OBJECTIVETo address the question whether bone marrow mesenchymal stem cells (MSCs) could lower responsiveness of allogeneic T lymphocytes against alloantigens, and explore a feasible strategy for prevention of graft versus host disease (GVHD) occurred in allogeneic bone marrow transplantation.

METHODST cells were co-cultured with (60)Co-irradiated bone marrow MSCs from different individuals. The proliferative activity of T cells and their reactivity to allogeneic cells and ConA were evaluated with (3)H-TdR incorporation assay.

RESULTST cells could not be activated upon primary or even secondary exposure to allogeneic MSCs (compared the CPM value of 27,529 +/- 969 of T cell alone with that of primary and secondary exposures to allogeneic MSCs were 9,126 +/- 654 and 13,260 +/- 874, respectively). When MSCs were induced to express HLA-DR, they still could not elicit T cell activation. The proliferation rate of allogenous T cells exposed to MSCs was dramatically declined when T cells from the same donor's MSCs were used as stimulator (CPM value decreased from 45,876 +/- 5285 before coculture to 9850 +/- 1618 after coculture). Furthermore, the results remained unchanged even ConA was added into the culture system.

CONCLUSIONSHeterogenetic MSCs could suppress T cell activation. MSCs pretreatment might be useful in the prevention of GVHD in HLA-mismatched bone marrow transplantation.