LOCAL AND REMOTE MATRIX RESPONSES TO CHONDROCYTE-LADEN COLLAGEN SCAFFOLD IMPLANTATION IN EXTENSIVE ARTICULAR-CARTILAGE DEFECTS

Chondrocyte-laden collagen scaffolds were evaluated in extensive carti lage defects in an equine model. Arthroscopic techniques were used to implant a chondrocyte-collagen culture product in 15-mm defects in the lateral trochlear ridge of the femoropatellar joint of 12 horses. Ung rafted control defects were formed in the opposite joint. Groups of si x horses were terminated at 4 and 8 months after implantation and the repair sites, adjacent cartilage, and remote cartilage within each fem oropatellar joint examined biochemically. Eight months following surge ry the relative proportions of type II collagen in grafted and ungraft ed defects, determined using the ratio of cyanogen bromide cleavage pr oducts alpha 1(II)CB10/alpha 2(I)CB3,5, were not significantly differe nt (31.57 +/- 2.76% and 26.88 +/- 2.76%, respectively). Aggrecan conte nt was significantly improved in grafted defects (85.61 +/- 6.51 and 7 4.91 +/- 10.31 mu g/mg dry weight). Cartilage surrounding grafted defe cts also showed improved maintenance of cartilage glycosaminoglycan co ntent. Thus, chondrocyte grafting in collagen scaffold vehicles improv ed the aggrecan content in extensive cartilage defects and surrounding normal cartilage. However, given the continued disparity between repa ir tissue and normal cartilage aggrecan content, and the low proportio n of type II collagen in grafted defects, the utility of collagen scaf folds for chondrocyte grafting of large cartilage defects seems limite d.