Foetal bovine serum-derived exosomes affect yeld and phenotype of human cardiac progenitor cell culture

Introduction: Cardiac Progenitor Cells represent a powerful tool in cardiac regenerative medicine. Pre-clinical studies suggest that most of the beneficial effects promoted by the injected cells are due to their paracrine activity exerted on endogenous cells and tissue. Exosomes are candidate mediators of this paracrine effects. According to their potential, many researchers are focusing on characterizing exosomes derived from specific cell types, but, up to date, only few studies have analysed the possible in vitro effects of bovine serum-derived exosomes on cell proliferation or differentiation. Methods: Aim of this study was to analyse, from a qualitative and quantitative point of view, the in vitro effects of bovine serum exosomes on human cardiac progenitor cells cultured either as cardiospheres or as monolayers of cardiosphere-forming cells. Results: Effects on proliferation, yield and molecular patterning were detected. We show, for the first time, that exogenous bovine exosomes support human cardiosphere-forming cells proliferation and migration, and that their depletion affects cardiospheres formation, in terms of size, yield and extra-cellular matrix production. Conclusion: These results stress the importance of considering differential biological effects of exogenous cell culture supplements on the final phenotype of primary human cell cultures.