Repair of articular cartilage defect by autologous transplantation of basic fibroblast growth factor gene–transduced chondrocytes with adeno‐associated virus vector

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Abstract
Objective To examine the effects of basic fibroblast growth factor (bFGF) gene–transduced chondrocytes on the repair of articular cartilage defects. Methods LacZ gene or bFGF gene was transduced into primary isolated rabbit chondrocytes with the use of a recombinant adeno‐associated virus (AAV) vector. These gene‐transduced chondrocytes were embedded in collagen gel and transplanted into a full‐thickness defect in the articular cartilage of the patellar groove of a rabbit. The efficiency of gene transduction was assessed according to the percentage of LacZ‐positive cells among the total number of living cells. The concentration of bFGF in the culture supernatant was measured by enzyme‐linked immunosorbent assay to confirm the production by bFGF gene–transduced chondrocytes. At 4, 8, and 12 weeks after transplantation, cartilage repair was evaluated histologically and graded semiquantitatively using a histologic scoring system ranging from 0 (complete regeneration) to 14 (no regeneration) points. Results LacZ gene expression by chondrocytes was maintained until 8 weeks in >85% of the in vitro population. LacZ‐positive cells were found at the transplant sites for at least 4 weeks after surgery. The mean concentration of bFGF was significantly increased in bFGF gene–transduced cells compared with control cells (P < 0.01). Semiquantitative histologic scoring indicated that the total score was significantly lower in the bFGF‐transduced group than in the control group throughout the observation period. Conclusion These results demonstrated that gene transfer to chondrocytes by an ex vivo method was established with the AAV vector, and transplantation of bFGF gene–transduced chondrocytes had a clear beneficial effect on the repair of rabbit articular cartilage defects.