Versatility of mesenchymal stem cell-derived extracellular vesicles in tissue repair and regenerative applications

Nanotechnology-Assisted mesenchymal stem cells treatment for improved cartilage regeneration: A review of current practices

Cartilage tissue does not promptly elicit an inflammatory response upon injury, hence constraining its capacity for healing and self-regeneration. Mesenchymal Stem Cells (MSC) therapy, enhanced by nanotechnology, offers promising advancements in cartilage repair. Injuries to cartilage often cause chronic pain, where current treatments are inadequate. As MSCs can readily differentiate into chondrocytes and secrete soluble factors, they are essential components in tissue engineering of cartilage repair. Although, like other stem cell applications, clinical applications are restricted by poor post implantation survival and differentiation. Recent studies show that nanoparticles (NPs) can further improve MSC outcomes by promoting cell adhesion, and chondrogenic differentiation allowing for sustained growth factor release. In addition, nanomaterials can improve the biological activity of MSCs, by also facilitating the composition of a conducive microenvironment for cartilage repair. In this review, the application of nanofibrous scaffolds, hydrogels and nanoscale particulate matter to improve mechanical properties in cartilage tissue engineering, are discussed. Moreover, the MSCs and nanotechnology synergistic effects present hope of overcoming the limitations of conventional treatments. Nanotechnology greatly enhances the MSC based cartilage regeneration strategies and could provide better treatment for cartilage related diseases in the future. Future research should be aimed at standardizing MSC harvesting and culturing protocols and contrasting their long-term efficacy.

MSC-derived extracellular vesicles: Precision miRNA delivery for overcoming cancer therapy resistance

Cancer remains a prominent worldwide health concern, presenting existing therapies with frequent difficulties, including major toxicity, limited effectiveness, and treatment resistance emergence. These issues highlight the necessity for novel and enhanced remedies. Exosomes, tiny extracellular vesicles that facilitate intercellular communication, have attracted interest for their potential medicinal applications. Carrying a variety of molecules, including microRNAs, small interfering RNAs, long non-coding RNAs, proteins, lipids, and DNA, these vesicles are positioned as promising cancer treatment options. Current studies have increasingly investigated the capacity of microRNAs as a strategic approach for combating malignancy. Mesenchymal stem cells (MSC) are recognized for their aptitude to augment blood vessel formation, safeguard against cellular death, and modulate immune responses. Consequently, researchers examine exosomes derived from MSCs as a safer, non-cellular choice over therapies employing MSCs, which risk undesirable differentiation. The focus is shifting towards employing miRNA-encapsulated exosomes sourced from MSCs to target and heal cancerous cells selectively. However, the exact functions of miRNAs within MSC-derived exosomes in the context of cancer are still not fully understood. Additional exploration is necessary to clarify the role of these miRNAs in malignancy progression and to pinpoint viable therapeutic targets. This review offers a comprehensive examination of exosomes derived from mesenchymal stem cells, focusing on the encapsulation of miRNAs, methods for enhancing cellular uptake and stability, and their potential applications in cancer treatment. It also addresses the difficulties linked to this methodology and considers future avenues, including insights from current clinical oncology research.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Improve Survival and Enhance Hematopoietic Recovery in Mice Exposed to High-Dose Irradiation

Exposure to high-dose radiation often results in hematopoietic acute radiation syndromes, leading to early mortality, while current therapies for patients exposed to lethal radiation doses are limited. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have shown promise in tissue repair and regeneration but have not been well investigated for mitigating high-dose radiation damage. We previously demonstrated that human or murine MSC-EVs can reverse bone marrow injury caused by mild or moderate radiation. The current study evaluated the therapeutic potential of human MSC-EVs in mice exposed to high-dose total body irradiation (TBI). Mice were exposed to 0, 700, or 950 cGy TBI and subsequently received daily intravenous MSC-EV injections (1 × 109 particles) for 3 days postirradiation. We evaluated survival rates, peripheral blood recovery, bone marrow engraftment, and bone marrow gene expression profiles at various intervals following treatment. MSC-EV administration significantly enhanced survival, with 70% of treated mice surviving 120 days after 950 cGy TBI exposure, compared with 0% survival in untreated controls by day 30. Although early peripheral blood recovery was not observed within 14 days, MSC-EV treatment facilitated substantial recovery at 3 months postirradiation, with significant increases in red blood cell, platelet, white blood cell, and hemoglobin levels, despite white blood cell and hemoglobin levels remaining slightly below normal. Furthermore, the engraftment capacity of bone marrow stem cells was significantly improved. The changes in hematopoietic-related gene expression presented at 14 days postirradiation returned to normal levels by 120 days in MSC-EV-treated mice. These results highlight the potential of MSC-EVs as a therapeutic strategy for high-dose radiation injuries by promoting hematopoietic recovery and improving survival. Our future research will focus on elucidating the radioprotective mechanisms and investigating their integration with existing therapies.

Microbead Encapsulation Strategy for Efficient Production of Extracellular Vesicles Derived From Human Mesenchymal Stem Cells

Human mesenchymal stem cell-derived extracellular vesicles (hMSC-EVs) have shown great potential in tissue repair and regeneration. However, their scalable production and functional quality are still limited by current expansion technologies. In this study, we propose a production technology for hMSC-EVs based on three-dimensional (3D) microbead culture, which enhances the secretory behaviour of hMSC. Fixed number of MSCs were encapsulated in Matrigel at appropriate densities and printed into 3D microbeads by the custom automated microfluidic bead-jet printing technique. Compared with 2D culture group, EVs derived from 3D hMSC microbead had smaller size and increased yield by 20-fold, and the actin depolymerisation of the cell may be an important mechanism for enhancing EV secretion. Further analysis confirmed that the EVs derived from 3D hMSC microbead exhibited enhanced angiogenic and proliferative capabilities, which promoted the viability and tube-forming capacity of human umbilical vein endothelial cells (HUVEC). In conclusion, this automated microfluidic microbead encapsulation technology increased the yield and therapeutic effect of hMSC-EVs and provides a platform for scalable EV production of regenerative therapies.

Extracellular Vesicles Derived from Mesenchymal Stromal Cells Reduce Pseudomonas aeruginosa Lung Infection and Inflammation in Mice

The World Health Organization and the U.S. Centers for Disease Control and Prevention have reported that antibiotic resistant infections with Pseudomonas aeruginosa present a significant health risk world-wide. In the genetic disease Cystic Fibrosis (CF), chronic antibiotic resistant Pseudomonas lung infections and persistent inflammation remain the leading causes of morbidity and mortality. While highly effective modulator therapy (HEMT) dramatically improves lung function in CF, they fail to eradicate chronic infections or eliminate the associated hyperinflammatory state. Thus, there is an urgent need for innovative therapies that can simultaneously eliminate antibiotic resistant P. aeruginosa lung infection and the attendant hyperinflammatory lung environment. Mesenchymal stromal cell-derived extracellular vesicles (MSC EVs) represent a promising solution, offering potent anti-inflammatory, immunomodulatory, and antimicrobial properties while being safe and non-toxic. This study demonstrates using a CF mouse model of infection that MSC EVs reduce acute P. aeruginosa lung infection and inflammation. MSC EVs reduced Pseudomonas burden, immune cell infiltration, and pro-inflammatory cytokine levels. As the first investigation of MSC EVs in CF, this research underscores the dual effects of MSC EVs; mitigating inflammation and reducing bacterial burden. These findings mark an important advancement in antimicrobial therapy, addressing the unmet need for reducing antibiotic resistant infections and hyperinflammation for people with CF as well as the multitude of others with chronic, antibiotic resistant P. aeruginosa lung infections.

GRAPHICAL ABSTRACT

NEW AND NOTEWORTHY

This is the first study demonstrating the ability of Mesenchymal Stromal Cell Extracellular Vesicles (MSC EVs) to reduce Pseudomonas aeruginosa burden and inflammation in a CF mouse model of infection.

Exosome-based miRNA delivery: Transforming cancer treatment with mesenchymal stem cells

Recently, increasing interest has been in utilizing mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), especially exosomes, as nanocarriers for miRNA delivery in cancer treatment. Due to such characteristics, nanocarriers are specific: biocompatible, low immunogenicity, and capable of spontaneous tumor accumulation. MSC-EVs were loaded with therapeutic miRNAs and minimized their susceptibility to degradation by protecting the miRNA from accessibility to degrading enzymes and providing targeted delivery of the miRNAs to the tumor cells to modulate oncogenic pathways. In vitro and in vivo experiments suggest that MSC-EVs loaded with miRNAs may inhibit tumor growth, prevent metastasis, and increase the effectiveness of chemotherapy and radiotherapy. However, these improvements present difficulties such as isolation, scalability, and stability of delivered miRNA during storage. Furthermore, the issues related to off-target effects, as well as immunogenicity, can be a focus. The mechanisms of miRNA loading into MSC-EVs, as well as their targeting efficiency and therapeutic potential, can be outlined in this manuscript. For the final part of the manuscript, the current advances in MSC-EV engineering and potential strategies for clinical application have been described. The findings of MSC-EVs imply that they present MSC-EVs as a second-generation tool for precise oncology.

Effects of Hydrogels on Mesenchymal Stem/Stromal Cells Paracrine Activity and Extracellular Vesicles Production

Mesenchymal stem/stromal cells (MSCs) are a valuable source of paracrine factors, as they have a remarkable secretory capacity, and there is a sizeable knowledge base to develop industrial and clinical production protocols. Promising cell-free approaches for tissue regeneration and immunomodulation are driving research towards secretome applications, among which extracellular vesicles (EVs) are steadily gaining attention. However, the manufacturing and application of EVs is limited by insufficient yields, knowledge gaps, and low standardization. Facing these limitations, hydrogels represent a versatile three-dimensional (3D) culture platform that can incorporate extracellular matrix (ECM) components to mimic the natural stem cell environment in vitro; via these niche-mimicking properties, hydrogels can regulate MSCs' morphology, adhesion, proliferation, differentiation and secretion capacities. However, the impact of the hydrogel's architectural, biochemical and biomechanical properties on the production of EVs remains poorly understood, as the field is still in its infancy and the interdependency of culture parameters compromises the comparability of the studies. Therefore, this review summarizes and discusses the reported effects of hydrogel encapsulation and culture on the secretion of MSC-EVs. Considering the effects of cell-material interactions on the overall paracrine activity of MSCs, we identify persistent challenges from low standardization and process control, and outline future paths of research, such as the synergic use of hydrogels and bioreactors to enhance MSC-EV generation.

Pyroptosis: candidate key targets for mesenchymal stem cell-derived exosomes for the treatment of bone-related diseases

Bone-related diseases impact a large portion of the global population and, due to their high disability rates and limited treatment options, pose significant medical and economic challenges. Mesenchymal stem cells (MSCs) can differentiate into multiple cell types and offer strong regenerative potential, making them promising for treating various diseases. However, issues with the immune response and cell survival limit the effectiveness of cell transplantation. This has led to increased interest in cell-free stem cell therapy, particularly the use of exosomes, which is the most studied form of this approach. Exosomes are extracellular vesicles that contain proteins, lipids, and nucleic acids and play a key role in cell communication and material exchange. Pyroptosis, a form of cell death involved in innate immunity, is also associated with many diseases. Studies have shown that MSC-derived exosomes have therapeutic potential for treating a range of conditions by regulating inflammation and pyroptosis. This study explored the role of MSC-derived exosomes in modulating pyroptosis to improve the treatment of bone-related diseases.

The Role of Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles in Modulating Dermal Fibroblast Activity: A Pathway to Enhanced Tissue Regeneration

Extracellular vesicles (EVs) secreted by umbilical cord-derived mesenchymal stem cells (UC-MSCs) hold significant promise as therapeutic agents in regenerative medicine. This study investigates the effects of UC-MSC-derived EVs on dermal fibroblast function, and their potential in wound healing applications. EVs were characterized by nanoparticle tracking analysis and transmission electron microscopy, revealing a mean size of 118.6 nm, consistent with exosomal properties. Dermal fibroblasts were treated with varying concentrations of EVs (25-100 µg/mL), and their impacts on cellular metabolism, mitochondrial activity, reactive oxygen species (ROS) production, wound closure, inflammatory cytokine secretion, growth factor production, and extracellular matrix (ECM) gene expression were evaluated. At lower concentrations (25-50 µg/mL), EVs significantly enhanced fibroblast metabolic and mitochondrial activity. However, higher concentrations (≥75 µg/mL) increased ROS levels, suggesting potential hormetic effects. EVs also modulated inflammation by reducing pro-inflammatory cytokines (IL-6, TNF-α) while promoting pro-regenerative cytokines (IL-33, TGF-β). Treatment with 50 µg/mL of EVs optimally stimulated wound closure and growth factor secretion (VEGF, BDNF, KGF, IGF), and upregulated ECM-related gene expression (type I and III collagen, fibronectin). These findings demonstrate that UC-MSC-derived EVs exert multifaceted effects on dermal fibroblast function, including enhanced cellular energetics, stimulation of cell migration, regulation of inflammation, promotion of growth factor production, and increased ECM synthesis. This study highlights the potential of EVs as a novel therapeutic strategy for wound healing and tissue regeneration, emphasizing the importance of optimizing EV concentration for maximal therapeutic efficacy.

miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

JOURNAL/nrgr/04.03/01300535-202501000-00035/figure1/v/2024-05-14T021156Z/r/image-tiff Our previous study found that rat bone marrow-derived neural crest cells (acting as Schwann cell progenitors) have the potential to promote long-distance nerve repair. Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication. Nevertheless, the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear. To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves, we collected conditioned culture medium from hypoxia-pretreated neural crest cells, and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation. The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells. We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells. Subsequently, to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons, we used a microfluidic axonal dissociation model of sensory neurons in vitro, and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons, which was greatly dependent on loaded miR-21-5p. Finally, we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb, as well as muscle tissue morphology of the hind limbs, were obviously restored. These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p. miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome. This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves, and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

Assessing the Effects of Dasatinib on Mesenchymal Stem/Stromal Cells

Introduction

Progressive aging, or senescence, of mesenchymal stem/stromal cells (MSCs) is a major obstacle faced when trying to culture potent stem cells for use in therapy. Senescent cells are irreversibly nondividing cells that cease performing critical functional effects. Elimination of senescent cells using biochemical means, such as the use of senolytic drugs like dasatinib, may be useful in retaining the viable and proliferating populations of the cells.

Methods

An in vitro approach was used to investigate the effect of dasatinib on phenotypic, genotypic, and immunomodulatory functionality of osteogenic and adipogenic differentiated MSCs. Replicative senescence was achieved through multiple sub-culturing in vitro, then senescent and non-senescent cultures were treated with a standard dosage of dasatinib. MSCs were then differentiated into osteogenic, adipogenic or chondrogenic cultures using conditioned media to be tested for the three criteria being investigated.

Results

Significant changes were observed in these criteria, indicated by evidence gathered from proliferation and indoleamine 2,3 dioxygenase activity assays. Phenotypic results of dasatinib were shown to reduce the population of senescent MSCs while allowing non-senescent MSCs to continue differentiating and proliferating without interference from senescent cells. Genotypic results showed no change to upregulation in markers associated with osteogenic and adipogenic cells when exposed to dasatinib. Indoleamine Dioxygenase activity showed insignificant differences in cells exposed to dasatinib versus control groups, providing evidence against compromised cellular immune function.

Conclusion

This investigation provides insight into how dasatinib effects MSCs functional ability and provides a better understanding of the function of senolytic agents.

The therapeutic efficacy of adipose mesenchymal stem cell-derived microvesicles versus infliximab in a dextran sodium sulfate induced ulcerative colitis rat model

Ulcerative colitis (UC) is a chronic relapsing intestinal inflammation that is becoming of increasing incidence worldwide and has insufficient treatment. Therefore, finding effective therapies remains a priority. A dextran sodium sulfate colitis model was established to elucidate colonic layers alterations and compare adipose mesenchymal stem cell-derived microvesicles (MSC-MVs) versus infliximab (IFX) efficacy through biochemical, light, and electron microscope studies. Fifty-four rats were allocated to 4 groups: Control (Con), UC, UC+IFX, and UC+MSC-MVs groups. End body weights (BW) and serum malondialdehyde (MDA) levels were recorded. Colitis severity was estimated by disease activity index (DAI). Colonic specimens were processed to evaluate the histological structure, collagen content, surface mucous and goblet cells, CD44, TNF-α, and GFAP immune expression. Morphometric and statistical analyses were performed. The UC group revealed congested, stenosed colons, a significant decline in end BW, and a significant increase in serum MDA and DAI. Furthermore, disturbed histoarchitecture, inflammatory infiltration, depletion of surface mucous and goblet cells, increased collagen, and TNF-α expression and decreased GFAP expression were observed. Alterations were partially attenuated by IFX therapy, whereas MSC-MVs significantly improved all parameters. In conclusion, MSC-MVs were a superior therapeutic option, via attenuating oxidative stress and inflammatory infiltration, in addition to restoring intestinal epithelial integrity and mucosal barrier.

Insights into the unique roles of extracellular vesicles for gut health modulation: Mechanisms, challenges, and perspectives

Extracellular vesicles (EVs), which play significant regulatory roles in maintaining homeostasis and influencing immune responses, significantly impact gut microbiota composition and function, affecting overall gut health. Despite considerable progress, there are still knowledge gaps regarding the mechanisms by which EVs, including plant-derived EVs (PDEVs), animal-derived EVs (ADEVs), and microbiota-derived EVs (MDEVs), modulate gut health. This review delves into the roles and mechanisms of EVs from diverse sources in regulating gut health, focusing on their contributions to maintaining epithelial barrier integrity, facilitating tissue healing, eliciting immune responses, controlling pathogens, and shaping microbiota. We emphasize open challenges and future perspectives for harnessing EVs in the modulation of gut health to gain a deeper understanding of their roles and impact. Importantly, a comprehensive research framework is presented to steer future investigations into the roles and implications of EVs on gut health, facilitating a more profound comprehension of this emerging field.

Successful salvage of a severe COVID-19 patient previously with lung cancer and radiation pneumonitis by mesenchymal stem cells: a case report and literature review

During the COVID-19 pandemic, elderly patients with underlying condition, such as tumors, had poor prognoses after progressing to severe pneumonia and often had poor response to standard treatment. Mesenchymal stem cells (MSCs) may be a promising treatment for patients with severe pneumonia, but MSCs are rarely used for patients with carcinoma. Here, we reported a 67-year-old female patient with lung adenocarcinoma who underwent osimertinib and radiotherapy and suffered from radiation pneumonitis. Unfortunately, she contracted COVID-19 and that rapidly progressed to severe pneumonia. She responded poorly to frontline treatment and was in danger. Subsequently, she received a salvage treatment with four doses of MSCs, and her symptoms surprisingly improved quickly. After a lung CT scan that presented with a significantly improved infection, she was discharged eventually. Her primary disease was stable after 6 months of follow-up, and no tumor recurrence or progression was observed. MSCs may be an effective treatment for hyperactive inflammation due to their ability related to immunomodulation and tissue repair. Our case suggests a potential value of MSCs for severe pneumonia that is unresponsive to conventional therapy after a COVID-19 infection. However, unless the situation is urgent, it needs to be considered with caution for patients with tumors. The safety in tumor patients still needs to be observed.

Innovative preconditioning strategies for improving the therapeutic efficacy of extracellular vesicles derived from mesenchymal stem cells in gastrointestinal diseases

Gastrointestinal (GI) diseases have become a global health issue and an economic burden due to their wide distribution, late prognosis, and the inefficacy of recent available medications. Therefore, it is crucial to search for new strategies for their management. In the recent decades, mesenchymal stem cells (MSCs) therapy has attracted attention as a viable option for treating a myriad of GI disorders such as hepatic fibrosis (HF), ulcerative colitis (UC), acute liver injury (ALI), and non-alcoholic fatty liver disease (NAFLD) due to their regenerative and paracrine properties. Importantly, recent studies have shown that MSC-derived extracellular vesicles (MSC-EVs) are responsible for most of the therapeutic effects of MSCs. In addition, EVs have revealed several benefits over their parent MSCs, such as being less immunogenic, having a lower risk of tumour formation, being able to cross biological barriers, and being easier to store. MSC-EVs exhibited regenerative, anti-oxidant, anti-inflammatory, anti-apoptotic, and anti-fibrotic effects in different experimental models of GI diseases. However, a key issue with their clinical application is the maintenance of their stability and efficacy following in vivo transplantation. Preconditioning of MSC-EVs or their parent cells is one of the novel methods used to improve their effectiveness and stability. Herein, we discuss the application of MSC-EVs in several GI disorders taking into account their mechanism of action. We also summarise the challenges and restrictions that need to be overcome to promote their clinical application in the treatment of various GI diseases as well as the recent developments to improve their effectiveness. A representation of the innovative preconditioning techniques that have been suggested for improving the therapeutic efficacy of MSC-EVs in GI diseases. The pathological conditions in various GI disorders (ALI, UC, HF and NAFLD) create a harsh environment for EVs and their parents, increasing the risk of apoptosis and senescence of MSCs and thereby diminishing MSC-EVs yield and restricting their large-scale applications. Preconditioning with pharmacological agents or biological mediators can improve the therapeutic efficacy of MSC-EVs through their adaption to the lethal environment to which they are subjected. This can result in establishment of a more conducive environment and activation of numerous vital trajectories that act to improve the immunomodulatory, reparative and regenerative activities of the derived EVs, as a part of MSCs paracrine system. ALI, acute liver injury; GI diseases, gastrointestinal diseases; HF, hepatic fibrosis; HSP, heat shock protein; miRNA, microRNA; mRNA, messenger RNA; MSC-EVs, mesenchymal stem cell-derived extracellular vesicles; NAFLD, non-alcoholic fatty liver disease; UC, ulcerative colitis.

Human retinal secretome: A cross-link between mesenchymal and retinal cells

In recent years, mesenchymal stem cells (MSC) have been considered the most effective source for regenerative medicine, especially due to released soluble paracrine bioactive components and extracellular vesicles. These factors, collectively called the secretome, play crucial roles in immunomodulation and in improving survival and regeneration capabilities of injured tissue. Recently, there has been a growing interest in the secretome released by retinal cytotypes, especially retinal pigment epithelium and Müller glia cells. The latter trophic factors represent the key to preserving morphofunctional integrity of the retina, regulating biological pathways involved in survival, function and responding to injury. Furthermore, these factors can play a pivotal role in onset and progression of retinal diseases after damage of cell secretory function. In this review, we delineated the importance of cross-talk between MSCs and retinal cells, focusing on common/induced secreted factors, during experimental therapy for retinal diseases. The cross-link between the MSC and retinal cell secretomes suggests that the MSC secretome can modulate the retinal cell secretome and vice versa. For example, the MSC secretome can protect retinal cells from degeneration by reducing oxidative stress, autophagy and programmed cell death. Conversely, the retinal cell secretome can influence the MSC secretome by inducing changes in MSC gene expression and phenotype.

Clinical utility of mesenchymal stem/stromal cells in regenerative medicine and cellular therapy

Mesenchymal stem/stromal cells (MSCs) have been carefully examined to have tremendous potential in regenerative medicine. With their immunomodulatory and regenerative properties, MSCs have numerous applications within the clinical sector. MSCs have the properties of multilineage differentiation, paracrine signaling, and can be isolated from various tissues, which makes them a key candidate for applications in numerous organ systems. To accentuate the importance of MSC therapy for a range of clinical indications, this review highlights MSC-specific studies on the musculoskeletal, nervous, cardiovascular, and immune systems where most trials are reported. Furthermore, an updated list of the different types of MSCs used in clinical trials, as well as the key characteristics of each type of MSCs are included. Many of the studies mentioned revolve around the properties of MSC, such as exosome usage and MSC co-cultures with other cell types. It is worth noting that MSC clinical usage is not limited to these four systems, and MSCs continue to be tested to repair, regenerate, or modulate other diseased or injured organ systems. This review provides an updated compilation of MSCs in clinical trials that paves the way for improvement in the field of MSC therapy.

Non-Classical Intercellular Communications: Basic Mechanisms and Roles in Biology and Medicine

In multicellular organisms, interactions between cells and intercellular communications form the very basis of the organism’s survival, the functioning of its systems, the maintenance of homeostasis and adequate response to the environment. The accumulated experimental data point to the particular importance of intercellular communications in determining the fate of cells, as well as their differentiation and plasticity. For a long time, it was believed that the properties and behavior of cells were primarily governed by the interactions of secreted or membrane-bound ligands with corresponding receptors, as well as direct intercellular adhesion contacts. In this review, we describe various types of other, non-classical intercellular interactions and communications that have recently come into the limelight—in particular, the broad repertoire of extracellular vesicles and membrane protrusions. These communications are mediated by large macromolecular structural and functional ensembles, and we explore here the mechanisms underlying their formation and present current data that reveal their roles in multiple biological processes. The effects mediated by these new types of intercellular communications in normal and pathological states, as well as therapeutic applications, are also discussed. The in-depth study of novel intercellular interaction mechanisms is required for the establishment of effective approaches for the control and modification of cell properties both for basic research and the development of radically new therapeutic strategies.

Extracellular vesicles and their cells of origin: Open issues in autoimmune diseases

The conventional therapeutic approaches to treat autoimmune diseases through suppressing the immune system, such as steroidal and non-steroidal anti-inflammatory drugs, are not adequately practical. Moreover, these regimens are associated with considerable complications. Designing tolerogenic therapeutic strategies based on stem cells, immune cells, and their extracellular vesicles (EVs) seems to open a promising path to managing autoimmune diseases' vast burden. Mesenchymal stem/stromal cells (MSCs), dendritic cells, and regulatory T cells (Tregs) are the main cell types applied to restore a tolerogenic immune status; MSCs play a more beneficial role due to their amenable properties and extensive cross-talks with different immune cells. With existing concerns about the employment of cells, new cell-free therapeutic paradigms, such as EV-based therapies, are gaining attention in this field. Additionally, EVs' unique properties have made them to be known as smart immunomodulators and are considered as a potential substitute for cell therapy. This review provides an overview of the advantages and disadvantages of cell-based and EV-based methods for treating autoimmune diseases. The study also presents an outlook on the future of EVs to be implemented in clinics for autoimmune patients.

Extracellular vesicles secreted by human gingival mesenchymal stem cells promote bone regeneration in rat femoral bone defects

Extracellular vesicles (EVs), important components of paracrine secretion, are involved in various pathological and physiological processes of the body. In this study, we researched the benefits of EVs secreted by human gingival mesenchymal stem cells (hGMSC-derived EVs) in promoting bone regeneration, thereby providing new ideas for EVs-based bone regeneration therapy. Here, we successfully demonstrated that hGMSC-derived EVs could enhance the osteogenic ability of rat bone marrow mesenchymal stem cells and the angiogenic capability of human umbilical vein endothelial cells. Then, femoral defect rat models were created and treated with phosphate-buffered saline, nanohydroxyapatite/collagen (nHAC), a grouping of nHAC/hGMSCs, and a grouping of nHAC/EVs. The results of our study indicated that the combination of hGMSC-derived EVs and nHAC materials could significantly promote new bone formation and neovascularization with a similar effect to that of the nHAC/hGMSCs group. Our outcomes provide new messages on the role of hGMSC-derived EVs in tissue engineering, which exhibit great potential in bone regeneration treatment.