Repair effects of bone marrow mesenchymal stem cells modified by adenovirus mediated bcl-xL gene on the cartilage defect of knee joint in rats

Abstract

Objective To observe the repair effects of bone marrow mesenchymal stem cells (BMSCs) modified by adenovirus mediated B cell lymphoma/leukemia-xL (bcl-xL) gene on the cartilage defect of knee joint in rats. Methods The adenovirus-mediated bcl-xL gene overexpression vector pAdTrack-bcl-xL was constructed. BMSCs were isolated, cultured and amplified, pAdTrack-bcl-xL and blank vector were transfected, and the bcl-xL expression level was detected by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). Fifty SD rats were randomly divided into five groups (n=10 each). The control group received no treatment, and the remaining four groups (model group, BMSCs treatment group, BMSCs treatment group transfected with empty vector and bcl-xL overexpressed BMSCs treatment group) were all used to make models of cartilage defect of the knee joint. Three days after surgery, the animals were treated accordingly. Rats in each group were sacrificed at 6th and 12th week after treatment, and the knee joints were collected and paraffin sections were made. Then the cartilage tissues of the knee joints were stained and observed by hematoxylin and eosin (HE), Masson and saffron-O methods. Results As compared with the empty vector group, the relative mRNA expression of bcl-xL gene in BMSCs of pAdTrack-bcl-xL group was significantly increased (1.07±0.08 vs. 8.15±0.31, t=-52.893, P<0.01), suggesting that BMSCs with stable over-expression of bcl-xL gene were successfully constructed. Pathological staining results showed that, after 6 weeks of treatment, as compared with the model group, in the BMSCs group and the BMSCs treatment group transfected with empty vector, a large amount of chondrogenesis was seen, the arrangement of chondrocytes tended to be orderly, and the number of chondrocytes significantly increased. However, the bcl-xL over-expressed BMSCs treatment group had more chondrogenesis, more orderly arrangement of chondrocytes and significantly greater number of chondrocytes than the BMSCs treatment group transfected with empty vector. As compared with the same group at 6th week, chondrogenesis was significantly increased in each treatment group at 12th week, especially in BMSCs treatment group with bcl-xL overexpression. Conclusion Bcl-xL over-expressed BMSCs can significantly promote the repair of cartilage defect of knee joints in rats, which will lay a theoretical foundation for the clinical treatment of articular cartilage defect. Key words: Bone marrow mesenchymal stem cells; B cell lymphoma/leukemia-xL over-expression; Knee joint; Cartilage defect