Mesenchymal stromal cells (MSC) are a heterogeneous cell population with the ability to control the immune response and act as an important tool for cell therapy, mainly in inflammatory and autoimmune diseases treatment, as well as in the Graft versus Host Disease (GvHD). The Regional Blood Center of Ribeirão Preto hosts the Center for Cell-based Therapy (CTC) that has as clinical research branches the treatment of steroid-refractory acute GvHD with MSC expanded in human AB serum as substitute for the fetal bovine serum. Such a substitution is performed in order to eliminate the xenoantigen contamination risks. Recent studies suggest that the MSC immunomodulatory activity is essentially mediated by paracrine factors, where extracellular vesicles (EV) play an important role for the MSC communication, transporting bioactive molecules in order to target cells and change their phenotypes or functional behavior. This proposal aims to evaluate the effect of the use of depleted EV media on the MSC immunophenotypic characteristics, proliferation rate, and differentiation properties. In addition, we intend to isolate and characterize MSC-derived EV (EV-MSC), compare cell culture under hypoxia and normoxia in order to analyze the EV immunosuppression potential and interactions between EVs and T lymphocytes. Preliminary results from our research group showed that culture with media supplemented with EV depleted human AB serum influences the MSC growth time, however do not not alter their morphology or immunomodulation capacity. This cultivation strategy allowed us to isolate EV-MSC and to characterize their exosomal profile based on the size and protein expression. These EV-MSC were also able to inhibit T lymphocytes proliferation. In this context, EV-MSC could be used as an important tool to control the steroid-refractory acute GvHD and to improve the patient's clinical response, reducing the treatment secondary effects and overcoming limitations of the MSC use.
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