Nasal chondrocytes (NC) were previously demonstrated to remain viable and to participate in the repair of articular cartilage defects in goats. Here, we investigated critical features of tissue-engineered grafts generated by NC in this large animal model, namely cell retention at the implantation site, architecture and integration with adjacent tissues, and effects on subchondral bone changes. In this study, isolated autologous goat NC (gNC) and goat articular chondrocytes (gAC, as control) were expanded, green fluorescent protein-labelled and seeded on a type I/III collagen membrane. After chondrogenic differentiation, tissue-engineered grafts were implanted into chondral defects (6 mm in diameter) in the stifle joint for 3 or 6 months. At the time of explantation, surrounding tissues showed no or very low (only in the infrapatellar fat pad <0.32%) migration of the grafted cells. In repair tissue, gNC formed typical structures of articular cartilage, such as flattened cells at the surface and column-like clusters in the middle layers. Semi-quantitative histological evaluation revealed efficient integration of the grafted tissues with the adjacent native cartilage and underlying subchondral bone. A significantly increased subchondral bone area, as a sign for the onset of osteoarthritis, was observed following treatment of cartilage defects with gAC-, but not with gNC-grafts. Our results reinforce the use of NC-based engineered tissue for articular cartilage repair and preliminarily indicate their potential for the treatment of early osteoarthritic defects.
Keywords: animal model; bone; cartilage; cell migration; extracellular matrix.