Abstract： Objective To explore the effect of retinoblastoma binding protein 2 (RBP-2), a histone H3K4 demethylase, on osteogenic differentiation of human adipose-derived stromal cell(hASC).Methods According to the GenBank sequence information of RBP-2, four different small interfering RNAs (siRNA) targeting RBP-2 gene were designed and the corresponding short hairpin RNAs (shRNA) were cloned into pLL 3.7 lentivirus RNA interference vector. The lentivirus with RBP-2-siRNA was packaged in 293T cells. The effective sequence was examined and selected by Western blotting and real-time PCR. The lentiviruses with efficient knockdown effects were used to infect hASC. On the 14th day after osteogenic differentiation, alkaline phosphatase (ALP) activities of hASC were quantitatively tested and at the same time, ALP staining and alizarin red staining were performed to assess the difference of osteogenic differentiation between the knockdown group and the control group. Results The recombinant lentivirus siRNA targeting RBP-2 was successfully constructed and the expression of RBP-2 mRNA and protein were dramatically suppressed by infection with RBP-2-siRNA lentivirus. On the 14th day after osteogenic induction, ALP activity of hASC in the knockdown group[(299.2 ±22.7), (224.3± 17.7) U/g]was much stronger than that in the control group[( 129.9 ± 12.9) U/g, P ＜ 0. 05]and the same result was achieved for the ALP staining and alizarin red staining. Conclusions The constructed RBP-2-siRNA lentivirus could markedly decrease the expression of RBP-2 and promote osteogenic differentiation of hASC.It indicated that RBP-2 can repress the osteogenic differentiation of hASC.