[Effects of human umbilical cord mesenchymal stem cells on the proliferation of hematopoietic malignancies].

OBJECTIVE: To study the effects of human umbilical cord mesenchymal stem cells (UC-MSCs) on proliferation of eight tumor cell lines from leukemia, lymphoma and multiple myeloma in vitro. METHODS: Tumor cells were labeled with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE). UC-MSCs were co-cultured with tumor cells at different ratios as experimental groups, meanwhile, tumor cells were cultured without UC-MSCs as control groups. After three days, mean fluorescence intensity and cell division generations of the tumor cells were measured by flow cytometry. RESULTS: UC-MSCs inhibited the proliferation of HL60, THP1, K562 and RPMI8226 cell lines, but promoted the proliferation of Raji and NCIH929 cell lines. UC-MSCs promoted the proliferation of Jurkat cells only at 1:1 ratio; as for U937 cells, UC-MSCs inhibited the proliferation at 2:1 ratio (UC-MSCs: U937), promoted proliferation at 1:4 and 1:16, whereas had no obvious effect at 1:1. CONCLUSION: UC-MSCs have different effects on the proliferation of different hematopoietic tumor cell lines. They have no promoting effects on four leukemic cell lines, but have bidirectional (promotion/inhibition) effects on lymphoma and multiple myeloma cell lines. The U937 cell line may serve as a good model for the mechanism study of this contradictory phenomenon.