Abstract: AIM:To explore the effect on the proliferation and the apoptosis of bone marrow mesenchymal stem cells (BMMSCs) regulated by PIM-1 gene mediated by lentivirus. METHODS: Antigen expressions of CD29, CD44, and CD45 were assayed in the cells of the fourth passage by flow cytometry to identify BMMSCs.The experiment was divided into control group, EGFP transfected group (EGFP group), and PIM-1 gene transfection group (PIM-1 group). The combinant lentivirus vector-PIM-1 (Lv-efgp-PIM-1) and lentivirus vector-EGFP were transfected into BMMSCs. PCR was performed to detect the expression of PIM-1. Western blot was used to detect the expression of PIM-1 protein level. MTT was used to evaluate the proliferation of BMMSCs regulated by PIM-1, and fluorescence-activated cell sorting (FACS) technology was employed to detect the rate of cell apoptosis. RESULTS: PIM-1 was successfully transfected into BMMSCs. Compared with those in control group, the cell PIM-1 protein levels and the cell proliferation activity significantly increased (both P<0.01), whereas the cell apoptosis rate significantly decreased (P<0.01). CONCLUSION: LV-PIM-1 transfection can markedly promote BMMSC growth and inhibit cell apoptosis.