Objectives:　The　repairing　of　large　segmental　bone　defects　is　difficult　for　clinical　orthopedists　at　present.　Gene　therapy　is　regarded　as　a　promising　method　for　bone　defects　repair.　The　present　study　aimed　to　construct　an　effective　and　controllable　Tet-On　expression　system　for　transferring　hBMP-2　gene　into　bone　marrow　mesenchymal　progenitor　cells　(BMSCs).　Meanwhile,　with　combination　of　alginate-poly-L-lysine-alginate　(APA)　microencapsulation　technology,　we　attempted　to　reduce　the　influence　of　immunologic　rejection　and　examine　the　effect　of　the　Tet-On　expression　system　on　osteogenesis　of　BMSCs.　Methods:　The　adenovirus　encoding　hBMP-2　(ADV-hBMP2)　was　constructed　using　the　means　of　molecular　cloning.　The　ADV-hBMP2　and　Adeno-X　Tet-On　virus　was　respectively　transfected　to　the　HEK293　for　amplification　and　afterward　BMSCs　were　co-infected　with　the　virus　of　ADV-hBMP2　and　the　Adeno-X　Tet-On.　The　expression　of　hBMP-2　was　measured　with　induction　by　doxycycline　(DOX)　at　different　concentration　by　means　of　RT-PCR　and　ELISA.　Combining　Tet-On　expression　system　and　APA　microcapsules　with　the　use　of　the　pulsed　high-voltage　electrostatic　microcapsule　instrument,　we　examined　the　expression　level　of　hBMP-2　in　APA　microcapsules　by　ELISA　as　well　as　the　osteogenesis　by　alizarin　red　S　staining.　Key　findings:　An　effective　Tet-On　expression　system　for　transferring　hBMP-2　gene　into　BMSCs　was　constructed　successfully.　Also,　the　expression　of　hBMP-2　could　be　regulated　by　concentration　of　DOX.　The　data　exhibited　that　BMSCs　in　APA　microcapsules　maintained　the　capability　of　proliferation　and　differentiation.　The　combination　of　Tet-On　expression　system　and　APA　microcapsules　could　promote　the　osteogenesis　of　BMSCs.　Conclusions:　According　to　the　results,　microencapsulated　Tet-On　expression　system　showed　the　effective　characteristics　of　secreting　hBMP-2　and　enhancing　osteogenesis,　which　would　provide　a　promising　way　for　bone　repair.