(516h) Regenerating Articular Cartilages By Genetically Engineered Ascs: Prolonged TGF-b3/BMP-6 Expression Improved Chondrogenesis and Restored Zonal Structure

Adipose-derived stem cells (ASCs) hold promise for cartilage regeneration but their chondrogenesis potential is inferior. Here we employed a baculovirus system that exploited FLPo/Frt-mediated transgene recombination and episomal minicircle formation to genetically engineer rabbit ASCs (rASCs). The baculovirus system conferred prolonged and robust TGF-β3/BMP-6 expression in rASCs cultured in porous scaffolds, which critically augmented rASCs chondrogenesis and suppressed osteogenesis/hypertrophy, leading to the formation of cartilaginous constructs with improved maturity and mechanical properties in 2-week culture. Twelve weeks after implantation into full-thickness articular cartilage defects in rabbits, these engineered constructs regenerated neocartilages that resembled native hyaline cartilages in cell morphology, matrix composition and mechanical properties. The neocartilages also displayed cartilage-specific zonal structures without signs of hypertrophy, ossification and degeneration, and eventually integrated with host cartilages. In conclusion, the baculovirus-engineered rASCs that persistently express TGF-b3/BMP-6 improved the chondrogenesis, in vitro cartilaginous constructs production and in vivo hyaline cartilage regeneration, thus representing a remarkable advance in cartilage engineering.