Mesenchymal Stem Cell-Derived Extracellular Vesicles: Opportunities and Challenges for Clinical Translation

Mesenchymal stem cell-derived exosomes ameliorate diabetic kidney disease through NOD2 signaling pathway

BACKGROUND AND AIMS

Diabetic kidney disease (DKD) is one of the most common complications of diabetes. It is reported that mesenchymal stem cells (MSCs) derived exosomes (MSCs-Exo) may have great clinical application potential for the treatment of DKD, but the underlying mechanism has not been illustrated. To clarify the effect of MSC-Exo on NOD2 signaling pathway in podocytes under high glucose (HG) and DKD, we conduct this study.

METHODS

We co-cultured podocytes and MSCs-Exo under 30 mM HG and injected MSCs-Exo into DKD mice, then we detected the NOD2 signaling pathway by western blot, qRT-PCT, immunofluorescence, transmission electron microscopy and immunohistochemistry both in vitro and in vivo.

RESULTS

In vitro, HG lead to the apoptosis, increased the ROS level and activated the NOD2 signaling pathway in podocytes, while MSCs-Exo protected podocytes from injury reduced the expression of inflammatory factors including TNF-α, IL-6, IL-1β, and IL-18 and alleviated the inflammatory response, inhibited the activation of NOD2 signaling pathway and the expression of it's downstream protein p-P65, p-RIP2, prevented apoptosis, increased cell viability in podocytes caused by HG. In vivo, MSCs-Exo alleviated renal injury in DKD mice, protected renal function, decreased urinary albumin excretion and inhibited the activation of NOD2 signaling pathway as well as the inflammation in renal tissue.

CONCLUSION

MSCs-Exo protected the podocytes and DKD mice from inflammation by mediating NOD2 pathway, MSCs-Exo may provide a new target for the treatment of DKD.

Profiling biomanufactured extracellular vesicles of human forebrain spheroids in a Vertical-Wheel Bioreactor

Extracellular vesicles (EVs) secreted by human brain cells have great potential as cell-free therapies in various diseases, including stroke. However, because of the significant amount of EVs needed in preclinical and clinical trials, EV application is still challenging. Vertical-Wheel Bioreactors (VWBRs) have designed features that allow for scaling up the generation of human forebrain spheroid EVs under low shear stress. In this study, EV secretion by human forebrain spheroids derived from induced pluripotent stem cells as 3D aggregates and on Synthemax II microcarriers in VWBRs were investigated with static aggregate culture as a control. The spheroids were characterized by metabolite and transcriptome analysis. The isolated EVs were characterized by nanoparticle tracking analysis, electron microscopy, and Western blot. The EV cargo was analyzed using proteomics and miRNA sequencing. The in vitro functional assays of an oxygen and glucose-deprived stroke model were conducted. Proof of concept in vivo study was performed, too. Human forebrain spheroid differentiated on microcarriers showed a higher growth rate than 3D aggregates. Microcarrier culture had lower glucose consumption per million cells and lower glycolysis gene expression but higher EV biogenesis genes. EVs from the three culture conditions showed no differences in size, but the yields from high to low were microcarrier cultures, dynamic aggregates, and static aggregates. The cargo is enriched with proteins (proteomics) and miRNAs (miRNA-seq), promoting axon guidance, reducing apoptosis, scavenging reactive oxygen species, and regulating immune responses. Human forebrain spheroid EVs demonstrated the ability to improve recovery in an in vitro stroke model and in vivo. Human forebrain spheroid differentiation in VWBR significantly increased the EV yields (up to 240-750 fold) and EV biogenesis compared to static differentiation due to the dynamic microenvironment and metabolism change. The biomanufactured EVs from VWBRs have exosomal characteristics and more therapeutic cargo and are functional in in vitro assays, which paves the way for future in vivo stroke studies.

iPSC-derived lung and lung cancer organoid model to evaluate cisplatin encapsulated autologous iPSC-derived mesenchymal stromal cell-isolated extracellular vesicles

BACKGROUND

Lung cancer remains a leading cause of cancer-related mortality globally. Although recent therapeutic advancements have provided targeted treatment approaches, the development of resistance and systemic toxicity remain primary concerns. Extracellular vesicles (EVs), especially those derived from mesenchymal stromal cells (MSC), have gained attention as promising drug delivery systems, offering biocompatibility and minimal immune responses. Recognizing the limitations of conventional 2D cell culture systems in mimicking the tumor microenvironment, this study aims to describe a proof-of-principle approach for using patient-specific organoid models for both lung cancer and normal lung tissue and the feasibility of employing autologous EVs derived from induced pluripotent stem cell (iPSC)-MSC in personalized medicine approaches.

METHODS

First, we reprogrammed healthy fibroblasts into iPSC. Next, we differentiated patient-derived iPSC into branching lung organoids (BLO) and generated patient-matched lung cancer organoids (LCO) from patient-derived tumor tissue. We show a streamlined process of MSC differentiation from iPSC and EV isolation from iPSC-MSC, encapsulated with 0.07 µg/mL of cytotoxic agent cisplatin and applied to both organoid models. Cytotoxicity of cisplatin and cisplatin-loaded EVs was recorded with LDH and CCK8 tests.

RESULTS

Fibroblast-derived iPSC showed a normal karyotype, pluripotency staining, and trilineage differentiation. iPSC-derived BLO showed expression of lung markers, like TMPRSS2 and MUC5A while patient-matched LCO showed expression of Napsin and CK5. Next, we compared the effects of iPSC-MSC derived EVs loaded with cisplatin against empty EVs and cisplatin alone in lung cancer organoid and healthy lung organoid models. As expected, we found a cytotoxic effect when LCO were treated with 20 µg/mL cisplatin. Treatment of LCO and BLO with empty EVs resulted in a cytotoxic effect after 24 h. However, EVs loaded with 0.07 µg/mL cisplatin failed to induce any cytotoxic effect in both organoid models.

CONCLUSION

We report on a proof-of-principle pipeline towards using autologous or allogeneic iPSC-MSC EVs as drug delivery tests for lung cancer in future. However, due to the time and labor-intensive processes, we conclude that this pipeline might not be feasible for personalized approaches at the moment.

Cellular In Vitro Responses Induced by Human Mesenchymal Stem/Stromal Cell-Derived Extracellular Vesicles Obtained from Suspension Culture

Mesenchymal stem/stromal cells (MSCs) and their extracellular vesicles (MSC-EVs) have been described to have important roles in tissue regeneration, including tissue repair, control of inflammation, enhancing angiogenesis, and regulating extracellular matrix remodeling. MSC-EVs have many advantages for use in regeneration therapies such as facility for dosage, histocompatibility, and low immunogenicity, thus possessing a lower possibility of rejection. In this work, we address the potential activity of MSC-EVs isolated from adipose-derived MSCs (ADMSC-EVs) cultured on cross-linked dextran microcarriers, applied to test the scalability and reproducibility of EV production. Isolated ADMSC-EVs were added into cultured human dermal fibroblasts (NHDF-1), keratinocytes (HaCat), endothelial cells (HUVEC), and THP-1 cell-derived macrophages to evaluate cellular responses (i.e., cell proliferation, cell migration, angiogenesis induction, and macrophage phenotype-switching). ADMSC viability and phenotype were assessed during cell culture and isolated ADMSC-EVs were monitored by nanotracking particle analysis, electron microscopy, and immunophenotyping. We observed an enhancement of HaCat proliferation; NHDF-1 and HaCat migration; endothelial tube formation on HUVEC; and the expression of inflammatory cytokines in THP-1-derived macrophages. The increased expression of TGF-β and IL-1β was observed in M1 macrophages treated with higher doses of ADMSC-EVs. Hence, EVs from microcarrier-cultivated ADMSCs are shown to modulate cell behavior, being able to induce skin tissue related cells to migrate and proliferate as well as stimulate angiogenesis and cause balance between pro- and anti-inflammatory responses in macrophages. Based on these findings, we suggest that the isolation of EVs from ADMSC suspension cultures makes it possible to induce in vitro cellular responses of interest and obtain sufficient particle numbers for the development of in vivo concept tests for tissue regeneration studies.

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.

Optimizing mesenchymal stem cell extracellular vesicles for chronic wound healing: Bioengineering, standardization, and safety

Chronic wounds represent a significant global burden, afflicting millions with debilitating complications. Despite standard care, impaired healing persists due to factors like persistent inflammation and impaired tissue regeneration. Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) offer an innovative regenerative medicine approach, delivering stem cell-derived therapeutic cargo in engineered nanoscale delivery systems. This review examines pioneering bioengineering strategies to engineer MSC-EVs into precision nanotherapeutics for chronic wounds. Emerging technologies like CRISPR gene editing, microfluidic manufacturing, and biomimetic delivery systems are highlighted for their potential to enhance MSC-EV targeting, optimize therapeutic cargo enrichment, and ensure consistent clinical-grade production. However, key hurdles remain, including batch variability, rigorous safety assessment for potential tumorigenicity, immunogenicity, and biodistribution profiling. Crucially, collaborative frameworks harmonizing regulatory science with bioengineering and patient advocacy hold the key to expediting global clinical translation. By overcoming these challenges, engineered MSC-EVs could catalyze a new era of off-the-shelf regenerative therapies, restoring hope and healing for millions afflicted by non-healing wounds.

What is the rationale for mesenchymal stromal cells based therapies in the management of hemophilic arthropathies?

Hemophilia A and B are rare X-linked genetic bleeding disorders due to a complete or partial deficiency in the coagulation factors VIII or IX, respectively. The main treatment for hemophilia is prophylactic and based on coagulation factor replacement therapies. These treatments have significantly reduced bleeding and improved the patients' quality of life. Nevertheless, repeated joint bleedings (hemarthroses), even subclinical hemarthroses, can lead to hemophilic arthropathy (HA). This disabling condition is characterized by chronic pain due to synovial inflammation, cartilage and bone destruction requiring ultimately joint replacement. HA resembles to rheumatoid arthritis because of synovitis but HA is considered as having similarities with osteoarthritis as illustrated by the migration of immune cells, production of inflammatory cytokines, synovial hypertrophy and cartilage damage. Various drugs have been evaluated for the management of HA with limited success. The objective of the review is to discuss new therapeutic approaches with a special focus on the studies that have investigated the potential of using mesenchymal stromal cells (MSCs) in the management of HA. A systematic review of the literature has been made. Most of the studies have focused on the interest of MSCs for the delivery of missing factors VIII or IX but in some studies, more insight on the effect of MSC injection on synovial inflammation or cartilage structure were provided and put in perspective for possible clinical applications.

Mesenchymal stromal cell-derived extracellular vesicles therapy openings new translational challenges in immunomodulating acute liver inflammation

Inflammation plays a critical role in conditions such as acute liver failure, acute-on-chronic liver failure, and ischemia-reperfusion-induced liver injury. Various pathogenic pathways contribute to liver inflammation, involving inflammatory polarization of macrophages and Küpffer cells, neutrophil infiltration, dysregulation of T cell subsets, oxidative stress, and activation of hepatic stellate cells. While mesenchymal stromal cells (MSCs) have demonstrated beneficial properties, their clinical translation is limited by their cellular nature. However, MSC-derived extracellular vesicles (MSC-EVs) have emerged as a promising cell-free therapeutic approach for immunomodulation. MSC-EVs naturally mirror their parental cell properties, overcoming the limitations associated with the use of MSCs. In vitro and in vivo preclinical studies have demonstrated that MSC-EVs replicate the beneficial effects of MSCs in liver injury. This includes the reduction of cell death and oxidative stress, improvement of hepatocyte function, induction of immunomodulatory effects, and mitigation of cytokine storm. Nevertheless, MSC-EVs face challenges regarding the necessity of defining consistent isolation methods, optimizing MSCs culture conditions, and establishing quality control measures for EV characterization and functional assessment. By establishing standardized protocols, guidelines, and affordable cost mass production, clinicians and researchers will have a solid foundation to conduct further studies, validate the therapeutic efficacy of MSC-EVs, and ultimately pave the way for their clinical implementation in acute liver injury.

Transitioning from static to suspension culture system for large-scale production of xeno-free extracellular vesicles derived from mesenchymal stromal cells

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have shown increasing therapeutic potential in the last years. However, large production of EV is required for therapeutic purposes. Thereby, scaling up MSC cultivation in bioreactors is essential to allow culture parameters monitoring. In this study, we reported the establishment of a scalable bioprocess to produce MSC-EV in suspension cultures using spinner flasks and human collagen-coated microcarriers (3D culture system). We compared the EV production in this 3D culture system with the standard static culture using T-flasks (2D culture system). The EV produced in both systems were characterized and quantify by western blotting and nanoparticle tracking analysis. The presence of the typical protein markers CD9, CD63, and CD81 was confirmed by western blotting analyses for EV produced in both culture systems. The cell fold-increase was 5.7-fold for the 3D culture system and 4.6-fold for the 2D culture system, signifying a fold-change of 1.2 (calculated as the ratio of fold-increase 3D to fold-increase 2D). Furthermore, it should be noted that the total cell production in the spinner flask cultures was 4.8 times higher than that in T-flask cultures. The total cell production in the spinner flask cultures was 5.2-fold higher than that in T-flask cultures. While the EV specific production (particles/cell) in T-flask cultures (4.40 ± 1.21 × 108 particles/mL, p < 0.05) was higher compared to spinner flask cultures (2.10 ± 0.04 × 108 particles/mL, p < 0.05), the spinner flask culture system offers scalability, making it capable of producing enough MSC-EV at a large scale for clinical applications. Therefore, we concluded that 3D culture system evaluated here serves as an efficient transitional platform that enables the scaling up of MSC-EV production for therapeutic purposes by utilizing stirred tank bioreactors and maintaining xeno-free conditions.

Dynamic cultivation of human mesenchymal stem/stromal cells for the production of extracellular vesicles in a 3D bioreactor system

PURPOSE

3D cell culture and hypoxia have been demonstrated to increase the therapeutic effects of mesenchymal stem/stromal cells (MSCs)-derived extracellular vesicles (EVs). In this study, a process for the production of MSC-EVs in a novel 3D bioreactor system under normoxic and hypoxic conditions was established and the resulting EVs were characterized.

METHODS

Human adipose-derived MSCs were seeded and cultured on a 3D membrane in the VITVO® bioreactor system for 7 days. Afterwards, MSC-EVs were isolated and characterized via fluorescence nanoparticle tracking analysis, flow cytometry with staining against annexin V (Anx5) as a marker for EVs exposing phosphatidylserine, as well as CD73 and CD90 as MSC surface markers.

RESULTS

Cultivation of MSC in the VITVO® bioreactor system demonstrated a higher concentration of MSC-EVs from the 3D bioreactor (9.1 × 109 ± 1.5 × 109 and 9.7 × 109 ± 3.1 × 109 particles/mL) compared to static 2D culture (4.2 × 109 ± 7.5 × 108 and 3.9 × 109 ± 3.0 × 108 particles/mL) under normoxic and hypoxic conditions, respectively. Also, the particle-to-protein ratio as a measure for the purity of EVs increased from 3.3 × 107 ± 1.1 × 107 particles/µg protein in 2D to 1.6 × 108 ± 8.3 × 106 particles/µg protein in 3D. Total MSC-EVs as well as CD73-CD90+ MSC-EVs were elevated in 2D normoxic conditions. The EV concentration and size did not differ significantly between normoxic and hypoxic conditions.

CONCLUSION

The production of MSC-EVs in a 3D bioreactor system under hypoxic conditions resulted in increased EV concentration and purity. This system could be especially useful in screening culture conditions for the production of 3D-derived MSC-EVs.

Exosomes: a promising avenue for cancer diagnosis beyond treatment

Exosomes, extracellular vesicles secreted by cells, have garnered significant attention in recent years for their remarkable therapeutic potential. These nanoscale carriers can be harnessed for the targeted delivery of therapeutic agents, such as pharmaceuticals, proteins, and nucleic acids, across biological barriers. This versatile attribute of exosomes is a promising modality for precision medicine applications, notably in the realm of cancer therapy. However, despite their substantial therapeutic potential, exosomes still confront challenges tied to standardization and scalability that impede their practice in clinical applications. Moreover, heterogeneity in isolation methodologies and limited cargo loading mechanisms pose obstacles to ensuring consistent outcomes, thereby constraining their therapeutic utility. In contrast, exosomes exhibit a distinct advantage in cancer diagnosis, as they harbor specific signatures reflective of the tumor's genetic and proteomic profile. This characteristic endows them with the potential to serve as valuable liquid biopsies for non-invasive and real-time monitoring, making possible early cancer detection for the development of personalized treatment strategies. In this review, we provide an extensive evaluation of the advancements in exosome research, critically examining their advantages and limitations in the context of cancer therapy and early diagnosis. Furthermore, we present a curated overview of the most recent technological innovations utilizing exosomes, with a focus on enhancing the efficacy of early cancer detection.

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.

Bibliometric Analysis of Stem Cells in Ischemic Stroke (2001-2022): Trends, Hotspots and Prospects

Background: Ischemic stroke is a common cerebrovascular accident with a high risk of neurological deficits. Stem cell therapy has progressively attracted the interest of scientists and clinicians due to the benefits of promoting neural regeneration and regulating the microenvironment surrounding the lesion after ischemic stroke. Our study aimed to evaluate the development trends and research hotspots in the field of stem cells and ischemic stroke. Materials and methods: Publications related to stem cells and ischemic stroke were retrieved from the Web of Science from 2001 to 2022. Data analysis and mapping were performed using VOSviewer, Citespace and ImageGP. Results: In total, 1932 papers were included in the analysis. Publications have steadily increased over the past 22 years. China has contributed the maximum number of publications, whereas the USA ranked first in the total number of citations and was considered the center of the international collaboration network. University of South Florida, Henry Ford Hospital, and Oakland University were the most influential institutions. Stroke, Brain Research, and Neural Regeneration Research were the most productive journals. The research in this field was primarily focused on the effects of stem cells on neurogenesis, inflammation, and angiogenesis following ischemic stroke, as well as their therapeutic potential for the disease. In addition, neural stem cells and mesenchymal stem cells are the most commonly utilized stem cells. The topics related to miRNA, extracellular vesicles, exosomes, mesenchymal stem cells, neuroinflammation, and autophagy are current research hotspots. Conclusion: Our bibliometric study provides a novel perspective on the research trends in the field of stem cells and ischemic stroke. The outcome of this study may benefit scientists to identify research hotspots and development directions, thereby advancing the application of stem cell-based therapy for ischemic stroke.

Nanoparticles and Mesenchymal Stem Cell (MSC) Therapy for Cancer Treatment: Focus on Nanocarriers and a si-RNA CXCR4 Chemokine Blocker as Strategies for Tumor Eradication In Vitro and In Vivo

Mesenchymal stem cells (MSCs) have a high tropism for the hypoxic microenvironment of tumors. The combination of nanoparticles in MSCs decreases tumor growth in vitro as well as in rodent models of cancers in vivo. Covalent conjugation of nanoparticles with the surface of MSCs can significantly increase the drug load delivery in tumor sites. Nanoparticle-based anti-angiogenic systems (gold, silica and silicates, diamond, silver, and copper) prevented tumor growth in vitro. For example, glycolic acid polyconjugates enhance nanoparticle drug delivery and have been reported in human MSCs. Labeling with fluorescent particles (coumarin-6 dye) identified tumor cells using fluorescence emission in tissues; the conjugation of different types of nanoparticles in MSCs ensured success and feasibility by tracking the migration and its intratumor detection using non-invasive imaging techniques. However, the biosafety and efficacy; long-term stability of nanoparticles, and the capacity for drug release must be improved for clinical implementation. In fact, MSCs are vehicles for drug delivery with nanoparticles and also show low toxicity but inefficient accumulation in tumor sites by clearance of reticuloendothelial organs. To solve these problems, the internalization or conjugation of drug-loaded nanoparticles should be improved in MSCs. Finally, CXCR4 may prove to be a promising target for immunotherapy and cancer treatment since the delivery of siRNA to knock down this alpha chemokine receptor or CXCR4 antagonism has been shown to disrupt tumor-stromal interactions.

Therapeutic potential in rheumatic diseases of extracellular vesicles derived from mesenchymal stromal cells

The incidence of rheumatic diseases such as rheumatoid arthritis and osteoarthritis and injuries to articular cartilage that lead to osteochondral defects is predicted to rise as a result of population ageing and the increase in high-intensity physical activities among young and middle-aged people. Current treatments focus on the management of pain and joint functionality to improve the patient's quality of life, but curative strategies are greatly desired. In the past two decades, the therapeutic value of mesenchymal stromal cells (MSCs) has been evaluated because of their regenerative potential, which is mainly attributed to the secretion of paracrine factors. Many of these factors are enclosed in extracellular vesicles (EVs) that reproduce the main functions of parental cells. MSC-derived EVs have anti-inflammatory, anti-apoptotic as well as pro-regenerative activities. Research on EVs has gained considerable attention as they are a potential cell-free therapy with lower immunogenicity and easier management than whole cells. MSC-derived EVs can rescue the pathogenetic phenotypes of chondrocytes and exert a protective effect in animal models of rheumatic disease. To facilitate the therapeutic use of EVs, appropriate cell sources for the production of EVs with the desired biological effects in each disease should be identified. Production and isolation of EVs should be optimized, and pre-isolation and post-isolation modifications should be considered to maximize the disease-modifying potential of the EVs.

Host and Pathogen-Directed Therapies against Microbial Infections Using Exosome- and Antimicrobial Peptide-derived Stem Cells with a Special look at Pulmonary Infections and Sepsis

Microbial diseases are a great threat to global health and cause considerable mortality and extensive economic losses each year. The medications for treating this group of diseases (antibiotics, antiviral, antifungal drugs, etc.) directly attack the pathogenic agents by recognizing the target molecules. However, it is necessary to note that excessive use of any of these drugs can lead to an increase in microbial resistance and infectious diseases. New therapeutic methods have been studied recently using emerging drugs such as mesenchymal stem cell-derived exosomes (MSC-Exos) and antimicrobial peptides (AMPs), which act based on two completely different strategies against pathogens including Host-Directed Therapy (HDT) and Pathogen-Directed Therapy (PDT), respectively. In the PDT approach, AMPs interact directly with pathogens to interrupt their intrusion, survival, and proliferation. These drugs interact directly with the cell membrane or intracellular components of pathogens and cause the death of pathogens or inhibit their replication. The mechanism of action of MSC-Exos in HDT is based on immunomodulation and regulation, promotion of tissue regeneration, and reduced host toxicity. This review studies the potential of mesenchymal stem cell-derived exosomes/ATPs therapeutic properties against microbial infectious diseases especially pulmonary infections and sepsis.

Expanding applications of allogeneic platelets, platelet lysates, and platelet extracellular vesicles in cell therapy, regenerative medicine, and targeted drug delivery

Platelets are small anucleated blood cells primarily known for their vital hemostatic role. Allogeneic platelet concentrates (PCs) collected from healthy donors are an essential cellular product transfused by hospitals to control or prevent bleeding in patients affected by thrombocytopenia or platelet dysfunctions. Platelets fulfill additional essential functions in innate and adaptive immunity and inflammation, as well as in wound-healing and tissue-repair mechanisms. Platelets contain mitochondria, lysosomes, dense granules, and alpha-granules, which collectively are a remarkable reservoir of multiple trophic factors, enzymes, and signaling molecules. In addition, platelets are prone to release in the blood circulation a unique set of extracellular vesicles (p-EVs), which carry a rich biomolecular cargo influential in cell-cell communications. The exceptional functional roles played by platelets and p-EVs explain the recent interest in exploring the use of allogeneic PCs as source material to develop new biotherapies that could address needs in cell therapy, regenerative medicine, and targeted drug delivery. Pooled human platelet lysates (HPLs) can be produced from allogeneic PCs that have reached their expiration date and are no longer suitable for transfusion but remain valuable source materials for other applications. These HPLs can substitute for fetal bovine serum as a clinical grade xeno-free supplement of growth media used in the in vitro expansion of human cells for transplantation purposes. The use of expired allogeneic platelet concentrates has opened the way for small-pool or large-pool allogeneic HPLs and HPL-derived p-EVs as biotherapy for ocular surface disorders, wound care and, potentially, neurodegenerative diseases, osteoarthritis, and others. Additionally, allogeneic platelets are now seen as a readily available source of cells and EVs that can be exploited for targeted drug delivery vehicles. This article aims to offer an in-depth update on emerging translational applications of allogeneic platelet biotherapies while also highlighting their advantages and limitations as a clinical modality in regenerative medicine and cell therapies.

The developing role of extracellular vesicles in autoimmune diseases: special attention to mesenchymal stem cell-derived extracellular vesicles

Autoimmune diseases are complex, chronic inflammatory conditions initiated by the loss of immunological tolerance to self-antigens. Nowadays, there is no effective and useful therapy for autoimmune diseases, and the existing medications have some limitations due to their nonspecific targets and side effects. During the last few decades, it has been established that mesenchymal stem cells (MSCs) have immunomodulatory functions. It is proposed that MSCs can exert an important therapeutic effect on autoimmune disorders. In parallel with these findings, several investigations have shown that MSCs alleviate autoimmune diseases. Intriguingly, the results of studies have demonstrated that the effective roles of MSCs in autoimmune diseases do not depend on direct intercellular communication but on their ability to release a wide spectrum of paracrine mediators such as growth factors, cytokines and extracellular vehicles (EVs). EVs that range from 50 to 5,000 nm were produced by almost any cell type, and these nanoparticles participate in homeostasis and intercellular communication via the transfer of a broad range of biomolecules such as modulatory proteins, nucleic acids (DNA and RNA), lipids, cytokines, and metabolites. EVs derived from MSCs display the exact properties of MSCs and can be safer and more beneficial than their parent cells. In this review, we will discuss the features of MSCs and their EVs, EVs biogenesis, and their cargos, and then we will highlight the existing discoveries on the impacts of EVs from MSCs on autoimmune diseases such as multiple sclerosis, arthritis rheumatic, inflammatory bowel disease, Type 1 diabetes mellitus, systemic lupus erythematosus, autoimmune liver diseases, Sjögren syndrome, and osteoarthritis, suggesting a potential alternative for autoimmune conditions therapy.

Dogs with canine visceral leishmaniasis have a boost of extracellular vesicles and miR-21-5p up-expression

This retrospective cohort study analysed extracellular vesicles (EVs) and microRNAs (miRNAs) excreted in canine sera from dogs with canine visceral leishmaniasis (CanVL). A total of 56 canine sera were divided into Group I (28, from healthy dogs) and Group II (28, from the same dogs, but already with CanVL). CanVL was determined by clinical and laboratory diagnoses. Canine sera were ultra-centrifuged to recover EVs (Can-EVs). Analyses by transmission electron microscopy, nanoparticle tracking analysis (NTA), sodium dodecyl sulfate-poli-acrylammide gel eletroforesis (SDS-PAGE) and, Immunoblot confirmed the presence of (i) microvesicles/exosomes and (ii) the tetraspanins CD63 and CD9. EVs secreted by Leishmania (Leishmania) infantum-EVs were reactive against sera from dogs with CanVL (performed by ELISA and Immunoblot). NTA analyses exhibited that concentrations of Can-EVs from dogs with CanVL (7.78 × 1010 Can-EVs/mL) were higher (p < .0001) than the non-infected dogs (mean: 1.47 × 1010 Can-EVs/mL). These results suggested that concentrations of Can-EVs were able to distinguish dogs with CanVL from healthy dogs. The relative expressions of 11 miRNAs species (miR-21-5p, miR-146a-5p, miR-125b-5p, miR-144-3p, miR-194-5p, miR-346, miR-29c-3p, miR-155-5p, miR-24-3p, miR-181a-5p, and miR-9-5p) were estimated in purified miRNAs of 30 canine sera. Dogs with CanVL up-expressed miR-21-5p and miR-146a-5p when compared with healthy dogs. The other miRNA species were poorly or not expressed in canine sera. In conclusion, this study suggests that CanVL induces changes in size and concentration of Can-EVs, as well as, the up-expression of miR-21-5p and miR-146a-5p in infected dogs.

Nature vs. Manmade: Comparing Exosomes and Liposomes for Traumatic Brain Injury

Traumatic brain injury (TBI) of all severities is a significant public health burden, causing a range of effects that can lead to death or a diminished quality of life. Liposomes and mesenchymal stem cell-derived exosomes are two drug delivery agents with potential to be leveraged in the treatment of TBI by increasing the efficacy of drug therapies as well as having additional therapeutic effects. They exhibit several physical similarities, but key differences affect their performances as nanocarriers. Liposomes can be produced commercially at scale, and liposomes achieve higher encapsulation efficiency. Meanwhile, the intrinsic cargo and targeting moieties of exosomes, which liposomes lack, give exosomes a greater ability to facilitate neural regeneration, and exosomes do not trigger the infusion reactions that liposomes can. However, there are concerns about both exosomes and liposomes regarding interactions with tumors. The same routes of administration can be used for both exosomes and liposomes, resulting in somewhat different distribution throughout the body. While the effect of the nanocarrier type on accumulation in the brain is not concrete, targeting leads to increased accumulation of both exosomes and liposomes in the brain, upon which on-demand release can be used for both drug deliverers. Although neither have been applied to TBI in humans, preclinical trials have shown their immense potential, as have clinical trials pertaining to other brain injuries and conditions. While questions remain, research thus far shows that the various differences make exosomes a better choice of nanocarrier for TBI.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: An Emerging Diagnostic and Therapeutic Biomolecules for Neurodegenerative Disabilities

Mesenchymal stem cells (MSCs) are a type of versatile adult stem cells present in various organs. These cells give rise to extracellular vesicles (EVs) containing a diverse array of biologically active elements, making them a promising approach for therapeutics and diagnostics. This article examines the potential therapeutic applications of MSC-derived EVs in addressing neurodegenerative disorders such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Furthermore, the present state-of-the-art for MSC-EV-based therapy in AD, HD, PD, ALS, and MS is discussed. Significant progress has been made in understanding the etiology and potential treatments for a range of neurodegenerative diseases (NDs) over the last few decades. The contents of EVs are carried across cells for intercellular contact, which often results in the control of the recipient cell's homeostasis. Since EVs represent the therapeutically beneficial cargo of parent cells and are devoid of many ethical problems connected with cell-based treatments, they offer a viable cell-free therapy alternative for tissue regeneration and repair. Developing innovative EV-dependent medicines has proven difficult due to the lack of standardized procedures in EV extraction processes as well as their pharmacological characteristics and mechanisms of action. However, recent biotechnology and engineering research has greatly enhanced the content and applicability of MSC-EVs.

Neural stem cell-derived exosomes and regeneration: cell-free therapeutic strategies for traumatic brain injury

Regenerative repair of the brain after traumatic brain injury (TBI) remains an extensive clinical challenge, inspiring intensified interest in therapeutic approaches to explore superior repair strategies. Exosome therapy is another research hotspot following stem cell alternative therapy. Prior research verified that exosomes produced by neural stem cells can participate in the physiological and pathological changes associated with TBI and have potential neuroregulatory and repair functions. In comparison with their parental stem cells, exosomes have superior stability and immune tolerance and lower tumorigenic risk. In addition, they can readily penetrate the blood‒brain barrier, which makes their treatment efficiency superior to that of transplanted stem cells. Exosomes secreted by neural stem cells present a promising strategy for the development of novel regenerative therapies. Their tissue regeneration and immunomodulatory potential have made them encouraging candidates for TBI repair. The present review addresses the challenges, applications and potential mechanisms of neural stem cell exosomes in regenerating damaged brains.

Mesenchymal Stem Cell Culture within Perfusion Bioreactors Incorporating 3D-Printed Scaffolds Enables Improved Extracellular Vesicle Yield with Preserved Bioactivity

Extracellular vesicles (EVs) are implicated as promising therapeutics and drug delivery vehicles in various diseases. However, successful clinical translation will depend on the development of scalable biomanufacturing approaches, especially due to the documented low levels of intrinsic EV-associated cargo that may necessitate repeated doses to achieve clinical benefit in certain applications. Thus, here the effects of a 3D-printed scaffold-perfusion bioreactor system are assessed on the production and bioactivity of EVs secreted from bone marrow-derived mesenchymal stem cells (MSCs), a cell type widely implicated in generating EVs with therapeutic potential. The results indicate that perfusion bioreactor culture induces an ≈40-80-fold increase (depending on measurement method) in MSC EV production compared to conventional cell culture. Additionally, MSC EVs generated using the perfusion bioreactor system significantly improve wound healing in a diabetic mouse model, with increased CD31+ staining in wound bed tissue compared to animals treated with flask cell culture-generated MSC EVs. Overall, this study establishes a promising solution to a major EV translational bottleneck, with the capacity for tunability for specific applications and general improvement alongside advancements in 3D-printing technologies.

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.

Impact of storage conditions and duration on function of native and cargo-loaded mesenchymal stromal cell extracellular vesicles

BACKGROUND AIMS

As evidenced by ongoing clinical trials and increased activity in the commercial sector, extracellular vesicle (EV)-based therapies have begun the transition from bench to bedside. As this progression continues, one critical aspect of EV clinical translation is understanding the effects of storage and transport conditions. Several studies have assessed the impact of storage on EV characteristics such as morphology, uptake and component content, but effects of storage duration and temperature on EV functional bioactivity and, especially, loaded cargo are rarely reported.

METHODS

The authors assessed EV outcomes following storage at different temperatures (room temperature, 4°C, -20°C, -80°C) for various durations as well as after lyophilization.

RESULTS

Mesenchymal stromal cell (MSC) EVs were observed to retain key aspects of their bioactivity (pro-vascularization, anti-inflammation) for up to 4-6 weeks at -20°C and -80°C and after lyophilization. Furthermore, via in vitro assays and an in vivo wound healing model, these same storage conditions were also demonstrated to enable preservation of the functionality of loaded microRNA and long non-coding RNA cargo in MSC EVs.

CONCLUSIONS

These findings extend the current understanding of how EV therapeutic potential is impacted by storage conditions and may inform best practices for handling and storing MSC EVs for both basic research and translational purposes.

Advances in mesenchymal stem/stromal cell-based therapy and their extracellular vesicles for skin wound healing

Wound healing is a dynamic and complicated process containing overlapping phases. Presently, definitive therapy is not available, and the investigation into optimal wound care is influenced by the efficacy and cost-effectiveness of developing therapies. Accumulating evidence demonstrated the potential role of mesenchymal stem/stromal cell (MSC) therapy in several tissue injuries and diseases due to their high proliferation and differentiation abilities along with an easy collection procedure, low tumorigenesis, and immuno-privileged status. MSCs have also accelerated wound repair in all phases through their advantageous properties, such as accelerating wound closure, improving re-epithelialization, elevating angiogenesis, suppressing inflammation, and modulating extracellular matrix (ECM) remodeling. In addition, the beneficial therapeutic impacts of MSCs are largely associated with their paracrine functions, including extracellular vesicles (EVs). Exosomes and microvesicles are the two main subgroups of EVs. These vesicles are heterogeneous bilayer membrane structures that contain several proteins, lipids, and nucleic acids. EVs have emerged as a promising alternative to stem cell-based therapies because of their lower immunogenicity, tumorigenicity, and ease of management. MSCs from various sources have been widely investigated in skin wound healing and regeneration. Considering these features, in this review, we highlighted recent studies that the investigated therapeutic potential of various MSCs and MSC-EVs in skin damages and wounds.

Mesenchymal stromal/stem cell (MSC)-derived exosomes in clinical trials

Mesenchymal stromal/stem cells (MSCs) are widely utilized in cell therapy because of their robust immunomodulatory and regenerative properties. Their paracrine activity is one of the most important features that contribute to their efficacy. Recently, it has been demonstrated that the production of various factors via extracellular vesicles, especially exosomes, governs the principal efficacy of MSCs after infusion in experimental models. Compared to MSCs themselves, MSC-derived exosomes (MSC-Exos) have provided significant advantages by efficiently decreasing unfavorable adverse effects, such as infusion-related toxicities. MSC-Exos is becoming a promising cell-free therapeutic tool and an increasing number of clinical studies started to assess the therapeutic effect of MSC-Exos in different diseases. In this review, we summarized the ongoing and completed clinical studies using MSC-Exos for immunomodulation, regenerative medicine, gene delivery, and beyond. Additionally, we summarized MSC-Exos production methods utilized in these studies with an emphasis on MSCs source, MSC-Exos isolation methods, characterization, dosage, and route of administration. Lastly, we discussed the current challenges and future directions of exosome utilization in different clinical studies as a novel therapeutic strategy.

Homogenous subpopulation of human mesenchymal stem cells and their extracellular vesicles restore function of endometrium in an experimental rat model of Asherman syndrome

BACKGROUND

Asherman syndrome (AS), or intrauterine adhesions, is a main cause of infertility in reproductive age women after endometrial injury. Mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) are promising candidates for therapies that repair damaged endometria. However, concerns about their efficacy are attributed to heterogeneity of the cell populations and EVs. A homogenous population of MSCs and effective EV subpopulation are needed to develop potentially promising therapeutic options in regenerative medicine.

METHODS

AS model was induced by mechanical injury in adult rat uteri. Then, the animals were treated immediately with homogeneous population of human bone marrow-derived clonal MSCs (cMSCs), heterogenous parental MSCs (hMSCs), or cMSCs-derived EV subpopulations (EV20K and EV110K). The animals were sacrificed two weeks post-treatment and uterine horns were collected. The sections were taken, and hematoxylin-eosin was used to examine the repair of endometrial structure. Fibrosis was measured by Masson's trichrome staining and α-SMA and cell proliferation by Ki67 immunostaining. The function of the uteri was explored by the result of mating trial test. Expression changes of TNFα, IL-10, VEGF, and LIF were assayed by ELISA.

RESULTS

Histological analysis indicated fewer glands, thinner endometria, increased fibrotic areas, and decreased proliferation of epithelial and stroma of the uteri in the treated compared with intact and sham-operated animals. However, these parameters improved after transplantation of both types of cMSCs and hMSCs and/or both cryopreserved EVs subpopulations. The cMSCs demonstrated more successful implantation of the embryos in comparison with hMSCs. The tracing of the transplanted cMSCs and EVs showed that they migrated and localized in the uteri. Protein expression analysis results demonstrated downregulation of proinflammatory factor TNFα and upregulation of anti-inflammatory cytokine IL-10, and endometrial receptivity cytokines VEGF and LIF in cMSC- and EV20K-treated animals.

CONCLUSION

Transplantation of MSCs and EVs contributed to endometrial repair and restoration of reproductive function, likely by inhibition of excessive fibrosis and inflammation, enhancement of endometrial cell proliferation, and regulation of molecular markers related to endometrial receptivity. Compared to classical hMSCs, cMSCs were more efficient than hMSCs in restoration of reproductive function. Moreover, EV20K is more cost-effective and feasible for prevention of AS in comparison with conventional EVs (EV110K).

The NG2-glia is a potential target to maintain the integrity of neurovascular unit after acute ischemic stroke

The neurovascular unit (NVU) plays a critical role in health and disease. In the current review, we discuss the critical role of a class of neural/glial antigen 2 (NG2)-expressing glial cells (NG2-glia) in regulating NVU after acute ischemic stroke (AIS). We first introduce the role of NG2-glia in the formation of NVU during development as well as aging-induced damage to NVU and accompanying NG2-glia change. We then discuss the reciprocal interactions between NG2-glia and the other component cells of NVU, emphasizing the factors that could influence NG2-glia. Damage to the NVU integrity is the pathological basis of edema and hemorrhagic transformation, the most dreaded complication after AIS. The role of NG2-glia in AIS-induced NVU damage and the effect of NG2-glia transplantation on AIS-induced NVU damage are summarized. We next discuss the role of NG2-glia and the effect of NG2-glia transplantation in oligodendrogenesis and white matter repair as well as angiogenesis which is associated with the outcome of the patients after AIS. Finally, we review the current strategies to promote NG2-glia proliferation and differentiation and propose to use the dental pulp stem cells (DPSC)-derived exosome as a promising strategy to reduce AIS-induced injury and promote repair through maintaining the integrity of NVU by regulating endogenous NG2-glia proliferation and differentiation.

Mesenchymal stem-cell-derived microvesicles ameliorate MPTP-induced neurotoxicity in mice: a role of the gut-microbiota-brain axis

RATIONALE

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder. Increasing evidence suggests the role of the gut-microbiota-brain axis in the pathogenesis of PD. Mesenchymal stem-cell-derived microvesicles (MSC-MVs) have emerged as a therapeutic potential for neurological disorders over the last years.

OBJECTIVE

The objective of this study was to investigate whether MSC-MVs could improve PD-like neurotoxicity in mice after administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine).

RESULTS

MPTP-induced reductions in the dopamine transporter and tyrosine hydroxylase expressions in the striatum and substantia nigra (SNr) were attenuated after a subsequent single administration of MSC-MVs. Increases in the phosphorylated α-synuclein (p-α-Syn)/α-Syn ratio in the striatum, SNr, and colon after MPTP injection were also attenuated after MSC-MVs injection. Furthermore, MSC-MVs restored MPTP-induced abnormalities of the gut microbiota composition. Interestingly, positive correlations between the genus Dubosiella and the p-α-Syn/α-Syn ratio were observed in the brain and colon, suggesting their roles in the gut-microbiota-brain communication. Moreover, MSC-MVs attenuated MPTP-induced reduction of the metabolite, 3,6-dihydroxy-2-[3-methoxy-4-(sulfooxy)phenyl]-7-(sulfinooxy)-3,4-dihydro-2H-1-benzopyran-5-olate, in the blood. Interestingly, a negative correlation between this compound and the p-α-Syn/α-Syn ratio was observed in the brain and colon.

CONCLUSIONS

These data suggest that MSC-MVs could ameliorate MPTP-induced neurotoxicity in the brain and colon via the gut-microbiota-brain axis. Therefore, MSC-MVs would have a new therapeutic potential for neurological disorders such as PD.

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.

Adipose Tissue and Adipose-Tissue-Derived Cell Therapies for the Treatment of the Face and Hands of Patients Suffering from Systemic Sclerosis

Adipose tissue is recognized as a valuable source of cells with angiogenic, immunomodulatory, reparative and antifibrotic properties and emerged as a therapeutic alternative for the regeneration and repair of damaged tissues. The use of adipose-tissue-based therapy is expanding in autoimmune diseases, particularly in Systemic Sclerosis (SSc), a disease in which hands and face are severely affected, leading to disability and a decrease in quality of life. Combining the advantage of an abundant supply of fat tissue and a high abundance of stem/stromal cells, fat grafting and adipose tissue-derived cell-based therapies are attractive therapeutic options in SSc. This review aims to synthesize the evidence to determine the effects of the use of these biological products for face and hands treatment in the context of SSc. This highlights several points: the need to use relevant effectiveness criteria taking into account the clinical heterogeneity of SSc in order to facilitate assessment and comparison of innovative therapies; second, it reveals some impacts of the disease on fat-grafting success; third, an important heterogeneity was noticed regarding the manufacturing of the adipose-derived products and lastly, it shows a lack of robust evidence from controlled trials comparing adipose-derived products with standard care.

Extracellular Vesicles as Therapeutic Resources in the Clinical Environment

The native role of extracellular vesicles (EVs) in mediating the transfer of biomolecules between cells has raised the possibility to use them as therapeutic vehicles. The development of therapies based on EVs is now expanding rapidly; here we will describe the current knowledge on different key points regarding the use of EVs in a clinical setting. These points are related to cell sources of EVs, isolation, storage, and delivery methods, as well as modifications to the releasing cells for improved production of EVs. Finally, we will depict the application of EVs therapies in clinical trials, considering the impact of the COVID-19 pandemic on the development of these therapies, pointing out that although it is a promising therapy for human diseases, we are still in the initial phase of its application to patients.

Thymoquinone-treated mouse mesenchymal stem cells-derived conditioned medium inhibits human breast cancer cells in vitro

Breast cancer is now the most prevalent cancer in females, therefore, it is essential to identify factors affecting its initiation and progression. Mesenchymal stem cells (MSCs) have received considerable attention in stem cell-based therapies and drug delivery applications. Because the therapeutic potential of MSCs is primarily achieved by their paracrine effects, thus identifying and employing bioactive molecules that promote the paracrine activity of MSCs is crucial for their efficient use in cancer treatment. Thymoquinone (TQ) has many biomedical properties, including anti-inflammatory, anti-diabetic, anti-aging, anti-cancer, etc. In addition, it has been found that TQ affects the self-renewal and immunomodulatory properties of MSCs. The present study aimed to investigate the effect of TQ-treated mouse bone marrow-derived MSCs conditioned medium (TQ-MSC-CM) on the biological characteristics of breast cancer cell line MCF7. MSCs were cultured and treated with TQ for 24 h. The TQ-MSC-CM and MSC-CM were collected, and their effects were investigated on ROS production, mitochondrial membrane potential (MMP), cell death, cell cycle, and migration of MCF7 cells by DCFDA-cellular ROS assay, Rhodamine-123 MMP assay, Annexin-PI staining and Caspase-3/7 activity assays, PI-staining and flow-cytometry, and in vitro wound healing assay, respectively. Moreover, the effects of TQ-MSC-CM and MSC-CM were studied on Cdk4, Sox2, c-Met, and Bcl2 gene expression by real-time PCR. Results demonstrated that MSC-CM and TQ-MSC-CM did not have a significant effect on the apoptosis induction in MCF7 cells; however, they significantly stimulated necrosis in the cells. Although TQ-MSC-CM promoted ROS production in MCF7 cells, it decreased the MMP of the cells. TQ-MSC-CM also induced Bcl2 anti-apoptosis gene expression and Casp-3/7 activity in cells. In addition, although MSC-CM induced MCF7 cells to enter the cell cycle, TQ-MSC-CM inhibited its progression. TQ-MSC-CM also downregulated the Cdk4 and Sox2 gene expression. Furthermore, TQ-MSC-CM induced the migration potential of MCF7 in a c-Met-independent manner. Altogether, we conclude that TQ may induce programmed necrosis and inhibits the proliferation and migration of the breast cancer cells by affecting the paracrine activity of MSCs.

Exosome engineering in cell therapy and drug delivery

Cell-derived exosomes have opened new horizons in modern therapy for advanced drug delivery and therapeutic applications, due to their key features such as low immunogenicity, high physicochemical stability, capacity to penetrate into tissues, and the innate capacity to communicate with other cells over long distances. Exosome-based liquid biopsy has been potentially used for the diagnosis and prognosis of a range of disorders. Exosomes deliver therapeutic agents, including immunological modulators, therapeutic drugs, and antisense oligonucleotides to certain targets, and can be used as vaccines, though their clinical application is still far from reality. Producing exosomes on a large-scale is restricted to their low circulation lifetime, weak targeting capacity, and inappropriate controls, which need to be refined before being implemented in practice. Several bioengineering methods have been used for refining therapeutic applications of exosomes and promoting their effectiveness, on the one hand, and addressing the existing challenges, on the other. In the short run, new diagnostic platforms and emerging therapeutic strategies will further develop exosome engineering and therapeutic potential. This requires a thorough analysis of exosome engineering approaches along with their merits and drawbacks, as outlined in this paper. The present study is a comprehensive review of novel techniques for exosome development in terms of circulation time in the body, targeting capacity, and higher drug loading/delivery efficacies.

Roles of extracellular vesicles in periodontal homeostasis and their therapeutic potential

Periodontal tissue is a highly dynamic and frequently stimulated area where homeostasis is easily destroyed, leading to proinflammatory periodontal diseases. Bacteria-bacteria and cell-bacteria interactions play pivotal roles in periodontal homeostasis and disease progression. Several reviews have comprehensively summarized the roles of bacteria and stem cells in periodontal homeostasis. However, they did not describe the roles of extracellular vesicles (EVs) from bacteria and cells. As communication mediators evolutionarily conserved from bacteria to eukaryotic cells, EVs secreted by bacteria or cells can mediate interactions between bacteria and their hosts, thereby offering great promise for the maintenance of periodontal homeostasis. This review offers an overview of EV biogenesis, the effects of EVs on periodontal homeostasis, and recent advances in EV-based periodontal regenerative strategies. Specifically, we document the pathogenic roles of bacteria-derived EVs (BEVs) in periodontal dyshomeostasis, focusing on plaque biofilm formation, immune evasion, inflammatory pathway activation and tissue destruction. Moreover, we summarize recent advancements in cell-derived EVs (CEVs) in periodontal homeostasis, emphasizing the multifunctional biological effects of CEVs on periodontal tissue regeneration. Finally, we discuss future challenges and practical perspectives for the clinical translation of EV-based therapies for periodontitis.

Cellular expansion of MSCs: Shifting the regenerative potential

Mesenchymal-derived stromal or progenitor cells, commonly called "MSCs," have attracted significant clinical interest for their remarkable abilities to promote tissue regeneration and reduce inflammation. Recent studies have shown that MSCs' therapeutic effects, originally attributed to the cells' direct differentiation capacity into the tissue of interest, are largely driven by the biomolecules the cells secrete, including cytokines, chemokines, growth factors, and extracellular vesicles containing miRNA. This secretome coordinates upregulation of endogenous repair and immunomodulation in the local microenvironment through crosstalk of MSCs with host tissue cells. Therapeutic applications for MSCs and their secretome-derived products often involve in vitro monolayer expansion. However, consecutive passaging of MSCs significantly alters their therapeutic potential, inducing a broad shift from a pro-regenerative to a pro-inflammatory phenotype. A consistent by-product of in vitro expansion of MSCs is the onset of replicative senescence, a state of cell arrest characterized by an increased release of proinflammatory cytokines and growth factors. However, little is known about changes in the secretome profile at different stages of in vitro expansion. Some culture conditions and bioprocessing techniques have shown promise in more effectively retaining the pro-regenerative and anti-inflammatory MSC phenotype throughout expansion. Understanding how in vitro expansion conditions influence the nature and function of MSCs, and their associated secretome, may provide key insights into the underlying mechanisms driving these alterations. Elucidating the dynamic and diverse changes in the MSC secretome at each stage of in vitro expansion is a critical next step in the development of standardized, safe, and effective MSC-based therapies.

The role of exercise-and high fat diet-induced bone marrow extracellular vesicles in stress hematopoiesis

Exercise and obesity regulate hematopoiesis, in part through alterations in cellular and soluble components of the bone marrow niche. Extracellular vesicles (EVs) are components of the bone marrow niche that regulate hematopoiesis; however, the role of exercise training or obesity induced EVs in regulating hematopoiesis remains unknown. To address this gap, donor EVs were isolated from control diet-fed, sedentary mice (CON-SED), control diet-fed exercise trained mice (CON-EX), high fat diet-fed, sedentary mice (HFD-SED), and high fat diet-fed, exercise trained mice (HFD-EX) and injected into recipient mice undergoing stress hematopoiesis. Hematopoietic and niche cell populations were quantified, and EV miRNA cargo was evaluated. EV content did not differ between the four groups. Mice receiving HFD-EX EVs had fewer hematopoietic stem cells (HSCs) (p < 0.01), long-term HSC (p < 0.05), multipotent progenitors (p < 0.01), common myeloid progenitors (p<0.01), common lymphoid progenitors (p < 0.01), and granulocyte-macrophage progenitors (p < 0.05), compared to mice receiving HFD-SED EVs. Similarly, mice receiving EX EVs had fewer osteoprogenitor cells compared to SED (p < 0.05) but enhanced mesenchymal stromal cell (MSC) osteogenic differentiation in vitro (p < 0.05) compared to SED EVs. HFD EVs enhanced mesenchymal stromal cell (MSC) adipogenesis in vitro (p < 0.01) compared to CON EVs. HFD-EX EVs had lower microRNA-193 and microRNA-331-5p content, microRNAs implicated in inhibiting osteogenesis and leukemic cell expansion respectively, compared to HFD-SED EVs. The results identify alterations in EV cargo as a novel mechanism by which exercise training alters stress hematopoiesis and the bone marrow niche.

Co-aggregation of MSC/chondrocyte in a dynamic 3D culture elevates the therapeutic effect of secreted extracellular vesicles on osteoarthritis in a rat model

Extracellular vesicles (EVs) have therapeutic effects on osteoarthritis (OA). Some recent strategies could elevate EV's therapeutic properties including cell aggregation, co-culture, and 3D culture. It seems that a combination of these strategies could augment EV production and therapeutic potential. The current study aims to evaluate the quantity of EV yield and the therapeutic effect of EVs harvested from rabbit mesenchymal stem cells (MSCs) aggregates, chondrocyte aggregates, and their co-aggregates in a dynamic 3D culture in a rat osteoarthritis model. MSC and chondrocytes were aggregated and co-aggregated by spinner flasks, and their conditioned medium was collected. EVs were isolated by size exclusion chromatography and characterized in terms of size, morphology and surface markers. The chondrogenic potential of the MSC-ag, Cho-ag and Co-ag EVs on MSC micromass differentiation in chondrogenic media were assessed by qRT-PCR, histological and immunohistochemical analysis. 50 μg of MSC-ag-EVs, Cho-ag-EVs and Co-ag-EVs was injected intra-articularly per knee of OA models established by monoiodoacetate in rats. After 8 weeks follow up, the knee joints were harvested and analyzed by radiographic, histological and immunohistochemical features. MSC/chondrocyte co-aggregation in comparison to MSC or chondrocyte aggregation could increase EV yield during dynamic 3D culture by spinner flasks. Although MSC-ag-, Cho-ag- and Co-ag-derived EVs could induce chondrogenesis similar to transforming growth factor-beta during in vitro study, Co-ag-EV could more effectively prevent OA progression than MSC-ag- and Cho-ag-EVs. Our study demonstrated that EVs harvested from the co-aggregation of MSCs and chondrocytes could be considered as a new therapeutic potential for OA treatment.

Extracellular vesicles over adeno-associated viruses: Advantages and limitations as drug delivery platforms in precision medicine

Tissue-specific uptake and sufficient biodistribution are central goals in drug development. Crossing the blood-brain barrier (BBB) represents a major challenge in delivering therapeutics to the central nervous system (CNS). Since its discovery in the late 19th century, considerable efforts have been invested in an attempt to decipher the BBB structure complexity and plasticity. In parallel, another prevalent approach is to improve a delivery system by harnessing the biological machinery in an attempt to enhance therapeutic-agent permeability. Here, we review the advantages and limitations of using extracellular vesicles over AAV systems as a delivery system for therapy, focusing on neurodevelopmental disorders.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Wound Healing

The well-orchestrated process of wound healing may be negatively impacted from interrupted or incomplete tissue regenerative processes. The healing potential is further compromised in patients with diabetes mellitus, chronic venous insufficiency, critical limb ischemia, and immunocompromised conditions, with a high health care burden and expenditure. Stem cell-based therapy has shown promising results in clinical studies. Mesenchymal stem cell-derived exosomes (MSC Exos) may favorably impact intercellular signaling and immunomodulation, promoting neoangiogenesis, collagen synthesis, and neoepithelization. This article gives an outline of the biogenesis and mechanism of extracellular vesicles (EVs), particularly exosomes, in the process of tissue regeneration and discusses the use of preconditioned exosomes, platelet-rich plasma-derived exosomes, and engineered exosomes in three-dimensional bioscaffolds such as hydrogels (collagen and chitosan) to prolong the contact time of exosomes at the recipient site within the target tissue. An appropriate antibiotic therapy based on culture-specific guidance coupled with the knowledge of biopolymers helps to fabricate nanotherapeutic materials loaded with MSC Exos to effectively deliver drugs locally and promote novel approaches for the management of chronic wounds.

Advances of engineered extracellular vesicles-based therapeutics strategy

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer membrane-bound vesicles which encapsulate bioactive molecules, such as nucleic acids, proteins, and lipids. They mediate intercellular communication through transporting internally packaged molecules, making them attractive therapeutics carriers. Over the last decades, a significant amount of research has implied the potential of EVs servings as drug delivery vehicles for nuclear acids, proteins, and small molecular drugs. However, several challenges remain unresolved before the clinical application of EV-based therapeutics, including lack of specificity, stability, biodistribution, storage, large-scale manufacturing, and the comprehensive analysis of EV composition. Technical development is essential to overcome these issues and enhance the pre-clinical therapeutic effects. In this review, we summarize the current advancements in EV engineering which demonstrate their therapeutic potential.

Bibliometric and visualization analysis of mesenchymal stem cells and rheumatoid arthritis (from 2012 to 2021)

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease that can lead to joint deformity and loss of function. Recent studies have shown great progress in the research of mesenchymal stem cells (MSCs) in RA. However, thus far, there have been no bibliometric or visualization analyses in this field. This bibliometric analysis provides a comprehensive overview of the general information and research hotspots of MSCs and RA.

Methods

Articles relevant to MSCs and RA, published between 2012 and 2021, were searched using the Web of Science Core Collection database. Irrelevant publications were excluded from the analysis. Bibliometric and visualization analyses were conducted using VOSviewer, CiteSpace, and Scimago Graphica.

Results

A total of 577 articles were analyzed. The annual number of publications increased from 2012 to 2017 and plateaued from 2017 to 2021. China and the USA had the largest number of publications. Collaboration among different organizations mainly occurs between institutes of the same country. Stem Cell Research and Therapy and Frontiers in Immunology were the most popular journals in this field. All the top 20 co-cited authors had a positive co-citation relationship. The top references indicate that MSCs can contribute to RA research and treatment mainly via immunomodulation. From 2012 to 2021, “collagen-induced arthritis,” “immunomodulation,” and “therapy” were some of the keywords associated with MSCs and RA, while “extracellular vesicles” showed a strong keyword burst from 2019 to 2021.

Conclusion

MSCs and RA have been widely studied in different countries and institutions and by different authors over the last ten years. China and the USA had the largest number of publications. Different types of journals provide admirable sources for researchers. Some keywords, including immunomodulation and extracellular vesicles, may be hot spots in the near future. There will be more basic research and clinical translation of MSCs and RA, and substantial new treatments for RA will soon be developed.

Paracrine Effects of Mesenchymal Stem Cells in Ischemic Stroke: Opportunities and Challenges

It is well acknowledged that neuroprotective effects of transplanted mesenchymal stem cells (MSCs) in ischemic stroke are attributed to their paracrine-mediated actions or bystander effects rather than to cell replacement in infarcted areas. This therapeutic plasticity is due to MSCs' ability to secrete a broad range of bioactive molecules including growth factors, trophic factors, cytokines, chemokines, and extracellular vesicles, overall known as the secretome. The secretome derivatives, such as conditioned medium (CM) or purified extracellular vesicles (EVs), exert remarkable advantages over MSC transplantation in stroke treating. Here, in this review, we used published information to provide an overview on the secretome composition of MSCs, underlying mechanisms of therapeutic effects of MSCs, and preclinical studies on MSC-derived products application in stroke. Furthermore, we discussed current advantages and challenges for successful bench-to-bedside translation.

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

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

Canine B Cell Lymphoma- and Leukemia-Derived Extracellular Vesicles Moderate Differentiation and Cytokine Production of T and B Cells In Vitro

Extracellular vesicles (EVs) are formed in physiological and pathological conditions by almost all mammalian cells. They are known as submicron “molecules” that transport and horizontally transfer their cargo from maternal cells to donor cells. Moreover, cancer cells produce tumor-derived EVs (TEVs), which are present in blood of patients with solid tumors and those with hematological malignancies. Their role in evading immune system surveillance and induction of immunosuppression in hematological cancer is limited. According to the authors’ best knowledge, there is no information about the impact of TEVs from canine lymphoma (CLBL-1) and leukemia (CLB70) on lymphocytes isolated from peripheral blood mononuclear cells (PBMCs). In conclusion, we demonstrate in in vitro experiments that CLBL-1 EVs and CLB70 EVs are effectively taken up by T and B lymphocytes. TEVs decrease the percentage of B lymphocytes and increase that of T lymphocytes, and change T cells’ phenotype into the effector memory (EM) or terminally differentiated effector memory (TEMRA) subtype after in vitro co-culturing. Moreover, CLBL70 EVs have pro-tumorogenic properties by inhibiting the production of CD8+IL-17+ cells.

Extracellular vesicles in bone homeostasis: key roles of physiological and pathological conditions

Extracellular vesicles (EVs) are small particles with lipid bilayer membranes that are secreted by all cell types and are widely known as crucial intercellular communication mediators, shuttling biologically active molecules. The bone is a typically preferred site of cancer metastasis due to its unique cellular compositions and dynamics. Bone cell-derived EVs serve as regulators that orchestrate harmonious bone homeostasis. Cancer cells secrete specific EVs in a series of the bone metastatic process to dominate the bone microenvironment. Additionally, cancer cell-related EVs contribute to pre-metastatic niche formation, bone homeostasis disruption, and tumor bone progression and survival. Here, we investigated recent studies on EV-mediated crosstalk in the bone tumor microenvironment. Furthermore, this review aimed to elucidate the EV-based therapeutic perspectives for bone metastasis.