miR-132-3p priming enhances the effects of mesenchymal stromal cell-derived exosomes on ameliorating brain ischemic injury

mir-330-5p from mesenchymal stem cell-derived exosomes targets SETD7 to reduce inflammation in rats with cerebral ischemia-reperfusion injury

This study was to investigate the role of microRNA (miR)-330-5p derived from mesenchymal stem cells-secreted exosomes (MSCs-Exo) in cerebral ischemia-reperfusion injury (CI/RI) through targeting lysine N-methyltransferase SET domain containing 7 (SETD7). MSCs-Exo were separated and identified. MSCs-Exo were used to treat the middle cerebral artery occlusion (MCAO) rat model. By using the nerve injury score, Nissl, hematoxylin and eosin, and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, the neural function, pathological alterations, and neuronal death in MCAO rats were examined. Using an enzyme-linked immunosorbent test, tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in brain homogenate were tested. Rat brain expression levels of SETD7 and miR-330-5p were examined. Subsequently, the effects of MSCs-Exo, miR-330-5p, and SETD7 on neurological function and pathological alterations were assessed using gain and loss function tests. miR-330-5p expression was decreased and SETD7 expression was increased in the brain tissue of MCAO rats. Both MSCs-Exo and MSCs-Exo-derived miR-330-5p reduced inflammation in MCAO rats. miR-330-5p targeted SETD7, and SETD7 upregulation blocked the therapeutic effect of MSCs-Exo-derived miR-330-5p on MCAO rats. MSCs-Exo-derived miR-330-5p targets SETD7 to reduce inflammation in MCAO rats, providing a new therapeutic target for CI/RI therapy.

Extracellular vesicles derived from creeping fat stem cells promote lymphatic function and restrain inflammation of Crohn's disease

BACKGROUND

Crohn's disease (CD) is a chronic inflammatory disease in the intestinal tract. Mesenteric fat wrapping and thickening, or creeping fat (CrF), is a typical characteristic of CD and it involves lymphangiogenesis and altered lymphatic function. By releasing extracellular vesicles (EVs), adipose tissue-derived stem cells (ADSCs) can regulate their adjacent cells. However, the regulating roles of ADSC-EVs in CrF (CrF-EVs) in CD, especially in modulating lymphatic function and mitigating the progression of mesenteritis and colitis, remains elusive.

METHODS

To evaluate the regulative roles of CrF-EVs on lymphatic functions, in vitro assays were performed using human lymphatic endothelial cells (HLECs). Next, Interleukin 10 knock-out (Il-10-/-) mice were used to assess the biological functions of CrF-EVs in spontaneous mesenteritis and colitis. Moreover, tissue and serum from various cohorts of CD patients were used to determine the prognostic value of miR-132-3p.

RESULTS

CrF-EVs significantly attenuated spontaneous mesenteritis and colitis in Il-10-/- mice via promoting lymphangiogenesis and lymphatic drainage. Using high-throughput sequencing, we demonstrated that CrF-EVs significantly increased HLEC proliferation, migration, tube formation and CCL-21 production in a miR-132-3p/RASA1/ERK1/2 axis-dependent manner. Accordingly, upregulated miR-132-3p was observed in patient CrF, positively correlated with lymphangiogenesis while negatively correlated with inflammatory factors (tumour necrosis factor-α and IL-6) level. Moreover, serum miR-132-3p demonstrated a positive correlation with disease activity.

CONCLUSIONS

EVs derived from CrF ADSCs, containing elevated levels of miR-132-3p, could promote lymphatic function and restrain inflammation of CD. Our results provide a novel insight into the role of mesenteric lymphatics in CD progression and reveal a new potential therapeutic.

KEY POINTS

Extracellular vesicles (EVs) of creeping fat (CrF) derived adipose stem cells effectively attenuate chronic mesenteritis and colitis in Crohn's disease (CD). The lymphatic vessels play an important role in disease development of CD and their functions are improved by CrF-EV-miR-132-3p through RASA1/ERK1/2 signaling. MiR-132-3p expression is upregulated in CrF and serum of CD patients, and tightly linked with inflammation and disease activity.

Challenges in tendon-bone healing: emphasizing inflammatory modulation mechanisms and treatment

Tendons are fibrous connective tissues that transmit force from muscles to bones. Despite their ability to withstand various loads, tendons are susceptible to significant damage. The healing process of tendons and ligaments connected to bone surfaces after injury presents a clinical challenge due to the intricate structure, composition, cellular populations, and mechanics of the interface. Inflammation plays a pivotal role in tendon healing, creating an inflammatory microenvironment through cytokines and immune cells that aid in debris clearance, tendon cell proliferation, and collagen fiber formation. However, uncontrolled inflammation can lead to tissue damage, and adhesions, and impede proper tendon healing, culminating in scar tissue formation. Therefore, precise regulation of inflammation is crucial. This review offers insights into the impact of inflammation on tendon-bone healing and its underlying mechanisms. Understanding the inflammatory microenvironment, cellular interactions, and extracellular matrix dynamics is essential for promoting optimal healing of tendon-bone injuries. The roles of fibroblasts, inflammatory cytokines, chemokines, and growth factors in promoting healing, inhibiting scar formation, and facilitating tissue regeneration are discussed, highlighting the necessity of balancing the suppression of detrimental inflammatory responses with the promotion of beneficial aspects to enhance tendon healing outcomes. Additionally, the review explores the significant implications and translational potential of targeted inflammatory modulation therapies in refining strategies for tendon-bone healing treatments.

Stem cell-derived exosomes for ischemic stroke: a conventional and network meta-analysis based on animal models

Objective

We aimed to evaluate the efficacy of stem cell-derived exosomes for treating ischemic stroke and to screen for the optimal administration strategy.

Methods

We searched PubMed, Web of Science, Embase, Cochrane Library, and Scopus databases for relevant studies published from their inception to 31 December 2023. Conventional and network meta-analyses of the routes of administration, types, and immune compatibility of stem cell-derived exosomes were performed using the cerebral infarct volume (%) and modified neurological severity score (mNSS) as outcome indicators.

Results

A total of 38 randomized controlled animal experiments were included. Conventional meta-analysis showed that compared with the negative control group: intravenous administration significantly reduced the cerebral infarct volume (%) and mNSS; intranasal administration significantly reduced the cerebral infarct volume (%); and intracerebral administration significantly reduced the mNSS. Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos), bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos), dental pulp stem cell-derived exosomes (DPSC-Exos) and neural stem cell-derived exosomes (NSC-Exos) significantly reduced the cerebral infarct volume (%) and mNSS; Endothelial progenitor cell-derived exosomes (EPC-Exos), embryonic stem cell-derived exosomes (ESC-Exos), induced pluripotent stem cell-derived exosomes (iPSC-Exos) and neural progenitor cell-derived exosomes (NPC-Exos) significantly reduced the cerebral infarct volume (%); Umbilical cord mesenchymal stem cell-derived exosomes (UCMSC-Exos) significantly reduced the mNSS; and there was no significant difference between urogenital stem cell-derived exosomes (USC-Exos) and negative controls. Engineered modified exosomes had better efficacy than unmodified exosomes. Both allogeneic and xenogeneic stem cell-derived exosomes significantly reduced the cerebral infarct volume (%) and the mNSS. The network meta-analysis showed that intravenous administration was the best route of administration for reducing the cerebral infarct volume (%) and mNSS. Among the 10 types of stem cell-derived exosomes that were administered intravenously, BMSC-Exos were the best type for reducing the cerebral infarct volume (%) and the mNSS. Allogeneic exosomes had the best efficacy in reducing the cerebral infarct volume (%), whereas xenogeneic stem cell-derived exosomes had the best efficacy in reducing the mNSS.

Conclusion

This meta-analysis, by integrating the available evidence, revealed that intravenous administration is the best route of administration, that BMSC-Exos are the best exosome type, that allogeneic exosomes have the best efficacy in reducing the cerebral infarct volume (%), and that xenogeneic exosomes have the best efficacy in reducing mNSS, which can provide options for preclinical studies. In the future, more high-quality randomized controlled animal experiments, especially direct comparative evidence, are needed to determine the optimal administration strategy for stem cell-derived exosomes for ischemic stroke.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42024497333, PROSPERO, CRD42024497333.

DDAH1 deficiency exacerbates cerebral vascular endothelial dysfunction by aggravating BBB disruption and oxidative stress in thoracic blast-induced brain injury

As terrorist incidents and underground explosion events have become more frequent around the world, brain injury caused by thoracic blast exposure has been more highlighted due to its injured organ, subsequent social and economic burden. It has been reported dimethylarginine dimethylaminohydrolase 1 (DDAH1) plays important roles in regulating vascular endothelial injury repair and angiogenesis, but its role in thoracic blast-induced brain injury remains to be explained. This study seeks to investigate the mechanism of DDAH1 on thoracic blast-induced brain injury. 40 C57BL/6 wild type mice and 40 DDAH1 knockout mice were randomly and equally divided into control group and blast group, respectively. The integrity of blood-brain barrier (BBB) was detected by Evans blue test. The serum inflammatory factors, nitric oxide (NO) contents, and asymmetric dimethylarginine (ADMA) levels were determined through ELISA. HE staining and reactive oxygen species (ROS) detection were performed for histopathological changes. Western blot was used to detect the proteins related to oxidative stress, tight junction, focal adhesion, vascular endothelial injury, and the DDAH1/ADMA/eNOS signaling pathway. DDAH1 deficiency aggravated thoracic blast-induced BBB leakage, inflammatory response, and the increased levels of inflammatory-related factors. Additionally, DDAH1 deficiency also increased ROS generation, MDA and IRE-α expression. Regarding cerebral vascular endothelial dysfunction, DDAH1 deficiency increased the expression of MCAM, FN1, LIMK1, VEGF, MMP9, Vimentin and N-cadherin, while lowering the expression of FMR1, Occludin, claudin-3, claudin-5, Lyn, LIMA1, Glrb, Sez6, Dystrophin, and phosphorylation of VASP. Also, DDAH1 deficiency exacerbated explosion-induced increase of ADMA and decrease of eNOS activity and NO contents. Thus, we conclude that DDAH1 could prevent cerebral vascular endothelial dysfunction and related injury by inhibiting ADMA signaling and increasing eNOS activity in thoracic blast induced brain injury.

Advances in different adult stem cell-derived exosomal non-coding RNAs for the treatment of neurological disorders: a narrative review

Neurological disorders are being increasingly recognized as major causes of death and disability around the world. Neurological disorders refer to a broad range of medical conditions that affect the brain and spinal cord. These disorders can have various causes, including genetic factors, infections, trauma, autoimmune reactions, or neurodegenerative processes. Each disorder has its own unique symptoms, progression, and treatment options. Optimal communication between interneurons and neuron-glia cells within the homeostatic microenvironment is of paramount importance. Within this microenvironment, exosomes play a significant role in promoting intercellular communication by transferring a diverse cargo of contents, including proteins, lipids, and non-coding RNAs (ncRNAs). Partially, nervous system homeostasis is preserved by various stem cell-derived exosomal ncRNAs, which include circular RNAs (circRNAs), long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and PIWI-interacting RNAs (piRNAs). The diversity of these exosomal ncRNAs suggests their potential to influence multiple pathways and cellular processes within the nervous system. Stem cell-derived exosomes and their ncRNA contents have been investigated for potential therapeutic uses in neurological disorders, owing to their demonstrated capabilities in neuroprotection, neuroregeneration, and modulation of disease-related pathways. The ability of stem cell-derived exosomes to cross the blood-brain barrier makes them a promising delivery vehicle for therapeutic ncRNAs. This review aims to summarize the current understanding of different stem cell-derived exosomal ncRNAs and their therapeutic potential and clinical applications.

Effects of Bone Marrow Mesenchymal Stem Cell-Derived Exosomes in Central Nervous System Diseases

Central nervous system (CNS) diseases are one of the diseases that threaten human health. The delivery of drugs targeting the CNS has always been a significant challenge; the blood-brain barrier (BBB) is the main obstacle that must be overcome. The rise of bone marrow mesenchymal stem cell (BMSC) therapy has brought hope for the treatment of CNS diseases. However, the problems of low homing rate, susceptibility differentiation into astrocytes, immune rejection, and formation of iatrogenic tumors of transplanted BMSCs limit their clinical application. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) have become a hot research topic in the treatment of CNS diseases in recent years because of their excellent histocompatibility, low immunogenicity, ease of crossing the BBB, and their ability to serve as natural carriers for treatment. This article reviews the mechanisms of BMSC-Exos in CNS diseases and provides direction for further research.

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Exosomes as therapeutic and drug delivery vehicle for neurodegenerative diseases

Neurodegenerative disorders are complex, progressive, and life-threatening. They cause mortality and disability for millions of people worldwide. Appropriate treatment for neurodegenerative diseases (NDs) is still clinically lacking due to the presence of the blood-brain barrier (BBB). Developing an effective transport system that can cross the BBB and enhance the therapeutic effect of neuroprotective agents has been a major challenge for NDs. Exosomes are endogenous nano-sized vesicles that naturally carry biomolecular cargoes. Many studies have indicated that exosome content, particularly microRNAs (miRNAs), possess biological activities by targeting several signaling pathways involved in apoptosis, inflammation, autophagy, and oxidative stress. Exosome content can influence cellular function in healthy or pathological ways. Furthermore, since exosomes reflect the features of the parental cells, their cargoes offer opportunities for early diagnosis and therapeutic intervention of diseases. Exosomes have unique characteristics that make them ideal for delivering drugs directly to the brain. These characteristics include the ability to pass through the BBB, biocompatibility, stability, and innate targeting properties. This review emphasizes the role of exosomes in alleviating NDs and discusses the associated signaling pathways and molecular mechanisms. Furthermore, the unique biological features of exosomes, making them a promising natural transporter for delivering various medications to the brain to combat several NDs, are also discussed.

M1-type microglia-derived exosomes contribute to blood-brain barrier damage

BACKGROUND

As a key substance for intercellular communication, exosomes could be a potential strategy for stroke treatment. Activated microglia disrupt the integrity of blood-brain barrier (BBB) to facilitate the stroke process. Hence, this study was designed to investigate the effect of microglia-derived exosomes on BBB cell model injury and to explore the underlying molecular mechanisms.

METHODS

M1 polarization of BV2 cells was induced with LPS and their derived exosomes were isolated. Astrocytes were cultured in primary culture and constructed with End3 cells as a BBB cell model. After co-culture with exosomes, the BBB cell model was examined for changes in TEER, permeability, and expression of BBB-related proteins (Claudin-1, Occludin, ZO-1 and JAM). Resting and M1-type BV2 cell-derived exosomes perform small RNA sequences and differentially expressed miRNAs (DE-miRNAs) are identified by bioinformatics.

RESULTS

M1-type BV2 cell-derived exosomes decreased End3 cell viability, and increased their apoptotic ratio. Moreover, M1 type BV2 cell-derived exosomes dramatically enhanced the permeability of BBB cell model, and diminished the TEER and BBB-related protein (Claudin-1, Occludin, ZO-1) expression. Notably, resting BV2 cell-derived exosomes had no effect on the integrity of BBB cell model. Sequencing results indicated that 71 DE-miRNAs were present in M1 BV2 cell-derived exosomes, and their targets mediated neurological development and signaling pathways such as MAPK and cAMP. RT-qPCR confirmed the differential expression of mmu-miR-125a-5p, mmu-miR-122b-3p, mmu-miR-139-3p, mmu-miR-330-3p, mmu-miR-3057-5p and mmu-miR-342-3p consistent with the small RNA sequence. Furthermore, Creb1, Jun, Mtor, Frk, Pabpc1 and Sdc1 are the most well-connected proteins in the PPI network.

CONCLUSION

M1-type microglia-derived exosomes contribute to the injury of BBB cell model, which has the involvement of miRNAs. Our findings provide new perspectives and potential mechanisms for future M1 microglia-derived exosomes as therapeutic targets in stroke.

Mesenchymal stem cells and their derived exosomes in multiple sclerosis disease: from paper to practice

Multiple sclerosis (MS) is a chronic neurodegenerative, inflammatory, and demyelinating disease of the central nervous system (CNS). Current medicines are not sufficient to control the inflammation and progressive damage to the CNS that is known in MS. These drawbacks highlight the need for novel treatment options. Cell therapy can now be used to treat complex diseases when conventional therapies are ineffective. Mesenchymal stem cells (MSCs) are a diverse group of multipotential non-hematopoietic stromal cells which have immunomodulatory, neurogenesis, and remyelinating capacity. Their advantageous effects mainly rely on paracrine, cell-cell communication and differentiation properties which introduced them as excellent candidates for MS therapy. Exosomes, as one of the MSCs secretomes, have unique properties that make them highly promising candidates for innovative approach in regenerative medicine. This review discusses the therapeutic potential of MSCs and their derived exosomes as a novel treatment for MS, highlighting the differences between these two approaches.

Neural stem cell-derived exosomes promote mitochondrial biogenesis and restore abnormal protein distribution in a mouse model of Alzheimer's disease

JOURNAL/nrgr/04.03/01300535-202407000-00040/figure1/v/2023-11-20T171125Z/r/image-tiff

Mitochondrial dysfunction is a hallmark of Alzheimer's disease. We previously showed that neural stem cell-derived extracellular vesicles improved mitochondrial function in the cortex of APP/PS1 mice. Because Alzheimer's disease affects the entire brain, further research is needed to elucidate alterations in mitochondrial metabolism in the brain as a whole. Here, we investigated the expression of several important mitochondrial biogenesis-related cytokines in multiple brain regions after treatment with neural stem cell-derived exosomes and used a combination of whole brain clearing, immunostaining, and lightsheet imaging to clarify their spatial distribution. Additionally, to clarify whether the sirtuin 1 (SIRT1)-related pathway plays a regulatory role in neural stem cell-derived exosomes interfering with mitochondrial functional changes, we generated a novel nervous system-SIRT1 conditional knockout APP/PS1 mouse model. Our findings demonstrate that neural stem cell-derived exosomes significantly increase SIRT1 levels, enhance the production of mitochondrial biogenesis-related factors, and inhibit astrocyte activation, but do not suppress amyloid-β production. Thus, neural stem cell-derived exosomes may be a useful therapeutic strategy for Alzheimer's disease that activates the SIRT1-PGC1α signaling pathway and increases NRF1 and COXIV synthesis to improve mitochondrial biogenesis. In addition, we showed that the spatial distribution of mitochondrial biogenesis-related factors is disrupted in Alzheimer's disease, and that neural stem cell-derived exosome treatment can reverse this effect, indicating that neural stem cell-derived exosomes promote mitochondrial biogenesis.

Engineering extracellular vesicles for ROS scavenging and tissue regeneration

Stem cell therapy holds promise for tissue regeneration, yet significant challenges persist. Emerging as a safer and potentially more effective alternative, extracellular vesicles (EVs) derived from stem cells exhibit remarkable abilities to activate critical signaling cascades, thereby facilitating tissue repair. EVs, nano-scale membrane vesicles, mediate intercellular communication by encapsulating a diverse cargo of proteins, lipids, and nucleic acids. Their therapeutic potential lies in delivering cargos, activating signaling pathways, and efficiently mitigating oxidative stress-an essential aspect of overcoming limitations in stem cell-based tissue repair. This review focuses on engineering and applying EVs in tissue regeneration, emphasizing their role in regulating reactive oxygen species (ROS) pathways. Additionally, we explore strategies to enhance EV therapeutic activity, including functionalization and incorporation of antioxidant defense proteins. Understanding these molecular mechanisms is crucial for optimizing EV-based regenerative therapies. Insights into EV and ROS signaling modulation pave the way for targeted and efficient regenerative therapies harnessing the potential of EVs.

Revealing the pharmacological mechanisms of nao-an dropping pill in preventing and treating ischemic stroke via the PI3K/Akt/eNOS and Nrf2/HO-1 pathways

Nao-an Dropping Pill (NADP) is a Chinese patent medicine which commonly used in clinic for ischemic stroke (IS). However, the material basis and mechanism of its prevention or treatment of IS are unclear, then we carried out this study. 52 incoming blood components were resolved by UHPLC-MS/MS from rat serum, including 45 prototype components. The potential active prototype components hydroxysafflor yellow A, ginsenoside F1, quercetin, ferulic acid and caffeic acid screened by network pharmacology showed strongly binding ability with PIK3CA, AKT1, NOS3, NFE2L2 and HMOX1 by molecular docking. In vitro oxygen-glucose deprivation/reperfusion (OGD/R) experimental results showed that NADP protected HA1800 cells from OGD/R-induced apoptosis by affecting the release of LDH, production of NO, and content of SOD and MDA. Meanwhile, NADP could improve behavioral of middle cerebral artery occlusion/reperfusion (MCAO/R) rats, reduce ischemic area of cerebral cortex, decrease brain water and glutamate (Glu) content, and improve oxidative stress response. Immunohistochemical results showed that NADP significantly regulated the expression of PI3K, Akt, p-Akt, eNOS, p-eNOS, Nrf2 and HO-1 in cerebral ischemic tissues. The results suggested that NADP protects brain tissues and ameliorates oxidative stress damage to brain tissues from IS by regulating PI3K/Akt/eNOS and Nrf2/HO-1 signaling pathways.

Mesenchymal stem cell‐derived extracellular vesicles: Recent therapeutics and targeted drug delivery advances

The targeted drug delivery field is rapidly advancing, focusing on developing biocompatible nanoparticles that meet rigorous criteria of non‐toxicity, biocompatibility, and efficient release of encapsulated molecules. Conventional synthetic nanoparticles (SNPs) face complications such as elevated immune responses, complex synthesis methods, and toxicity, which restrict their utility in therapeutics and drug delivery. Extracellular vesicles (EVs) have emerged as promising substitutes for SNPs, leveraging their ability to cross biological barriers, biocompatibility, reduced toxicity, and natural origin. Notably, mesenchymal stem cell‐derived EVs (MSC‐EVs) have garnered much curiosity due to their potential in therapeutics and drug delivery. Studies suggest that MSC‐EVs, the central paracrine contributors of MSCs, replicate the therapeutic effects of MSCs. This review explores the characteristics of MSC‐EVs, emphasizing their potential in therapeutics and drug delivery for various diseases, including CRISPR/Cas9 delivery for gene editing. It also delves into the obstacles and challenges of MSC‐EVs in clinical applications and provides insights into strategies to overcome the limitations of biodistribution and target delivery.

Allogeneic bone marrow mesenchymal stem cell-derived exosomes alleviate human hypoxic AKI-on-a-Chip within a tight treatment window

BACKGROUND

Acute hypoxic proximal tubule (PT) injury and subsequent maladaptive repair present high mortality and increased risk of acute kidney injury (AKI) - chronic kidney disease (CKD) transition. Human bone marrow mesenchymal stem cell-derived exosomes (hBMMSC-Exos) as potential cell therapeutics can be translated into clinics if drawbacks on safety and efficacy are clarified. Here, we determined the real-time effective dose and treatment window of allogeneic hBMMSC-Exos, evaluated their performance on the structural and functional integrity of 3D microfluidic acute hypoxic PT injury platform.

METHODS

hBMMSC-Exos were isolated and characterized. Real-time impedance-based cell proliferation analysis (RTCA) determined the effective dose and treatment window for acute hypoxic PT injury. A 2-lane 3D gravity-driven microfluidic platform was set to mimic PT in vitro. ZO-1, acetylated α-tubulin immunolabelling, and permeability index assessed structural; cell proliferation by WST-1 measured functional integrity of PT.

RESULTS

hBMMSC-Exos induced PT proliferation with ED50 of 172,582 µg/ml at the 26th hour. Hypoxia significantly decreased ZO-1, increased permeability index, and decreased cell proliferation rate on 24-48 h in the microfluidic platform. hBMMSC-Exos reinforced polarity by a 1.72-fold increase in ZO-1, restored permeability by 20/45-fold against 20/155 kDa dextran and increased epithelial proliferation 3-fold compared to control.

CONCLUSIONS

The real-time potency assay and 3D gravity-driven microfluidic acute hypoxic PT injury platform precisely demonstrated the therapeutic performance window of allogeneic hBMMSC-Exos on ischemic AKI based on structural and functional cellular data. The novel standardized, non-invasive two-step system validates the cell-based personalized theragnostic tool in a real-time physiological microenvironment prior to safe and efficient clinical usage in nephrology.

The dual role of mesenchymal stem cells in apoptosis regulation

Mesenchymal stem cells (MSCs) are widely distributed pluripotent stem cells with powerful immunomodulatory capacity. MSCs transplantation therapy (MSCT) is widely used in the fields of tissue regeneration and repair, and treatment of inflammatory diseases. Apoptosis is an important way for tissues to maintain cell renewal, but it also plays an important role in various diseases. And many studies have shown that MSCs improves the diseases by regulating cell apoptosis. The regulation of MSCs on apoptosis is double-sided. On the one hand, MSCs significantly inhibit the apoptosis of diseased cells. On the other hand, MSCs also promote the apoptosis of tumor cells and excessive immune cells. Furthermore, MSCs regulate apoptosis through multiple molecules and pathways, including three classical apoptotic signaling pathways and other pathways. In this review, we summarize the current evidence on the regulation of apoptosis by MSCs.

Therapeutic gene delivery by mesenchymal stem cell for brain ischemia damage: Focus on molecular mechanisms in ischemic stroke

Cerebral ischemic damage is prevalent and the second highest cause of death globally across patient populations; it is as a substantial reason of morbidity and mortality. Mesenchymal stromal cells (MSCs) have garnered significant interest as a potential treatment for cerebral ischemic damage, as shown in ischemic stroke, because of their potent intrinsic features, which include self-regeneration, immunomodulation, and multi-potency. Additionally, MSCs are easily obtained, isolated, and cultured. Despite this, there are a number of obstacles that hinder the effectiveness of MSC-based treatment, such as adverse microenvironmental conditions both in vivo and in vitro. To overcome these obstacles, the naïve MSC has undergone a number of modification processes to enhance its innate therapeutic qualities. Genetic modification and preconditioning modification (with medications, growth factors, and other substances) are the two main categories into which these modification techniques can be separated. This field has advanced significantly and is still attracting attention and innovation. We examine these cutting-edge methods for preserving and even improving the natural biological functions and therapeutic potential of MSCs in relation to adhesion, migration, homing to the target site, survival, and delayed premature senescence. We address the use of genetically altered MSC in stroke-induced damage. Future strategies for improving the therapeutic result and addressing the difficulties associated with MSC modification are also discussed.

MiR129-5p-loaded exosomes suppress seizure-associated neurodegeneration in status epilepticus model mice by inhibiting HMGB1/TLR4-mediated neuroinflammation

BACKGROUND

Neuroinflammation contributes to both epileptogenesis and the associated neurodegeneration, so regulation of inflammatory signaling is a potential strategy for suppressing epilepsy development and pathological progression. Exosomes are enriched in microRNAs (miRNAs), considered as vital communication tools between cells, which have been proven as potential therapeutic method for neurological disease. Here, we investigated the role of miR129-5p-loaded mesenchymal stem cell (MSC)-derived exosomes in status epilepticus (SE) mice model.

METHODS

Mice were divided into four groups: untreated control (CON group), kainic acid (KA)-induced SE groups (KA group), control exosome injection (KA + Exo-con group), miR129-5p-loaded exosome injection (KA + Exo-miR129-5p group). Hippocampal expression levels of miR129-5p, HMGB1, and TLR4 were compared among groups. Nissl and Fluoro-jade B staining were conducted to evaluate neuronal damage. In addition, immunofluorescence staining for IBA-1 and GFAP was performed to assess glial cell activation, and inflammatory factor content was determined by ELISA. Hippocampal neurogenesis was assessed by BrdU staining.

RESULTS

The expression of HMGB1 was increased after KA-induced SE and peaking at 48 h, while hippocampal miR129-5p expression decreased in SE mice. Exo-miR129-5p injection reversed KA-induced upregulation of hippocampal HMGB1 and TLR4, alleviated neuronal damage in the hippocampal CA3, reduced IBA-1 + and GFAP + staining intensity, suppressed SE-associated increases in inflammatory factors, and decreased BrdU + cell number in dentate gyrus.

CONCLUSIONS

Exosomes loaded with miR129-5p can protect neurons against SE-mediated degeneration by inhibiting the pro-inflammatory HMGB1/TLR4 signaling axis.

Lyoprotectant Constituents Suited for Lyophilization and Reconstitution of Stem-Cell-Derived Extracellular Vesicles

Stem-cell-derived extracellular vesicles (EVs) are emerging as an alternative approach to stem cell therapy. Successful lyophilization of EVs could enable convenient storage and distribution of EV medicinal products at room temperature for long periods, thus considerably increasing the accessibility of EV therapeutics to patients. In this study, we aimed to identify an appropriate lyoprotectant composition for the lyophilization and reconstitution of stem-cell-derived EVs. MSC-derived EVs were lyophilized using different lyoprotectants, such as dimethyl sulfoxide, mannitol, trehalose, and sucrose, at varying concentrations. Our results revealed that a mixture of trehalose and sucrose at high concentrations could support the formation of amorphous ice by enriching the amorphous phase of the solution, which successfully inhibited the acceleration of buffer component crystallization during lyophilization. Lyophilized and reconstituted EVs were thoroughly evaluated for concentration and size, morphology, and protein and RNA content. The therapeutic effects of the reconstituted EVs were examined using a tube formation assay with human umbilical vein endothelial cells. After rehydration of the lyophilized EVs, most of their generic characteristics were well-maintained, and their therapeutic capacity recovered to levels similar to those of freshly collected EVs. The concentrations and morphologies of the lyophilized EVs were similar to the initial features of the fresh EV group until day 30 at room temperature, although their therapeutic capacity appeared to decrease after 7 days. Our study suggests an appropriate composition of lyoprotectants, particularly for EV lyophilization, which could encourage the applications of stem-cell-derived EV therapeutics in the health industry.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

The MSC-EV-microRNAome: A Perspective on Therapeutic Mechanisms of Action in Sepsis and ARDS

Mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (EVs) have emerged as innovative therapeutic agents for the treatment of sepsis and acute respiratory distress syndrome (ARDS). Although their potential remains undisputed in pre-clinical models, this has yet to be translated to the clinic. In this review, we focused on the role of microRNAs contained in MSC-derived EVs, the EV microRNAome, and their potential contribution to therapeutic mechanisms of action. The evidence that miRNA transfer in MSC-derived EVs has a role in the overall therapeutic effects is compelling. However, several questions remain regarding how to reconcile the stochiometric issue of the low copy numbers of the miRNAs present in the EV particles, how different miRNAs delivered simultaneously interact with their targets within recipient cells, and the best miRNA or combination of miRNAs to use as therapy, potency markers, and biomarkers of efficacy in the clinic. Here, we offer a molecular genetics and systems biology perspective on the function of EV microRNAs, their contribution to mechanisms of action, and their therapeutic potential.

The emerging role of exosomes in communication between the periphery and the central nervous system

Exosomes, membrane-enclosed vesicles, are secreted by all types of cells. Exosomes can transport various molecules, including proteins, lipids, functional mRNAs, and microRNAs, and can be circulated to various recipient cells, leading to the production of local paracrine or distal systemic effects. Numerous studies have proved that exosomes can pass through the blood-brain barrier, thus, enabling the transfer of peripheral substances into the central nervous system (CNS). Consequently, exosomes may be a vital factor in the exchange of information between the periphery and CNS. This review will discuss the structure, biogenesis, and functional characterization of exosomes and summarize the role of peripheral exosomes deriving from tissues like the lung, gut, skeletal muscle, and various stem cell types in communicating with the CNS and influencing the brain's function. Then, we further discuss the potential therapeutic effects of exosomes in brain diseases and the clinical opportunities and challenges. Gaining a clearer insight into the communication between the CNS and the external areas of the body will help us to ascertain the role of the peripheral elements in the maintenance of brain health and illness and will facilitate the design of minimally invasive techniques for diagnosing and treating brain diseases.

Hydrogel-Loaded Exosomes: A Promising Therapeutic Strategy for Musculoskeletal Disorders

Clinical treatment strategies for musculoskeletal disorders have been a hot research topic. Accumulating evidence suggests that hydrogels loaded with MSC-derived EVs show great potential in improving musculoskeletal injuries. The ideal hydrogels should be capable of promoting the development of new tissues and simulating the characteristics of target tissues, with the properties matching the cell-matrix constituents of autologous tissues. Although there have been numerous reports of hydrogels loaded with MSC-derived EVs for the repair of musculoskeletal injuries, such as intervertebral disc injury, tendinopathy, bone fractures, and cartilage injuries, there are still many hurdles to overcome before the clinical application of modified hydrogels. In this review, we focus on the advantages of the isolation technique of EVs in combination with different types of hydrogels. In this context, the efficacy of hydrogels loaded with MSC-derived EVs in different musculoskeletal injuries is discussed in detail to provide a reference for the future application of hydrogels loaded with MSC-derived EVs in the clinical treatment of musculoskeletal injuries.

Unveiling Mesenchymal Stem Cells' Regenerative Potential in Clinical Applications: Insights in miRNA and lncRNA Implications

It is now widely recognized that mesenchymal stem cells (MSCs) possess the capacity to differentiate into a wide array of cell types. Numerous studies have identified the role of lncRNA in the regulation of MSC differentiation. It is important to elucidate the role and interplay of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of signalling pathways that govern MSC function. Furthermore, miRNAs and lncRNAs are important clinical for innovative strategies aimed at addressing a wide spectrum of existing and emerging disease. Hence it is important to consider their impact on MSC function and differentiation. Examining the data available in public databases, we have collected the literature containing the latest discoveries pertaining to human stem cells and their potential in both fundamental research and clinical applications. Furthermore, we have compiled completed clinical studies that revolve around the application of MSCs, shedding light on the opportunities presented by harnessing the regulatory potential of miRNAs and lncRNAs. This exploration of the therapeutic possibilities offered by miRNAs and lncRNAs within MSCs unveils exciting prospects for the development of precision therapies and personalized treatment approaches. Ultimately, these advancements promise to augment the efficacy of regenerative strategies and produce positive outcomes for patients. As research in this field continues to evolve, it is imperative to explore and exploit the vast potential of miRNAs and lncRNAs as therapeutic agents. The findings provide a solid basis for ongoing investigations, fuelling the quest to fully unlock the regenerative potential of MSCs.

Engineered extracellular vesicles for ischemic stroke: a systematic review and meta-analysis of preclinical studies

BACKGROUND

This systematic review and meta-analysis aimed to evaluate the efficacy of engineered extracellular vesicles (EEVs) in the treatment of ischemic stroke (IS) in preclinical studies and to compare them with natural extracellular vesicles (EVs). The systematic review provides an up-to-date overview of the current state of the literature on the use of EEVs for IS and informs future research in this area.

METHODS

We searched PubMed, EMBASE, Web of Science, Cochrane Library, and Scopus databases for peer-reviewed preclinical studies on the therapeutic effect of EEVs on IS.Databases ranged from the inception to August 1, 2023. The outcome measures included infarct volumes, neurological scores, behavioral scores, apoptosis rates, numbers of neurons, and levels of IL-1β, IL-6, and TNF-α. The CAMARADES checklist was used to assess the quality and bias risks of the studies. All statistical analyses were performed using RevMan 5.4 software.

RESULTS

A total of 28 studies involving 1760 animals met the inclusion criteria. The results of the meta-analysis showed that compared to natural EVs, EEVs reduced infarct volume (percentage: SMD = -2.33, 95% CI: -2.92, -1.73; size: SMD = -2.36, 95% CI: -4.09, -0.63), improved neurological scores (mNSS: SMD = -1.78, 95% CI: -2.39, -1.17; Zea Longa: SMD = -2.75, 95% CI: -3.79, -1.71), promoted behavioral recovery (rotarod test: SMD = 2.50, 95% CI: 1.81, 3.18; grid-walking test: SMD = -3.45, 95% CI: -5.15, -1.75; adhesive removal test: SMD = -2.60, 95% CI: -4.27, -0.93; morris water maze test: SMD = -3.91, 95% CI: -7.03, -0.79), and reduced the release of proinflammatory factors (IL-1β: SMD = -2.02, 95% CI: -2.77, -1.27; IL-6: SMD = -3.01, 95% CI: -4.47, -1.55; TNF-α: SMD = -2.72, 95% CI: -4.30, -1.13), increasing the number of neurons (apoptosis rate: SMD = -2.24, 95% CI: -3.32, -1.16; the number of neurons: SMD = 3.70, 95% CI: 2.44, 4.96). The funnel plots for the two main outcome measures were asymmetric, indicating publication bias. The median score on the CAMARADES checklist was 7 points (IQR: 6-9).

CONCLUSIONS

This meta-analysis shows that EEVs are superior to natural EVs for the treatment of IS. However, research in this field is still at an early stage, and more research is needed to fully understand the potential therapeutic mechanism of EEVs and their potential use in the treatment of IS.

PROSPERO REGISTRATION NUMBER

CRD42022368744.

Exosomes Interactions with the Blood-Brain Barrier: Implications for Cerebral Disorders and Therapeutics

The Blood-Brain Barrier (BBB) is a selective structural and functional barrier between the circulatory system and the cerebral environment, playing an essential role in maintaining cerebral homeostasis by limiting the passage of harmful molecules. Exosomes, nanovesicles secreted by virtually all cell types into body fluids, have emerged as a major mediator of intercellular communication. Notably, these vesicles can cross the BBB and regulate its physiological functions. However, the precise molecular mechanisms by which exosomes regulate the BBB remain unclear. Recent research studies focused on the effect of exosomes on the BBB, particularly in the context of their involvement in the onset and progression of various cerebral disorders, including solid and metastatic brain tumors, stroke, neurodegenerative, and neuroinflammatory diseases. This review focuses on discussing and summarizing the current knowledge about the role of exosomes in the physiological and pathological modulation of the BBB. A better understanding of this regulation will improve our understanding of the pathogenesis of cerebral diseases and will enable the design of effective treatment strategies.

The pathological and therapeutically role of mesenchymal stem cell (MSC)-derived exosome in degenerative diseases; Particular focus on LncRNA and microRNA

By releasing exosomes, which create the ideal milieu for the resolution of inflammation, mesenchymal stem cells (MSCs) enhance tissue healing and have strong immunomodulatory capabilities. MSCs-derived exosome also can affect tumor progress by a myriad of mechanisms. Exosomes function as a cell-cell communication tool to affect cellular activity in recipient cells and include an array of efficient bioactive chemicals. Understanding the fundamental biology of inflammation ablation, tissue homeostasis, and the creation of therapeutic strategies is particularly interested in the horizontal transfer of exosomal long non-coding RNAs (lncRNA) and microRNAs (miRNAs) to recipient cells, where they affect target gene expression. Herein, we propose an exosomal lncRNA and microRNA profile in neurological, renal, cardiac, lung, and liver diseases as well as skin wounds and arthritis.

Mesenchymal Stem Cell-Derived Exosomes: A Novel Approach to Diabetes-Associated Cognitive Impairment

The progression of diabetes frequently results in a myriad of neurological disorders, including ischemic stroke, depression, blood-brain barrier impairment, and cognitive dysfunction. Notably, diabetes-associated cognitive impairment, a prevalent comorbidity during the course of diabetes, progressively affects patients' cognitive abilities and may reciprocally influence diabetes management, thereby severely impacting patients' quality of life. Extracellular vesicles, particularly nanoscale exosomes, have garnered considerable attention in recent years. These exosomes carry and transfer various functional molecules, such as proteins, lipids, and diverse non-coding RNAs, serving as novel regulators and communicators in intercellular interactions. Of particular interest, mesenchymal stem cell-derived exosomes (MSC-Exos) have been reported to traverse the blood-brain barrier and ameliorate intracerebral pathologies. This review elucidates the role of MSC-Exos in diabetes-related cognitive impairment, with a focus on their applications as biomarkers, modulation of neuronal regeneration and synaptic plasticity, anti-inflammatory properties, antioxidative effects, and their involvement in regulating the functionality of β-amyloid proteins during the course of cognitive impairment. The immense therapeutic potential of MSC-Exos in the treatment of diabetes-induced cognitive dysfunction is emphasized.

Clinical Theragnostic Signature of Extracellular Vesicles in Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) is a common cause of disability and fatality worldwide. Depending on the clinical presentation, it is a type of acquired brain damage that can be mild, moderate, or severe. The degree of patient's discomfort, prognosis, therapeutic approach, survival rates, and recurrence can all be strongly impacted by an accurate diagnosis made early on. The Glasgow Coma Scale (GCS), along with neuroimaging (MRI (Magnetic Resonance Imaging) and CT scan), is a neurological assessment tools used to evaluate and categorize the severity of TBI based on the patient's level of consciousness, eye opening, and motor response. Extracellular vesicles (EVs) are a growing domain, explaining neurological complications in a more detailed manner. EVs, in general, play a role in cellular communication. Its molecular signature such as DNA, RNA, protein, etc. contributes to the status (health or pathological stage) of the parental cell. Brain-derived EVs support more specific screening (diagnostic and prognostic) in TBI research. Therapeutic impact of EVs are more promising for aiding in TBI healing. It is nontoxic, biocompatible, and capable of crossing the blood-brain barrier (BBB) to transport therapeutic molecules. This review has highlighted the relationships between EVs and TBI theranostics, EVs and TBI-related clinical trials, and related research domain-associated challenges and solutions. This review motivates further exploration of associations between EVs and TBI and develops a better approach to TBI management.

Harnessing the therapeutic potential of mesenchymal stem cell-derived exosomes in cardiac arrest: Current advances and future perspectives

BACKGROUND

Cardiac arrest (CA), characterized by sudden onset and high mortality rates, is one of the leading causes of death globally, with a survival rate of approximately 6-24%. Studies suggest that the restoration of spontaneous circulation (ROSC) hardly improved the mortality rate and prognosis of patients diagnosed with CA, largely due to ischemia-reperfusion injury.

MAIN BODY

Mesenchymal stem cells (MSCs) exhibit self-renewal and strong potential for multilineage differentiation. Their effects are largely mediated by extracellular vesicles (EVs). Exosomes are the most extensively studied subgroup of EVs. EVs mainly mediate intercellular communication by transferring vesicular proteins, lipids, nucleic acids, and other substances to regulate multiple processes, such as cytokine production, cell proliferation, apoptosis, and metabolism. Thus, exosomes exhibit significant potential for therapeutic application in wound repair, tissue reconstruction, inflammatory reaction, and ischemic diseases.

CONCLUSION

Based on similar pathological mechanisms underlying post-cardiac arrest syndrome involving various tissues and organs in many diseases, the review summarizes the therapeutic effects of MSC-derived exosomes and explores the prospects for their application in the treatment of CA.

Research progress of extracellular vesicles and exosomes derived from mesenchymal stem cells in the treatment of oxidative stress-related diseases

There is growing evidence that mesenchymal stem cell-derived extracellular vesicles and exosomes can significantly improve the curative effect of oxidative stress-related diseases. Mesenchymal stem cell extracellular vesicles and exosomes (MSC-EVs and MSC-Exos) are rich in bioactive molecules and have many biological regulatory functions. In this review, we describe how MSC-EVs and MSC-Exos reduce the related markers of oxidative stress and inflammation in various systemic diseases, and the molecular mechanism of MSC-EVs and MSC-Exos in treating apoptosis and vascular injury induced by oxidative stress. The results of a large number of experimental studies have shown that both local and systemic administration can effectively inhibit the oxidative stress response in diseases and promote the survival and regeneration of damaged parenchymal cells. The mRNA and miRNAs in MSC-EVs and MSC-Exos are the most important bioactive molecules in disease treatment, which can inhibit the apoptosis, necrosis and oxidative stress of lung, heart, kidney, liver, bone, skin and other cells, and promote their survive and regenerate.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles for Vasculopathies and Angiogenesis: Therapeutic Applications and Optimization

Extracellular vesicles (EVs), as part of the cellular secretome, have emerged as essential cell-cell communication regulators in multiple physiological and pathological processes. Previous studies have widely reported that mesenchymal stromal cell-derived EVs (MSC-EVs) have potential therapeutic applications in ischemic diseases or regenerative medicine by accelerating angiogenesis. MSC-EVs also exert beneficial effects on other vasculopathies, including atherosclerosis, aneurysm, vascular restenosis, vascular calcification, vascular leakage, pulmonary hypertension, and diabetic retinopathy. Consequently, the potential of MSC-EVs in regulating vascular homeostasis is attracting increasing interest. In addition to native or naked MSC-EVs, modified MSC-EVs and appropriate biomaterials for delivering MSC-EVs can be introduced to this area to further promote their therapeutic applications. Herein, we outline the functional roles of MSC-EVs in different vasculopathies and angiogenesis to elucidate how MSC-EVs contribute to maintaining vascular system homeostasis. We also discuss the current strategies to optimize their therapeutic effects, which depend on the superior bioactivity, high yield, efficient delivery, and controlled release of MSC-EVs to the desired regions, as well as the challenges that need to be overcome to allow their broad clinical translation.

Physiological and pathological consequences of exosomes at the blood-brain-barrier interface

Blood-brain barrier (BBB) interface with multicellular structure controls strictly the entry of varied circulating macromolecules from the blood-facing surface into the brain parenchyma. Under several pathological conditions within the central nervous system, the integrity of the BBB interface is disrupted due to the abnormal crosstalk between the cellular constituents and the recruitment of inflammatory cells. Exosomes (Exos) are nano-sized extracellular vesicles with diverse therapeutic outcomes. These particles transfer a plethora of signaling molecules with the potential to modulate target cell behavior in a paracrine manner. Here, in the current review article, the therapeutic properties of Exos and their potential in the alleviation of compromised BBB structure were discussed. Video Abstract.

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.

The Exosome-Mediated PI3K/Akt/mTOR Signaling Pathway in Neurological Diseases

As major public health concerns associated with a rapidly growing aging population, neurodegenerative diseases (NDDs) and neurological diseases are important causes of disability and mortality. Neurological diseases affect millions of people worldwide. Recent studies have indicated that apoptosis, inflammation, and oxidative stress are the main players of NDDs and have critical roles in neurodegenerative processes. During the aforementioned inflammatory/apoptotic/oxidative stress procedures, the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway plays a crucial role. Considering the functional and structural aspects of the blood-brain barrier, drug delivery to the central nervous system is relatively challenging. Exosomes are nanoscale membrane-bound carriers that can be secreted by cells and carry several cargoes, including proteins, nucleic acids, lipids, and metabolites. Exosomes significantly take part in the intercellular communications due to their specific features including low immunogenicity, flexibility, and great tissue/cell penetration capabilities. Due to their ability to cross the blood-brain barrier, these nano-sized structures have been introduced as proper vehicles for central nervous system drug delivery by multiple studies. In the present systematic review, we highlight the potential therapeutic effects of exosomes in the context of NDDs and neurological diseases by targeting the PI3K/Akt/mTOR signaling pathway.

MiR-17-5p Mediates the Effects of ACE2-Enriched Endothelial Progenitor Cell-Derived Exosomes on Ameliorating Cerebral Ischemic Injury in Aged Mice

Aging is one of the key mechanisms of vascular dysfunction and contributes to the initiation and progression of ischemic stroke (IS). Our previous study demonstrated that ACE2 priming enhanced the protective effects of exosomes derived from endothelial progenitor cells (EPC-EXs) on hypoxia-induced injury in aging endothelial cells (ECs). Here, we aimed to investigate whether ACE2-enriched EPC-EXs (ACE2-EPC-EXs) could attenuate brain ischemic injury by inhibiting cerebral EC damage through their carried miR-17-5p and the underlying molecular mechanisms. The enriched miRs in ACE2-EPC-EXs were screened using the miR sequencing method. EPC-EXs, ACE2-EPC-EXs, and ACE2-EPC-EXs with miR-17-5p deficiency (ACE2-EPC-EXs^{antagomiR-17-5p}) were administered to transient middle cerebral artery occlusion (tMCAO)-operated aged mice or coincubated with hypoxia/reoxygenation (H/R)-treated aging ECs. The results showed that (1) the level of brain EPC-EXs and their carried ACE2 were significantly decreased in aged mice compared to in young mice, and (2) after tMCAO, aged mice displayed increases in brain cell senescence, infarct volume, and neurological deficit score (NDS) and a decrease in cerebral blood flow (CBF). (3) Compared with EPC-EXs, ACE2-EPC-EXs were enriched with miR-17-5p and more effective in increasing ACE2 and miR-17-5p expression in cerebral microvessels, accompanied by obvious increases in cerebral microvascular density (cMVD) and cerebral blood flow (CBF) and decreases in brain cell senescence, infarct volume, neurological deficit score (NDS), cerebral EC ROS production, and apoptosis in tMCAO-operated aged mice. Moreover, silencing of miR-17-5p partially abolished the beneficial effects of ACE2-EPC-EXs. (4) In H/R-treated aging ECs, ACE2-EPC-EXs were more effective than EPC-EXs in decreasing cell senescence, ROS production, and apoptosis and increasing cell viability and tube formation. In a mechanistic study, ACE2-EPC-EXs more effectively inhibited PTEN protein expression and increased the phosphorylation of PI3K and Akt, which were partially abolished by miR-17-5p knockdown. Altogether, our data suggest that ACE-EPC-EXs have better protective effects on ameliorating aged IS mouse brain neurovascular injury by inhibiting cell senescence, EC oxidative stress, apoptosis, and dysfunction by activating the miR-17-5p/PTEN/PI3K/Akt signaling pathway.

Human umbilical cord mesenchymal stem cells-derived exosomal circDLGAP4 promotes angiogenesis after cerebral ischemia-reperfusion injury by regulating miR-320/KLF5 axis

Accumulating evidence suggests that human umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSCs-Exos) are a promising therapeutic strategy for cerebral ischemia-reperfusion injury (CIRI). However, the underlying mechanism remains unclear. hUC-MSCs-Exos were identified by electron microscopy, NTA, and Western blotting. In the hypoxia/reoxygenation (H/R) cell model, human brain microvascular endothelial cells (HBMECs) were cocultured with hUC-MSCs-Exos. Then, cell viability, migration, apoptosis, and tube formation were measured by MTT, flow cytometry, transwell, and tube formation assays. RT-qPCR and Western blotting were used to detect the changes in RNA and protein. RNA pull-down and dual luciferase reporter assays confirmed the relationship between circDLGAP4, miR-320, and KLF5. Ischemia-reperfusion (I/R) rat model was established for in vivo experiments. hUC-MSCs-Exos increased the expression levels of circDLGAP4 and KLF5 but decreased miR-320 in H/R-treated HBMECs by transferring exosomal circDLGAP4. Knockdown of circDLGAP4 in hUC-MSCs-Exos reversed the promoting effects of hUC-MSCs-Exos on cell viability, migration, and tube formation in H/R-treated HBMECs in vitro and also abolished the protective effects of hUC-MSCs-Exos on cerebrovascular injury in I/R rats. Mechanistically, exosomal circDLGAP4 negatively regulated miR-320 in HBMECs, which directly bound to KLF5. In addition, the downregulation of miR-320 could reverse the regulatory effect of exosomal shcircDLGAL5 in H/R-treated HBMECs by upregulating KLF5. hUC-MSCs-Exos-derived circDLGAP4 reduced cerebrovascular injury by regulating miR-320/KLF5 signaling. These results provide a stem cell-based approach to treat CIRI.

Exosomes for angiogenesis induction in ischemic disorders

Ischaemic disorders are leading causes of morbidity and mortality worldwide. While the current therapeutic approaches have improved life expectancy and quality of life, they are unable to "cure" ischemic diseases and instate regeneration of damaged tissues. Exosomes are a class of extracellular vesicles with an average size of 100-150 nm, secreted by many cell types and considered a potent factor of cells for paracrine effects. Since exosomes contain multiple bioactive components such as growth factors, molecular intermediates of different intracellular pathways, microRNAs and nucleic acids, they are considered as cell-free therapeutics. Besides, exosomes do not rise cell therapy concerns such as teratoma formation, alloreactivity and thrombotic events. In addition, exosomes are stored and utilized more convenient. Interestingly, exosomes could be an ideal complementary therapeutic tool for ischemic disorders. In this review, we discussed therapeutic functions of exosomes in ischemic disorders including angiogenesis induction through various mechanisms with specific attention to vascular endothelial growth factor pathway. Furthermore, different delivery routes of exosomes and different modification strategies including cell preconditioning, gene modification and bioconjugation, were highlighted. Finally, pre-clinical and clinical investigations in which exosomes were used were discussed.

Targeting Non-Coding RNA for CNS Injuries: Regulation of Blood-Brain Barrier Functions

Central nervous system (CNS) injuries are the most common cause of death and disability around the world. The blood-brain barrier (BBB) is located at the interface between the CNS and the surrounding environment, which protects the CNS from exogenous molecules, harmful agents or microorganisms in the blood. The disruption of BBB is a common feature of CNS injuries and participates in the pathological processes of secondary brain damage. Recently, a growing number of studies have indicated that non-coding RNAs (ncRNAs) play an important role in brain development and are involved in CNS injuries. In this review, we summarize the mechanisms of BBB breakdown after CNS injuries. We also discuss the effects of ncRNAs including long noncoding RNAs (lncRNAs), circular RNAs (circRNAs) and microRNAs (miRNAs) on BBB damage in CNS injuries such as ischemic stroke, traumatic brain injury (TBI), intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH). In addition, we clarify the pharmacotherapies that could regulate BBB function via ncRNAs in CNS injuries, as well as the challenges and perspectives of ncRNAs on modulation of BBB function. Hence, on the basis of these effects, ncRNAs may be developed as therapeutic agents to protect the BBB for CNS injury patients.

Extracellular Vesicles from Mesenchymal Stem Cells: Towards Novel Therapeutic Strategies for Neurodegenerative Diseases

Neurodegenerative diseases are fatal disorders of the central nervous system (CNS) which currently lack effective treatments. The application of mesenchymal stem cells (MSCs) represents a new promising approach for treating these incurable disorders. Growing evidence suggest that the therapeutic effects of MSCs are due to the secretion of neurotrophic molecules through extracellular vesicles. The extracellular vesicles produced by MSCs (MSC-EVs) have valuable innate properties deriving from parental cells and could be exploited as cell-free treatments for many neurological diseases. In particular, thanks to their small size, they are able to overcome biological barriers and reach lesion sites inside the CNS. They have a considerable pharmacokinetic and safety profile, avoiding the critical issues related to the fate of cells following transplantation. This review discusses the therapeutic potential of MSC-EVs in the treatment of neurodegenerative diseases, focusing on the strategies to further enhance their beneficial effects such as tracking methods, bioengineering applications, with particular attention to intranasal delivery as a feasible strategy to deliver MSC-EVs directly to the CNS in an effective and minimally invasive way. Current progresses and limiting issues to the extent of the use of MSC-EVs treatment for human neurodegenerative diseases will be also revised.

Stem Cell-derived Extracellular Vesicles: A Promising Nano Delivery Platform to the Brain?

A very important cause of the frustration with drug therapy for central nervous system (CNS) diseases is the failure of drug delivery. The blood-brain barrier (BBB) prevents most therapeutic molecules from entering the brain while maintaining CNS homeostasis. Scientists are keen to develop new brain drug delivery systems to solve this dilemma. Extracellular vesicles (EVs), as a class of naturally derived nanoscale vesicles, have been extensively studied in drug delivery due to their superior properties. This review will briefly present current brain drug delivery strategies, including invasive and non-invasive techniques that target the brain, and the application of nanocarriers developed for brain drug delivery in recent years, especially EVs. The cellular origin of EVs affects the surface protein, size, yield, luminal composition, and other properties of EVs, which are also crucial in determining whether EVs are useful as drug carriers. Stem cell-derived EVs, which inherit the properties of parental cells and avoid the drawbacks of cell therapy, have always been favored by researchers. Thus, in this review, we will focus on the application of stem cell-derived EVs for drug delivery in the CNS. Various nucleic acids, proteins, and small-molecule drugs are loaded into EVs with or without modification and undergo targeted delivery to the brain to achieve their therapeutic effects. In addition, the challenges facing the clinical application of EVs as drug carriers will also be discussed. The directions of future efforts may be to improve drug loading efficiency and precise targeting.

Therapeutic potential and mechanisms of mesenchymal stem cell-derived exosomes as bioactive materials in tendon-bone healing

Tendon-bone insertion (TBI) injuries, such as anterior cruciate ligament injury and rotator cuff injury, are the most common soft tissue injuries. In most situations, surgical tendon/ligament reconstruction is necessary for treating such injuries. However, a significant number of cases failed because healing of the enthesis occurs through scar tissue formation rather than the regeneration of transitional tissue. In recent years, the therapeutic potential of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies, such as chronic paraplegia, non-ischemic heart failure, and osteoarthritis of the knee. MSCs are multipotent stem cells, which have self-renewability and the ability to differentiate into a wide variety of cells such as chondrocytes, osteoblasts, and adipocytes. Numerous studies have suggested that MSCs could promote angiogenesis and cell proliferation, reduce inflammation, and produce a large number of bioactive molecules involved in the repair. These effects are likely mediated by the paracrine mechanisms of MSCs, particularly through the release of exosomes. Exosomes, nano-sized extracellular vesicles (EVs) with a lipid bilayer and a membrane structure, are naturally released by various cell types. They play an essential role in intercellular communication by transferring bioactive lipids, proteins, and nucleic acids, such as mRNAs and miRNAs, between cells to influence the physiological and pathological processes of recipient cells. Exosomes have been shown to facilitate tissue repair and regeneration. Herein, we discuss the prospective applications of MSC-derived exosomes in TBI injuries. We also review the roles of MSC-EVs and the underlying mechanisms of their effects on promoting tendon-bone healing. At last, we discuss the present challenges and future research directions.

Analysis of the Research Hotspot of Exosomes in Cardiovascular Disease: A Bibliometric-based Literature Review

OBJECTIVE

To investigate the current status and development trend of research on exosomes in cardiovascular disease (CVD) using bibliometric analysis and to elucidate trending research topics.

METHODS

Research articles on exosomes in CVD published up to April 2022 were retrieved from the Web of Science database. Data were organized using Microsoft Office Excel 2019. CiteSpace 6.1 and VOSviewer 1.6.18 were used for bibliometric analysis and result visualization.

RESULTS

Overall, 256 original research publications containing 190 fundamental research publications and 66 clinical research publications were included. "Extracellular vesicle" was the most frequent research keyword, followed by "microrna," "apoptosis," and "angiogenesis." Most publications were from China (187, 73.05%), followed by the United States (57, 22.27%), the United Kingdom (7, 2.73%), and Japan (7, 2.73%). A systematic review of the publications revealed that myocardial infarction and stroke were the most popular topics and that exosomes and their contents, such as microRNAs (miRNAs), play positive roles in neuroprotection, inhibition of autophagy and apoptosis, promotion of angiogenesis, and protection of cardiomyocytes.

CONCLUSION

Research on exosomes in CVD has attracted considerable attention, with China having the most published studies. Fundamental research has focused on CVD pathogenesis; exosomes regulate the progression of CVD through biological processes, such as the inflammatory response, autophagy, and apoptosis. Clinical research has focused on biomarkers for CVD; studies on using miRNAs in exosomes as disease markers for diagnosis could become a future trend.

Exosomes in pathogenesis, diagnosis, and therapy of ischemic stroke

Ischemic stroke is one of the major contributors to death and disability worldwide. Thus, there is an urgent need to develop early brain tissue perfusion therapies following acute stroke and to enhance functional recovery in stroke survivors. The morbidity, therapy, and recovery processes are highly orchestrated interactions involving the brain with other tissues. Exosomes are natural and ideal mediators of intercellular information transfer and recognized as biomarkers for disease diagnosis and prognosis. Changes in exosome contents express throughout the physiological process. Accumulating evidence demonstrates the use of exosomes in exploring unknown cellular and molecular mechanisms of intercellular communication and organ homeostasis and indicates their potential role in ischemic stroke. Inspired by the unique properties of exosomes, this review focuses on the communication, diagnosis, and therapeutic role of various derived exosomes, and their development and challenges for the treatment of cerebral ischemic stroke.

Mesenchymal stem cells for regenerative medicine in central nervous system

Mesenchymal stem cells (MSCs) are multipotent stem cells, whose paracrine and immunomodulatory potential has made them a promising candidate for central nervous system (CNS) regeneration. Numerous studies have demonstrated that MSCs can promote immunomodulation, anti-apoptosis, and axon re-extension, which restore functional neural circuits. The therapeutic effects of MSCs have consequently been evaluated for application in various CNS diseases including spinal cord injury, cerebral ischemia, and neurodegenerative disease. In this review, we will focus on the research works published in the field of mechanisms and therapeutic effects of MSCs in CNS regeneration.

Effects and Mechanisms of Exosomes from Different Sources in Cerebral Ischemia

Cerebral ischemia refers to the symptom of insufficient blood supply to the brain. Cells of many different origins participate in the process of repairing damage after cerebral ischemia occurs, in which exosomes secreted by the cells play important roles. For their characteristics, such as small molecular weight, low immunogenicity, and the easy penetration of the blood-brain barrier (BBB), exosomes can mediate cell-to-cell communication under pathophysiological conditions. In cerebral ischemia, exosomes can reduce neuronal damage and improve the brain microenvironment by regulating inflammation, mediating pyroptosis, promoting axonal growth, and stimulating vascular remodeling. Therefore, exosomes have an excellent application prospect for the treatment of cerebral ischemia. This article reviews the roles and mechanisms of exosomes from different sources in cerebral ischemia and provides new ideas for the prevention and treatment of cerebral ischemia.

Inhibition of Cerebral Ischemia/Reperfusion Injury by MSCs-Derived Small Extracellular Vesicles in Rodent Models: A Systematic Review and Meta-Analysis

Small extracellular vesicles (sEVs) secreted by mesenchymal stem cells (MSCs) have shown great therapeutic potential in cerebral ischemia-reperfusion injury (CIRI). In this study, we firstly performed a systematic review to evaluate the efficacy of MSCs-derived sEV for experimental cerebral ischemia/reperfusion injury. 24 studies were identified by searching 8 databases from January 2012 to August 2022. The methodological quality was assessed by using the SYRCLE 's risk of bias tool for animal studies. All the data were analyzed using RevMan 5.3 software. As a result, the score of study quality ranged from 3 to 9 in a total of ten points. Meta-analyses showed that MSCs-derived sEVs could effectively alleviate neurological impairment scores, reduced the volume of cerebral infarction and brain water content, and attenuated neuronal apoptosis. Additionally, the possible mechanisms of MSCs-derived sEVs for attenuating neuronal apoptosis were inhibiting microglia-mediated neuroinflammation. Thus, MSCs-derived sEVs might be regarded as a novel insight for cerebral ischemic stroke. However, further mechanistic studies, therapeutic safety, and clinical trials are required. Systematic review registration. PROSPERO CRD42022312227.

Mesenchymal Stem Cell-Derived Exosomes Ameliorate Delayed Neurocognitive Recovery in Aged Mice by Inhibiting Hippocampus Ferroptosis via Activating SIRT1/Nrf2/HO-1 Signaling Pathway

Delayed neurocognitive recovery (dNCR) is a prevalent perioperative neurological complication in older patients and has common characteristics such as acute cognitive dysfunction, impaired memory, and inattention. Mesenchymal stem cell-derived exosomes (MSCs-Exo) are enclosed by a lipid bilayer contain proteins, DNA, miRNA, and other components, which are important mediators of intercellular communication. It has been reported that exosomes could play an important role in the treatment of neurodegenerative diseases, nerve injury, and other neurological diseases. In this study, we examined the effects of MSCs-Exo on dNCR aged mice after exploratory laparotomy and evaluated their potential regulatory mechanisms. We found that MSCs-Exo treatment ameliorated cognitive impairment in dNCR aged mice. MSCs-Exo inhibit hippocampus ferroptosis and increase the expression of silent information regulator 1 (SIRT1), factor nuclear factor-erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in dNCR aged mice. Interestingly, the above effects of MSCs-Exo on dNCR aged mice were abolished by SIRT1 selective inhibitor EX-527. In conclusion, these findings indicated that MSCs-Exo can ameliorate cognitive impairment by inhibiting hippocampus ferroptosis in dNCR aged mice via activating SIRT1/Nrf2/HO-1 signaling pathway, providing a potential avenue for the treatment of dNCR.