Abstract： Background Bone morphogenetic protein (BMP) is a member of the superfamily of transforming growth factor-β.Recent studies show that it is an indispensable factor in hematopoiesis.To better characterize the effect of recombinant human BMP (rhBMP)-2 in hematopoiesis,we set out to determine whether rhBMP-2 could promote the proliferation of mesenchymal stem cells (MSCs) and increase the levels of hematopoietic cytokines in MSCs.Methods 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino) carbonyl)-2H-tetrazolium hydroxide (XTT),real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) were used to deteMP-2 on the proliferation and hematopoietic cytokine levels of MSCs.In addition,MSCs marked with Hoechst33342 were transplanted into BALB/c mice by the intravenous route or intra-bone marrow transplantation,and cluster numbers were counted.Results The XTT test revealed that rhBMP-2 significantly induced proliferation of MSCs in doses ranging from 10 ng/ml to 0.1 mg/ml in a dose-dependent manner.The experiments in vivo showed that there were more clusters of donor cells in bone marrow,spleen,liver and lung of the BMP group than those in the control group after both intra-bone marrow transplantation (P＜0.001,P ＜0.001,P ＜0.001,and P=0.001,respectively) and intravenous transplantation (P ＜0.001,P ＜0.001,and P ＜0.001 respectively).The results of real-time PCR and ELISA revealed that rhBMP-2 significantly increased mRNA expressions and protein levels of IL-6,IL-7,IL-11,G-CSF,M-CSF and SCF.Conclusions The treatment with rhBMP-2 promotes the proliferation of MSCs in vivo and in vitro and increases the levels of hematopoietic cytokines in MSCs,which may contribute to the improvement of hematopoietic function.