Proposed effects of EXOs released by islet MSCs. Although there is the possibility that EXOs directly stimulate T and B cells,
it is likely that EXOs affect DCs that, in turn, initiate anti-β-cell–specific T-cell response. EXOs may lead to the maturation
of inflammatory DCs or “feed” DCs with relevant islet antigens. B7, B7-1, B7-2; FasL, Fas ligand; MHC, major histocompatibility
complex; ROS, reactive oxygen species; TCR, T-cell receptor; TNF, tumor necrosis factor.