Ex vivo gene delivery using an adenovirus vector in treatment for cartilage defects

Objective. To realize local selective gene expression in grafted chondrocytes for cartilage defect, we investigated the usefulness of an ex vivo gene delivery method using an adenovirus vector. Methods. β- galactosidase gene (LacZ) was transfected using an adenovirus vector to chondrocytes isolated from rat joints. The cells were then embedded into collagen gel, and LacZ expression in the gel was examined using 5-bromo-4- chloro-3-indolyl-β-D-galactopyranoside (X-gal) staining; β-galactosidase activity was also measured. The collagen gel containing transfected chondrocytes was grafted to the experimental cartilage defects, and the expression of delivered gene was histologically examined after X-gal staining of the tissue containing the grafted area. Results. X-gal positive chondrocytes in the gel accounted for 82% at one week and 55% at 8 weeks after gene delivery. β-galactosidase activity decreased with time, but its expression was maintained even at 8 weeks after gene delivery. Chondrocytes used in the allograft maintained their morphology, and the expression of delivered gene continued during the 8 week period. Conclusion. In this ex vivo method, delivered gene can be expressed efficiently for a long time; this method would be useful in allografts for cartilage defects.