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

Objective. To realize local selective gene expression in grafted chondrocyt es for cartilage defect, we investigated the usefulness of an ex vivo gene delivery method using an adenovirus vector. Methods. beta-galactosidase gene (LacZ) was transfected using an adenovirus vector to chondrocytes isolated from rat joints. The cells were then embed ded into collagen gel, and LacZ expression in the gel was examined using 5- bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) staining; beta-ga lactosidase activity was also measured. The collagen gel containing transfe cted chondrocytes was grafted to the experimental cartilage defects, and th e expression of delivered gene was histologically examined after X-gal stai ning of the tissue containing the grafted area. Results. X-gal positive chondrocytes in the gel accounted for 82% at one we ek and 55% at 8 weeks after gene delivery. beta-galactosidase activity decr eased with time, but its expression was maintained even at 8 weeks after ge ne 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 efficie ntly for a long time; this method would be useful in allografts for cartila ge defects.