic stroke employing polymeric nanoparticles, liposomes, inorganic nanoparticles, and biomimetic nanoparticles in this study. We outline new nanoparticles in detail, review the hurdles and strategies for conveying nanoparticle to lesions, and demonstrate the most recent advances in nanoparticle in angiogenesis for stroke treatment.

Extracellular vesicles as nanotheranostic platforms for targeted neurological disorder interventions

Central Nervous System (CNS) disorders represent a profound public health challenge that affects millions of people around the world. Diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and traumatic brain injury (TBI) exemplify the complexities and diversities that complicate their early detection and the development of effective treatments. Amid these challenges, the emergence of nanotechnology and extracellular vesicles (EVs) signals a new dawn for treating and diagnosing CNS ailments. EVs are cellularly derived lipid bilayer nanosized particles that are pivotal in intercellular communication within the CNS and have the potential to revolutionize targeted therapeutic delivery and the identification of novel biomarkers. Integrating EVs with nanotechnology amplifies their diagnostic and therapeutic capabilities, opening new avenues for managing CNS diseases. This review focuses on examining the fascinating interplay between EVs and nanotechnology in CNS theranostics. Through highlighting the remarkable advancements and unique methodologies, we aim to offer valuable perspectives on how these approaches can bring about a revolutionary change in disease management. The objective is to harness the distinctive attributes of EVs and nanotechnology to forge personalized, efficient interventions for CNS disorders, thereby providing a beacon of hope for affected individuals. In short, the confluence of EVs and nanotechnology heralds a promising frontier for targeted and impactful treatments against CNS diseases, which continue to pose significant public health challenges. By focusing on personalized and powerful diagnostic and therapeutic methods, we might improve the quality of patients.

HMGB1/STAT3/p65 axis drives microglial activation and autophagy exert a crucial role in chronic Stress-Induced major depressive disorder

INTRODUCTION

Neuroinflammation and autophagy are implicated in stress-related major depressive disorder (MDD), but the underlying molecular mechanisms remain largely unknown.

OBJECTIVES

Here, we identified that MDD regulated by HMGB1/STAT3/p65 axis mediated microglial activation and autophagy for the first time. Further investigations were performed to uncover the effects of this axis on MDD in vivo and in vitro.

METHODS

Bioinformatics analyses were used to re-analysis the transcriptome data from the dorsolateral prefrontal cortex (dlPFC) of post-mortem male MDD patients. The expression level of HMGB1 and its correlation with depression symptoms were explored in MDD clinical patients and chronic social defeat stress (CSDS)-induced depression model mice. Specific adeno-associated virus and recombinant (r)HMGB1 injection into the medial PFC (mPFC) of mice, and pharmacological inhibitors with rHMGB1 in two microglial cell lines exposed to lipopolysaccharide were used to analyze the effects of HMGB1/STAT3/p65 axis on MDD.

RESULTS

The differential expression of genes from MDD patients implicated in microglial activation and autophagy regulated by HMGB1/STAT3/p65 axis. Serum HMGB1 level was elevated in MDD patients and positively correlated with symptom severity. CSDS not only induced depression-like states in mice, but also enhanced microglial reactivity, autophagy as well as activation of the HMGB1/STAT3/p65 axis in mPFC. The expression level of HMGB1 was mainly increased in the microglial cells of CSDS-susceptible mice, which also correlated with depressive-like behaviors. Specific HMGB1 knockdown produced a depression-resilient phenotype and suppressed the associated microglial activation and autophagy effects of CSDS-induced. The effects induced by CSDS were mimicked by exogenous administration of rHMGB1 or specific overexpression of HMGB1, while blocked by STAT3 inhibitor or p65 knockdown. In vitro, inhibition of HMGB1/STAT3/p65 axis prevented lipopolysaccharide-induced microglial activation and autophagy, while rHMGB1 reversed these changes.

CONCLUSION

Our study established the role of microglial HMGB1/STAT3/p65 axis in mPFC in mediating microglial activation and autophagy in MDD.

CD73-positive pediatric urethral mesenchymal stem-like cell-derived small extracellular vesicles stimulate angiogenesis

Introduction

Angiogenesis plays an important role in the repair of urethral injury, and stem cells and their secretomes can promote angiogenesis. We obtained pediatric urethral mesenchymal stem-like cells (PU-MSLCs) in an earlier study. This project studied the pro-angiogenic effect of PU-MSLC-derived small extracellular vesicles (PUMSLC-sEVs) and the underlying mechanisms.

Materials and methods

PUMSLCs and PUMSLC-sEVs were cultivated and identified. Then, biological methods such as the ethynyl deoxyuridine (EdU) incorporation assay, Cell Counting Kit-8 (CCK-8) assay, scratch wound assay, Transwell assay, and tube formation assay were used to study the effect of PUMSLC-sEVs on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). We explored whether the proangiogenic effect of PUMSLC-sEVs is related to CD73 and whether adenosine (ADO, a CD73 metabolite) promoted angiogenesis. GraphPad Prism 8 software was used for data analysis.

Results

We observed that PUMSLC-sEVs significantly promoted the proliferation, migration, and tube-forming abilities of HUVECs. PUMSLC-sEVs delivered CD73 molecules to HUVECs to promote angiogenesis. The angiogenic ability of HUVECs was enhanced after treatment with extracellular ADO produced by CD73, and PUMSLC-sEVs further promoted angiogenesis by activating Adenosine Receptor A2A (A2AR).

Conclusions

These observations suggest that PUMSLC-sEVs promote angiogenesis, possibly through activation of the CD73/ADO/A2AR signaling axis.

Therapeutic potential of mesenchymal stem cells for cerebral small vessel disease

Cerebral small vessel disease (CSVD), as the most common, chronic and progressive vascular disease on the brain, is a serious neurological disease, whose pathogenesis remains unclear. The disease is a leading cause of stroke and vascular cognitive impairment and dementia, and contributes to about 20% of strokes, including 25% of ischemic strokes and 45% of dementias. Undoubtedly, the high incidence and poor prognosis of CSVD have brought a heavy economic and medical burden to society. The present treatment of CSVD focuses on the management of vascular risk factors. Although vascular risk factors may be important causes or accelerators of CSVD and should always be treated in accordance with best clinical practice, controlling risk factors alone could not curb the progression of CSVD brain injury. Therefore, developing safer and more effective treatment strategies for CSVD is urgently needed. Recently, mesenchymal stem cells (MSCs) therapy has become an emerging therapeutic modality for the treatment of central nervous system disease, given their paracrine properties and immunoregulatory. Herein, we discussed the therapeutic potential of MSCs for CSVD, aiming to enable clinicians and researchers to understand of recent progress and future directions in the field.

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

Background

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

Methods

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

Results

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

Conclusion

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

Mesenchymal Stem Cells Accelerate Recovery of Acetic Acid-Induced Chronic Gastric Ulcer by Regulating Ekt/Akt/TRIM29 Axis

Chronic gastric ulcer (CGU), a prevalent digestive disease, has a high incidence and is seriously harmful to human health. Mesenchymal stem cells (MSCs) have been proven to have beneficial therapeutic effects in many human diseases. Here, a CGU model induced by acetic acid in mice was used to evaluate the repair effects and potential mechanism of human umbilical cord-derived MSCs (hUC-MSCs) and hUC-MSCs derived conditioned medium (hUC-MSC-CM). We found that hUC-MSCs and hUC-MSC-CM treatment significantly repaired morphological characteristics of CGU, improved proliferation and decreased apoptosis of gastric cells, and promoted the generation of new blood vessels in granulation tissues. In addition, we could detect the homing of MSCs in gastric tissue, and MSCs may differentiate into Lgr5-positive cells. As well as this, in vitro experiments showed that hUC-MSC-CM could promote cell proliferation, stimulate cell cycle progression, and reduce the incidence of apoptosis. The transcriptome of cells and the iTRAQ proteome of gastric tissues suggest that MSCs may play a therapeutic role by increasing the expression of TRIM29. Additionally, it was found that knocking down TRIM29 significantly decreased the ameliorative effects of hUC-MSC-CM on cell apoptosis. As a result of further molecular experiments, it was found that TRIM29 is capable of phosphorylating Erk/Akt in specific cell type. As a whole, it appears that hUC-MSCs can be an effective therapeutic approach for promoting gastric ulcer healing and may exert therapeutic effects in the form of paracrine and differentiation into gastric cells.

Extracellular vesicle biogenesis of three-dimensional human pluripotent stem cells in a novel Vertical-Wheel bioreactor

Extracellular vesicles (EVs) secreted by human-induced pluripotent stem cells (hiPSCs) have great potential as cell-free therapies in various diseases, including prevention of blood-brain barrier senescence and stroke. However, there are still challenges in pre-clinical and clinical use of hiPSC-EVs due to the need for large-scale production of a large quantity. Vertical-Wheel bioreactors (VWBRs) have design features that allow the biomanufacturing of hiPSC-EVs using a scalable aggregate or microcarrier-based culture system under low shear stress. EV secretion by undifferentiated hiPSCs expanded as 3-D aggregates and on Synthemax II microcarriers in VWBRs were investigated. Additionally, two types of EV collection media, mTeSR and HBM, were compared. The hiPSCs were characterized by metabolite and transcriptome analysis as well as EV biogenesis markers. Protein and microRNA cargo were analysed by proteomics and microRNA-seq, respectively. The in vitro functional assays of microglia stimulation and proliferation were conducted. HiPSCs expanded as 3-D aggregates and on microcarriers had comparable cell number, while microcarrier culture had higher glucose consumption, higher glycolysis and lower autophagy gene expression based on mRNA-seq. The microcarrier cultures had at least 17-23 fold higher EV secretion, and EV collection in mTeSR had 2.7-3.7 fold higher yield than HBM medium. Microcarrier culture with mTeSR EV collection had a smaller EV size than other groups, and the cargo was enriched with proteins (proteomics) and miRNAs (microRNA-seq) reducing apoptosis and promoting cell proliferation (e.g. Wnt-related pathways). hiPSC-EVs demonstrated the ability of stimulating proliferation and M2 polarization of microglia in vitro. HiPSC expansion on microcarriers produces much higher yields of EVs than hiPSC aggregates in VWBRs. EV collection in mTeSR increases yield compared to HBM. The biomanufactured EVs from microcarrier culture in mTeSR have exosomal characteristics and are functional in microglia stimulation, which paves the ways for future in vivo anti-aging study.

Extracellular vesicles from induced pluripotent stem cell-derived mesenchymal stem cells enhance the recovery of acute kidney injury

BACKGROUND AIMS

To investigate whether the extracellular vesicles (EVs) from mesenchymal stem cell-like cells derived from induced pluripotent stem cells (iMSC-EVs) can inhibit the progression of acute kidney injury (AKI).

METHODS

The characteristics of iMSC-EVs were confirmed by immunoblotting, cryo-transmission electron microscopy, nanoparticle tracking analysis, and their localization in kidneys. Using human renal epithelial cells, the potential of iMSC-EVs to stimulate the growth and survival of HK-2 cells undergoing cisplatin-induced cell death was investigated. The anti-inflammatory effects of iMSC-EVs was examined in M1-polarized THP-1 macrophages. Subsequently, the therapeutic potential of iMSC-EVs was assessed in cisplatin-induced acute kidney injury in BALB/c mice. The anti-apoptotic and anti-inflammatory effect of iMSC-EVs was evaluated using serum biochemistry, histology, immunohistochemistry, and gene expression analysis.

RESULTS

iMSC-EVs promoted the growth of renal epithelial cell (HK-2) and enhanced the survival of HK-2 undergoing cisplatin-induced cell death. In cisplatin-induced mice with AKI, iMSC-EVs alleviated AKI, as shown by reduced blood nitrogen urea/creatinine and increased body weight. Also, iMSC-EVs enhanced renal tissue integrity and the number of proliferating cell nuclear antigen-positive tubules. iMSC-EVs decreased the infiltration of immune cells, reduced the expression of inflammatory genes in M1-induced THP-1 cells and enhanced capillary density in the kidney of AKI mice. Real-time quantitative polymerase chain reaction analysis showed that the expression of inflammatory genes in the kidney of AKI mice was reduced compared with that received vehicle. Immunoblotting revealed that iMSC-EVs led to a decreased protein expression of key inflammatory genes. Also, iMSC-EVs reversed the activation of ERK1/2 signaling induced by AKI. Finally, iMSC-EVs inhibited the apoptosis of HK-2 cells induced by cisplatin as well as that of renal tissue of AKI mice.

CONCLUSIONS

Our data suggest that iMSC-EVs have potential to become a novel, cell-free therapeutic for cisplatin-induced AKI.

mTOR signalling pathway in stem cell bioactivities and angiogenesis potential

The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.

Stem cell-based interventions for the treatment of stroke in newborn infants

BACKGROUND

Perinatal stroke refers to a diverse but specific group of cerebrovascular diseases that occur between 20 weeks of fetal life and 28 days of postnatal life. Acute treatment options for perinatal stroke are limited supportive care, such as controlling hypoglycemia and seizures. Stem cell-based therapies offer a potential therapeutic approach to repair, restore, or regenerate injured brain tissue. Preclinical findings have culminated in ongoing human neonatal studies.

OBJECTIVES

To evaluate the benefits and harms of stem cell-based interventions for the treatment of stroke in newborn infants compared to control (placebo or no treatment) or stem-cell based interventions of a different type or source.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, and three trials registries in February 2023. We planned to search the reference lists of included studies and relevant systematic reviews for studies not identified by the database searches.

SELECTION CRITERIA

We attempted to include randomized controlled trials, quasi-randomized controlled trials, and cluster trials that evaluated any of the following comparisons. • Stem cell-based interventions (any type) versus control (placebo or no treatment) • Mesenchymal stem/stromal cells (MSCs) of a specifictype (e.g. number of doses or passages) or source (e.g. autologous/allogeneic or bone marrow/cord) versus MSCs of another type or source • Stem cell-based interventions (other than MSCs) of a specific type (e.g. mononuclear cells, oligodendrocyte progenitor cells, neural stem cells, hematopoietic stem cells, or induced pluripotent stem cell-derived cells) or source (e.g. autologous/allogeneic or bone marrow/cord) versus stem cell-based interventions (other than MSCs) of another type or source • MSCs versus stem cell-based interventions other than MSCs We planned to include all types of transplantation regardless of cell source (bone marrow, cord blood, Wharton's jelly, placenta, adipose tissue, peripheral blood), type of graft (autologous or allogeneic), and dose.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were all-cause neonatal mortality, major neurodevelopmental disability, and immune rejection or any serious adverse event. Our secondary outcomes included all-cause mortality prior to first hospital discharge, seizures, adverse effects, and death or major neurodevelopmental disability at 18 to 24 months of age. We planned to use GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified no completed or ongoing randomized trials that met our inclusion criteria. We excluded three studies: two were phase 1 trials, and one included newborn infants with conditions other than stroke (i.e. cerebral ischemia and anemia). Among the three excluded studies, we identified the first phase 1 trial on the use of stem cells for neonatal stroke. It reported that a single intranasal application of bone marrow-derived MSCs in term neonates with a diagnosis of perinatal arterial ischemic stroke (PAIS) was feasible and apparently not associated with severe adverse events. However, the trial included only 10 infants, and follow-up was limited to three months.

AUTHORS' CONCLUSIONS

No evidence is currently available to evaluate the benefits and harms of stem cell-based interventions for treatment of stroke in newborn infants. We identified no ongoing studies. Future clinical trials should focus on standardizing the timing and method of cell delivery and cell processing to optimize the therapeutic potential of stem cell-based interventions and safety profiles. Phase 1 and large animal studies might provide the groundwork for future randomized trials. Outcome measures should include all-cause mortality, major neurodevelopmental disability and immune rejection, and any other serious adverse events.

Novel Strategies for Angiogenesis in Tissue Injury: Therapeutic Effects of iPSCs-Derived Exosomes

Regeneration after tissue injury is a dynamic and complex process, and angiogenesis is necessary for normal physiological activities and tissue repair. Induced pluripotent stem cells are a new approach in regenerative medicine, which provides good model for the study of difficult-to-obtain human tissues, patient-specific therapy, and tissue repair. As an innovative cell-free therapeutic strategy, the main advantages of the treatment of induced pluripotent stem cells (iPSCs)-derived exosomes are low in tumorigenicity and immunogenicity, which become an important pathway for tissue injury. This review focuses on the mechanism of the angiogenic effect of iPSCs-derived exosomes on wound repair in tissue injury and their potential therapeutic targets, with a view to providing a theoretical basis for the use of iPSCs-derived exosomes in clinical therapy.

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.

Signaling pathways in brain ischemia: Mechanisms and therapeutic implications

Ischemic stroke occurs when the arteries supplying blood to the brain are narrowed or blocked, inducing damage to brain tissue due to a lack of blood supply. One effective way to reduce brain damage and alleviate symptoms is to reopen blocked blood vessels in a timely manner and reduce neuronal damage. To achieve this, researchers have focused on identifying key cellular signaling pathways that can be targeted with drugs. These pathways include oxidative/nitrosative stress, excitatory amino acids and their receptors, inflammatory signaling molecules, metabolic pathways, ion channels, and other molecular events involved in stroke pathology. However, evidence suggests that solely focusing on protecting neurons may not yield satisfactory clinical results. Instead, researchers should consider the multifactorial and complex mechanisms underlying stroke pathology, including the interactions between different components of the neurovascular unit. Such an approach is more representative of the actual pathological process observed in clinical settings. This review summarizes recent research on the multiple molecular mechanisms and drug targets in ischemic stroke, as well as recent advances in novel therapeutic strategies. Finally, we discuss the challenges and future prospects of new strategies based on the biological characteristics of stroke.

Neuroprotective Effects of Human-Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cell Extracellular Vesicles in Ischemic Stroke Models

BACKGROUND

Stroke represents the second leading cause of death and the primary cause of long-term disability in humans. The transplantation of mesenchymal stem cells (MSC) reportedly improves functional outcomes in animal models of cerebral ischemia. Here, we evaluate the neuroprotective potential of extracellular vesicles secreted from human-induced pluripotent stem cell-derived mesenchymal stem cells (hiPS-MSC-EV) using preclinical cell-based and animal-based models of ischemic strokes.

METHODS

hiPS-MSC-EV were isolated using an ultrafiltration method. HT22 cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury for 2 h, followed by treatment with hiPS-MSC-EV (100 μg/mL). Male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) followed by an intravenous injection of hiPS-MSC-EV (100 μg) at three distinct time points.

RESULTS

Our experimental approach revealed hiPS-MSC-EV promoted HT22 cell proliferation, reduced apoptosis, and altered cellular morphology following OGD/R. In addition, hiPS-MSC-EV reduced the volume of infarcts, improved spontaneous movement abilities, and enhanced angiogenesis by expressing the VEGF and CXCR4 proteins in the infarcted hemisphere of the MCAO-treated mouse model.

CONCLUSION

Our findings provide evidence of the potential neuroprotective effects of hiPS-MSC-derived extracellular vesicles (hiPS-MSC-EVs) in both in vitro and in vivo mouse models of ischemic stroke. These results suggest that hiPS-MSC-EVs may play a role in neurorestoration and offer insights into potential cell-free strategies for addressing cerebral ischemia.

iPSC-derived mesenchymal stem cells attenuate cerebral ischemia-reperfusion injury by inhibiting inflammatory signaling and oxidative stress

Induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) hold great promise as a cell source for transplantation into injured tissues to alleviate inflammation. However, the therapeutic efficacy of iMSC transplantation for ischemic stroke remains unknown. In this study, we evaluated the therapeutic effects of iMSC transplantation on brain injury after ischemia-reperfusion using a rat transient middle cerebral artery occlusion model and compared its therapeutic efficacy with that of bone marrow mesenchymal stem cells (BMMSCs). We showed that iMSCs and BMMSCs reduced infarct volumes after reperfusion and significantly improved motor function on days 3, 7, 14, 28, and 56 and cognitive function on days 28 and 56 after reperfusion compared with the vehicle group. Furthermore, immunological analyses revealed that transplantation of iMSCs and BMMSCs inhibited microglial activation and expression of proinflammatory cytokines and suppressed oxidative stress and neuronal cell death in the cerebral cortex at the ischemic border zone. No difference in therapeutic effect was observed between the iMSC and BMMSC groups. Taken together, our results demonstrate that iMSC therapy can be a practical alternative as a cell source for attenuation of brain injury and improvement of neurological function because of the unlimited supply of uniform therapeutic cells.

Novel Therapeutic Opportunities for Neurodegenerative Diseases with Mesenchymal Stem Cells: The Focus on Modulating the Blood-Brain Barrier

Neurodegenerative disorders encompass a broad spectrum of profoundly disabling situations that impact millions of individuals globally. While their underlying causes and pathophysiology display considerable diversity and remain incompletely understood, a mounting body of evidence indicates that the disruption of blood-brain barrier (BBB) permeability, resulting in brain damage and neuroinflammation, is a common feature among them. Consequently, targeting the BBB has emerged as an innovative therapeutic strategy for addressing neurological disorders. Within this review, we not only explore the neuroprotective, neurotrophic, and immunomodulatory benefits of mesenchymal stem cells (MSCs) in combating neurodegeneration but also delve into their recent role in modulating the BBB. We will investigate the cellular and molecular mechanisms through which MSC treatment impacts primary age-related neurological conditions like Alzheimer's disease, Parkinson's disease, and stroke, as well as immune-mediated diseases such as multiple sclerosis. Our focus will center on how MSCs participate in the modulation of cell transporters, matrix remodeling, stabilization of cell-junction components, and restoration of BBB network integrity in these pathological contexts.

Current trends and promising clinical utility of IPSC-derived MSC (iMSC)

Mesenchymal stem cells (MSCs) differentiated from human induced pluripotent stem cells (iPSC) or induced MSC (iMSCs) are expected to address issues of scalability and safety as well as the difficulty in producing homogenous clinical grade MSCs as demonstrated by the promising outcomes from preclinical and clinical trials, currently ongoing. The assessment of iMSCs based in vitro and in vivo studies have thus far showed more superior performance as compared to that of the primary or native human MSCs, in terms of cell proliferation, expansion capacity, immunomodulation properties as well as the influence of paracrine signaling and exosomal influence in cell-cell interaction. In this chapter, an overview of current well-established methods in generating a sustainable source of iMSCs involving well defined culture media is discussed followed by the properties of iMSC as compared to that of MSC and its promising prospects for continuous development into potential clinical grade applications.

Engineering considerations of iPSC-based personalized medicine

Personalized medicine aims to provide tailored medical treatment that considers the clinical, genetic, and environmental characteristics of patients. iPSCs have attracted considerable attention in the field of personalized medicine; however, the inherent limitations of iPSCs prevent their widespread use in clinical applications. That is, it would be important to develop notable engineering strategies to overcome the current limitations of iPSCs. Such engineering approaches could lead to significant advances in iPSC-based personalized therapy by offering innovative solutions to existing challenges, from iPSC preparation to clinical applications. In this review, we summarize how engineering strategies have been used to advance iPSC-based personalized medicine by categorizing the development process into three distinctive steps: 1) the production of therapeutic iPSCs; 2) engineering of therapeutic iPSCs; and 3) clinical applications of engineered iPSCs. Specifically, we focus on engineering strategies and their implications for each step in the development of iPSC-based personalized medicine.

JAM-A Overexpression in Human Umbilical Cord-Derived Mesenchymal Stem Cells Accelerated the Angiogenesis of Diabetic Wound By Enhancing Both Paracrine Function and Survival of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) is promising in promoting wound healing mainly due to their paracrine function. Nonetheless, the transplanted MSCs presented poor survival with cell dysfunction and paracrine problem in diabetic environment, thus limiting their therapeutic efficacy and clinical application. JAM-A, an adhesion molecule, has been reported to play multi-functional roles in diverse cells. We therefore investigated the potential effect of JAM-A on MSCs under diabetic environment and explored the underlying mechanism. Indeed, high-glucose condition inhibited MSCs viability and JAM-A expression. However, JAM-A abnormality was rescued by lentivirus transfection and JAM-A overexpression promoted MSCs proliferation, migration and adhesion under hyperglycemia. Moreover, JAM-A overexpression attenuated high-glucose-induced ROS production and MSCs apoptosis. The bio-effects of JAM-A on MSCs under hyperglycemia were confirmed by RNA-seq with enrichment analyses. Moreover, Luminex chip results showed JAM-A overexpression dramatically upregulated PDGF-BB and VEGF in the supernatant of MSCs, which was verified by RT-qPCR and western blotting. The supernatant was further found to facilitate HUVECs proliferation, migration and angiogenesis under hyperglycemia. In vivo experiments revealed JAM-A overexpression significantly enhanced MSCs survival, promoted wound angiogenesis, and thus accelerated diabetic wound closure, partially by enhancing PDGF-BB and VEGF expression. This study firstly demonstrated that JAM-A expression of MSCs was inhibited upon high-glucose stimulation. JAM-A overexpression alleviated high-glucose-induced MSCs dysfunction, enhanced their anti-oxidative capability, protected MSCs from hyperglycemia-induced apoptosis and improved their survival, thus strengthening MSCs paracrine function to promote angiogenesis and significantly accelerating diabetic wound healing, which offers a promising strategy to maximize MSCs-based therapy in diabetic wound.

Angiogenesis after ischemic stroke

Owing to its high disability and mortality rates, stroke has been the second leading cause of death worldwide. Since the pathological mechanisms of stroke are not fully understood, there are few clinical treatment strategies available with an exception of tissue plasminogen activator (tPA), the only FDA-approved drug for the treatment of ischemic stroke. Angiogenesis is an important protective mechanism that promotes neural regeneration and functional recovery during the pathophysiological process of stroke. Thus, inducing angiogenesis in the peri-infarct area could effectively improve hemodynamics, and promote vascular remodeling and recovery of neurovascular function after ischemic stroke. In this review, we summarize the cellular and molecular mechanisms affecting angiogenesis after cerebral ischemia registered in PubMed, and provide pro-angiogenic strategies for exploring the treatment of ischemic stroke, including endothelial progenitor cells, mesenchymal stem cells, growth factors, cytokines, non-coding RNAs, etc.

Therapeutic potential of stem cell extracellular vesicles for ischemic stroke in preclinical rodent models: a meta-analysis

BACKGROUND

Extracellular vesicles derived from stem cells (SC-EVs) have been proposed as a novel therapy for ischemic stroke. However, their effects remain incompletely understood. Therefore, we conducted this meta-analysis to systematically review the efficacy of SC-EVs on ischemic stroke in preclinical rodent models.

METHODS

Using PubMed, EMBASE, and the Web of Science, we searched through studies published up to August 2021 that investigated the treatment effects of SC-EVs in a rodent ischemic stroke model. Infarct volume was the primary outcome. Neurological severity scores (mNSS) were the secondary outcome. The standard mean difference (SMD) and the confidence interval (CI) were calculated using a random-effects model. R and Stata 15.1 were used to conduct the meta-analysis.

RESULTS

Twenty-one studies published from 2015 to 2021 met the inclusion criteria. We also found that SCs-EVs reduced infarct volume by an SMD of - 2.05 (95% CI - 2.70, - 1.40; P < 0.001). Meanwhile, our results revealed an overall positive effect of SCs-derived EVs on the mNSS with an SMD of - 1.42 (95% CI - 1.75, - 1.08; P < 0.001). Significant heterogeneity among studies was observed. Further stratified and sensitivity analyses did not identify the source of heterogeneity.

CONCLUSION

The present meta-analysis confirmed that SC-EV therapy could improve neuron function and reduce infarct volume in a preclinical rodent ischemic stroke model, providing helpful clues for human clinical trials on SC-EVs.

Current developments and therapeutic potentials of exosomes from induced pluripotent stem cells-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells derived from adult human tissues that have the ability to proliferate in vitro and maintain their multipotency, making them attractive cell sources for regenerative medicine. However, MSCs reportedly show limited proliferative capacity with inconsistent therapeutic outcomes due to their heterogeneous nature. On the other hand, induced pluripotent stem cells (iPSC) have emerged as an alternative source for the production of various specialized cell types via their ability to differentiate from all three primary germ layers, leading to applications in regenerative medicine, disease modeling, and drug therapy. Notably, iPSCs can differentiate into MSCs in monolayer, commonly referred to as induced mesenchymal stem cells (iMSCs). These cells show superior therapeutic qualities compared with adult MSCs as the applications of the latter are restricted by passage number and autoimmune rejection when applied in tissue regeneration trials. Furthermore, increasing evidence shows that the therapeutic properties of stem cells are a consequence of the paracrine effects mediated by their secretome such as from exosomes, a type of extracellular vesicle secreted by most cell types. Several studies that investigated the potential of exosomes in regenerative medicine and therapy have revealed promising results. Therefore, this review focuses on the recent findings of exosomes secreted from iMSCs as a potential noncell-based therapy.

iPSC-sEVs alleviate microglia senescence to protect against ischemic stroke in aged mice

The polarization of microglia plays an important role in the outcome of ischemic stroke (IS). In the aged population, senescent microglia show a predominant pro-inflammatory phenotype, which leads to worse outcomes in aged ischemic stroke compared to young ischemic stroke. Recent research demonstrated that inducible pluripotent stem cell-derived small extracellular vesicles (iPSC-sEVs) possess the significant anti-ageing ability. We hypothesized that iPSC-sEVs could alleviate microglia senescence to regulate microglia polarization in aged ischemic stroke. In this study, we showed that treatment with iPSC-sEVs significantly alleviated microglia senescence as indicated by the decreased senescence-associated proteins including P16, P21, P53, and γ-H2AX as well as the activity of SA-β-gal, and inhibited pro-inflammatory activation of microglia both in vivo and in vitro. Furthermore, iPSC-sEVs shifted microglia from pro-inflammatory phenotype to anti-inflammatory phenotype, which reduced the apoptosis of neurons, and improved the outcome of aged stroke mice. Mechanism studies showed that iPSC-sEVs reversed the loss of Rictor and downstream p-AKT (s473) in senescent microglia, which was involved in the senescence and pro-inflammatory phenotype regulation of microglia. Inhibition of Rictor abolished the iPSC-sEVs-afforded phosphorylation of AKT and alleviation of inflammation of senescent microglia. Proteomics results indicated that iPSC-sEVs carried transforming growth factor-β1 (TGF-β1) to upregulate Rictor and p-AKT in senescent microglia, which could be hindered by blocking TGF-β1. Taken together, our work demonstrates iPSC-sEVs reverse the senescent characteristic of microglia in aged brains and therefore improve the outcome after stroke, at least, via delivering TGF-β1 to upregulate Rictor and p-AKT. Our data suggest that iPSC-sEVs might be a novelty therapeutic method for aged ischemic stroke and other diseases involving senescent microglia.

The Applications and Potentials of Extracellular Vesicles from Different Cell Sources in Periodontal Regeneration

Periodontitis is a chronic infectious disease worldwide that can cause damage to periodontal supporting tissues including gingiva, bone, cementum and periodontal ligament (PDL). The principle for the treatment of periodontitis is to control the inflammatory process. Achieving structural and functional regeneration of periodontal tissues is also essential and remains a major challenge. Though many technologies, products, and ingredients were applied in periodontal regeneration, most of the strategies have limited outcomes. Extracellular vesicles (EVs) are membranous particles with a lipid structure secreted by cells, containing a large number of biomolecules for the communication between cells. Numerous studies have demonstrated the beneficial effects of stem cell-derived EVs (SCEVs) and immune cell-derived EVs (ICEVs) on periodontal regeneration, which may be an alternative strategy for cell-based periodontal regeneration. The production of EVs is highly conserved among humans, bacteria and plants. In addition to eukaryocyte-derived EVs (CEVs), a growing body of literature suggests that bacterial/plant-derived EVs (BEVs/PEVs) also play an important role in periodontal homeostasis and regeneration. The purpose of this review is to introduce and summarize the potential therapeutic values of BEVs, CEVs and PEVs in periodontal regeneration, and discuss the current challenges and prospects for EV-based periodontal regeneration.

Large extracellular vesicles secreted by human iPSC-derived MSCs ameliorate tendinopathy via regulating macrophage heterogeneity

Tendinopathy is a common musculoskeletal disorder which results in chronic pain and reduced performance. The therapeutic effect of stem cell derived-small extracellular vesicles (sEVs) for tendinopathy has been validated in recent years. However, whether large extracellular vesicles (lEVs), another subset of extracellular vesicles, possesses the ability for the improvement of tendinopathy remains unknown. Here, we showed that lEVs secreted from iPSC-derived MSCs (iMSC-lEVs) significantly mitigated pain derived from tendinopathy in rats. Immunohistochemical analysis showed that iMSC-lEVs regulated the heterogeneity of infiltrated macrophages and several inflammatory cytokines in rat tendon tissue. Meanwhile, in vitro experiments revealed that the M1 pro-inflammatory macrophages were repolarized towards M2 anti-inflammatory macrophages by iMSC-lEVs, and this effect was mediated by regulating p38 MAPK pathway. Moreover, liquid chromatography-tandem mass spectrometry analysis identified 2208 proteins encapsulated in iMSC-lEVs, including 134 new-found proteins beyond current Vesiclepedia database. By bioinformatics and Western blot analyses, we showed that DUSP2 and DUSP3, the negative regulator of p38 phosphorylation, were enriched in iMSC-lEVs and could be transported to macrophages. Further, the immunomodulatory effect of iMSC-lEVs on macrophages was validated in explant tendon tissue from tendinopathy patients. Taken together, our results demonstrate that iMSC-lEVs could reduce inflammation in tendinopathy by regulating macrophage heterogeneity, which is mediated via the p38 MAPK pathway by delivery of DUSP2 and DUSP3, and might be a promising candidate for tendinopathy therapy.

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iMSC-lEVs significantly ameliorate tendinopathy both in a rat model and explant tendon tissue from human patient.

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iMSC-lEVs modulate macrophages polarization via p38 MAPK signaling pathway.

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Proteomics analysis of iMSC-lEVs discovers a new set of 134 proteins beyond current Vesiclepedia Database.

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The p38 MAPK signaling pathway-mediated macrophage repolarization was partly regulated by the delivery of DUSP2 and DUSP3.

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The immunoregulatory function of iMSC-lEVs are similar with iMSC-sEVs.

Neuroprotective Strategies for Ischemic Stroke-Future Perspectives

Ischemic stroke is the main cause of death and the most common cause of acquired physical disability worldwide. Recent demographic changes increase the relevance of stroke and its sequelae. The acute treatment for stroke is restricted to causative recanalization and restoration of cerebral blood flow, including both intravenous thrombolysis and mechanical thrombectomy. Still, only a limited number of patients are eligible for these time-sensitive treatments. Hence, new neuroprotective approaches are urgently needed. Neuroprotection is thus defined as an intervention resulting in the preservation, recovery, and/or regeneration of the nervous system by interfering with the ischemic-triggered stroke cascade. Despite numerous preclinical studies generating promising data for several neuroprotective agents, successful bench-to-bedside translations are still lacking. The present study provides an overview of current approaches in the research field of neuroprotective stroke treatment. Aside from "traditional" neuroprotective drugs focusing on inflammation, cell death, and excitotoxicity, stem-cell-based treatment methods are also considered. Furthermore, an overview of a prospective neuroprotective method using extracellular vesicles that are secreted from various stem cell sources, including neural stem cells and bone marrow stem cells, is also given. The review concludes with a short discussion on the microbiota-gut-brain axis that may serve as a potential target for future neuroprotective therapies.

Stem cell‐based interventions for the treatment of stroke in newborn infants

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To evaluate the benefits and harms of stem cell‐based interventions for the treatment of stroke in newborn infants compared to control (placebo or no treatment) or stem‐cell based interventions of a different type or source.

Inducible Pluripotent Stem Cell-Derived Small Extracellular Vesicles Rejuvenate Senescent Blood-Brain Barrier to Protect against Ischemic Stroke in Aged Mice

Blood-brain barrier (BBB) breakdown after ischemic stroke exacerbates brain injury and BBB senescence can cause severe neurological deficits in aged ischemic stroke population. Recent evidence reveals that inducible pluripotent stem cell-derived small extracellular vesicles (iPSC-sEVs) possess phenomenal antisenescence capability. However, whether iPSC-sEVs can rejuvenate BBB senescence to improve stroke outcomes in aged mice remains unknown. Here, we showed that long-term treatment with iPSC-sEVs alleviated aging-induced BBB senescence in aged mice. In aged stroke mice, iPSC-sEVs significantly mitigated BBB integrity damage, reduced the following infiltration of peripheral leukocytes, and decreased the release of pro-inflammatory factors from the leukocytes, which ultimately inhibited neuronal death and improved neurofunctional recovery. Mechanism studies showed that iPSC-sEVs could activate the endothelial nitric oxide synthase (eNOS) and up-regulate sirtuin 1 (Sirt1) in senescent endothelial cells. Blocking the activation of eNOS abolished iPSC-sEV-mediated rejuvenation of BBB senescence and the protection of BBB integrity. Proteomics results demonstrated that iPSC-sEVs were enriched with bioactive factors including AKT serine/threonine kinase 1 (AKT1) and calmodulin (CALM) to activate the eNOS-Sirt1 axis. Further investigation showed that AKT1 and CALM inhibitors blocked iPSC-sEV-afforded activation of the eNOS-Sirt1 axis in senescent endothelial cells. Taken together, iPSC-sEVs can protect against ischemic stroke in aged mice by rejuvenating BBB senescence, partially, through delivering AKT1 and CALM to activate eNOS-Sirt1 axis, which indicates that iPSC-sEVs treatment is an effective alternative to treat ischemic stroke in the aged population.

Enhanced angiogenic properties of umbilical cord blood primed by OP9 stromal cells ameliorates neurological deficits in cerebral infarction mouse model

Umbilical cord blood (UCB) transplantation shows proangiogenic effects and contributes to symptom amelioration in animal models of cerebral infarction. However, the effect of specific cell types within a heterogeneous UCB population are still controversial. OP9 is a stromal cell line used as feeder cells to promote the hematoendothelial differentiation of embryonic stem cells. Hence, we investigated the changes in angiogenic properties, underlying mechanisms, and impact on behavioral deficiencies caused by cerebral infarction in UCB co-cultured with OP9 for up to 24 h. In the network formation assay, only OP9 pre-conditioned UCB formed network structures. Single-cell RNA sequencing and flow cytometry analysis showed a prominent phenotypic shift toward M2 in the monocytic fraction of OP9 pre-conditioned UCB. Further, OP9 pre-conditioned UCB transplantation in mice models of cerebral infarction facilitated angiogenesis in the peri-infarct lesions and ameliorated the associated symptoms. In this study, we developed a strong, fast, and feasible method to augment the M2, tissue-protecting, pro-angiogenic features of UCB using OP9. The ameliorative effect of OP9-pre-conditioned UCB in vivo could be partly due to promotion of innate angiogenesis in peri-infarct lesions.

Stroke: Molecular mechanisms and therapies: Update on recent developments

Stroke, a neurological disease, is one of the leading causes of death worldwide, resulting in long-term disability in most survivors. Annual stroke costs in the United States alone were estimated at $46 billion recently. Stroke pathophysiology is complex, involving multiple causal factors, among which atherosclerosis, thrombus, and embolus are prevalent. The molecular mechanisms involved in the pathophysiology are essential to understanding targeted drug development. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress, and neuroinflammation. In addition, various modifiable and non-modifiable risk factors increase the chances of stroke manifolds. Once a patient encounters a stroke, complete restoration of motor ability and cognitive skills is often rare. Therefore, shaping therapeutic strategies is paramount for finding a viable therapeutic agent. Apart from tPA, an FDA-approved therapy that is applied in most stroke cases, many other therapeutic strategies have been met with limited success. Stroke therapies often involve a combination of multiple strategies to restore the patient's normal function. Certain drugs like Gamma-aminobutyric receptor agonists (GABA), Glutamate Receptor inhibitors, Sodium, and Calcium channel blockers, and fibrinogen-depleting agents have shown promise in stroke treatment. Recently, a drug, DM199, a recombinant (synthetic) form of a naturally occurring protein called human tissue kallikrein-1 (KLK1), has shown great potential in treating stroke with fewer side effects. Furthermore, DM199 has been found to overcome the limitations presented when using tPA and/or mechanical thrombectomy. Cell-based therapies like Neural Stem Cells, Hematopoietic stem cells (HSCs), and Human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) are also being explored as a treatment of choice for stroke. These therapeutic agents come with merits and demerits, but continuous research and efforts are being made to develop the best therapeutic strategies to minimize the damage post-stroke and restore complete neurological function in stroke patients.

Mesenchymal stem cell therapy for neurological disorders: The light or the dark side of the force?

Neurological disorders are recognized as major causes of death and disability worldwide. Because of this, they represent one of the largest public health challenges. With awareness of the massive burden associated with these disorders, came the recognition that treatment options were disproportionately scarce and, oftentimes, ineffective. To address these problems, modern research is increasingly looking into novel, more effective methods to treat neurological patients; one of which is cell-based therapies. In this review, we present a critical analysis of the features, challenges, and prospects of one of the stem cell types that can be employed to treat numerous neurological disorders-mesenchymal stem cells (MSCs). Despite the fact that several studies have already established the safety of MSC-based treatment approaches, there are still some reservations within the field regarding their immunocompatibility, heterogeneity, stemness stability, and a range of adverse effects-one of which is their tumor-promoting ability. We additionally examine MSCs' mechanisms of action with respect to in vitro and in vivo research as well as detail the findings of past and ongoing clinical trials for Parkinson's and Alzheimer's disease, ischemic stroke, glioblastoma multiforme, and multiple sclerosis. Finally, this review discusses prospects for MSC-based therapeutics in the form of biomaterials, as well as the use of electromagnetic fields to enhance MSCs' proliferation and differentiation into neuronal cells.

Engineering Human Mesenchymal Bodies in a Novel 3D-Printed Microchannel Bioreactor for Extracellular Vesicle Biogenesis

Human Mesenchymal Stem Cells (hMSCs) and their derived products hold potential in tissue engineering and as therapeutics in a wide range of diseases. hMSCs possess the ability to aggregate into "spheroids", which has been used as a preconditioning technique to enhance their therapeutic potential by upregulating stemness, immunomodulatory capacity, and anti-inflammatory and pro-angiogenic secretome. Few studies have investigated the impact on hMSC aggregate properties stemming from dynamic and static aggregation techniques. hMSCs' main mechanistic mode of action occur through their secretome, including extracellular vesicles (EVs)/exosomes, which contain therapeutically relevant proteins and nucleic acids. In this study, a 3D printed microchannel bioreactor was developed to dynamically form hMSC spheroids and promote hMSC condensation. In particular, the manner in which dynamic microenvironment conditions alter hMSC properties and EV biogenesis in relation to static cultures was assessed. Dynamic aggregation was found to promote autophagy activity, alter metabolism toward glycolysis, and promote exosome/EV production. This study advances our knowledge on a commonly used preconditioning technique that could be beneficial in wound healing, tissue regeneration, and autoimmune disorders.

Role of STAT3 and NRF2 in Tumors: Potential Targets for Antitumor Therapy

Signal transducer and activator of transcription 3 (STAT3) and nuclear factor erythroid-derived 2-like 2 (NRF2, also known as NFE2L2), are two of the most complicated transcription regulators, which participate in a variety of physiological processes. Numerous studies have shown that they are overactivated in multiple types of tumors. Interestingly, STAT3 and NRF2 can also interact with each other to regulate tumor progression. Hence, these two important transcription factors are considered key targets for developing a new class of antitumor drugs. This review summarizes the pivotal roles of the two transcription regulators and their interactions in the tumor microenvironment to identify potential antitumor drug targets and, ultimately, improve patients' health and survival.

Extracellular vesicles from IFN-γ-primed mesenchymal stem cells repress atopic dermatitis in mice

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by immune dysregulation, pruritus, and abnormal epidermal barrier function. Compared with conventional mesenchymal stem cell (MSC), induced pluripotent stem cell (iPSC)-derived mesenchymal stem cell (iMSC) is recognized as a unique source for producing extracellular vesicles (EVs) because it can be obtained in a scalable manner with an enhanced homogeneity. Stimulation of iMSCs with inflammatory cytokines can improve the immune-regulatory, anti-inflammatory, and tissue-repairing potential of iMSC-derived EVs.

RESULTS

Proteome analysis showed that IFN-γ-iMSC-EVs are enriched with protein sets that are involved in regulating interferon responses and inflammatory pathways. In AD mice, expression of interleukin receptors for Th2 cytokines (IL-4Rα/13Rα1/31Rα) and activation of their corresponding intracellular signaling molecules was reduced. IFN-γ-iMSC-EVs decreased itching, which was supported by reduced inflammatory cell infiltration and mast cells in AD mouse skin; reduced IgE receptor expression and thymic stromal lymphopoietin and NF-kB activation; and recovered impaired skin barrier, as evidenced by upregulation of key genes of epidermal differentiation and lipid synthesis.

CONCLUSIONS

IFN-γ-iMSC-EVs inhibit Th2-induced immune responses, suppress inflammation, and facilitate skin barrier restoration, contributing to AD improvement.

Exosomes in Cerebral Ischemia-Reperfusion Injury: Current Perspectives and Future Challenges

Cerebral ischemia impedes the functional or metabolic demands of the central nervous system (CNS), which subsequently leads to irreversible brain damage. While recanalization of blocked vessels recovers cerebral blood flow, it can also aggravate brain injury, termed as ischemia/reperfusion (I/R) injury. Exosomes, nanometric membrane vesicles, attracted wide attention as carriers of biological macromolecules. In the brain, exosomes can be secreted by almost all types of cells, and their contents can be altered during the pathological and clinical processes of cerebral I/R injury. Herein, we will review the current literature on the possible role of cargos derived from exosomes and exosomes-mediated intercellular communication in cerebral I/R injury. The PubMed and Web of Science databases were searched through January 2015. The studies published in English were identified using search terms including "exosomes", "cerebral ischemia-reperfusion injury", "brain ischemia-reperfusion injury", and "stroke". We will also focus on the potential therapeutic effects of stem cell-derived exosomes and underlying mechanisms in cerebral I/R injury. Meanwhile, with the advantages of low immunogenicity and cytotoxicity, high bioavailability, and the capacity to pass through the blood-brain barrier, exosomes also attract more attention as therapeutic modalities for the treatment of cerebral I/R injury.

Investigation into the potential mechanism and molecular targets of Fufang Xueshuantong capsule for the treatment of ischemic stroke based on network pharmacology and molecular docking

Fufang Xueshuantong (FFXST) capsule is a traditional Chinese medicine (TCM) preparation used to activate blood circulation, resolve stasis, benefit qi, and nourish yin in clinical practice. However, its potential mechanism and molecular targets after ischemic stroke (IS) have not been investigated. The aim of this research was to investigate the molecular mechanisms of FFXST in the treatment of IS based on network pharmacology and molecular docking. We used the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) to collect candidate compounds of four herbs in FFXST; disease-related differential genes were screened using the Gene Expression Omnibus (GEO) database, and a compound–disease network was created using Cytoscape 3.8.2 software. The topological analysis of the protein–protein interaction (PPI) network was then created to determine the candidate targets of FFXST against IS. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the clusterProfiler package in R. The gene–pathway network of FFXST against IS was created to obtain the key target genes. Molecular docking was used to validate the core targets using AutoDock Vina 1.1.2. A total of 455 candidate compounds of FFXST and 18,544 disease-related differential genes were screened. Among them, FFXST targets for IS treatment had 67 active compounds and 10 targets in the PPI network related to STAT1, STAT3, and HIF1A. The biological processes of GO analysis included the regulation of reactive oxygen species metabolic process, cellular response to chemical stress, regulation of angiogenesis, regulation of vasculature development, positive regulation of cytokine production, and response to oxidative stress. The KEGG enrichment analysis showed that Kaposi sarcoma-associated herpesvirus infection, microRNAs in the cancer signaling pathway, Th17 cell differentiation, and HIF-1 signaling pathway were significantly enriched. The network pharmacology outcomes were further verified by molecular docking. We demonstrated that FFXST protection against IS may relate to the regulation of oxidative stress, immune inflammatory response, and angiogenesis through the relevant signaling pathways. Our study systematically illustrated the application of network pharmacology and molecular docking in evaluating characteristics of multi-component, multi-target, and multi-pathway of FFXST for IS.

Recent Advances in Extracellular Vesicle-Based Therapies Using Induced Pluripotent Stem Cell-Derived Mesenchymal Stromal Cells

Extracellular vesicles (EVs) are being widely investigated as acellular therapeutics in regenerative medicine applications. EVs isolated from mesenchymal stromal cells (MSCs) are by far the most frequently used in preclinical models for diverse therapeutic applications, including inflammatory, degenerative, or acute diseases. Although they represent promising tools as cell-free therapeutic agents, one limitation to their use is related to the batch-to-batch unreliability that may arise from the heterogeneity between MSC donors. Isolating EVs from MSCs derived from induced pluripotent stem cells (iMSCs) might allow unlimited access to cells with a more stable phenotype and function. In the present review, we first present the latest findings regarding the functional aspects of EVs isolated from iMSCs and their interest in regenerative medicine for the treatment of various diseases. We will then discuss future directions for their translation to clinics with good manufacturing practice implementation.

Chrysophanol facilitates long-term neurological recovery through limiting microglia-mediated neuroinflammation after ischemic stroke in mice

BACKGROUND

Inflammation plays an important role in ischemic brain injury and affects brain recovery and neuroplasticity. Chrysophanol (CHR), has attracted attention for its protective effects through immunomodulatory and anti-inflammatory properties. However, the effect of CHR for brain recovery and neuroplasticity is not clear. The current study aimed to investigate the effect of CHR in the chronic phase of stroke in mice, and to elucidate the underlying mechanisms.

METHODS

C57BL/6 mice were subjected to treatment with Vehicle or CHR immediately through intraperitoneal injection daily for 14 d after distal middle cerebral artery occlusion (dMCAO). Neurological deficits were monitored up to 28 days after stroke. Nissl and Golgi stain, neural plasticity, and microglia-associated inflammatory cytokines were detected. Primary cortical neuron and BV2 microglia cell lines were employed to explore the underlying mechanism in vitro.

RESULTS

Compared with Vehicle group, CHR mitigated the histological damage, facilitated the neural plasticity and improved the neurological function up to 4 weeks after stroke. In vitro, CHR promoted the complexity of neurons and the spine density by modulating microglial polarization and reducing the expression of microglia-associated inflammatory cytokines, especially IL-6. In vivo, microglia activation and inflammatory cytokines were significantly increased after dMCAO and downregulated by CHR. Further investigation showed STAT3 is the major downstream effector of IL-6 signaling.

CONCLUSIONS

CHR ameliorated microenvironment for neural plasticity and exhibited neuroprotection via arresting microglia toward pro-inflammatory phenotype and downregulation of the expressions of pro-inflammatory cytokines, especially of IL-6. IL-6-STAT3 signaling might be CHR's therapeutic target for neuroinflammatory responses after stroke.

Small extracellular vesicles derived from mesenchymal stem cell facilitate functional recovery in spinal cord injury by activating neural stem cells via the ERK1/2 pathway

Spinal cord injury (SCI) causes severe neurological dysfunction leading to a devastating disease of the central nervous system that is associated with high rates of disability and mortality. Small extracellular vesicles (sEVs) derived from human umbilical cord mesenchymal stem cells (hucMSC-sEVs) have been explored as a promising strategy for treating SCI. In this study, we investigated the therapeutic effects of the intralesional administration of hucMSC-sEVs after SCI and determined the potential mechanisms of successful repair by hucMSC-sEVs. In vivo, we established the rat model of SCI. The Basso, Beattie, Bresnahan (BBB) scores showed that hucMSC-sEVs dramatically promoted the recovery of spinal cord function. The results of the hematoxylin–eosin (HE) staining, Enzyme-Linked Immunosorbent Assay (ELISA), and immunohistochemistry showed that hucMSC-sEVs inhibited inflammation and the activation of glia, and promoted neurogenesis. Furthermore, we studied the effect of hucMSC-sEVs on neural stem cells(NSCs) in vitro. We found that hucMSC-sEVs did not improve the migration ability of NSCs, but promoted NSCs to proliferate and differentiate via the ERK1/2 signaling pathway. Collectively, these findings suggested that hucMSC-sEVs promoted the functional recovery of SCI by activating neural stem cells via the ERK1/2 pathway and may provide a new perspective and therapeutic strategy for the clinical application of hucMSC-sEVs in SCI treatment.

Biomaterials constructed for MSC-derived extracellular vesicle loading and delivery—a promising method for tissue regeneration

Mesenchymal stem cells (MSCs) have become the preferred seed cells for tissue regeneration. Nevertheless, due to their immunogenicity and tumorigenicity, MSC transplantation remains questionable. Extracellular vesicles (EVs) derived from MSCs are becoming a promising substitute for MSCs. As a route of the MSC paracrine, EVs have a nano-sized and bilayer lipid-enclosed structure, which can guarantee the integrity of their cargoes, but EVs cannot obtain full function in vivo because of the rapid biodegradation and clearance by phagocytosis. To improve the efficacy and targeting of EVs, methods have been proposed and put into practice, especially engineered vesicles and EV-controlled release systems. In particular, EVs can be cell or tissue targeting because they have cell-specific ligands on their surfaces, but their targeting ability may be eliminated by the biodegradation of the phagocytic system during circulation. Novel application strategies have been proposed beyond direct injecting. EV carriers such as biodegradable hydrogels and other loading systems have been applied in tissue regeneration, and EV engineering is also a brand-new method for higher efficacy. In this review, we distinctively summarize EV engineering and loading system construction methods, emphasizing targeting modification methods and controlled release systems for EVs, which few literature reviews have involved.