摘要Background:A stable and standardized source of mesenchymal stem cells is a pre-requisite for bone repair tissue engineering research and application.We aimed to establish a stable cell line of bone marrow mesenchymal stem cells from New Zealand rabbits and explore their osteogenic differentiation capacity.Methods:Primary rabbit bone marrow mesenchymal stem cells(RBMSCs)were iso-lated and immortalized via retroviral expression of SV40 Large T antigen(LTA).To assess the osteogenic differentiation capacity of the cells in vitro,we studied the alkaline phosphatase(ALP)expression level and calcium deposition in bone morpho-genetic protein 9(BMP9)-induced immortalized cells using ALP staining and quan-tification,as well as alizarin red staining.Ectopic bone formation by the cells was assessed using micro-computed tomography(μCT)and histological examination.Results:The immortalized cell line we established using SV40 LTA,which we termed iRBMSCs,was non-tumorigenic and maintained long-term proliferative activity.We further discovered that BMP9(MOI=30)effectively induced the osteogenic differ-entiation capacity of iRBMSCs in vitro,and there was a synergy with GelMA hydrogel in inducing osteogenic differentiation of the iRBMSCs in vivo.Conclusion:We confirmed that iRBMSCs are promising as a stable cell line source for bone defect repair engineering.