Abstract: Objective:To investigate the effects of umbilical cord mesenchymal stem cells(MSCs)on hemopoietic function of bone marrow in mice with aplastic anemia(AA).Methods:Umbilical cord MSCs were primarily cultured with adherent method.All mice were divided into the model group,control group and MSCs infusion group.The aplastic anemia model mice established by immune-mediated means were infused with MSCs through caudalis vena.The peripheral hemogram and bone marrow morphology were observed at 3,7,14,21 and 28 days.The level of hematopoiesis negative regulatory factor(IFN-)was detected by ELISA.The colony-forming unit counts of bone marrow hemopoietic progenitor cells were measured.Results:The spindle-shaped MSCs extended from the tissue edge at 8-10 days after primary adherent culture of umbilical cord,and those were parallelly or whirlpool-shape growth with the cultivation.The increasing peripheral hemogram and decreasing IFN- levels of AA mice treated with MSCs were significant(P0.01).The colony forming units-erythroid and colony forming units-granulocyte macrophage of the treatment group were significantly higher than those in the control group(P0.01),but there was no significant difference in the colony forming units-fibroblast count between the two groups(P0.05).Conclusions:MSCs derived from human umbilical cord can play some poles on hemopoietic function of the bone marrow of AA mice.