A 'waste product' to save the day in the field of transplantation: The evolving potential of extracellular vesicles.

Graft rejection and graft-versus-host disease constitute the leading causes of morbidity and early mortality after solid organ and haematopoietic stem cell transplantation, respectively. Despite the current advances in immunotherapy, their incidence remains significant, underlying the need for new therapies to be developed. Extracellular vesicles (EV), and particularly small EV (sEV), have emerged as significant mediators of intercellular communication and immune modulation. Depending on the parental cell, they may exert potent immunostimulatory or immunosuppressive functions, attracting a major interest in field of transplantation. An increasing number of publications, studying their role in graft dysfunction pathophysiology, early detection of graft failure and in prevention and/or therapy of graft rejection, have emerged in recent years with enthusiastic results. In this review, we discuss the role and various applications of sEV in the transplant setting and present their huge potential for clinical translation.