Enhancement of therapeutic potential of mesenchymal stem cell-derived extracellular vesicles

High throughput screening of mesenchymal stromal cell morphological response to inflammatory signals for bioreactor-based manufacturing of extracellular vesicles that modulate microglia

Due to their immunomodulatory function, mesenchymal stromal cells (MSCs) are a promising therapeutic with the potential to treat neuroinflammation associated with neurodegenerative diseases. This function is mediated by secreted extracellular vesicles (MSC-EVs). Despite established safety, MSC clinical translation has been unsuccessful due to inconsistent clinical outcomes resulting from functional heterogeneity. Current approaches to mitigate functional heterogeneity include 'priming' MSCs with inflammatory signals to enhance function. However, comprehensive evaluation of priming and its effects on MSC-EV function has not been performed. Furthermore, clinical translation of MSC-EV therapies requires significant manufacturing scale-up, yet few studies have investigated the effects of priming in bioreactors. As MSC morphology has been shown to predict their immunomodulatory function, we screened MSC morphological response to an array of priming signals and evaluated MSC-EV identity and potency in response to priming in flasks and bioreactors. We identified unique priming conditions corresponding to distinct morphologies. These conditions demonstrated a range of MSC-EV preparation quality and lipidome, allowing us to discover a novel MSC-EV manufacturing condition, as well as gain insight into potential mechanisms of MSC-EV microglia modulation. Our novel screening approach and application of priming to MSC-EV bioreactor manufacturing informs refinement of larger-scale manufacturing and enhancement of MSC-EV function.

Exosomes in the Real World of Medical Aesthetics: A Review

BACKGROUND

Exosomes are cell-derived nanovesicles that transport proteins, nucleic acids, and lipids and play a significant role in almost every physiological process in the human body. They have generated great interest, especially in the field of tissue regeneration. Studies in the last decade support their great regenerating and rejuvenating potential. However, the lack of standardized procedures, limited knowledge regarding their action mechanism, and little clinical evidence impair their implementation and approval in the medical setting. This review aimed to identify published studies and clinical trials using exosomes in human patients for clinical treatments in aesthetic medicine.

MATERIALS AND METHODS

A systematic search was conducted in the PubMed database using the search term "exosomes" and 25 terms related to aesthetic medicine treatments in human patients. Additionally, a search was conducted in the ClinicalTrials.gov database for interventional clinical trials using exosomes for aesthetic treatments in adults 18 to ≥ 65 years of age.

RESULTS

Nine articles were selected after debugging the initial list of published articles in which exosomes were related to Aesthetic Medicine (633 articles). Nine studies were identified from the initial search on ClinicalTrial.gov (104 trials with exosomes).

CONCLUSIONS

There is no doubt about the scientific basis of exosome regenerative potential and the growing interest in exosomes in Aesthetic Medicine. However, companies must spend more on research to develop standardized and reliable procedures to obtain exosomes for their approval and application in clinical practice.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 . This review highlights the large amount of published research on exosomes related to aesthetic medicine and, at the same time, the lack of products approved by regulatory agencies. Several issues have been suggested to elucidate a response, such as the need for standardized protocols and more knowledge to ensure safe treatments. It also highlights the few clinical trials conducted to evaluate exosome properties in aesthetic medicine treatments.

Precision Nanomedicine with Bio-Inspired Nanosystems: Recent Trends and Challenges in Mesenchymal Stem Cells Membrane-Coated Bioengineered Nanocarriers in Targeted Nanotherapeutics

In the recent past, the formulation and development of nanocarriers has been elaborated into the broader fields and opened various avenues in their preclinical and clinical applications. In particular, the cellular membrane-based nanoformulations have been formulated to surpass and surmount the limitations and restrictions associated with naïve or free forms of therapeutic compounds and circumvent various physicochemical and immunological barriers including but not limited to systemic barriers, microenvironmental roadblocks, and other cellular or subcellular hinderances-which are quite heterogeneous throughout the diseases and patient cohorts. These limitations in drug delivery have been overcome through mesenchymal cells membrane-based precision therapeutics, where these interventions have led to the significant enhancements in therapeutic efficacies. However, the formulation and development of nanocarriers still focuses on optimization of drug delivery paradigms with a one-size-fits-all resolutions. As mesenchymal stem cell membrane-based nanocarriers have been engineered in highly diversified fashions, these are being optimized for delivering the drug payloads in more and better personalized modes, entering the arena of precision as well as personalized nanomedicine. In this Review, we have included some of the advanced nanocarriers which have been designed and been utilized in both the non-personalized as well as precision applicability which can be employed for the improvements in precision nanotherapeutics. In the present report, authors have focused on various other aspects of the advancements in stem cells membrane-based nanoparticle conceptions which can surmount several roadblocks and barriers in drug delivery and nanomedicine. It has been suggested that well-informed designing of these nanocarriers will lead to appreciable improvements in the therapeutic efficacy in therapeutic payload delivery applications. These approaches will also enable the tailored and customized designs of MSC-based nanocarriers for personalized therapeutic applications, and finally amending the patient outcomes.

Large-Area Silicon Nitride Nanosieve for Enhanced Diffusion-Based Exosome Isolation

Nanoporous membranes have a variety of applications, one of which is the size-selective separation of nanoparticles. In drug delivery, nanoporous membranes are becoming increasingly important for the isolation of exosomes, which are bio-nanoparticles. However, the low pore density and thickness of commercial membranes limit their efficiency. There have been many attempts to fabricate sub-micrometer thin membranes, but the limited surface area has restricted their practicality. In this study, large-area silicon nitride nanosieves for enhanced diffusion-based isolation of exosomes are presented. Notably, these nanosieves are scaled to sizes of up to 4-inch-wafers, a significant achievement in overcoming the fabrication challenges associated with such expansive areas. The method employs a 200 nm porous sieve (38.2% porosity) for exosome separation and a 50 nm sieve (10.7% porosity) for soluble protein removal. These 300 nm thick nanosieves outperform conventional polycarbonate membranes by being 50 times thinner, thereby increasing nanoparticle permeability. The method enables a 90% recovery rate of intact exosomes from human serum and a purity ratio of 3 × 107 particles/µg protein, 4.6 times higher than ultracentrifugation methods. The throughput of the method is up to 15 mL by increasing the size of the nanosieve, making it an ideal solution for large-scale exosome production for therapeutic purposes.

Extracellular vesicles (EVs): A promising therapeutic tool in the heart tissue regeneration

Mesenchymal stem cells (MSCs) treatment has been widely explored as a therapy for myocardial infarction, peripheral ischemic vascular diseases, dilated cardiomyopathy, and pulmonary hypertension. Latest in vitro studies suggest that MSCs can differentiate into contractile cardiomyocytes. One of the best-characterized MSCs products are MSCs-derived extracellular vesicles (EVs). EVs are crucial paracrine effectors of MSCs. Based on previous works, paracrine effects of MSCs play a primary role in the regenerative ability. Hence, in the current paper, we focused our attention on an alternative approach, exploiting products derived from human dental pulp stem cells (hDPSCs) rather than MSCs themselves, which may denote a cost-effective and safer approach. The focus has been on EVs and the bioactive molecules they contain to evaluate their ability to influence the differentiation process toward cardiomyogenic lineage. The expression of GATA4, ACTC1, CX43, and Nkx2.5 was evaluated using Immunofluorescence, real time-PCR, and Western blotting analyses. Furthermore, the expression profiling analysis of the microRNA hsa-miR-200c-3p, targeting the GATA4 gene, was studied. The hsa-miR-200c-3p was found significantly down-regulated in both c-hDPSCs + EVs-hDPSCs and c-hDPSCs + EVs-HL-1 compared to untreated c-hDPSCs underlying a possible epigenetic mechanism behind the prevalent up-regulation of its targeted GATA4 gene. The aim of the present work was to develop an in vitro model of hDPSCs able to differentiate into cardiomyocytes in order to investigate the role of EVs derived from hDPSCs and derived from HL-1 cardiomyocyte cell line in modulating the differentiation process toward cardiomyogenic lineage.

Transcriptome analysis reveals therapeutic potential of NAMPT in protecting against abdominal aortic aneurysm in human and mouse

Abdominal Aortic Aneurysm (AAA) is a life-threatening vascular disease characterized by the weakening and ballooning of the abdominal aorta, which has no effective therapeutic approaches due to unclear molecular mechanisms. Using single-cell RNA sequencing, we analyzed the molecular profile of individual cells within control and AAA abdominal aortas. We found cellular heterogeneity, with increased plasmacytoid dendritic cells and reduced endothelial cells and vascular smooth muscle cells (VSMCs) in AAA. Up-regulated genes in AAA were associated with muscle tissue development and apoptosis. Genes controlling VSMCs aberrant switch from contractile to synthetic phenotype were significantly enriched in AAA. Additionally, VSMCs in AAA exhibited cell senescence and impaired oxidative phosphorylation. Similar observations were made in a mouse model of AAA induced by Angiotensin II, further affirming the relevance of our findings to human AAA. The concurrence of gene expression changes between human and mouse highlighted the impairment of oxidative phosphorylation as a potential target for intervention. Nicotinamide phosphoribosyltransferase (NAMPT, also named VISFATIN) signaling emerged as a signature event in AAA. NAMPT was significantly downregulated in AAA. NAMPT-extracellular vesicles (EVs) derived from mesenchymal stem cells restored NAMPT levels, and offered protection against AAA. Furthermore, NAMPT-EVs not only repressed injuries, such as cell senescence and DNA damage, but also rescued impairments of oxidative phosphorylation in both mouse and human AAA models, suggesting NAMPT supplementation as a potential therapeutic approach for AAA treatment. These findings shed light on the cellular heterogeneity and injuries in AAA, and offered promising therapeutic intervention for AAA treatment.

MiR-17-5p-engineered sEVs Encapsulated in GelMA Hydrogel Facilitated Diabetic Wound Healing by Targeting PTEN and p21

Delayed wound healing is a major complication of diabetes, and is associated with impaired cellular functions. Current treatments are unsatisfactory. Based on the previous reports on microRNA expression in small extracellular vesicles (sEVs), miR-17-5p-engineered sEVs (sEVs17-OE) and encapsulated them in gelatin methacryloyl (GelMA) hydrogel for diabetic wounds treatment are fabricated. SEVs17-OE are successfully fabricated with a 16-fold increase in miR-17-5p expression. SEVs17-OE inhibited senescence and promoted the proliferation, migration, and tube formation of high glucose-induced human umbilical vein endothelial cells (HG-HUVECs). Additionally, sEVs17-OE also performs a promotive effect on high glucose-induced human dermal fibroblasts (HG-HDFs). Mechanism analysis showed the expressions of p21 and phosphatase and tensin homolog (PTEN), as the target genes of miR-17-5p, are downregulated significantly by sEVs17-OE. Accordingly, the downstream genes and pathways of p21 and PTEN, are activated. Next, sEVs17-OE are loaded in GelMA hydrogel to fabricate a novel bioactive wound dressing and to evaluate their effects on diabetic wound healing. Gel-sEVs17-OE effectively accelerated wound healing by promoting angiogenesis and collagen deposition. The cellular mechanism may be associated with local cell proliferation. Therefore, a novel bioactive wound dressing by loading sEVs17-OE in GelMA hydrogel, offering an option for chronic wound management is successfully fabricated.

Mesenchymal stem cell-derived extracellular vesicles: A novel promising neuroprotective agent for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive loss of neurons in the brain. However, there are no effective drugs for AD. Mesenchymal stem cell-derived extracellular vesicles (MSCs-EVs), as a new mediator of intercellular communication, are associated with low immunogenicity, low risk of tumor formation, and good safety profile. Therefore, MSCs-EVs may be a safe and attractive cell-free nanotherapeutics, offering a new perspective for AD treatment. Although preclinical studies have demonstrated that MSCs-EVs have significant neuroprotective effects, the underlying mechanism is unclear. This study aimed to: outline the diagnostic and delivery roles of MSCs-EVs for AD treatment; summarize the optimal sources and delivery methods of MSCs-EVs; provide a comprehensive review on the neuroprotective mechanisms of MSCs-EVs; explore how to enhance the neuroprotective effects of MSCs-EVs; and discuss the limitations and potential of their translation to the clinic. Therefore, this study may provide a more precise theoretical reference and practical basis for clinical research of MSCs-EVs.

Modulation of experimental acute lung injury by exosomal miR-7704 from mesenchymal stromal cells acts through M2 macrophage polarization

Acute lung injury (ALI) is a life-threatening condition with limited treatment options. The pathogenesis of ALI involves macrophage-mediated disruption and subsequent repair of the alveolar barriers, which ultimately results in lung damage and regeneration, highlighting the pivotal role of macrophage polarization in ALI. Although exosomes derived from mesenchymal stromal cells have been established as influential modulators of macrophage polarization, the specific role of exosomal microRNAs (miRNAs) remains underexplored. This study aimed to elucidate the role of specific exosomal miRNAs in driving macrophage polarization, thereby providing a reference for developing novel therapeutic interventions for ALI. We found that miR-7704 is the most abundant and efficacious miRNA for promoting the switch to the M2 phenotype in macrophages. Mechanistically, we determined that miR-7704 stimulates M2 polarization by inhibiting the MyD88/STAT1 signaling pathway. Notably, intra-tracheal delivery of miR-7704 alone in a lipopolysaccharide-induced murine ALI model significantly drove M2 polarization in lung macrophages and remarkably restored pulmonary function, thus increasing survival. Our findings highlight miR-7704 as a valuable tool for treating ALI by driving the beneficial M2 polarization of macrophages. Our findings pave the way for deeper exploration into the therapeutic potential of exosomal miRNAs in inflammatory lung diseases.

Biology and Therapeutic Properties of Mesenchymal Stem Cells in Leukemia

This comprehensive review delves into the multifaceted roles of mesenchymal stem cells (MSCs) in leukemia, focusing on their interactions within the bone marrow microenvironment and their impact on leukemia pathogenesis, progression, and treatment resistance. MSCs, characterized by their ability to differentiate into various cell types and modulate the immune system, are integral to the BM niche, influencing hematopoietic stem cell maintenance and functionality. This review extensively explores the intricate relationship between MSCs and leukemic cells in acute myeloid leukemia, acute lymphoblastic leukemia, chronic myeloid leukemia, and chronic lymphocytic leukemia. This review also addresses the potential clinical applications of MSCs in leukemia treatment. MSCs' role in hematopoietic stem cell transplantation, their antitumor effects, and strategies to disrupt chemo-resistance are discussed. Despite their therapeutic potential, the dual nature of MSCs in promoting and inhibiting tumor growth poses significant challenges. Further research is needed to understand MSCs' biological mechanisms in hematologic malignancies and develop targeted therapeutic strategies. This in-depth exploration of MSCs in leukemia provides crucial insights for advancing treatment modalities and improving patient outcomes in hematologic malignancies.

Mesenchymal stromal cell derived extracellular vesicles as a therapeutic tool: immune regulation, MSC priming, and applications to SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE.

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.

Influence of the isolation method on characteristics and functional activity of mesenchymal stromal cell-derived extracellular vesicles

BACKGROUND AIMS

Extracellular vesicle (EV) isolation methods are based on different physicochemical properties and may result in the purification of distinct EV populations. We compared two different isolation methods suitable for producing clinical-grade mesenchymal stromal cell-derived EVs (MSC-EVs)-ion exchange chromatography (IEX) and ultrafiltration (UF)-and evaluated their impact on the composition and functional properties of EVs.

METHODS

EVs were purified from conditioned culture medium using an anion exchange resin (IEX) or Amicon filters with a 100-kDa cutoff (UF) (MilliporeSigma, Burlington, MA, USA). We assessed nanoparticle size and distribution by nanoparticle tracking analysis (NTA) and tunable resistive pulse sensing (TRPS) and morphology by transmission electron microscopy. We also measured protein, lipid and total RNA concentration and immunophenotyped both EV populations by flow cytometry (MACSPlex assay; Miltenyi Biotec, Bergisch Gladbach, Germany). Moreover, immunomodulatory activity was tested using a standardized macrophage polarization assay and T-cell stimulation assay. Finally, proteomic analysis and cytokine quantification were carried out to better characterize both EV populations.

RESULTS

We found by both TRPS and NTA that IEX and UF yielded a comparable amount of total particles with similar size and distribution. In addition, a similar quantity of lipids was obtained with the two procedures. However, IEX yielded 10-fold higher RNA quantity and a larger amount of proteins than UF. MSC-EVs isolated from IEX and UF were positive for the exosome markers CD9, CD63 and CD81 and showed a comparable surface marker expression pattern. Both populations demonstrated immunomodulatory activity in vitro, as they prevented acquisition of the M1 phenotype in lipopolysaccharide-stimulated macrophages and inhibited acquisition of the activation markers CD69 and CD25 on T cells, but the IEX-EVs exerted a significantly greater immunomodulatory effect on both macrophages and T cells compared with UF-EVs. Proteomic analysis and gene ontology enrichment analysis revealed no major differences between the preparations. Finally, cytokine quantification revealed that IEX-EVs were more enriched in some crucial anti-inflammatory and immunomodulatory cytokines (e.g., IL-2, IL-10, transforming growth factor beta and vascular endothelial growth factor) compared with UF-EVs.

CONCLUSIONS

MSC-EVs isolated by IEX and UF displayed similar physicochemical, phenotypic and functional characteristics. In our conditions, both EV populations demonstrated important anti-inflammatory activity in macrophages and T cells. However, IEX-EVs were more potent than UF-EVs, which may indicate the superiority of this method for the production of clinical-grade EVs.

Transcriptional profiling of human cartilage endplate cells identifies novel genes and cell clusters underlying degenerated and non-degenerated phenotypes

BACKGROUND

Low back pain is a leading cause of disability worldwide and is frequently attributed to intervertebral disc (IVD) degeneration. Though the contributions of the adjacent cartilage endplates (CEP) to IVD degeneration are well documented, the phenotype and functions of the resident CEP cells are critically understudied. To better characterize CEP cell phenotype and possible mechanisms of CEP degeneration, bulk and single-cell RNA sequencing of non-degenerated and degenerated CEP cells were performed.

METHODS

Human lumbar CEP cells from degenerated (Thompson grade ≥ 4) and non-degenerated (Thompson grade ≤ 2) discs were expanded for bulk (N=4 non-degenerated, N=4 degenerated) and single-cell (N=1 non-degenerated, N=1 degenerated) RNA sequencing. Genes identified from bulk RNA sequencing were categorized by function and their expression in non-degenerated and degenerated CEP cells were compared. A PubMed literature review was also performed to determine which genes were previously identified and studied in the CEP, IVD, and other cartilaginous tissues. For single-cell RNA sequencing, different cell clusters were resolved using unsupervised clustering and functional annotation. Differential gene expression analysis and Gene Ontology, respectively, were used to compare gene expression and functional enrichment between cell clusters, as well as between non-degenerated and degenerated CEP samples.

RESULTS

Bulk RNA sequencing revealed 38 genes were significantly upregulated and 15 genes were significantly downregulated in degenerated CEP cells relative to non-degenerated cells (|fold change| ≥ 1.5). Of these, only 2 genes were previously studied in CEP cells, and 31 were previously studied in the IVD and other cartilaginous tissues. Single-cell RNA sequencing revealed 11 unique cell clusters, including multiple chondrocyte and progenitor subpopulations with distinct gene expression and functional profiles. Analysis of genes in the bulk RNA sequencing dataset showed that progenitor cell clusters from both samples were enriched in "non-degenerated" genes but not "degenerated" genes. For both bulk- and single-cell analyses, gene expression and pathway enrichment analyses highlighted several pathways that may regulate CEP degeneration, including transcriptional regulation, translational regulation, intracellular transport, and mitochondrial dysfunction.

CONCLUSIONS

This thorough analysis using RNA sequencing methods highlighted numerous differences between non-degenerated and degenerated CEP cells, the phenotypic heterogeneity of CEP cells, and several pathways of interest that may be relevant in CEP degeneration.

Biogenesis and delivery of extracellular vesicles: harnessing the power of EVs for diagnostics and therapeutics

Extracellular vesicles (EVs) are membrane-enclosed particles secreted by a variety of cell types. These vesicles encapsulate a diverse range of molecules, including proteins, nucleic acids, lipids, metabolites, and even organelles derived from their parental cells. While EVs have emerged as crucial mediators of intercellular communication, they also hold immense potential as both biomarkers and therapeutic agents for numerous diseases. A thorough understanding of EV biogenesis is crucial for the development of EV-based diagnostic developments since the composition of EVs can reflect the health and disease status of the donor cell. Moreover, when EVs are taken up by target cells, they can exert profound effects on gene expression, signaling pathways, and cellular behavior, which makes these biomolecules enticing targets for therapeutic interventions. Yet, despite decades of research, the intricate processes underlying EV biogenesis by donor cells and subsequent uptake by recipient cells remain poorly understood. In this review, we aim to summarize current insights and advancements in the biogenesis and uptake mechanisms of EVs. By shedding light on the fundamental mechanisms governing EV biogenesis and delivery, this review underscores the potential of basic mechanistic research to pave the way for developing novel diagnostic strategies and therapeutic applications.

Exosomes for hair growth and regeneration

Exosomes are lipid bilayer vesicles, 30-200 nm in diameter, that are produced by cells and play essential roles in cell-cell communication. Exosomes have been studied in several medical fields including dermatology. Hair loss, a major disorder that affects people and sometimes causes mental stress, urgently requires more effective treatment. Because the growth and cycling of hair follicles are governed by interactions between hair follicle stem cells (HFSCs) and dermal papilla cells (DPCs), a better understanding of the mechanisms responsible for hair growth and cycling through exosomes may provide new insights into novel treatments for hair loss. In this review, we focused on the comprehensive knowledge and recent studies on exosomes in the field of hair development and regeneration. We classified exosomes of several cellular origins for the treatment of hair loss. Exosomes and their components, such as microRNAs, are promising drugs for effective hair loss treatment.

Extracellular vesicle-carried GTF2I from mesenchymal stem cells promotes the expression of tumor-suppressive FAT1 and inhibits stemness maintenance in thyroid carcinoma

Through bioinformatics predictions, we identified that GTF2I and FAT1 were downregulated in thyroid carcinoma (TC). Further, Pearson's correlation coefficient revealed a positive correlation between GTF2I expression and FAT1 expression. Therefore, we selected them for this present study, where the effects of bone marrow mesenchymal stem cell-derived EVs (BMSDs-EVs) enriched with GTF2I were evaluated on the epithelial-to-mesenchymal transition (EMT) and stemness maintenance in TC. The under-expression of GTF2I and FAT1 was validated in TC cell lines. Ectopically expressed GTF2I and FAT1 were found to augment malignant phenotypes of TC cells, EMT, and stemness maintenance. Mechanistic studies revealed that GTF2I bound to the promoter region of FAT1 and consequently upregulated its expression. MSC-EVs could shuttle GTF2I into TPC-1 cells, where GTF2I inhibited TC malignant phenotypes, EMT, and stemness maintenance by increasing the expression of FAT1 and facilitating the FAT1-mediated CDK4/FOXM1 downregulation. In vivo experiments confirmed that silencing of GTF2I accelerated tumor growth in nude mice. Taken together, our work suggests that GTF2I transferred by MSC-EVs confer antioncogenic effects through the FAT1/CDK4/FOXM1 axis and may be used as a promising biomarker for TC treatment.

Advances in mesenchymal stem cell-derived extracellular vesicles therapy for Sjogren's syndrome-related dry eye disease

Sjogren's syndrome (SS) is a chronic autoimmune disorder that affects exocrine glands, particularly lacrimal glands, leading to dry eye disease (DED). DED is a common ocular surface disease that affects millions of people worldwide, causing discomfort, visual impairment, and even blindness in severe cases. However, there is no definitive cure for DED, and existing treatments primarily relieve symptoms. Consequently, there is an urgent need for innovative therapeutic strategies based on the pathophysiology of DED. Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic tool for various autoimmune disorders, including SS-related DED (SS-DED). A particularly intriguing facet of MSCs is their ability to produce extracellular vesicles (EVs), which contain various bioactive components such as proteins, lipids, and nucleic acids. These molecules play a key role in facilitating communication between cells and modulating a wide range of biological processes. Importantly, MSC-derived EVs (MSC-EVs) have therapeutic properties similar to those of their parent cells, including immunomodulatory, anti-inflammatory, and regenerative properties. In addition, MSC-EVs offer several notable advantages over intact MSCs, including lower immunogenicity, reduced risk of tumorigenicity, and greater convenience in terms of storage and transport. In this review, we elucidate the underlying mechanisms of SS-DED and discuss the relevant mechanisms and targets of MSC-EVs in treating SS-DED. In addition, we comprehensively review the broader landscape of EV application in autoimmune and corneal diseases. This review focuses on the efficacy of MSC-EVs in treating SS-DED, a field of study that holds considerable appeal due to its multifaceted regulation of immune responses and regenerative functions.

Recombinant Human Bone Morphogenetic Protein-2 Priming of Mesenchymal Stem Cells Ameliorate Acute Lung Injury by Inducing Regulatory T Cells

Mesenchymal stromal/stem cells (MSCs) possess immunoregulatory properties and their regulatory functions represent a potential therapy for acute lung injury (ALI). However, uncertainties remain with respect to defining MSCs-derived immunomodulatory pathways. Therefore, this study aimed to investigate the mechanism underlying the enhanced effect of human recombinant bone morphogenic protein-2 (rhBMP-2) primed ES-MSCs (MSCBMP2) in promoting Tregs in ALI mice. MSC were preconditioned with 100 ng/ml rhBMP-2 for 24 h, and then administrated to mice by intravenous injection after intratracheal injection of 1 mg/kg LPS. Treating MSCs with rhBMP-2 significantly increased cellular proliferation and migration, and cytokines array reveled that cytokines release by MSCBMP2 were associated with migration and growth. MSCBMP2 ameliorated LPS induced lung injury and reduced myeloperoxidase activity and permeability in mice exposed to LPS. Levels of inducible nitric oxide synthase were decreased while levels of total glutathione and superoxide dismutase activity were further increased via inhibition of phosphorylated STAT1 in ALI mice treated with MSCBMP2. MSCBMP2 treatment increased the protein level of IDO1, indicating an increase in Treg cells, and Foxp3+CD25+ Treg of CD4+ cells were further increased in ALI mice treated with MSCBMP2. In co-culture assays with MSCs and RAW264.7 cells, the protein level of IDO1 was further induced in MSCBMP2. Additionally, cytokine release of IL-10 was enhanced while both IL-6 and TNF-α were further inhibited. In conclusion, these findings suggest that MSCBMP2 has therapeutic potential to reduce massive inflammation of respiratory diseases by promoting Treg cells.

High throughput screening of mesenchymal stromal cell morphological response to inflammatory signals for bioreactor-based manufacturing of extracellular vesicles that modulate microglia

Due to their immunomodulatory function, mesenchymal stromal cells (MSCs) are a promising therapeutic with the potential to treat neuroinflammation associated with neurodegenerative diseases. This function can be mediated by secreted extracellular vesicles (MSC-EVs). Despite established safety, MSC clinical translation has been unsuccessful due to inconsistent clinical outcomes resulting from functional heterogeneity. Current approaches to mitigate functional heterogeneity include 'priming' MSCs with inflammatory signals to enhance function. However, comprehensive evaluation of priming and its effects on MSC-EV function has not been performed. Clinical translation of MSC-EV therapies requires significant manufacturing scale-up, yet few studies have investigated the effects of priming in bioreactors. As MSC morphology has been shown to predict their immunomodulatory function, we screened MSC morphological response to an array of priming signals and evaluated MSC-EV identity and potency in response to priming in flasks and bioreactors. We identified unique priming conditions corresponding to distinct morphologies. These conditions demonstrated a range of MSC-EV preparation quality and lipidome, allowing us to discover a novel MSC-EV manufacturing condition, as well as gain insight into potential mechanisms of MSC-EV microglia modulation. Our novel screening approach and application of priming to MSC-EV bioreactor manufacturing informs refinement of larger-scale manufacturing and enhancement of MSC-EV function.

Therapeutic potentials of mesenchymal stromal cells-derived extracellular vesicles in liver failure and marginal liver graft rehabilitation: a scoping review

Liver failure includes distinct subgroups of diseases: Acute liver failure (ALF) without preexisting cirrhosis, acute-on-chronic liver failure (ACLF) (severe form of cirrhosis associated with organ failures and excess mortality), and liver fibrosis (LF). Inflammation plays a key role in ALF, LF, and more specifically in ACLF for which we have currently no treatment other than liver transplantation (LT). The increasing incidence of marginal liver grafts and the shortage of liver grafts require us to consider strategies to increase the quantity and quality of available liver grafts. Mesenchymal stromal cells (MSCs) have shown beneficial pleiotropic properties with limited translational potential due to the pitfalls associated with their cellular nature. MSC-derived extracellular vesicles (MSC-EVs) are innovative cell-free therapeutics for immunomodulation and regenerative purposes. MSC-EVs encompass further advantages: pleiotropic effects, low immunogenicity, storage stability, good safety profile, and possibility of bioengineering. Currently, no human studies explored the impact of MSC-EVs on liver disease, but several preclinical studies highlighted their beneficial effects. In ALF and ACLF, data showed that MSC-EVs attenuate hepatic stellate cells activation, exert antioxidant, anti-inflammatory, anti-apoptosis, anti-ferroptosis properties, and promote regeneration of the liver, autophagy, and improve metabolism through mitochondrial function recovery. In LF, MSC-EVs demonstrated anti-fibrotic properties associated with liver tissue regeneration. Normothermic-machine perfusion (NMP) combined with MSC-EVs represents an attractive therapy to improve liver regeneration before LT. Our review suggests a growing interest in MSC-EVs in liver failure and gives an appealing insight into their development to rehabilitate marginal liver grafts through NMP.

Manufacture of extracellular vesicles derived from mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are a promising therapy for various diseases ranging from ischemic stroke to wound healing and cancer. Their therapeutic effects are mainly mediated by secretome-derived paracrine factors, with extracellular vesicles (EVs) proven to play a key role. This has led to promising research on the potential of MSC-EVs as regenerative, off-the-shelf therapeutic agents. However, the translation of MSC-EVs into the clinic is hampered by the poor scalability of their production. Recently, new advanced methods have been developed to upscale MSC cultivation and EV production yields, ranging from new cell culture devices to priming procedures. This review gives an overview of these innovative strategies for manufacturing MSC-EVs.

Human pluripotent stem cell-derived extracellular vesicles: From now to the future

Extracellular vesicles (EVs) are nanometric particles that enclose cell-derived bioactive molecules in a lipid bilayer and serve as intercellular communication tools. Accordingly, in various biological contexts, EVs are reported to engage in immune modulation, senescence, and cell proliferation and differentiation. Therefore, EVs could be key elements for potential off-the-shelf cell-free therapy. Little has been studied regarding EVs derived from human pluripotent stem cells (hPSC-EVs), even though hPSCs offer good opportunities for induction of tissue regeneration and unlimited proliferative ability. In this review article, we provide an overview of studies using hPSC-EVs, focusing on identifying the conditions in which the cells are cultivated for the isolation of EVs, how they are characterized, and applications already demonstrated. The topics reported in this article highlight the incipient status of the studies in the field and the significance of hPSC-EVs’ prospective applications as PSC-derived cell-free therapy products.

A non-invasive strategy for suppressing asthmatic airway inflammation and remodeling: Inhalation of nebulized hypoxic hUCMSC-derived extracellular vesicles

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are extremely promising nanoscale cell-free therapeutic agents. We previously identified that intravenous administration (IV) of human umbilical cord MSC-EVs (hUCMSC-EVs), especially hypoxic hUCMSC-EVs (Hypo-EVs), could suppress allergic airway inflammation and remodeling. Here, we further investigated the therapeutic effects of Hypo-EVs administration by atomizing inhalation (INH), which is a non-invasive and efficient drug delivery method for lung diseases. We found that nebulized Hypo-EVs produced by the atomization system (medical/household air compressor and nebulizer) maintained excellent structural integrity. Nebulized Dir-labeled Hypo-EVs inhaled by mice were mainly restricted to lungs. INH administration of Hypo-EVs significantly reduced the airway inflammatory infiltration, decreased the levels of IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid (BALF), declined the content of OVA-specific IgE in serum, attenuated the goblet cell metaplasia, and the expressions of subepithelial collagen-1 and α-smooth muscle actin (α-SMA). Notably, Hypo-EV INH administration was generally more potent than Hypo-EV IV in suppressing IL-13 levels and collagen-1 and α-SMA expressions. RNA sequencing revealed that various biological processes, such as cell adhesion, innate immune response, B cell activation, and extracellular space, were associated with the activity of Hypo-EV INH against asthma mice. In addition, Hypo-EVs could load exogenous miR-146a-5p (miR-146a-5p-EVs). Furthermore, INH administration of miR-146a-5p-EVs resulted in a significantly increased expression of miR-146a-5p mostly in lungs, and offered greater protection against the OVA-induced increase in airway inflammation, subepithelial collagen accumulation and myofibroblast compared with nebulized Hypo-EVs. Overall, nebulized Hypo-EVs effectively attenuated allergic airway inflammation and remodeling, potentially creating a non-invasive route for the use of MSC-EVs in asthma treatment.

MicroRNA-22-3p in human umbilical cord mesenchymal stem cell-secreted exosomes inhibits granulosa cell apoptosis by targeting KLF6 and ATF4-ATF3-CHOP pathway in POF mice

BACKGROUND

Human umbilical cord mesenchymal stem cells (hUCMSCs)-derived exosomes carrying microRNAs (miRNAs) have promising therapeutic potential in various disorders, including premature ovarian failure (POF). Previous evidence has revealed the low plasma level of miR-22-3p in POF patients. Nevertheless, exosomal miR-22-3p specific functions underlying POF progression are unclarified.

METHODS

A cisplatin induced POF mouse model and in vitro murine ovarian granulosa cell (mOGC) model were established. Exosomes derived from miR-22-3p-overexpressed hUCMSCs (Exos-miR-22-3p) were isolated. CCK-8 assay and flow cytometry were utilized for measuring mOGC cell viability and apoptosis. RT-qPCR and western blotting were utilized for determining RNA and protein levels. The binding ability between exosomal miR-22-3p and Kruppel-like factor 6 (KLF6) was verified using luciferase reporter assay. Hematoxylin-eosin staining, ELISA, and TUNEL staining were performed for examining the alteration of ovarian function in POF mice.

RESULTS

Exos-miR-22-3p enhanced mOGC viability and attenuated mOGC apoptosis under cisplatin treatment. miR-22-3p targeted KLF6 in mOGCs. Overexpressing KLF6 reversed the above effects of Exos-miR-22-3p. Exos-miR-22-3p ameliorated cisplatin-triggered ovarian injury in POF mice. Exos-miR-22-3p repressed ATF4-ATF3-CHOP pathway in POF mice and cisplatin-treated mOGCs.

CONCLUSION

Exosomal miR-22-3p from hUCMSCs alleviates OGC apoptosis and improves ovarian function in POF mouse models by targeting KLF6 and ATF4-ATF3-CHOP pathway.

Role of stem cell derivatives in inflammatory diseases

Mesenchymal stem cells (MSCs) are pluripotent stem cells of mesodermal origin with the ability of self-renewal and multidirectional differentiation, which have all the common characteristics of stem cells and the ability to differentiate into adipocytes, osteoblasts, neuron-like cells and other cells. Stem cell derivatives are extracellular vesicles(EVs) released from mesenchymal stem cells that are involved in the process of body’s immune response, antigen presentation, cell differentiation, and anti-inflammatory. EVs are further divided into ectosomes and exosomes are widely used in degenerative diseases, cancer, and inflammatory diseases due to their parental cell characteristics. However, most diseases are closely related to inflammation, and exosomes can mitigate the damage caused by inflammation in terms of suppressing the inflammatory response, anti-apoptosis and promoting tissue repair. Stem cell-derived exosomes have become an emerging modality for cell-free therapy because of their high safety and ease of preservation and transportation through intercellular communication. In this review, we highlight the characteristics and functions of MSCs-derived exosomes and discuss the regulatory mechanisms of MSCs-derived exosomes in inflammatory diseases and their potential applications in clinical diagnosis and therapy.

Bioengineered extracellular vesicles: future of precision medicine for sepsis

Sepsis is a syndromic response to infection and is frequently a final common pathway to death from many infectious diseases worldwide. The complexity and high heterogeneity of sepsis hinder the possibility to treat all patients with the same protocol, requiring personalized management. The versatility of extracellular vesicles (EVs) and their contribution to sepsis progression bring along promises for one-to-one tailoring sepsis treatment and diagnosis. In this article, we critically review the endogenous role of EVs in sepsis progression and how current advancements have improved EVs-based therapies toward their translational future clinical application, with innovative strategies to enhance EVs effect. More complex approaches, including hybrid and fully synthetic nanocarriers that mimic EVs, are also discussed. Several pre-clinical and clinical studies are examined through the review to offer a general outlook of the current and future perspectives of EV-based sepsis diagnosis and treatment.

Regenerative potential of different extracellular vesicle subpopulations derived from clonal mesenchymal stem cells in a mouse model of chemotherapy-induced premature ovarian failure

AIMS

Some studies have shown that mesenchymal stem cells (MSCs) and their derived extracellular vesicles (MSC-EVs) can restore ovarian function in premature ovarian failure (POF), however, concerns about their efficacy are attributed to the heterogeneity of the cell populations and EVs. Here, we assessed the therapeutic potential of a homogeneous population of clonal MSCs (cMSCs) and their EVs subpopulations in a mouse model of POF.

MAIN METHODS

Granulosa cells were treated with cyclophosphamide (Cy) in the absence or presence of cMSCs, or cMSCs-derived EV subpopulations (EV20K and EV110K, isolated by high-speed centrifugation and differential ultracentrifugation, respectively). In addition, POF mice were treated with cMSCs, EV20K and/or EV110K.

KEY FINDINGS

cMSC and both EV types protected granulosa cells from Cy-induced damage. Calcein-EVs were detected in the ovaries. Moreover, cMSC and both EV subpopulations significantly increased body weight, ovary weight, and the number of follicles, restored FSH, E2, and AMH levels, increased the granulosa cell numbers and restored the fertility of POF mice. cMSC, EV20K, and EV110K alleviated inflammatory-related genes expression (Tnf-α and IL8), and improved angiogenesis via upregulation expression of Vegf and Igf1 at the mRNA level and VEGF and αSMA at the protein level. They also inhibited apoptosis through the PI3K/AKT signaling pathway.

SIGNIFICANCE

The administration of cMSCs and two cMSC-EVs subpopulations improved ovarian function and restored fertility in a POF model. EV20K is more cost-effective and feasible in terms of isolation, particularly in good manufacturing practice (GMP) facilities for treatment of POF patients in comparison with conventional EVs (EV110K).

Prospects of magnetically based approaches addressing inflammation in tendon tissues

Tendon afflictions constitute a significant share of musculoskeletal diseases and represent a primary cause of incapacity worldwide. Unresolved/chronic inflammatory states have been associated with the onset and progression of tendon disorders, contributing to undesirable immune stimulation and detrimental tissue effects. Thus, targeting persistent inflammatory events could assist important developments to solve pathophysiological processes and innovative therapeutics to address impaired healing and accomplish complete tendon regeneration. This review overviews the impact of inflammation and inflammatory mediators in tendon niches, unveiling the importance of tendon cell populations and their signature features, and the influence of microenvironmental factors on inflamed and injured tendons. The demand for non-invasive instructive strategies to manage persistent inflammatory mediators, guide inflammatory pathways, and modulate cellular responses will also be approached by exploring the role of pulsed electromagnetic field (PEMF). PEMF alone or combined with more sophisticated systems triggered by magnetic fields will be considered in the design of successful therapies to control inflammation in tendinopathic conditions.

Mechanisms behind therapeutic potentials of mesenchymal stem cell mitochondria transfer/delivery

Mesenchymal stromal/stem cells (MSCs) perform their therapeutic effects through various mechanisms, including their ability to differentiate, producing different growth factors, immunomodulatory factors, and extracellular vesicles (EVs). In addition to the mentioned mechanisms, a new aspect of the therapeutic potential of MSCs has recently been noticed, which occurs through mitochondrial transfer. Various methods of MSCs mitochondria transfer have been used in studies to benefit from their therapeutic potential. Among these methods, mitochondrial transfer after MSCs transplantation in cell-to-cell contact, EVs-mediated transfer of mitochondria, and the use of MSCs isolated mitochondria (MSCs-mt) are well studied. Pathological conditions can affect the cells in the damaged microenvironment and lead to cells mitochondrial damage. Since the defect in the mitochondrial function of the cell leads to a decrease in ATP production and the subsequent cell death, restoring the mitochondrial content, functions, and hemostasis can affect the functions of the damaged cell. Various studies show that the transfer of MSCs mitochondria to other cells can affect vital processes such as proliferation, differentiation, cell metabolism, inflammatory responses, cell senescence, cell stress, and cell migration. These changes in cell attributes and behavior are very important for therapeutic purposes. For this reason, their investigation can play a significant role in the direction of the researchers'.

THE ROLES OF EXTRACELLULAR VESICLES IN SEPSIS AND SYSTEMIC INFLAMMATORY RESPONSE SYNDROME

ABSTRACT

Sepsis is a life-threatening organ dysfunction, caused by dysregulation of the host response to infection. To understand the underlying mechanisms of sepsis, the vast spectrum of extracellular vesicles (EVs) is gaining importance in this research field. A connection between EVs and sepsis was shown in 1998 in an endotoxemia pig model. Since then, the number of studies describing EVs as markers and mediators of sepsis increased steadily. Extracellular vesicles in sepsis could be friends and foes at the same time depending on their origin and cargo. On the one hand, transfer of EVs or outer membrane vesicles can induce sepsis or systemic inflammatory response syndrome with comparable efficiency as well-established methods, such as cecal ligation puncture or lipopolysaccharide injection. On the other hand, EVs could provide certain therapeutic effects, mediated via reduction of reactive oxygen species, inflammatory cytokines and chemokines, influence on macrophage polarization and apoptosis, as well as increase of anti-inflammatory cytokines. Moreover, EVs could be helpful in the diagnosis of sepsis. Extracellular vesicles of different cellular origin, such as leucocytes, macrophages, platelets, and granulocytes, have been suggested as potential sepsis biomarkers. They ensure the diagnosis of sepsis earlier than classical clinical inflammation markers, such as C-reactive protein, leucocytes, or IL-6. This review summarizes the three roles of EVs in sepsis-mediator/inducer, biomarker, and therapeutic tool.

A crucial exosome-related gene pair (AAMP and ABAT) is associated with inflammatory cells in intervertebral disc degeneration

Identification of exosome-related genes (ERGs) and competing endogenous RNAs (ceRNAs) associated with intervertebral disc degeneration (IDD) may improve its diagnosis and reveal its underlying mechanisms. We downloaded 49 samples from Gene Expression Omnibus and identified candidate ERGs using differentially expressed ERGs (De-ERGs), exosome-related gene pairs (ERGPs), and machine learning algorithms [least absolute shrinkage and selection operator (LASSO) and support vector machine (SVM)]. Immune cell-related ERGs were selected via immune-infiltration analysis, and clinical values were assessed using receiver operating characteristic curves. Based on the De-ERGs, a ceRNA network comprising 1,512 links and 330 nodes was constructed and primarily related to signal transduction pathways, apoptosis-related biological processes, and multiple kinase-related molecular functions. In total, two crucial De-ERGs [angio-associated migratory cell protein (AAMP) and 4-aminobutyrate aminotransferase (ABAT)] were screened from results in De-ERGs, ERGPs, LASSO, and SVM. Increased AAMP expression and decreased ABAT expression were positively and negatively correlated with CD8⁺ T cell infiltration, respectively. AAMP/ABAT was the only pair differentially expressed in IDD and correlated with CD8⁺ T cell infiltration. Furthermore, AAMP/ABAT displayed higher accuracy in predicting IDD than individual genes. These results demonstrated the ERGP AAMP/ABAT as a robust signature for identifying IDD and associated with increased CD8⁺ T cell infiltration, suggesting it as a promising IDD biomarker.

Combinatorial Effect of Mesenchymal Stem Cells and Extracellular Vesicles in a Hydrogel on Cartilage Regeneration

BACKGROUND

Mesenchymal stem cells (MSCs) are used for tissue regeneration due to their wide differentiation capacity and anti-inflammatory effects. Extracellular vesicles (EVs) derived from MSCs are also known for their regenerative effects as they contain nucleic acids, proteins, lipids, and cytokines similar to those of parental cells. There are several studies on the use of MSCs or EVs for tissue regeneration. However, the combinatorial effect of human MSCs (hMSCs) and EVs is not clear. In this study, we investigated the combinatorial effect of hMSCs and EVs on cartilage regeneration via co-encapsulation in a hyaluronic-acid (HA)-based hydrogel.

METHODS

A methacrylic-acid-based HA hydrogel was prepared to encapsulate hMSCs and EVs in hydrogels. Through in vitro and in vivo analyses, we investigated the chondrogenic potential of the HA hydrogel-encapsulated with hMSCs and EVs.

RESULTS

Co-encapsulation of hMSCs with EVs in the HA hydrogel increased the chondrogenic differentiation of hMSCs and regeneration of damaged cartilage tissue compared with that of the HA hydrogel loaded with hMSCs only.

CONCLUSION

Co-encapsulation of hMSCs and EVs in the HA hydrogel effectively enhances cartilage tissue regeneration due to the combinatorial therapeutic effect of hMSCs and EVs. Thus, in addition to cartilage tissue regeneration for the treatment of osteoarthritis, this approach would be a useful strategy to improve other types of tissue regeneration.

Extracellular-Vesicle-Based Drug Delivery Systems for Enhanced Antitumor Therapies through Modulating the Cancer-Immunity Cycle

Although immunotherapy harnessing activity of the immune system against tumors has made great progress, the treatment efficacy remains limited in most cancers. Current anticancer immunotherapy is primarily based on T-cell-mediated cellular immunity, which highly relies on efficiency of triggering the cancer-immunity cycle, namely, tumor antigen release, antigen presentation by antigen presenting cells, T cell activation, recruitment and infiltration of T cells into tumors, and recognition and killing of tumor cells by T cells. Unfortunately, these immunotherapies are restricted by inefficient drug delivery and acting on only a single step of the cancer-immunity cycle. Due to high biocompatibility, low immunogenicity, intrinsic cell targeting, and easy chemical and genetic manipulation, extracellular vesicle (EV)-based drug delivery systems are widely used to amplify anticancer immune responses by serving as an integrated platform for multiple drugs or therapeutic strategies to synergistically activate several steps of cancer-immunity cycle. This review summarizes various mechanisms related to affecting cancer-immunity cycle disorders. Meanwhile, preparation and application of EV-based drug delivery systems in modulating cancer-immunity cycle are introduced, especially in the improvement of T cell recruitment and infiltration into tumors. Finally, opportunities and challenges of EV-based drug delivery systems in translational clinical applications are briefly discussed.

Regenerative medicine applications: An overview of clinical trials

Insights into the use of cellular therapeutics, extracellular vesicles (EVs), and tissue engineering strategies for regenerative medicine applications are continually emerging with a focus on personalized, patient-specific treatments. Multiple pre-clinical and clinical trials have demonstrated the strong potential of cellular therapies, such as stem cells, immune cells, and EVs, to modulate inflammatory immune responses and promote neoangiogenic regeneration in diseased organs, damaged grafts, and inflammatory diseases, including COVID-19. Over 5,000 registered clinical trials on ClinicalTrials.gov involve stem cell therapies across various organs such as lung, kidney, heart, and liver, among other applications. A vast majority of stem cell clinical trials have been focused on these therapies' safety and effectiveness. Advances in our understanding of stem cell heterogeneity, dosage specificity, and ex vivo manipulation of stem cell activity have shed light on the potential benefits of cellular therapies and supported expansion into clinical indications such as optimizing organ preservation before transplantation. Standardization of manufacturing protocols of tissue-engineered grafts is a critical first step towards the ultimate goal of whole organ engineering. Although various challenges and uncertainties are present in applying cellular and tissue engineering therapies, these fields' prospect remains promising for customized patient-specific treatments. Here we will review novel regenerative medicine applications involving cellular therapies, EVs, and tissue-engineered constructs currently investigated in the clinic to mitigate diseases and possible use of cellular therapeutics for solid organ transplantation. We will discuss how these strategies may help advance the therapeutic potential of regenerative and transplant medicine.

Cell-Based Therapy Approaches in Treatment of Non-obstructive Azoospermia

The rate of infertility has globally increased in recent years for a variety of reasons. One of the main causes of infertility in men is azoospermia that is defined by the absence of sperm in the ejaculate and classified into two categories: obstructive azoospermia and non-obstructive azoospermia. In non-obstructive azoospermia, genital ducts are not obstructed, but the testicles do not produce sperm at all, due to various reasons. Non-obstructive azoospermia in most cases has no therapeutic options other than assisted reproductive techniques, which in most cases require sperm donors. Here we discuss cell-based therapy approaches to restore fertility in men with non-obstructive azoospermia including cell-based therapies of non-obstructive azoospermia using regenerative medicine and cell-based therapies of non-obstructive azoospermia by paracrine and anti-inflammatory pathway, technical and ethical challenges for using different cell sources and alternative options will be described, and then the more effectual approaches will be mentioned as future trends.

Human Umbilical Cord Mesenchymal Stem Cells-Derived Small Extracellular Vesicles Can Be Considered as Cell-Free Therapeutics for Angiogenesis Promotion

OBJECTIVE

Angiogenesis has critical roles in several physiological processes. Restoring angiogenesis in some pathological conditions such as a few vascular diseases can be a therapeutic approach to controlling this issue. Mesenchymal stem cells (MSCs) secrete specific intracellular products known as extracellular vesicles (EVs) with high therapeutic potential which compared to their source cells, do not have the limitations of cell therapy. The angiogenic effect of the human umbilical cord MSCs (hUCMSCs)-derived small EVs are evaluated in the present work. Aim of this research is to show that hUCMSCs-derived small EVs cause differentiation of genes involved in angiogenesis like FGFR-1, FGF, VEGF, and VEGFR-2.

MATERIALS AND METHODS

In this experimental study, MSCs were isolated from the human umbilical cord, and after confirming their identities, their secreted EVs (including exosomes) were extracted by ultracentrifugation. The isolated small EVs were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), bicinchoninic acid assay (BCA), and Western Blotting. Then, the human umbilical vein endothelial cells (HUVECs) were treated with derived small EVs for 72 hours, and the expression of the angiogenic factors including FGFR-1, FGF, VEGF, and VEGFR-2 was evaluated by quantitative real-time-polymerase chain reaction (qPCR). Angiogenesis was also evaluated via a tube formation assay.

RESULTS

The results demonstrated that FGFR-1, FGF, VEGF, and VEGFR-2 could be elevated 2, 2, 3.5, and 2 times, respectively, in EVs treated HUVECs, and derivative EVs can encourage tube formation in HUVECs.

CONCLUSION

These findings imply that hUCMSCs-derived small EVs are valuable resources in promoting angiogenesis and are very promising in cell-free therapy.

Targeting Myd88 using peptide-loaded mesenchymal stem cell membrane-derived synthetic vesicles to treat systemic inflammation

Mesenchymal stem cells (MSC) secrete extracellular vesicles (EV) with a regenerative profile, and an increasing number of studies have focused on the utilization of MSC-EV for therapeutic drug delivery. However, EV are usually produced by cells in low quantities and are packed with numerous cytoplasmic components, which may be unfavorable for further drug loading. In this study, we developed a simple process for generating membrane vesicles directly from the cells, which we refer to as synthetic eukaryotic vesicles (SyEV). We hypothesized that MSC-derived SyEV can be efficiently loaded with an anti-inflammatory drug and the loaded vesicles can strongly suppress the systemic inflammation induced by bacterial outer membrane vesicles (OMV). SyEV were generated from MSC membranes through serial extrusion of the cells, ionic stress, and subsequent vesiculation of the membrane sheets, leading to high yield and purity of the SyEV with few cytosolic components remaining. When these SyEV were given to macrophages or mice exposed to OMV, the release of pro-inflammatory cytokines was similarly attenuated comparable to treatment with natural EV. We then loaded the SyEV with large numbers of peptides targeting Myd88 and observed enhanced therapeutic potential of the loaded vesicles in OMV-induced macrophages. Further, in vivo experiments showed that the peptide-encapsulated MSC-SyEV suppressed cytokine production synergistically. Taken together, these findings suggest that SyEV-based therapeutics is a highly interesting platform for delivering an advanced therapeutic drug for the treatment of systemic inflammation without severe side effects.

Investigating the consistency of extracellular vesicle production from breast cancer subtypes using CELLine adherent bioreactors

Extracellular vesicle (EV) research has grown rapidly in recent years, largely due to the potential use of EVs as liquid biopsy biomarkers or therapeutics. However, in-depth characterisation and validation of EVs produced using conventional in vitro cultures can be challenging due to the large area of cell monolayers and volumes of culture media required. To overcome this obstacle, multiple bioreactor designs have been tested for EV production with varying success, but the consistency of EVs produced over time in these systems has not been reported previously. In this study, we demonstrate that several breast cancer cell lines of different subtypes can be cultured simultaneously in space, resource, and time efficient manner using CELLine AD 1000 systems, allowing the consistent production of vast amounts of EVs for downstream experimentation. We report an improved workflow used for inoculating, maintaining, and monitoring the bioreactors, their EV production, and the characterisation of the EVs produced. Lastly, our proteomic analyses of the EVs produced throughout the lifetime of the bioreactors show that core EV-associated proteins are relatively consistent, with few minor variations over time, but that tracking the production of EVs is a convenient method to indirectly monitor the bioreactor and consistency of the yielded EVs. These findings will aid future studies requiring the simultaneous production of large amounts of EVs from several cell lines of different subtypes of a disease and other EV biomanufacturing applications.

Endometrial Regenerative Cell-Derived Exosomes Attenuate Experimental Colitis through Downregulation of Intestine Ferroptosis

Background

Endometrial regenerative cells (ERCs) have been identified to ameliorate colitis in mice; however, whether exosomes derived from ERCs (ERC-exos) own similar effects on colitis remains unclear. Ferroptosis, an iron-dependent cell programmed death form, has been reported to promote inflammation in UC. Thus, in this study, whether ERC-exos can treat colitis and regulate intestine ferroptosis will be explored.

Methods

In this study, iron, malondialdehyde (MDA) production, glutathione (GSH) synthesis, and acyl-CoA synthetase long-chain family member (ACSL) 4 and glutathione peroxidase 4 (GPX4) expressions were measured in colon samples from healthy people and UC patients to explore the effects of ferroptosis. In vitro, ERC-exos were cocultured with ferroptosis inducer erastin-treated NCM460 human intestinal epithelial cell line, and ferroptotic parameters were measured. In vivo, colitis was induced by 3% dextran sulfate sodium (DSS) in BALB/c mice, and animals were randomly assigned to normal, untreated, and ERC-exos-treated groups. The Disease Activity Index (DAI) score, histological features, tissue iron, MDA, GSH, ACSL4, and GPX4 were measured to verify the role of ERC-exos in attenuating UC.

Results

Compared with healthy people, UC samples exhibited higher levels of iron, MDA, and ACSL4, while less levels of GSH and GPX4. In vitro, the CCK-8 assay showed that ERC-exos rescued erastin-induced cell death, and ERC-exos treatment significantly increased the levels of GSH and expression of GPX4, while markedly decreasing the levels of iron, MDA, and expression of ACSL4. In vivo, ERC-exos treatment effectively reduced DAI score, ameliorated colon pathological damage, and improved disease symptoms. Moreover, ERC-exos treatment further enhanced the levels of GSH and the expression of GPX4 but reduced the levels of iron, MDA, and expression of ACSL4 in the colon of colitis mice.

Conclusions

Ferroptosis was involved in the pathogenesis of UC, and ERC-exos attenuated DSS-induced colitis through downregulating intestine ferroptosis. This study may provide a novel insight into treating UC in the future.

Challenges and Opportunities in Downstream Separation Processes for Mesenchymal Stromal Cells Cultured in Microcarrier-based Stirred Suspension Bioreactors

Mesenchymal stromal cells (MSC) are a promising platform for regenerative medicine applications because of their multi-lineage differentiation abilities and ease of collection, isolation, and growth ex-vivo. To meet the demand for clinical applications, large scale manufacturing will be required using three-dimension culture platforms in vessels such as stirred suspension bioreactors. As MSCs are an adherent cell type, microcarriers are added to the culture to increase the available surface area for attachment and growth. Although extensive research has been performed on efficiently culturing MSCs using microcarriers, challenges persist in downstream processing including harvesting, filtration, and volume reduction which all play a critical role for the translation of cell therapies to the clinic. The objective of this review is to assess the current state of downstream technologies available for microcarrier-based MSC cultures. This includes a review of current research within the three stages: harvesting, filtration, and volume reduction. Using this information, a downstream process for MSCs is proposed which can be applied for a wide range of applications. This article is protected by copyright. All rights reserved.

Liquid Biopsy in Pre-Metastatic Niche: From Molecular Mechanism to Clinical Application

Metastatic dissemination represents a hallmark of cancer that is responsible for the high mortality rate. Recently, emerging evidence demonstrates a time-series event—pre-metastatic niche (PMN) has a profound impact on cancer metastasis. Exosomes, cell-free DNA (cfDNA), circulating tumor cells (CTC), and tumor microenvironment components, as critical components in PMN establishment, could be monitored by liquid biopsy. Intensive studies based on the molecular profile of liquid biopsy have made it a viable alternative to tissue biopsy. Meanwhile, the complex molecular mechanism and intercellular interaction are great challenges for applying liquid biopsy in clinical practice. This article reviews the cellular and molecular components involved in the establishment of the PMN and the promotion of metastasis, as well as the mechanisms of their interactions. Better knowledge of the characteristics of the PMN may facilitate the application of liquid biopsy for clinical diagnosis, prognosis, and treatment.

Preconditioning and Engineering Strategies for Improving the Efficacy of Mesenchymal Stem Cell-Derived Exosomes in Cell-Free Therapy

Mesenchymal stem cells (MSCs) have been widely applied to regenerative medicine owing to their multiple differentiation, self-renewal, and immunomodulatory abilities. Exosomes are cell-secreted natural nanovesicles and thought to be mediators of intercellular communication and material transport. The therapeutic potential of MSCs can be largely attributed to MSC-derived exosomes (MSC-exosomes). Emerging evidence suggests that the therapeutic efficacy of MSC-exosomes is highly dependent on the status of MSCs, and optimization of the extracellular environment affects the exosomal content. Pretreatment methods including three-dimensional cultures, hypoxia, and other biochemical cues have been shown to potentially enhance the biological activity of MSC-exosomes while maintaining or enhancing their production. On the other hand, engineering means to enhance the desired function of MSC-exosomes has been rapidly gaining attention. In particular, biologically active molecule encapsulation and membrane modification can alter or enhance biological functions and targeting of MSC-exosomes. In this review, we summarize two possible strategies to improve the therapeutic activity of MSC-exosomes: preconditioning approaches and engineering exosomes. We also explore the underlying mechanisms of different strategies and discuss their advantages and limitations of the upcoming clinical applications.

Preconditioning Methods to Improve Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Bone Regeneration—A Systematic Review

Simple Summary

The evidence of the therapeutic effects of mesenchymal stromal cells (MSCs), so-called stem cells, in several diseases relies mostly on the substances they secrete, including their extracellular vesicles (EVs). EVs are an important component of cell communication and they carry a cargo that is similar to their parent cell. Cells respond differently based on their microenvironment, and so it is expected that the therapeutic potential of these vesicles can be modulated by the enrichment of their parent cell microenvironment. With this in mind, we conducted a systematic search for papers that preconditioned MSCs and collected their EVs to assess their potential to favor bone formation. The results showed different methods for MSC preconditioning, including chemical induction, culture conditions, and genetic modifications. All methods were able to improve the therapeutic effects of the derived EVs for bone formation. However, the heterogeneity among studies—regarding the type of cell, EV concentration, and scaffolds—made it difficult to compare fairly the types of preconditioning methods. In summary, the microenvironment greatly influences MSCs, and using preconditioning methods can potentially improve the therapeutic effects of their derived EVs in bone regeneration and other bone diseases.

Abstract

Mesenchymal stromal cells (MSCs) have long been used in research for bone regeneration, with evidence of their beneficial properties. In the segmental area of MSC-based therapies, MSC-derived extracellular vesicles (EVs) have also shown great therapeutic effects in several diseases, including bone healing. This study aimed to assess whether the conditioning of MSCs improves the therapeutic effects of their derived extracellular vesicles for bone regeneration. Electronic research was performed until February 2021 to recover the studies in the following databases: PubMed, Scopus, and Web of Science. The studies were screened based on the inclusion criteria. Relevant information was extracted, including in vitro and in vivo experiments, and the animal studies were evaluated for risk of bias by the SYRCLE tool. A total of 463 studies were retrieved, and 18 studies met the inclusion criteria (10 studies for their in vitro analysis, and 8 studies for their in vitro and in vivo analysis). The conditioning methods reported included: osteogenic medium; dimethyloxalylglycine; dexamethasone; strontium-substituted calcium silicate; hypoxia; 3D mechanical microenvironment; and the overexpression of miR-375, bone morphogenetic protein-2, and mutant hypoxia-inducible factor-1α. The conditioning methods of MSCs in the reported studies generate exosomes able to significantly promote bone regeneration. However, heterogeneity regarding cell source, conditioning method, EV isolation and concentration, and defect model was observed among the studies. The different conditioning methods reported in this review do improve the therapeutic effects of MSC-derived EVs for bone regeneration, but they still need to be addressed in larger animal models for further clinical application.

miR-124-3p delivered by exosomes from heme oxygenase-1 modified bone marrow mesenchymal stem cells inhibits ferroptosis to attenuate ischemia-reperfusion injury in steatotic grafts

Background

Steatotic livers tolerate ischemia–reperfusion injury (IRI) poorly, increasing the risk of organ dysfunction. Ferroptosis is considered the initiating factor of organ IRI. Heme oxygenase oxygen-1 (HO-1)-modified bone marrow mesenchymal stem cells (BMMSCs) (HO-1/BMMSCs) can reduce hepatic IRI; however, the role of ferroptosis in IRI of steatotic grafts and the effect of HO-1/BMMSCs-derived exosomes (HM-exos) on ferroptosis remain unknown.

Methods

A model of rat liver transplantation (LT) with a severe steatotic donor liver and a model of hypoxia and reoxygenation (H/R) of steatotic hepatocytes were established. Exosomes were obtained by differential centrifugation, and the differentially expressed genes (DEGs) in liver after HM-exo treatment were detected using RNA sequencing. The expression of ferroptosis markers was analyzed. microRNA (miRNA) sequencing was used to analyze the miRNA profiles in HM-exos.

Results

We verified the effect of a candidate miRNA on ferroptosis of H/R treated hepatocytes, and observed the effect of exosomes knockout of the candidate miRNA on hepatocytes ferroptosis. In vitro, HM-exo treatment reduced the IRI in steatotic grafts, and enrichment analysis of DEGs suggested that HM-exos were involved in the regulation of the ferroptosis pathway. In vitro, inhibition of ferroptosis by HM-exos reduced hepatocyte injury. HM-exos contained more abundant miR-124-3p, which reduced ferroptosis of H/R-treated cells by inhibiting prostate six transmembrane epithelial antigen 3 (STEAP3), while overexpression of Steap3 reversed the effect of mir-124-3p. In addition, HM-exos from cell knocked out for miR-124-3p showed a weakened inhibitory effect on ferroptosis. Similarly, HM-exo treatment increased the content of miR-124-3p in grafts, while decreasing the level of STEAP3 and reducing the degree of hepatic ferroptosis.

Conclusion

Ferroptosis is involved in the IRI during LT with a severe steatotic donor liver. miR-124-3p in HM-exos downregulates Steap3 expression to inhibit ferroptosis, thereby attenuating graft IRI, which might be a promising strategy to treat IRI in steatotic grafts.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01407-8.

Characteristics of Extracellular Vesicles and Preclinical Testing Considerations Prior to Clinical Applications

Cell therapy products have significant limitations, such as storage instability, difficulties with transportation, and toxicity issues such as tumorigenicity and immunogenicity. Extracellular vesicles (EVs) secreted from cells show potential for therapeutic agent development. EVs have not been widely examined as investigational drugs, and non-clinical studies for the clinical approval of EV therapeutic agents are challenging. EVs contain various materials, such as DNA, cellular RNA, cytokines, chemokines, and microRNAs, but do not proliferate or divide like cells, thus avoiding safety concerns related to tumorigenicity. However, the constituents of EVs may induce the proliferation of normal cells; therefore, the suitability of vesicles should be verified through non-clinical safety evaluations. In this review, the findings of non-clinical studies on EVs are summarized. We describe non-clinical toxicity studies of EVs, which should be useful for researchers who aim to develop these vesicles into therapeutic agents. A new method for evaluating the immunotoxicity and tumorigenicity of EVs should also be developed.