Objective: Mesenchyme stem cells (MSCs) have potent regulatory effects on immune and inflammatory responses. The MSC-mediated immunosuppression mainly acts through the secretion of soluble molecules such as NO. NO plays a major role in immune regulation and has been shown to affect TCR signaling, cytokine receptor expression, and the phenotype of T cells. Murine MSC (muMSCs) TLR activation is essential for inducing the immune response and enhancing adaptive immunity against pathogens. We have investigated the effect of peptidoglycan-lipopolysaccharides (LPS), a ligand of TLR4, priming MSCs on the production NO.Materials and Methods: MSCs were isolated from bone-marrow of male mice and culturedin vitro. MSCs were nontreatment (control) or treatment with a TLR2, 4-agonist (peptidoglycan-LPS, 10 ng/ml) for different times (1 hour and 12 hours) and assessed NO with Graise test.Results: Results: Data showed that short term exposure (1 hour) with agonist TLR2, 4 on MSCs significantly increases on the production No as compared to the control group.Conclusion: Findings suggest that the different-Time of MSCs exposure to TLR2, 4 agonist, differently affected NO production of MSCs. The results can be applied potently for more successful MSC-based therapy programs.

Background and Objectives The decrease in mesenchymal stem cells (MSCs) survival rate after transplantation is a major challenge in MSC-cell-therapy. Hence, it is promising to employ some proper strategies for addressing this problem. This study was conducted to assay the therapeutic effects of MSCs treated with Nrf2 -manipulated-MSC conditioned medium in acute kidney injury (AKI) -induced animal models.Materials and Methods In an experimental study, recombinant plasmid pcDNA3.1-Nrf2 was transfected into bone marrow-derived MSCs and the resulted conditioned medium was harvested. The MSCs was cultivated with Nrf2 -manipulated-derived conditioned medium. The conditioned mediumtreated-MSCs were transplanted to AKI-induced rats (each group containing 10 rats) and the therapeutic potentialities of these MSCs were evaluated using biochemical and pathological methods.Results Fourteen days after MSCs transplantation, there was a significant difference in BUN decreasing in rat groups injected with conditioned medium-treated-MSCs (48±3.5 mg/dL) in comparison with those injected with normal MSCs (100±9.9 mg/dL) (p<0.001). The number of observed casts (0.26) in kidney tissue sections of these rat groups were also less than (0.51) the groups transplanted with normal MSCS.Conclusions Cultivation of MSCs in the presence of Nrf2 -manipulated-derived conditioned medium increase the therapeutic effects of these cells in AKI-induced models.

Background and purpose: Degenerative joint disease, especially osteoarthritis (OA), is a global disease characterized by the destruction of articular cartilage, and subchondral bone. It is estimated that about 250 million people currently suffer from cartilage defects. So far, no definite and standard treatment method for OA has been reported. Recently, cell-based therapeutic techniques have been considered one of the best therapeutic strategies for the long-term treatment of articular cartilage diseases. However, many challenges include the large scale of cells required, thus the cell-free approaches are novel tools for cartilage defect treatment. For instance, extracellular vesicles (EVs) secreted by various cells such as MSCs are in charge of the therapeutic effects of stem cells. Therefore, recently EVs have advanced as powerful cell-free transfer tools, due to their high physicochemical strength and biocompatibility. Materials and methods: This study is a review study that summarizes the preclinical and clinical studies that used EV-derived from different cell sources and investigates their effectiveness in treating cartilaginous tissue lesions. Current studies used small or large animal models with experimental critical size defects in knee articular cartilage to examine the effectiveness of EVs derived from MSCs. The EVs were isolated from cell sources such as adipose-derived MSCs, Bone marrow-derived MSCs, or transgenic cells. In addition, EV isolation techniques as a main challenge in studies using EVs to treat OA, specifically described in the current study. We also showed EVs isolated from each cell have unique features such as anti-inflammatory, differentiation, and therapeutic properties. We explain recent studies that use EVs as a drug carrier such as small molecules, and microRNA bioactive factors. In addition, the isolation techniques of EVs and their characterization are other challenges that we explain. Results: Recent studies have shown that EVs isolated from different sources inhibit the progression of OA. Also, the results of some studies indicate the ability of EVs to repair injured cartilage. Many studies showed that in critical size defects of cartilage, the use of EVs needs scaffolds. Several studies have investigated the challenges of EV release and the required EV dose based on the size of the lesion. EVs are rapidly emerging as novel therapeutic approaches for treating cartilage lesions and OA. Despite many advances in cell therapy and promising results reported in numerous disease models, the use of cells especially genetically modified cells has limitations in regenerative medicine. It is worth noting that the use of EVs derived from stem cells or transgenic cells has no harm to the human body. As a result, therapeutic EVs have been introduced as a new therapeutic approach that does not have the same potential risks as cells. Conclusion: Despite the positive results of EV in the treatment of cartilaginous lesions, it appears that the EV therapeutic barrier requires further testing in larger animal models before clinical trials. For instance, the regeneration of critical-size lesions requires the use of EVs incorporated by suitable scaffolds under dynamic conditions. Therefore, the fundamental questions to be considered are: How to use EVs as a nanoparticle instead of stem cells in combination with tissue engineering methods? What are the biological properties of EVs? What doses of EVs have the mechanistic potential for the treatment of different sizes of cartilage lesions and how EVs are stable in lesions? What is the role of EVs in the homeostasis and pathogenesis of junctions?