HLA-DRB1 and graft versus host disease: A recent study showed that adipose tissue-derived MSCs enhance the immunosuppressive function of Tregs by transferring active mitochondria and fragments of the plasma membrane to Tregs and that this transfer mode was dependent on MSC-expressed HLA and positively correlated with the HLA-C and HLA-DRB1 epitope mismatch load between Tregs and MSCs donors [137]. Angela et al. reported that MSC-mediated mitochondrial transfer induces Treg production by increasing the expression of FoxP3 miRNA, which was confirmed in a graft-versus-host disease (GVHD) model [138].