[Inhibitory effects of human bone marrow mesenchymal stem cells and cord blood mononuclear cells on mixed lymphocyte response and PHA induction transformation].

To study and compare the immunomodulatory functions of human bone marrow mesenchymal stem cell (MSC) and cord blood mononuclear cell (CBMNC) in vitro, human bone marrow MSC were separated with Percoll (1.073 g/L) and cultured in low-glucose DMEM, and cord blood mononuclear cells were isolated with Ficoll (1.077 g/L). These two kinds of cells were added to mixed lymphocyte cultures and PHA induction transformation cultures with various concentrations. The proliferation of lymphocytes was measured by MTT method, effects of MSC and CBMNC on mixed lymphocyte response and PHA-induced lymphocyte transformation were investigated. The results showed that both 5 x 10(4), 1 x 10(4) MSC and 2 x 10(5) CBMNC could inhibit the mixed lymphocyte response (MLR) and PHA induced transformation. But with lower concentrations (MSC < or = 1 x 10(3), CBMNC < or = 1 x 10(5)), the inhibition effects of MSC and CBMNC were less consistent. 1 x 10(2) MSC and 1 x 10(4) CBMNC mainly increased the lymphocyte activation. In addition, the inhibition ratio of 5 x 10(4) MSC (MLC 65.3%, PHA 79.1%) was higher than that of 2 x 10(5) CBMNC (MLC 8.6%, PHA 37.3%). It is concluded that larger numbers of both MSC and CBMNC showed negative immunomodulatory functions and inhibited the mixed lymphocyte response and induction of transformation in vitro. Moreover, the inhibitory effect of MSC was much stronger than that of CBMNC.