Human placenta-derived mesenchymal stem cells suppress T cell proliferation and support the culture expansion of cord blood CD34+ cells: A comparison with human bone marrow-derived mesenchymal stem cells

Human placenta-derived mesenchymal stem cells (hPMSCs) have been shown to possess immunosuppressive effects against T cells and support the expansion of hematopoietic stem/progenitor cells (HSPCs) from umbilical cord blood (UCB). However, the characteristics of hPMSCs compared with human bone marrow-derived mesenchymal stem cells (hBMSCs) are not fully understood. Here, we show that hPMSCs have similar regulatory effects on T cell activation, proliferation and cytokine secretion as hBMSCs and demonstrate that PDL1 and B7H4, negative co-stimulatory molecules, are involved in the T cell immunosuppressive activities of hPMSCs and hBMSCs, respectively. hPMSCs efficiently enhanced the expansion of CD34+ cells from UCB compared with hBMSCs. Furthermore, hPMSCs maintained the expression of adhesion molecules (CD11a, CD44 and CD49e) in CD34+ cells. Similar effects were observed for both hPMSCs and hBMSCs on CD34+ cell chemotaxis and cytokine production, such as SDF-1α, IL-6 and SCF. Therefore, hPMSCs may be an ideal alternative source of hBMSCs for basic research and clinical applications, which may be significant in future efforts to explore the potential clinical utility of hPMSCs.