Mesenchymal Stem Cell-Derived Exosomes and Other Extracellular Vesicles as New Remedies in the Therapy of Inflammatory Diseases. Cells. 2019;8. [PMID: 31835680 PMCID: PMC6952783 DOI: 10.3390/cells8121605]

Wharton's jelly-derived stromal cells and their cell therapy applications in allogeneic haematopoietic stem cell transplantation

For decades, mesenchymal stromal cells (MSCs) have been of great interest in the fields of regenerative medicine, tissue engineering and immunomodulation. Their tremendous potential makes it desirable to cryopreserve and bank MSCs to increase their accessibility and availability. Postnatally derived MSCs seem to be of particular interest because they are harvested after delivery without ethical controversy, they have the capacity to expand at a higher rate than adult‐derived MSCs, in which expansion decreases with ageing, and they have demonstrated immunological and haematological supportive properties similar to those of adult‐derived MSCs. In this review, we focus on MSCs obtained from Wharton's jelly (the mucous connective tissue of the umbilical cord between the amniotic epithelium and the umbilical vessels). Wharton's jelly MSCs (WJ‐MSCs) are a good candidate for cellular therapy in haematology, with accumulating data supporting their potential to sustain haematopoietic stem cell engraftment and to modulate alloreactivity such as Graft Versus Host Disease (GVHD). We first present an overview of their in‐vitro properties and the results of preclinical murine models confirming the suitability of WJ‐MSCs for cellular therapy in haematology. Next, we focus on clinical trials and discuss tolerance, efficacy and infusion protocols reported in haematology for GVHD and engraftment.

Potential of Mesenchymal Stem Cell-Derived Exosomes as a Novel Treatment for Female Infertility Caused by Bacterial Infections

Neisseria gonorrhoeae and Chlamydia trachomatis are the most common causes of bacterial sexually transmitted diseases (STDs) with complications in women, including pelvic inflammatory disease (PID), ectopic pregnancy, and infertility. The main concern with these infections is that 70% of infected women are asymptomatic and these infections ascend to the upper female reproductive tract (FRT). Primary infection in epithelial cells creates a cascade of events that leads to secretion of pro-inflammatory cytokines that stimulate innate immunity. Production of various cytokines is damaging to mucosal barriers, and tissue destruction leads to ciliated epithelial destruction that is associated with tubal scarring and ultimately provides the conditions for infertility. Mesenchymal stem cells (MSCs) are known as tissue specific stem cells with limited self-renewal capacity and the ability to repair damaged tissues in a variety of pathological conditions due to their multipotential differentiation capacity. Moreover, MSCs secrete exosomes that contain bioactive factors such as proteins, lipids, chemokines, enzymes, cytokines, and immunomodulatory factors which have therapeutic properties to enhance recovery activity and modulate immune responses. Experimental studies have shown that local and systemic treatment of MSC-derived exosomes (MSC-Exos) suppresses the destructive immune response due to the delivery of immunomodulatory proteins. Interestingly, some recent data have indicated that MSC-Exos display strong antimicrobial effects, by the secretion of antimicrobial peptides and proteins (AMPs), and increase bacterial clearance by enhancing the phagocytic activity of host immune cells. Considering MSC-Exos can secrete different bioactive factors that can modulate the immune system and prevent infection, exosome therapy is considered as a new therapeutic method in the treatment of inflammatory and microbial diseases. Here we intend to review the possible application of MSC-Exos in female reproductive system bacterial diseases.

Evaluating the safety and efficacy of mesenchymal stem cell-derived exosomes for treatment of refractory perianal fistula in IBD patients: clinical trial phase I

Background

Exosome administration is a novel medical approach that promises excellent immunomodulatory properties without the conventional side effects of current antitumor necrosis factor drugs and stem cells. This study aimed to assess the safety and efficacy of using mesenchymal stem cell (MSC) exosomes to treat refractory fistulas in patients with inflammatory bowel disease.

Methods

MSCs were derived from the umbilical cords and their exosomes were isolated. Five patients with refractory perianal Crohn’s disease fistulas with a median age of 35 years (range 31–47 years) were enrolled in the study. Exosome injections were administered in the operating room to patients with refractory fistula (fistulas that are irresponsive to anti-tumor necrosis factor-α administration within 6 months). Six months later, a physical examination, face-to-face interviews, and magnetic resonance imaging were employed to evaluate the therapy responses of patients.

Results

The outcomes within 6 months after initiation of therapy showed that four patients had responded to therapy. Three patients who received exosome injections exhibited complete healing, while one reported no improvement and active discharge from the fistula site. In addition, five patients (100%) reported neither systemic nor local adverse effects.

Conclusions

Injection of exosomes extracted from MSCs demonstrates safety and a satisfactory therapeutic effect, as evidenced in this and other studies, and may play a significant role in the future treatment of gastrointestinal fistulas.

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Alleviate Psoriasis-like Skin Inflammation

Immunomodulatory effects of mesenchymal stem cells (MSCs) in inflammatory diseases, including psoriasis, are well documented. However, the role of MSC-derived exosomes (MSCs-Exo) in psoriasis-like skin inflammation remains largely unknown. This study aimed to investigate whether MSCs-Exo play a regulatory role in psoriasis-like skin inflammation. We found that subcutaneous injection of human umbilical cord MSCs-Exo (hucMSCs-Exo) significantly suppressed the proliferation of epidermis and reduced Psoriasis Area and Severity Index (PASI) scores in imiquimod (IMQ)-induced mice. hucMSCs-Exo also reduced the expression of interleukin (IL)-17, IL-23, and chemokine C-C-motif ligand 20 (CCL20) and inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) in the skin of IMQ-induced mice and in human keratinocyte (HaCaT) cells. In addition, co-cultured with hucMSCs-Exo in vitro, the maturation and activation of dendritic cells (DCs) were suppressed, and the expression level of IL-23 was decreased. These results indicate that hucMSCs-Exo can effectively ameliorate psoriasis-like skin inflammation in mice by regulating the expression of IL-23 and IL-17, and inhibiting the maturation and activation of DCs. Our data offer a promising therapeutic approach for psoriasis by leveraging the immunomodulatory effects of hucMSCs-Exo.

Mesenchymal Stem-Cell Derived Exosome Therapy as a Potential Future Approach for Treatment of Male Infertility Caused by Chlamydia Infection

Some microbial sexually transmitted infections (STIs) have adverse effects on the reproductive tract, sperm function, and male fertility. Given that STIs are often asymptomatic and cause major complications such as urogenital inflammation, fibrosis, and scarring, optimal treatments should be performed to prevent the noxious effect of STIs on male fertility. Among STIs, Chlamydia trachomatis is the most common asymptomatic preventable bacterial STI. C. trachomatis can affect both sperm and the male reproductive tract. Recently, mesenchymal stem cells (MSCs) derived exosomes have been considered as a new therapeutic medicine due to their immunomodulatory, anti-inflammatory, anti-oxidant, and regenerative effects without consequences through the stem cell transplantation based therapies. Inflammation of the genital tract and sperm dysfunction are the consequences of the microbial infections, especially Chlamydia trachomatis. Exosome therapy as a noninvasive approach has shown promising results on the ability to regenerate the damaged sperm and treating asthenozoospermia. Recent experimental methods may be helpful in the novel treatments of male infertility. Thus, it is demonstrated that exosomes play an important role in preventing the consequences of infection, and thereby preventing inflammation, reducing cell damage, inhibiting fibrogenesis, and reducing scar formation. This review aimed to overview the studies about the potential therapeutic roles of MSCs-derived exosomes on sperm abnormalities and male infertility caused by STIs.

Mesenchymal Stem Cell Therapy in Diabetic Cardiomyopathy

The incidence and prevalence of diabetes mellitus (DM) are increasing worldwide, and the resulting cardiac complications are the leading cause of death. Among these complications is diabetes-induced cardiomyopathy (DCM), which is the consequence of a pro-inflammatory condition, oxidative stress and fibrosis caused by hyperglycemia. Cardiac remodeling will lead to an imbalance in cell survival and death, which can promote cardiac dysfunction. Since the conventional treatment of DM generally does not address the prevention of cardiac remodeling, it is important to develop new alternatives for the treatment of cardiovascular complications induced by DM. Thus, therapy with mesenchymal stem cells has been shown to be a promising approach for the prevention of DCM because of their anti-apoptotic, anti-fibrotic and anti-inflammatory effects, which could improve cardiac function in patients with DM.

Mesenchymal Stem Cell-Derived Exosomes Modulate Chondrocyte Glutamine Metabolism to Alleviate Osteoarthritis Progression

Osteoarthritis (OA) had a high incidence in people over 65 years old, and there is currently no drug that could completely cure it. This study is aimed at studying the role of exosomes in regulating glutamine metabolism in the treatment of OA. First, we identified the exosomes extracted from the mouse OA model's bone marrow mesenchymal stem cells (MSC). In vitro, compared with the control group, the cell apoptosis in the OA group increased, while the cell proliferation of the OA group was suppressed. After exosomal treatment, cell apoptosis and cell proliferation were reversed. Inflammatory factors (TNFα, IL-6), glutamine metabolic activity-related proteins (c-MYC, GLS1), glutamine, and GSH/GSSG were increased in the OA group. The overexpression of c-MYC reduced the therapeutic effect of exosomes. At the same time, we found that chondrocyte functional factors (collagen II, Aggrecan) were improved under the treatment of exosomes. However, oe-c-MYC reversed the therapeutic effect of exosomes. In vivo, we found that the running capacity of the mice in the OA group was reduced, and the cartilage tissue was severely damaged. In addition, TNFα, IL-6, and chondrocyte apoptosis increased, while the metabolism of collagen II, Aggrecan, and glutamate decreased in the OA group. After exosomal treatment, the mice's exercise capacity, tissue damage, inflammation, and chondrocyte function were improved, and glutamate metabolism was increased. This study showed that exosomes regulated the level of chondrocyte glutamine metabolism by regulating c-MYC, thereby alleviating OA.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for the Treatment of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in premature infants. However, there is a lack of effective treatment. Mesenchymal stromal cells derived extracellular vesicles (MSC-EVs), as nano- and micron-sized heterogeneous vesicles secreted by MSCs, are the main medium for information exchange between MSCs and injured tissue and organ, playing an important role in repairing tissue and organ injury. EVs include exosomes, microvesicles and so on. They are rich with various proteins, nucleic acids, and lipids. Now, EVs are considered as a new way of cell-to-cell communication. EVs mainly induce regeneration and therapeutic effects in different tissues and organs through the biomolecules they carry. The surface membrane protein or loaded protein and nucleic acid molecules carried by EVs, can activate the signal transduction of target cells and regulate the biological behavior of target cells after binding and cell internalization. MSC-EVs can promote the development of pulmonary vessels and alveoli and reduce pulmonary hypertension (PH) and inflammation and play an important role in the repair of lung injury in BPD. The regeneration potential of MSC-EVs is mainly due to the regulation of cell proliferation, survival, migration, differentiation, angiogenesis, immunoregulation, anti-inflammatory, mitochondrial activity and oxidative stress. As a new type of cell-free therapy, MSC-EVs have non-immunogenic, and are small in size and go deep into most tissues. What's more, it has good biological stability and can be modified and loaded with drugs of interest. Obviously, MSC-EVs have a good application prospect in the treatment of lung injury and BPD. However, there are still many challenges to make MSC-EVs really enter clinical application.

Exosomal Circular RNA hsa_circ_0046060 of Umbilical Cord Mesenchymal Stromal Cell Ameliorates Glucose Metabolism and Insulin Resistance in Gestational Diabetes Mellitus via the miR-338-3p/G6PC2 Axis

BACKGROUND

Impaired glucose metabolism and insulin sensitivity have been linked to the pathogenesis of gestational diabetes mellitus (GDM). Exosomes secreted by the umbilical cord mesenchymal stromal cells (UMSCs) and circular RNAs (circRNAs) derived from exosomes have been shown to be associated with the progression of GDM-related complications.

METHODS

UMSCs were isolated from umbilical cords and identified through flow cytometry. Exosomes were isolated from UMSCs and were then characterized. The expression levels of RNA of hsa_circ_0046060, mmu_circ_0002819, and miR-338-3p were determined by quantitative real-time polymerase chain reaction (RT-qPCR). The intracellular glucose intake and glycogen content were measured using a High Sensitivity Glucose Assay Kit and Glycogen Assay Kit, respectively. Bioinformatics analysis and luciferase reporter assay were used to validate interactions among hsa_circ_0046060, miR-338-3p, and G6PC2. The expression of insulin receptor substrate-1 (IRS-1) and its phosphorylated form, (p-IRS-1), as well as G6PC2, was determined through western blotting.

RESULTS

UMSCs and exosomes were successfully isolated and identified. The upregulation of hsa_circ_0046060 decreased the intracellular glucose content in L-02 cells (43.45 vs. 16.87 pM/mg, P=0.0002), whereas shRNA-mediated downregulation reversed this effect (16.87 vs. 33.16 pM/mg, P=0.0011). Mmu_circ_0002819 in mice aggravated dysregulated glucose metabolism (49.88 vs. 21.69 pM/mg, P=0.0031) and insulin sensitivity (0.20 vs. 0.11 mg/mL, P=0.03) in GDM mice, which was abrogated by the knockdown of mmu_circ_0002819. The results of luciferase reporter assay revealed that miR-338-3p and G6PC2 were the potential targets of has_circ_0046060. Western blotting results showed that the reduced activation of IRS-1 induced by GDM (1.25 vs. 0.54, P=0.0001) could be rescued by the administration of si-circ-G-UMSC-EXOs (0.54 vs. 1.17, P=0.0001).

CONCLUSION

Taken together, the inhibition of hsa_circ_0046060 expression in exosomes from GDM-derived UMSCs can alleviate GDM by reversing abnormal glucose metabolism and insulin resistance in vivo and in vitro.

The Potential Use of Mesenchymal Stem Cells and Their Derived Exosomes for Orthopedic Diseases Treatment

Musculoskeletal disorders (MSDs) are conditions that can affect muscles, bones, and joints. These disorders are very painful and severely limit patients' mobility and are more common in the elderly. MSCs are multipotent stem cells isolated from embryonic (such as the umbilical cord) and mature sources (such as adipose tissue and bone marrow). These cells can differentiate into various cells such as osteoblasts, adipocytes, chondrocytes, NP-like cells, Etc. Due to MSC characteristics such as immunomodulatory properties, ability to migrate to the site of injury, recruitment of cells involved in repair, production of growth factors, and large amount production of extracellular vesicles, these cells have been used in many regenerative-related medicine studies. Also, MSCs produce different types of EVs, such as exosomes, to the extracellular environment. Exosomes reflect MSCs' characteristics and do not have cell therapy-associated problems because they are cell-free. These vesicles carry proteins, nucleic acids, and lipids to the host cell and change their function. This review focuses on MSCs and MSCs exosomes' role in repairing dense connective tissues such as tendons, cartilage, invertebrate disc, bone fracture, and osteoporosis treatment.

Small Extracellular Vesicles Loaded with Immunosuppressive miRNAs Leads to an Inhibition of Dendritic Cell Maturation

In particular conditions, inhibition of an immune response is required to prevent tissue damage. Among these conditions are diseases caused by an over-reactive immune response, such as autoimmune or allergic disorders, or imminent organ rejection after transplantation. To avoid tissue damage, drug-mediated systemic immune suppression is an option, but it comes with high costs in the form of susceptibility to viral and bacterial infections. Thus, the induction of antigen-specific tolerance is preferable. Extracellular vesicles (EVs) are capable of delivering antigen together with immunosuppressive signals and may be used to specifically induce antigen-specific tolerance. However, naturally occurring EVs are heterogeneous and not all of them show immunosuppressive character. In our trials to engineer cell culture derived EVs to increase their tolerogenic potential, we equipped them with immunosuppressive miRNA mimics. Small EVs (sEVs) were isolated and purified from the human monocytic THP-1 cell line or from healthy donor peripheral blood mononuclear cells, and electroporated with miR-494 and miR-146a mimics. The acquired immunosuppressive potential of the modified sEVs was demonstrated by their ability to alter the major histocompatibility complex molecules and co-stimulatory receptors present on dendritic cells (DCs). To avoid allogeneic responses, the same cells that produced the sEVs served also as recipient cells. In contrast to the treatment with unmodified sEVs, the tolerogenic sEVs impeded lipopolysaccharide-induced maturation and kept DCs in a more immature developmental stage. Our experiments show that simple manipulations of sEVs using immunosuppressive cargo can lead to the inhibition of DC maturation.

SKP-SC-EVs Mitigate Denervated Muscle Atrophy by Inhibiting Oxidative Stress and Inflammation and Improving Microcirculation

Denervated muscle atrophy is a common clinical disease that has no effective treatments. Our previous studies have found that oxidative stress and inflammation play an important role in the process of denervated muscle atrophy. Extracellular vesicles derived from skin precursor-derived Schwann cells (SKP-SC-EVs) contain a large amount of antioxidants and anti-inflammatory factors. This study explored whether SKP-SC-EVs alleviate denervated muscle atrophy by inhibiting oxidative stress and inflammation. In vitro studies have found that SKP-SC-EVs can be internalized and caught by myoblasts to promote the proliferation and differentiation of myoblasts. Nutrient deprivation can cause myotube atrophy, accompanied by oxidative stress and inflammation. However, SKP-SC-EVs can inhibit oxidative stress and inflammation caused by nutritional deprivation and subsequently relieve myotube atrophy. Moreover, there is a remarkable dose-effect relationship. In vivo studies have found that SKP-SC-EVs can significantly inhibit a denervation-induced decrease in the wet weight ratio and myofiber cross-sectional area of target muscles. Furthermore, SKP-SC-EVs can dramatically inhibit highly expressed Muscle RING Finger 1 and Muscle Atrophy F-box in target muscles under denervation and reduce the degradation of the myotube heavy chain. SKP-SC-EVs may reduce mitochondrial vacuolar degeneration and autophagy in denervated muscles by inhibiting autophagy-related proteins (i.e., PINK1, BNIP3, LC3B, and ATG7). Moreover, SKP-SC-EVs may improve microvessels and blood perfusion in denervated skeletal muscles by enhancing the proliferation of vascular endothelial cells. SKP-SC-EVs can also significantly inhibit the production of reactive oxygen species (ROS) in target muscles after denervation, which indicates that SKP-SC-EVs elicit their role by upregulating Nrf2 and downregulating ROS production-related factors (Nox2 and Nox4). In addition, SKP-SC-EVs can significantly reduce the levels of interleukin 1β, interleukin-6, and tumor necrosis factor α in target muscles. To conclude, SKP-SC-EVs may alleviate the decrease of target muscle blood perfusion and passivate the activities of ubiquitin-proteasome and autophagy-lysosome systems by inhibiting oxidative stress and inflammatory response, then reduce skeletal muscle atrophy caused by denervation. This study not only enriches the molecular regulation mechanism of denervated muscle atrophy, but also provides a scientific basis for SKP-SC-EVs as a protective drug to prevent and treat muscle atrophy.

Exosomes isolated during dopaminergic neuron differentiation suppressed neuronal inflammation in a rodent model of Parkinson's disease

Our previous investigation showed Wnt signal pathway was significantly activated during DA neuron differentiation of epiblast-derived stem cells. In this study, we next attempt to examine the therapeutic potential of the purified exosomes derived bone marrow mesenchymal stem cells (BMSCs) by administrating exosomes into the rat striatum of parkinson's disease (PD) animal model. Results revealed that the protein levels of interleukin (IL)-6, IL-1β, tumor necrosis factor-alpha (TNF-α), and reactive oxygen species (ROS) in the substantia nigra of PD rats were down regulated after injection of BMSC induced-Exosomes into the striatum of PD model compared to BMSC quiescent-Exosomes. In addition, the expression of ionized calcium binding adaptor molecule 1 (Iba1) mRNA was significantly decreased, while the expression of tyrosine hydroxylase (TH) mRNA was increased after injection of BMSC induced-Exosomes. Injection of BMSC induced-Exosomes into the striatum rescued the rotation behavior and climbing speed in the PD rats. More importantly, Wnt5a was found to be enriched in BMSC induced Exosomes, which could be effectively transferred to the substantia nigra of PD rats. In conclusion, these findings demonstrated that exosomes isolated during dopaminergic neuron differentiation could rescue the pathogenic features of Parkinson's disease by reshaping the inflammatory microenvironment in the substantia nigra and repairing the injury to DA nerves.

COVID-19 immunopathology with emphasis on Th17 response and cell-based immunomodulation therapy: Potential targets and challenges

The role of the immune system against coronavirus disease 2019 (COVID-19) is unknown in many aspects, and the protective or pathologic mechanisms of the immune response are poorly understood. Pro-inflammatory cytokine release and a consequent cytokine storm can lead to acute respiratory distress syndrome (ARDS) and result in multi-organ failure. There are many T cell subsets during anti-viral immunity. The Th17-associated response, as a pro-inflammatory pathway, and its consequent outcomes in many autoimmune disorders play a fundamental role in progression of systemic hyper-inflammation during COVID-19. Therapeutic strategies based on immunomodulation therapy could be helpful for targeting hyper-inflammatory immune responses in COVID-19, especially Th17-related inflammation and hyper-cytokinemia. Cell-based immunotherapeutic approaches including mesenchymal stem cells (MSCs), tolerogenic dendritic cells (tolDCs) and regulatory T cells (Tregs) seem to be promising strategies as orchestrators of the immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this review, we highlight Th17-related immunopathology of SARS-CoV-2 infection and discuss cell-based immunomodulatory strategies and their mechanisms for regulation of the hyper-inflammation during COVID-19.

Protective effects of umbilical cord mesenchymal stem cell exosomes in a diabetic rat model through live retinal imaging

AIM

To assess the protective effect of human umbilical cord mesenchymal stem cell exosomes (hucMSC-Exs) in a diabetic rat model by using a variety of retinal bioassays.

METHODS

hucMSCs were subjected to differential ultracentrifugation for the collection of exosomes, and transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) using a NanoSight analysis system and Western blotting (WB) were used to analyze the expression of surface marker proteins such as CD63, CD9 and Calnexin. Streptozotocin (STZ) was injected into the intraperitoneal cavity to establish a diabetic model. Rats were divided into a normal group, diabetic group and hucMSC-Ex group. Fundus fluorescein angiography (FFA), optical coherence tomography (OCT) and other live imaging methods were used to observe the fundus of the rats. Finally, the eyeballs of rats from each group were collected for hematoxylin-eosin (HE) staining to further analyze the retinal structure.

RESULTS

Through TEM, NTA and WB, we successfully isolated hucMSC-Exs. Subsequent FFA and OCT confirmed that hucMSC-Exs effectively prevented early retinal vascular damage and thickening of the retina. Finally, HE staining of rat retinal sections revealed that exosomes effectively alleviated retinal structure disruption caused by diabetes.

CONCLUSION

hucMSC-Exs have a protective effect on the retina in diabetic rat through FFA, OCT and HE staining.

Exosome-loaded extracellular matrix-mimic hydrogel with anti-inflammatory property Facilitates/promotes growth plate injury repair

Growth plate cartilage has limited self-repair ability, leading to poor bone bridge formation post-injury and ultimately limb growth defects in children. The current corrective surgeries are highly invasive, and outcomes can be unpredictable. Following growth plate injury, the direct loss of extracellular matrix (ECM) coupled with further ECM depletion due to the inhibitory effects of inflammation on the cartilage matrix protein greatly hinder chondrocyte regeneration. We designed an exosome (Exo) derived from bone marrow mesenchymal stem cells (BMSCs) loaded ECM-mimic hydrogel to promote cartilage repair by directly supplementing ECM and anti-inflammatory properties. Aldehyde-functionalized chondroitin sulfate (OCS) was introduced into gelatin methacryloyl (GM) to form GMOCS hydrogel. Our results uncovered that GMOCS hydrogel could significantly promote the synthesis of ECM due to the doping of OCS. In addition, the GMOCS-Exos hydrogel could further promote the anabolism of chondrocytes by inhibiting inflammation and ultimately promote growth plate injury repair through ECM remodeling.

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Chondrocytes are difficult to regenerate after growth plate injury due to extensive degradation of ECM (extracellular matrix).

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GMOCS-Exos can promote the synthesis of ECM by directly supplementing ECM and anti-inflammatory properties.

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GMOCS-Exos can boost cartilage regeneration after growth plate injury and reduce bone bridge formation.

The Roles of Exosomes in Immunoregulation and Autoimmune Thyroid Diseases

Exosomes are extracellular microvesicles (30-150 nm) released from cells that contain proteins, lipids, RNA and DNA. They can deliver bioactive molecules and serve as carriers facilitating cell-cell communication, such as antigen presentation, inflammatory activation, autoimmune diseases (AIDs) and tumor metastasis. Recently, much attention has been attracted to the biology and functions of exosomes in immune regulation and AIDs, including autoimmune thyroid diseases (AITDs). Some studies have shown that exosomes are involved in the occurrence and development of AITDs, but they are still in the preliminary stage of exploration. This review mainly introduces the association of exosomes with immune regulation and emphasizes the potential role of exosomes in AITDs, aiming to provide new research strategies and directions for the pathogenesis and early diagnosis of AITDs.

The Potential Therapeutic Role of Mesenchymal Stem Cells-Derived Exosomes in Osteoradionecrosis

As one of the most serious complications of radiotherapy, osteoradionecrosis (ORN) seriously affects the quality of life of patients and even leads to death. Vascular injury and immune disorders are the main causes of bone lesions. The traditional conservative treatment of ORN has a low cure rate and high recurrent. Exosomes are a type of extracellular bilayer lipid vesicles secreted by almost all cell types. It contains cytokines, proteins, mRNA, miRNA, and other bioactive cargos, which contribute to several distinct processes. The favorable biological functions of mesenchymal stem cells-derived exosomes (MSC exosomes) include angiogenesis, immunomodulation, bone regeneration, and ferroptosis regulation. Exploring the characteristic of ORN and MSC exosomes can promote bone regeneration therapies. In this review, we summarized the current knowledge of ORN and MSC exosomes and highlighted the potential application of MSC exosomes in ORN treatment.

Biomimetic immunomodulation strategies for effective tissue repair and restoration

Inflammation plays a central role in wound healing following injury or disease and is mediated by a precise cascade of cellular and molecular events. Unresolved inflammatory processes lead to chronic inflammation and fibrosis, which can result in prolonged wound healing lasting months or years that hampers tissue function. Therapeutic interventions mediated by immunomodulatory drugs, cells, or biomaterials, are therefore most effective during the inflammatory phase of wound healing when a pro-regenerative environment is essential. In this review, we discuss the advantages of exploiting knowledge of the native tissue microenvironment to develop therapeutics capable of modulating the immune response and promoting functional tissue repair. In particular, we provide examples of the most recent biomimetic platforms proposed to accomplish this goal, with an emphasis on those able to induce macrophage polarization towards a pro-regenerative phenotype.

Mesenchymal stem cell treatment improves outcome of COVID-19 patients via multiple immunomodulatory mechanisms

The infusion of coronavirus disease 2019 (COVID-19) patients with mesenchymal stem cells (MSCs) potentially improves clinical symptoms, but the underlying mechanism remains unclear. We conducted a randomized, single-blind, placebo-controlled (29 patients/group) phase II clinical trial to validate previous findings and explore the potential mechanisms. Patients treated with umbilical cord-derived MSCs exhibited a shorter hospital stay (P = 0.0198) and less time required for symptoms remission (P = 0.0194) than those who received placebo. Based on chest images, both severe and critical patients treated with MSCs showed improvement by day 7 (P = 0.0099) and day 21 (P = 0.0084). MSC-treated patients had fewer adverse events. MSC infusion reduced the levels of C-reactive protein, proinflammatory cytokines, and neutrophil extracellular traps (NETs) and promoted the maintenance of SARS-CoV-2-specific antibodies. To explore how MSCs modulate the immune system, we employed single-cell RNA sequencing analysis on peripheral blood. Our analysis identified a novel subpopulation of VNN2⁺ hematopoietic stem/progenitor-like (HSPC-like) cells expressing CSF3R and PTPRE that were mobilized following MSC infusion. Genes encoding chemotaxis factors - CX3CR1 and L-selectin - were upregulated in various immune cells. MSC treatment also regulated B cell subsets and increased the expression of costimulatory CD28 in T cells in vivo and in vitro. In addition, an in vivo mouse study confirmed that MSCs suppressed NET release and reduced venous thrombosis by upregulating kindlin-3 signaling. Together, our results underscore the role of MSCs in improving COVID-19 patient outcomes via maintenance of immune homeostasis.

Mesenchymal Stem Cell: A Friend or Foe in Anti-Tumor Immunity

Mesenchymal stem cells (MSCs) are self-renewable, multipotent stem cells that regulate the phenotype and function of all immune cells that participate in anti-tumor immunity. MSCs modulate the antigen-presenting properties of dendritic cells, affect chemokine and cytokine production in macrophages and CD4+ T helper cells, alter the cytotoxicity of CD8+ T lymphocytes and natural killer cells and regulate the generation and expansion of myeloid-derived suppressor cells and T regulatory cells. As plastic cells, MSCs adopt their phenotype and function according to the cytokine profile of neighboring tumor-infiltrated immune cells. Depending on the tumor microenvironment to which they are exposed, MSCs may obtain pro- and anti-tumorigenic phenotypes and may enhance or suppress tumor growth. Due to their tumor-homing properties, MSCs and their exosomes may be used as vehicles for delivering anti-tumorigenic agents in tumor cells, attenuating their viability and invasive characteristics. Since many factors affect the phenotype and function of MSCs in the tumor microenvironment, a better understanding of signaling pathways that regulate the cross-talk between MSCs, immune cells and tumor cells will pave the way for the clinical use of MSCs in cancer immunotherapy. In this review article, we summarize current knowledge on the molecular and cellular mechanisms that are responsible for the MSC-dependent modulation of the anti-tumor immune response and we discuss different insights regarding therapeutic potential of MSCs in the therapy of malignant diseases.

Mesenchymal Stromal Cells for the Treatment of Graft Versus Host Disease

Graft versus host disease (GvHD) is a life-threating complication of allogeneic hematopoietic stem cell transplantation, which is initially treated with high dose corticosteroids. Approximately 50% of acute GvHD cases are resistant to steroid treatment, and two-year mortality rates in those steroid-resistant patients exceed 80%. Chronic GvHD necessitates prolonged corticosteroid use, which is typically associated with limited efficacy and troublesome adverse effects. No agent has yet been established as an optimal second line therapy for either acute or chronic GvHD, but mesenchymal stromal cells (MSCs) have shown substantial promise. MSCs promote an immunosuppressive and immunoregulatory environment via multifactorial mechanisms, including: secretion of proteins/peptides/hormones; transfer of mitochondria; and transfer of exosomes or microvesicles containing RNA and other molecules. A large number of clinical studies have investigated MSCs from various sources as a treatment for acute and/or chronic GvHD. MSCs are generally safe and well tolerated, and most clinical studies have generated encouraging efficacy results, but response rates have varied. Confounding factors include variability in MSC donor types, production methodology and dose regimens, as well as variations in study design. It is well-established that extensive culture expansion of primary donor-derived MSCs leads to marked changes in functionality, and that there is a high level of inter-donor variability in MSC properties. However, recent manufacturing innovations may be capable of overcoming these problems. Further adequately powered prospective studies are required to confirm efficacy and establish the place of MSC therapy in the treatment of this condition.

Advances in mesenchymal stem cell conditioned medium-mediated periodontal tissue regeneration

Periodontitis is a chronic inflammatory disease that leads to the destruction of both soft and hard periodontal tissues. Complete periodontal regeneration in clinics using the currently available treatment approaches is still a challenge. Mesenchymal stem cells (MSCs) have shown promising potential to regenerate periodontal tissue in various preclinical and clinical studies. The poor survival rate of MSCs during in vivo transplantation and host immunogenic reaction towards MSCs are the main drawbacks of direct use of MSCs in periodontal tissue regeneration. Autologous MSCs have limited sources and possess patient morbidity during harvesting. Direct use of allogenic MSCs could induce host immune reaction. Therefore, the MSC-based indirect treatment approach could be beneficial for periodontal regeneration in clinics. MSC culture conditioned medium (CM) contains secretomes that had shown immunomodulatory and tissue regenerative potential in pre-clinical and clinical studies. MSC-CM contains a cocktail of growth factors, cytokines, chemokines, enzymes, and exosomes, extracellular vesicles, etc. MSC-CM-based indirect treatment has the potential to eliminate the drawbacks of direct use of MSCs for periodontal tissue regeneration. MSC-CM holds the tremendous potential of bench-to-bed translation in periodontal regeneration applications. This review focuses on the accumulating evidence indicating the therapeutic potential of the MSC-CM in periodontal regeneration-related pre-clinical and clinical studies. Recent advances on MSC-CM-based periodontal regeneration, existing challenges, and prospects are well summarized as guidance to improve the effectiveness of MSC-CM on periodontal regeneration in clinics.

Extracellular Vesicles: A New Paradigm for Cellular Communication in Perioperative Medicine, Critical Care, and Pain Management

Extracellular vesicles (EVs) play critical roles in many health and disease states, including ischemia, inflammation, and pain, which are major concerns in the perioperative period and in critically ill patients. EVs are functionally active, nanometer-sized, membrane-bound vesicles actively secreted by all cells. Cell signaling is essential to physiological and pathological processes, and EVs have recently emerged as key players in intercellular communication. Recent studies in EV biology have improved our mechanistic knowledge of the pathophysiological processes in perioperative and critical care patients. Studies also show promise in using EVs in novel diagnostic and therapeutic clinical applications. This review considers the current advances and gaps in knowledge of EVs in the areas of ischemia, inflammation, pain, and in organ systems that are most relevant to anesthesiology, perioperative medicine, critical care, and pain management. We expect the reader will better understand the relationship between EVs and perioperative and critical care pathophysiological states and their potential use as novel diagnostic and therapeutic modalities.

The Exosomal lncRNA KLF3-AS1 From Ischemic Cardiomyocytes Mediates IGF-1 Secretion by MSCs to Rescue Myocardial Ischemia-Reperfusion Injury

The purpose of the study was to explore the mechanism by which myocardial ischemia-reperfusion (I/R) injury-induced exosomes modulate mesenchymal stem cells (MSCs) to regulate myocardial injury. In this study, we established an I/R injury model in vivo and a hypoxia-reoxygenation (H/R) model in vitro. Then, exosomes isolated from H/R-exposed H9c2 cells were characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot analysis. CCK-8 assays and flow cytometry were performed to assess cell injury. ELISA was applied to determine the level of insulin-like growth factor 1 (IGF-1). Echocardiography was used to assess cardiac function in vivo. HE staining and TUNEL assays were conducted to analyze myocardial injury in vivo. In the present study, H/R-exposed H9c2 cells induced IGF-1 secretion from MSCs to inhibit cell myocardial injury. Moreover, exosomes derived from H/R-exposed H9c2 cells were introduced to MSCs to increase IGF-1 levels. The lncRNA KLF3-AS1 was dramatically upregulated in exosomes derived from H/R-treated H9c2 cells. Functional experiments showed that the exosomal lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and increased H9c2 cell viability. In addition, miR-23c contains potential binding sites for both KLF3-AS1 and STAT5B, and miR-23c directly bound to the 3'-UTRs of KLF3-AS1 and STAT5B. Furthermore, the lncRNA KLF3-AS1 promoted IGF-1 secretion from MSCs and rescued myocardial cell injury in vivo and in vitro by upregulating STAT5B expression. The lncRNA KLF3-AS1 may serve as a new direction for the treatment of myocardial I/R injury.

Therapeutic effects of mesenchymal stem cells-derived extracellular vesicles' miRNAs on retinal regeneration: a review

Extracellular vesicles (EVs), which consist of microvesicles and exosomes, are secreted from all cells to transform vital information in the form of lipids, proteins, mRNAs and small RNAs such as microRNAs (miRNAs). Many studies demonstrated that EVs' miRNAs have effects on target cells. Numerous people suffer from the blindness caused by retinal degenerations. The death of retinal neurons is irreversible and creates permanent damage to the retina. In the absence of acceptable cures for retinal degenerative diseases, stem cells and their paracrine agents including EVs have become a promising therapeutic approach. Several studies showed that the therapeutic effects of stem cells are due to the miRNAs of their EVs. Considering the effects of microRNAs in retinal cells development and function and studies which provide the possible roles of mesenchymal stem cells-derived EVs miRNA content on retinal diseases, we focused on the similarities between these two groups of miRNAs that could be helpful for promoting new therapeutic techniques for retinal degenerative diseases.

Mesenchymal Stem Cell Exosomes in the Treatment of Myocardial Infarction: a Systematic Review of Preclinical In Vivo Studies

Several prior studies have highlighted the promise of mesenchymal stem cells (MSCs) as tools for treating myocardial infarction (MI) patients. While MSCs were initially thought to mediate post-MI repair through differentiation and replacement of injured cells, they are now thought to function by releasing exosomes carrying important cargos which can prevent apoptosis and facilitate revascularization in the context of MI. Herein, we comprehensively survey prior preclinical studies examining MSC-derived exosomes (MSC-Exos) utility for the repair of MI-related tissue injury. In total, 24 relevant studies were identified in the PubMed, Web of Science, Embase, and Cochrane Library databases as per the PRISMA guidelines. In most studies, exosome-treated rodents exhibited improved cardiac function and angiogenesis together with decreased apoptotic cell death. MSC-Exos thus offer beneficial therapeutic efficacy when treating MI injury. However, further work will be necessary to standardize experimental preclinical models and to validate these results. This systematic review provides a comprehensive overview of previous preclinical studies on the utility of exosomes derived from mesenchymal stem cells (MSCs) in the repair of myocardial infarction (MI) injury.

Immunomodulatory Effect of MSCs and MSCs-Derived Extracellular Vesicles in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a common autoimmune connective tissue disease with unclear etiology and pathogenesis. Mesenchymal stem cell (MSC) and MSC derived extracellular vesicles (EVs) play important roles in regulating innate and adaptive immunity, which are involved in many physiological and pathological processes and contribute to the immune homeostasis in SLE. The effects of MSCs and EVs on SLE have been drawing more and more attention during the past few years. This article reviews the immunomodulatory effects and underlying mechanisms of MSC/MSC-EVs in SLE, which provides novel insight into understanding SLE pathogenesis and guiding the biological therapy.

Human Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells Acquire Rejuvenation and Reduced Heterogeneity

Despite the uniform selection criteria for the isolation of human mesenchymal stem cells (MSCs), considerable heterogeneity exists which reflects the distinct tissue origins and differences between individuals with respect to their genetic background and age. This heterogeneity is manifested by the variabilities seen in the transcriptomes, proteomes, secretomes, and epigenomes of tissue-specific MSCs. Here, we review literature on different aspects of MSC heterogeneity including the role of epigenetics and the impact of MSC heterogeneity on therapies. We then combine this with a meta-analysis of transcriptome data from distinct MSC subpopulations derived from bone marrow, adipose tissue, cruciate, tonsil, kidney, umbilical cord, fetus, and induced pluripotent stem cells derived MSCs (iMSCs). Beyond that, we investigate transcriptome differences between tissue-specific MSCs and pluripotent stem cells. Our meta-analysis of numerous MSC-related data sets revealed markers and associated biological processes characterizing the heterogeneity and the common features of MSCs from various tissues. We found that this heterogeneity is mainly related to the origin of the MSCs and infer that microenvironment and epigenetics are key drivers. The epigenomes of MSCs alter with age and this has a profound impact on their differentiation capabilities. Epigenetic modifications of MSCs are propagated during cell divisions and manifest in differentiated cells, thus contributing to diseased or healthy phenotypes of the respective tissue. An approach used to reduce heterogeneity caused by age- and tissue-related epigenetic and microenvironmental patterns is the iMSC concept: iMSCs are MSCs generated from induced pluripotent stem cells (iPSCs). During iMSC generation epigenetic and chromatin remodeling result in a gene expression pattern associated with rejuvenation thus allowing to overcome age-related shortcomings (e.g., limited differentiation and proliferation capacity). The importance of the iMSC concept is underlined by multiple clinical trials. In conclusion, we propose the use of rejuvenated iMSCs to bypass tissue- and age-related heterogeneity which are associated with native MSCs.

Mesenchymal stromal cell extracellular vesicles as therapy for acute and chronic respiratory diseases: A meta-analysis

Preclinical studies suggest mesenchymal stromal cell extracellular vesicles (MSC-EVs) reduce inflammation and improve organ function in lung diseases; however, an objective analysis of all available data is needed prior to translation. Using rigorous meta-research methods, we determined the effectiveness of MSC-EVs for preclinical respiratory diseases and identified experimental conditions that may further refine this therapy. A systematic search of MEDLINE/Embase identified 1167 records. After screening, 52 articles were included for data extraction and evaluated for risk of bias and quality of reporting in study design. A random effects meta-analysis was conducted for acute lung injury (ALI; N = 23), bronchopulmonary dysplasia (BPD; N = 8) and pulmonary arterial hypertension (PAH; N = 7). Subgroup analyses identified EV methods/characteristics that may be associated with improved efficacy. Data is presented as standardized mean differences (SMD) or risk ratios (RR) with 95% confidence intervals (CI). For ALI, MSC-EVs markedly reduced lung injury (SMD -4.33, CI -5.73 to -2.92), vascular permeability (SMD -2.43, CI -3.05 to -1.82), and mortality (RR 0.39, CI 0.22 to 0.68). Small EVs were more consistently effective than large EVs whereas no differences were observed between tissue sources, immunocompatibility or isolation techniques. For BPD, alveolarization was improved by MSC-EVs (SMD -1.45, CI -2.08 to -0.82) with small EVs more consistently beneficial then small/large EVs. In PAH, right ventricular systolic pressure (SMD -4.16, CI -5.68 to -2.64) and hypertrophy (SMD -2.80, CI -3.68 to -1.91) were significantly attenuated by EVs. In BPD and PAH, EVs isolated by ultracentrifugation demonstrated therapeutic benefit whereas tangential flow filtration (N = 2) displayed minimal efficacy. Lastly, risk of bias and quality of reporting for experimental design were consistently unclear across all studies. Our findings demonstrate clear potential of MSC-EVs to be developed as therapy for acute and chronic lung diseases. However, greater transparency in research design and direct comparisons of isolation technique and EV subtypes are needed to generate robust evidence to guide clinical translation. Protocol Registration: PROSPERO CRD42020145334.

Mesenchymal Stem Cell-Derived Exosomes Ameliorate Dermal Fibrosis in a Murine Model of Bleomycin-Induced Scleroderma

Mesenchymal stem cells (MSCs) have become a promising therapeutic strategy for scleroderma. Exosomes derived from MSCs (MSC-exosomes) possess functional properties similar to those of their source cells. In this study, we aimed to explore the potential role of MSC-exosomes in the treatment of scleroderma. MSC-exosomes were isolated from human umbilical cords through ultracentrifugation and characterized. An experimental fibrosis model was established in BALB/c mice by a subcutaneous injection of bleomycin, followed by treatment with MSC-exosomes or MSC infusions once a week for a total of four doses. Using hematoxylin and eosin and Masson's trichrome staining and immunohistochemistry, hydroxyproline content, and quantitative real-time polymerase chain reaction analyses, we investigated the effects of MSC-exosomes on dermal fibrosis and explored the underlying mechanism. MSC-exosome treatment restored the dermal architecture, reduced dermal thickness, and partially increased subcutaneous adipose tissue thickness. In addition, MSC-exosomes inhibited the expression of collagen (COL)-I, COL-III, and α-smooth muscle actin. The transforming growth factor (TGF)-β/Smad signaling pathway was also suppressed in MSC-exosome-treated mice. Taken together, our results suggest that MSC-exosomes can attenuate myofibroblast activation and collagen deposition in dermal fibrosis by downregulating the TGF-β/Smad signaling pathway. Therefore, the use of MSC-exosomes may be a potential therapeutic approach for the treatment of scleroderma.

Exosomes from 3T3-J2 promote expansion of tracheal basal cells to facilitate rapid epithelization of 3D-printed double-layer tissue engineered trachea

Functional epithelization plays a pivotal role in maintaining long-term lumen patency of tissue-engineered trachea (TET). Due to the slow migration of autologous epithelium, spontaneous epithelization process of transplanted TET is always tardive. Seeding tracheal basal cells (TBCs) on TET before transplantation might be favorable for accelerating epithelization, but rapid expansion of TBCs in vitro is still relatively intractable. In this study, we proposed a promising expansion strategy which enables the TBCs to proliferate rapidly in vitro. TBCs were isolated from the autologous tracheal mucosae of rabbit, and co-cultured with exosomes derived from 3T3-J2 cells. After co-culture with exosomal component, TBCs could vigorously proliferate in vitro and retained their multi-potency. It was in stark contrast to that the single-cultured TBCs could only be expand to passage 2 in about 30 days, moreover, the most majority of single-cultured cells entered late apoptotic stage. On the other hand, a bionic tubular double-layer scaffold with good mechanical property and bio-compatibility was designed and fabricated by 3D printing technology. Then TET with bi-lineage cell-type was constructed in vitro by implanting autologous chondrocytes on the outer-layer of scaffold, and TBCs on the inner-layer, respectively. And then TET was pre-vascularized in vivo, and pedicled transplanted to restore long-segmental defect in recipient rabbits. It was found that the chondrocytes and TBCs seeded on double-layer scaffolds developed well as expected. And almost complete coverage with ciliated epitheliums was observed on the lumen surface of TET 2-week after operation, in comparison with that the epithelization of TET without pre-seeding of TBCs accomplished nearly 2-month after operation. In conclusion, the promising expansion strategy of TBCs together with 3D-printed double-layer scaffolds facilitate the rapid epithelization process of transplanted TET, which might be of vital significance for clinical and translational medicine.

Mesenchymal Stem Cell-Derived Exosomes and Their Potential Agents in Hematological Diseases

Mesenchymal stem cells (MSCs) are the most exploited stem cells with multilineage differentiation potential and immunomodulatory properties. Numerous lines of findings have reported their successful applications in a multitude of inflammatory conditions and immune disorders. However, it is currently discovered that these effects are mainly mediated in a paracrine manner by MSC-exosomes. Moreover, MSC-exosomes have been implicated in a wide variety of biological responses including immunomodulation, oxidative stress, tumor progression, and tissue regeneration. Meanwhile, they are reported to actively participate in various hematological diseases by the means of transferring different types of exosomal components to the target cells. Therefore, in this review, we briefly discuss the sources and biological features of MSCs and then illustrate the biogenesis and biological processes of MSC-exosomes. Of note, this paper especially highlights the latest research progress of MSC-exosomes in hematological diseases.

Extracellular Vesicles (Exosomes) as Immunosuppressive Mediating Variables in Tumor and Chronic Inflammatory Microenvironments

Exosomes are extracellular vesicles released by most of the eukaryotic cells. Exosomes’ components include proteins, lipids, microRNA, circular RNA, long noncoding RNA, DNA, etc. Exosomes may carry both pro and anti-inflammatory cargos; however, exosomes are predominantly filled with immunosuppressive cargos such as enzymes and microRNAs in chronic inflammation. Exosomes have surfaced as essential participants in physiological and pathological intercellular communication. Exosomes may prevent or promote the formation of an aggressive tumor and chronic inflammatory microenvironments, thus influencing tumor and chronic inflammatory progression as well as clinical prognosis. Exosomes, which transmit many signals that may either enhance or constrain immunosuppression of lymphoid and myeloid cell populations in tumors, are increasingly becoming recognized as significant mediators of immune regulation in cancer. In this review, we outline the function of exosomes as mediators of immunosuppression in tumor and chronic inflammatory microenvironments, with the aim to improve cancer therapy.

Beneficial effects of secretome derived from mesenchymal stem cells with stigmasterol to negate IL-1β-induced inflammation in-vitro using rat chondrocytes-OA management

Osteoarthritis (OA) is the most prevalent joint disease predominantly characterized by inflammation which drives cartilage destruction. Mesenchymal stem cells-condition medium (MSC-CM) or the secretome is enriched with bioactive factors and possesses anti-inflammatory and regenerative effects. The present study aimed at evaluating the effects of combining MSC-conditioned medium with stigmasterol compared with the individual treatments in alleviating interleukin-1 beta (IL-1β)-induced inflammation in rat chondrocytes. Stigmasterol is a phytosterol exhibiting anti-inflammatory effects. IL-1β (10 ng/ml) was used to induce inflammation and mimic OA in-vitro in primary rat articular chondrocytes. The IL-1β-stimulated chondrocytes were treated with MSC-CM, stigmasterol, and a combination of MSC-CM and stigmasterol for 24 h. Cell viability was measured using MTT assay. Protein expression of inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), collagen II (COL2A1) and matrix metalloproteinase (MMP)-13 were evaluated by immunofluorescence. Gene expression levels of MMP-3, MMP-13 and A Disintegrin-like and Metalloproteinases with Thrombospondin Motifs (ADAMTS)-5 were measured using qRT-PCR. NF-κB signaling pathway was studied using western blotting. A significant reduction in the expression of iNOS, IL-6, MMP-3, MMP-13 and ADAMTS-5, and a significant increase in COL2A1 expression was observed in the rat chondrocytes across all the treatment groups. However, the combination treatment of MSC-CM and stigmasterol remarkably reversed the IL-1β-induced pro-inflammatory/pro-catabolic responses to near normal levels comparable to the control group. The combination treatment (MSC-CM + stigmasterol) elicited a superior anti-inflammatory/anti-catabolic effect by inhibiting the IL-1β-induced NF-κB activation evidenced by the negligible phosphorylation of p65 and IκBα subunits, thereby emphasizing the benefit of the combination therapy over the individual treatments.

Mesenchymal stem cell-derived exosomes regulate the polarization and inflammatory response of macrophages via miR-21-5p to promote repair after myocardial reperfusion injury

Background

Myocardial ischemia-reperfusion injury is a type of myocardial ischemia that has a significant impact on patients' health. We aimed to explore the protective effect of mesenchymal stem cell-derived exosomes (MSC-EXOs) on myocardial ischemia-reperfusion injury and their specific mechanism.

Methods

The effects of MSC-EXOs on myocardial ischemia-reperfusion injury were recorded. An enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of IL-6 and IL-10 in mouse myocardial tissue or culture supernatant. Co-cultured MSC-EXOs and RAW264.7 cells were used to study the effect of MSC-EXOs on the polarization of macrophages at the cellular level. The ratio of M1 and M2 macrophages were detected by flow cytometry, and RT-qPCR detected the mRNA expression levels of corresponding markers. After transfection with miR-21-5p inhibitors or mimics, flow cytometry and RT-qPCR experiments were performed to explore the specific role of MSC-EXOs in macrophage polarization.

Results

After injection of MSC-EXOs, the mRNA expression of M1 macrophage markers (iNOS, IL-1β, IL-6, and TNFα) in the myocardial tissue of model mice was significantly reduced (P<0.05), and the mRNA expression of M2 macrophage markers was significantly increased (P<0.05). The injection also reduced the inflammation response in the model mice (P<0.05). In the in vitro experiment, lipopolysaccharide (LPS) induced the inflammatory microenvironment. After MSC-EXOs were fixed in the cytoplasm of RAW264.7 cells, the level of IL-6 in the culture supernatant decreased (P<0.05), and the level of IL-10 increased (P<0.05). The addition of MSC-EXOs to LPS-induced RAW264.7 cells promoted their polarization toward the M2 phenotype and upregulated their marker expression levels (P<0.05). Following inhibition of miR-21-5p in MSC cells, the EXOs were collected, and it was found that MSC-EXOs that inhibited the expression of miR-21-5p promoted LPS-induced polarization of RAW264.7 cells to the M1 phenotype and upregulated inflammation in the culture supernatant. Furthermore, transfection with miR-21-5p mimics promoted the polarization of RAW264.7 cells to the M2 phenotype and reduced the level of inflammatory factors in the culture supernatant.

Conclusions

MSC-EXOs promote the polarization of macrophages to the M2 phenotype via miR-21-5p, thereby reducing inflammation and promoting heart repair.

Pro-regenerative Dialogue Between Macrophages and Mesenchymal Stem/Stromal Cells in Osteoarthritis

Osteoarthritis (OA), the most common degenerative and inflammatory joint disorder, is multifaceted. Indeed, OA characteristics include cartilage degradation, osteophytes formation, subchondral bone changes, and synovium inflammation. The difficulty in discovering new efficient treatments for OA patients up to now comes from the adoption of monotherapy approaches targeting either joint tissue repair/catabolism or inflammation to address the diverse components of OA. When satisfactory, these approaches only provide short-term beneficial effects, since they only result in the repair and not the full structural and functional reconstitution of the damaged tissues. In the present review, we will briefly discuss the current therapeutic approaches used to repair the damaged OA cartilage. We will highlight the results obtained with cell-based products in clinical trials and demonstrate how the current strategies result in articular cartilage repair showing restricted early-stage clinical improvements. In order to identify novel therapeutic targets and provide to OA patients long-term clinical benefits, herein, we will review the basis of the regenerative process. We will focus on macrophages and their ambivalent roles in OA development and tissue regeneration, and review the therapeutic strategies to target the macrophage response and favor regeneration in OA.

Cardioprotective Roles of Endothelial Progenitor Cell-Derived Exosomes

With the globally increasing prevalence, cardiovascular diseases (CVDs) have become the leading cause of mortality. The transplantation of endothelial progenitor cells (EPCs) holds a great promise due to their potential for vasculogenesis, angiogenesis, and protective cytokine release, whose mechanisms are essential for CVD therapies. In reality, many investigations have attributed the therapeutic effects of EPC transplantation to the secretion of paracrine factors rather than the differentiation function. Of note, previous studies have suggested that EPCs could also release exosomes (diameter range of 30–150 nm), which carry various lipids and proteins and are abundant in microRNAs. The EPC-derived exosomes (EPC-EXs) were reported to act on the heart and blood vessels and were implicated in anti-inflammation, anti-oxidation, anti-apoptosis, the inhibition of endothelial-to-mesenchymal transition (EndMT), and cardiac fibrosis, as well as anti-vascular remodeling and angiogenesis, which were considered as protective effects against CVDs. In this review, we summarize the current knowledge on using EPC-EXs as therapeutic agents and provide a detailed description of their identified mechanisms of action to promote the prognosis of CVDs.

Potential Therapeutic Effect of Micrornas in Extracellular Vesicles from Mesenchymal Stem Cells against SARS-CoV-2

Extracellular vesicles (EVs) are cell-released, nanometer-scaled, membrane-bound materials and contain diverse contents including proteins, small peptides, and nucleic acids. Once released, EVs can alter the microenvironment and regulate a myriad of cellular physiology components, including cell–cell communication, proliferation, differentiation, and immune responses against viral infection. Among the cargoes in the vesicles, small non-coding micro-RNAs (miRNAs) have received attention in that they can regulate the expression of a variety of human genes as well as external viral genes via binding to the complementary mRNAs. In this study, we tested the potential of EVs as therapeutic agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. First, we found that the mesenchymal stem-cell-derived EVs (MSC-EVs) enabled the rescue of the cytopathic effect of SARS-CoV-2 virus and the suppression of proinflammatory responses in the infected cells by inhibiting the viral replication. We found that these anti-viral responses were mediated by 17 miRNAs matching the rarely mutated, conserved 3′-untranslated regions (UTR) of the viral genome. The top five miRNAs highly expressed in the MSC-EVs, miR-92a-3p, miR-26a-5p, miR-23a-3p, miR-103a-3p, and miR-181a-5p, were tested. They were bound to the complemented sequence which led to the recovery of the cytopathic effects. These findings suggest that the MSC-EVs are a potential candidate for multiple variants of anti-SARS-CoV-2.

Mesenchymal Stem Cell Exosomes Derived from Feline Adipose Tissue Enhance the Effects of Anti-Inflammation Compared to Fibroblasts-Derived Exosomes

Adipose tissue-derived mesenchymal stem cells (AD-MSCs) release extracellular vesicles such as exosomes, apoptotic bodies, and microparticles. In particular, exosomes are formed inside cells via multivesicular bodies (MVBs), thus their protein, DNA, and RNA content are similar to those of the parent cells. Exosome research is rapidly expanding, with an increase in the number of related publications observed in recent years; therefore, the function and application of MSC-derived exosomes could emerge as cell-free therapeutics. Exosomes have been isolated from feline AD-MSCs and feline fibroblast cell culture media using ultracentrifugation. Feline exosomes have been characterized by FACS, nanoparticle tracking analysis, and transmission electron microscopy imaging. Moreover, cytokine levels were detected by sandwich enzyme-linked immunosorbent assay in exosomes and LPS-induced THP-1 macrophages. The size of the isolated exosomes was that of a typical exosome, i.e., approximately 150 nm, and they expressed tetraspanins CD9 and CD81. The anti-inflammatory factor IL-10 was increased in feline AD-MSC-derived exosomes. However, pro-inflammatory factors such as IL-1β, IL-8, IL-2, RANTES, and IFN-gamma were significantly decreased in feline AD-MSC-derived exosomes. This was the first demonstration that feline AD-MSC-derived exosomes enhance the inflammatory suppressive effects and have potential for the treatment of immune diseases or as an inflammation-inhibition therapy.

Exosomes derived from vascular endothelial cells antagonize glucocorticoid-induced osteoporosis by inhibiting ferritinophagy with resultant limited ferroptosis of osteoblasts

High dose and long-term steroid treatment can alter antioxidative ability and decrease the viability and function of osteoblasts, leading to osteoporosis and osteonecrosis. Ferroptosis, a new type of cell death characterized by excessive lipid peroxidation due to the downregulation of GPX4 and system Xc- , is involved in glucocorticoid-induced osteoporosis. Endothelial cell-secreted exosomes (EC-Exos) are important mediators of cell-to-cell communication and are involved in many physiological and pathological processes. However, the effect of EC-Exos on osteoblasts exposed to glucocorticoids has not been reported. Here, we explored the role of EC-Exos in glucocorticoid-induced osteoporosis. In vivo and in vitro experiments indicated that EC-Exos reversed the glucocorticoid-induced osteogenic inhibition of osteoblasts by inhibiting ferritinophagy-dependent ferroptosis.

Mesenchymal stem cells-derived exosomes modulate vascular endothelial injury via miR-144-5p/PTEN in intracranial aneurysm

Phosphatase and tensin homolog (PTEN) is known to be involved in the pathogenesis of intracranial aneurysm (IA). This study investigated the molecular mechanism of exosomal miR-144-5p (ex-miR-144-5p) and PTEN in IA. Ex-miR-144-5p expression was assessed in serum from individuals with ruptured intracranial aneurysm (RA) or unruptured intracranial aneurysm (UA), and healthy controls (HC). Vascular endothelial cells (VECs) were co-cultured with exosomes isolated from mesenchymal stem cells (MSCs) with transfection of miR-144-5p mimic or miR-144-5p inhibitor. IA rats were induced by combing systemic hypertension and intrathecal elastase injection. VECs were transfected with miR-144-5p mimic or inhibitor to verify the impacts of miR-144-5p on cell viability and proliferation. The connection between miR-144-5p and PTEN was verified by luciferase activity assay. Our data proved that ex-miR-144-5p was decreased in both UA and RA patients. MiR-144-5p overexpression in MSCs-derived exosome promoted VEC viability, inhibited VEC proliferation of VEs, and decreased the protein levels of matrix metalloproteinase-9 (MMP-9), proliferating cell nuclear antigen (PCNA) and osteopontin (OPN). IA rats injected with ex-miR-144-5p mimic showed significant luminal dilation, declined smooth muscle layers, and thinned vascular wall. Besides, inhibited cell apoptosis and decreased protein expressions were also observed. However, ex-miR-144-5p inhibitor had the opposite effects both in vivo and in vitro. We validated that miR-144-5p directly targeted PTEN. MiR-144-5p mimic increased cell viability and proliferation and reduced protein expressions, which could be blunted by PTEN overexpression. This study suggests that miR-144-5p elevates PTEN expression, thereby boosting apoptosis and attenuating viability of VECs in IA.

Exosome: Function and Application in Inflammatory Bone Diseases

In the skeletal system, inflammation is closely associated with many skeletal disorders, including periprosthetic osteolysis (bone loss around orthopedic implants), osteoporosis, and rheumatoid arthritis. These diseases, referred to as inflammatory bone diseases, are caused by various oxidative stress factors in the body, resulting in long-term chronic inflammatory processes and eventually causing disturbances in bone metabolism, increased osteoclast activity, and decreased osteoblast activity, thereby leading to osteolysis. Inflammatory bone diseases caused by nonbacterial factors include inflammation- and bone resorption-related processes. A growing number of studies show that exosomes play an essential role in developing and progressing inflammatory bone diseases. Mechanistically, exosomes are involved in the onset and progression of inflammatory bone disease and promote inflammatory osteolysis, but specific types of exosomes are also involved in inhibiting this process. Exosomal regulation of the NF-κB signaling pathway affects macrophage polarization and regulates inflammatory responses. The inflammatory response further causes alterations in cytokine and exosome secretion. These signals regulate osteoclast differentiation through the receptor activator of the nuclear factor-kappaB ligand pathway and affect osteoblast activity through the Wnt pathway and the transcription factor Runx2, thereby influencing bone metabolism. Overall, enhanced bone resorption dominates the overall mechanism, and over time, this imbalance leads to chronic osteolysis. Understanding the role of exosomes may provide new perspectives on their influence on bone metabolism in inflammatory bone diseases. At the same time, exosomes have a promising future in diagnosing and treating inflammatory bone disease due to their unique properties.

Altered Proteomic Profile of Adipose Tissue-Derived Mesenchymal Stem Cell Exosomes from Cats with Severe Chronic Gingivostomatitis

Simple Summary

Feline chronic gingivostomatitis (FCGS) is a common pathology in cats, related to an aberrant immune response. The cause of FCGS remains elusive, despite extensive investigations. A multitude of conditions and infectious agents have been related, without proof of causation, as follows: virus, bacteria, environmental stress, hypersensitivity, etc. In recent years, therapies based on feline adipose-derived mesenchymal stem cells (fAd-MSC) have become an interesting alternative for the treatment of different complex pathologies in cats. Mesenchymal stem cells secrete a wide variety of therapeutic elements, such as bioactive molecules and extracellular vesicles, such as exosomes. It is essential to characterize these elements, to better understand their mechanisms of action. In this study, we show, for the first time, that the proteomic profile of fAd-MSC-derived exosomes, from calicivirus-positive patients with severe FCGS, is altered. Using bioinformatic tools, we have demonstrated the existence of different proteins in the exosomes from diseased patients, responsible for an altered biological effect. In addition, the exosomes do not only experience changes in their cargo, but are also produced in larger quantities. This study might contribute to the better prediction of the clinical outcomes of mesenchymal stem cell treatments in veterinary patients with immune-mediated diseases, such as FCGS.

Abstract

Feline chronic gingivostomatitis (FCGS) is a pathology with a complicated therapeutic approach and with a prevalence between 0.7 and 12%. Although the etiology of the disease is diverse, feline calicivirus infection is known to be a predisposing factor. To date, the available treatment helps in controlling the disease, but cannot always provide a cure, which leads to a high percentage of refractory animals. Mesenchymal stem cells (MSCs) play a pivotal role in the homeostasis and reparation of different tissues and have the ability to modulate the immune system responses. This ability is, in part, due to the capacity of exosomes to play a part in intercellular cell communication. However, the precise role of MSC-derived exosomes and their alterations in immunocompromised pathologies remains unknown, especially in veterinary patients. The goal of this work was to analyze the proteomic profile of feline adipose tissue-derived MSCs (fAd-MSCs) from calicivirus-positive FCGS patients, and to detect possible modifications of the exosomal cargo, to gain better knowledge of the disease’s etiopathogenesis. Using high-resolution mass spectrometry and functional enrichment analysis with Gene Ontology, exosomes isolated from the fAd-MSCs of five healthy cats and five calicivirus-positive FCGS patients, were pooled and compared. The results showed that the fAd-MSCs from cats suffering from FCGS not only had a higher exosome production, but also their exosomes showed significant alterations in their proteomic profile. Eight proteins were exclusively found in the exosomes from the FCGS group, and five proteins could only be found in the exosomes from the healthy cats. When comparing the exosomal cargo between the two groups, significant upregulation of 17 and downregulation of 13 proteins were detected in the FCGS group compared to the control group. These findings shed light on new perspectives on the roles of MSCs and their relation to this disease, which may help in identifying new therapeutic targets and selecting specific biomarkers.

T cell activator-carrying extracellular vesicles induce antigen-specific regulatory T cells

The mechanism of antigen-specific regulatory T cell (T_reg ) induction is not yet fully understood. Curcumin has an immune regulatory function. This study aims to induce antigen-specific T_regs by employing extracellular vesicles (EVs) that carry two types of T cell activators. Two types of T cell activators, ovalbumin (OVA)/major histocompatibility complex-II (MHC-II) and tetramethylcurcumin (FLLL31) (a curcumin analog) were carried by dendritic cell-derived extracellular vesicles, designated OFexo. A murine model of allergic rhinitis (AR) was developed with OVA as the specific antigen. AR mice were treated with a nasal instillation containing OFexo. We observed that OFexo recognized antigen-specific T cell receptors (TCR) on CD4⁺ T cells and enhanced Il10 gene transcription in CD4⁺ T cells. Administration of the OFexo-containing nasal instillation induced antigen-specific type 1 T_regs (Tr1 cells) in the mouse airway tissues. OFexo-induced Tr1 cells showed immune suppressive functions on CD4⁺ T cell proliferation. Administration of OFexo efficiently alleviated experimental AR in mice. In conclusion, OFexo can induce antigen-specific Tr1 cells that can efficiently alleviate experimental AR. The results suggest that OFexo has the translational potential to be employed for the treatment of AR or other allergic disorders.

Adipose-derived mesenchymal stem cell-secreted exosome alleviates dextran sulfate sodium-induced acute colitis by Treg cell induction and inflammatory cytokine reduction

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is an inflammatory condition that results in gastrointestinal tract damage. Various factors, including environmental and genetic agents, disrupt the function of the intestinal immune system that can lead to IBD. Mesenchymal stem cells (MSCs) display an immunoregulatory function and demonstrate regenerative potential by paracrine action. In this study, we evaluated the immunomodulatory effects of MSCs' derived exosomes in the acute form of dextran sulfate sodium (DSS)-induced colitis. Exosomes were isolated from adipose-derived MSCs. Acute colitis was induced by DSS. The exosome was used by intraperitoneal injection into mice with acute colitis. Stool consistency, body weight changes, bleeding severity, colon length, and weight were examined. At the experimental endpoint (Day 7), the changes in the colon tissue were evaluated. The level of cytokines of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), IL-4, IL-12, transforming growth factor-β (TGF-β) and, IL-10, and Treg cells percentage were assayed. Results showed that exosome administration diminished colon shortening, bodyweight loss, bleeding, and colon injury. The levels of IFN-γ, TNF-α, IL-12, and IL-17 were decreased, and the level of TGF-β, IL-4, and IL-10 were increased in lymph node and spleen of mice treated with exosome.  Percentages of CD4+ CD25+ Foxp3+ Treg cells were grown in the lymph node and spleen of mice treated with exosomes. Overall, current data suggest that MSC-derived exosome could regulate the Treg population and improves inflammation in DSS-induced acute colitis.

MicroRNA 21 Elicits a Pro-inflammatory Response in Macrophages, with Exosomes Functioning as Delivery Vehicles

MicroRNAs can regulate inflammatory responses by modulating macrophage polarization. Although microRNA miR-21 is linked to crucial processes involved in inflammatory responses, its precise role in macrophage polarization is controversial. In this study, we investigated the functional relevance of endogenous miRNA-21 and the role of exosomes. RAW 264.7 macrophages were transfected with miR-21 plasmid, and the inflammatory response was evaluated by flow cytometry, phagocytosis, and real-time PCR analysis of inflammatory cytokines. To understand the signaling pathways' role, the cells were treated with inhibitors specific for PI3K or NFĸB. Exosomes from transfected cells were used to study the paracrine action of miR-21 on naive macrophages. Overexpression of miR-21 resulted in significant upregulation of pro-inflammatory cytokines, pushing the cells towards a pro-inflammatory phenotype, with partial involvement of PI3K and NFĸB signal pathways. The cells also secreted miR-21 rich exosomes, which, on delivery to naive macrophages, caused them to exhibit pro-inflammatory activity. The presence of miR-21 inhibitor quenched the inflammatory response. This study validates the pro-inflammatory property of miR-21 with a tendency to foster an inflammatory milieu. Our findings also reinforce the dual importance of exosomal miR-21 as a biomarker and therapeutic target in inflammatory conditions.

Recent advances in Extracellular Vesicles and their involvements in vasculitis

Systemic vasculitis is a heterogeneous group of multisystem autoimmune disorders characterized by inflammation of blood vessels. Although many progresses in diagnosis and immunotherapies have been achieved over the past decades, there are still many unanswered questions about vasculitis from pathological understanding to more advanced therapies. Extracellular vesicles (EVs) are double-layer phospholipid membrane vesicles harboring various cargoes. EVs can be classified into exosomes, microvesicles (MVs), and apoptotic bodies depending on their size and origin of cellular compartment. EVs can be released by almost all cell types and may be involved in physical and pathological processes including inflammation and autoimmune responses. In systemic vasculitis, EVs may have pathogenic involvement in inflammation, autoimmune responses, thrombosis, endothelium injury, angiogenesis and intimal hyperplasia. EV-associated redox reaction may also be involved in vasculitis pathogenesis by inducing inflammation, endothelial injury and thrombosis. Additionally, EVs may serve as specific biomarkers for diagnosis or monitoring of disease activity and therapeutic efficacy, i.e. AAV-associated renal involvement. In this review, we have discussed the recent advances of EVs, especially their roles in pathogenesis and clinical involvements in vasculitis.