OBJECTIVETo study osteoblastic phenotype expression of New Zealand rabbit skin fibroblasts transfected with mouse core binding factor a1/osteoblast specific transplanting factor-2 gene (Cbfa1/Osf2).

METHODSCbfa1/Osf2 gene, engineered into eukaryotic expression vector pSG5, was introduced into New Zealand rabbit skin fibroblasts with catholyte liposomes-Lipofectamine 2000. Meanwhile, those transfected pSG5 and un-transfected were set the control groups. The expression of Cbfa1 gene, osteocalcin (OCN) gene, alkaline phosphatase (ALP) gene and pre-peptide 2 alpha gene of collagen type I were detected by RT-PCR assay. Cbfa1 protein was detected by Western-Blot assay, in-cell ALP activity by p-nitrophenyl phosphate (PNPP) assay and OCN content in the supernatant by radio-immunity method. The ossification nodules was detected by Alizarin-Red staining and scanning electron microscope.

RESULTSCbfa 1mRNA and Cbfa1 protein were expressed in New Zealand rabbit skin fibroblasts transfected with pSG5-Cbfa1/Osf2 from the first day to the fifth day, but they were not detected in the control groups. In the pSG5-Cbfa1/Osf2 transfected group, the expression of ALP gene and OCN gene were respectively induced from the third day and the forth day, pre-peptide 2 alpha gene of collagen type I was enhanced from the third day. From the sixth day, ALP activity greatly increased, OCN strongly secreted, and they were maintained at a high level for about 4 weeks, and the difference was significant compared with the control group (P < 0.05). On the forty-second day, ossification nodules were found on the surface of pSG5-Cbfa1/Osf2 gene transfected cells.

CONCLUSIONSNew Zealand rabbit skin fibroblasts transfected with pSG5-Cbfa1/Osf2 can express osteogenesis-related genes and proteins, and form ossification nodules on their surface.