The repair of osteochondral defects using baculovirus-mediated gene transfer with de-differentiated chondrocytes in bioreactor culture

Baculovirus has emerged as a promising gene delivery vector. Hereby de-differentiated rabbit chondrocytes were transduced ex vivo with a recombinant baculovirus expressing BMP-2 (Bac-CB), seeded to scaffolds and Cultured statically for 1 day (Bac-w0 group) or in a rotating-shaft bioreactor (RSB) for 1 week (Bac-w1 group) or 3 weeks (Bac-w3 group). Mock-transduced constructs were Cultured statically for 1 day to serve as the control (Mock-w0 group). We unraveled that Bac-CB transduction and increasing culture time in the RSB yielded more mature cartilaginous constructs in vitro. Eight weeks after implanting into the rabbit osteochondral defects, Mock-w0 Constructs failed to repair the lesion while Bac-w0 constructs resulted in augmented, yet incomplete, repair. Bac-w1 constructs yielded neocartilage layers rich in glycosaminoglycans and collagen II, but the integration between the graft and host cartilages was not complete, In contrast, Bac-w3 constructs led to the regeneration of hyaline cartilages as characterized by cartilage-like appearance, improved integration, chondrocytes clustered in lacunae, smooth and homogeneous matrix rich in collagen II and glycosaminoglycans but deficient in collagen I. In conclusion, combining baculovirus-modified de-differentiated chondrocytes and RSB Culture creates constructs that repair osteochondral defects, and in vitro culture time dictates the construct maturation and subsequent in vivo repair. (C) 2008 Elsevier Ltd. All rights reserved.