In vitro generation of osteochondral composites

Osteochondral repair involves the regeneration of articular cartilage and u nderlying bone, and the development of a well-defined tissue-to-tissue inte rface. We investigated tissue engineering of three-dimensional cartilage/bo ne composites based on biodegradable polymer scaffolds, chondrogenic and os teogenic cells. Cartilage constructs were created by cultivating primary bo vine calf articular chondrocytes on polyglycolic acid meshes; bone-like con structs were created by cultivating expanded bovine calf periosteal cells o n foams made of a blend of poly-lactic-co-glycolic acid and polyethylene gl ycol. Pairs of constructs were sutured together after 1 or 4 weeks of isola ted culture, and the resulting composites were cultured for an additional 4 weeks. All composites were structurally stable and consisted of well-defin ed cartilaginous and bone-like tissues. The fraction of glycosaminoglycan i n the cartilaginous regions increased with time, both in isolated and compo site cultures. In contrast, the mineralization in bone-like regions increas ed during isolated culture, but remained approximately constant during the subsequent composite culture. The integration at the cartilage/bone interfa ce was generally better for composites consisting of immature (1-week) than mature (4-week) constructs. This study demonstrates that osteochondral tis sue composites for potential use in osteochondral repair can be engineered in vitro by culturing mammalian chondrocytes and periosteal cells on approp riate polymer scaffolds. (C) 2000 Elsevier Science Ltd. All rights reserved .