CHONDROGENIC PHENOTYPE OF PERICHONDRIUM-DERIVED CHONDROPROGENITOR CELLS IS INFLUENCED BY TRANSFORMING-GROWTH-FACTOR-BETA-1

Our laboratory has developed a method for the repair of osteochondral defects by implanting cultured perichondrial cells attached to a biode gradable polylactic acid scaffold. The success of this approach depend s in part on the proliferative characteristics and the phenotype of th e implanted cells. Transforming growth factor-beta 1 has been reported to influence these parameters in several mesenchymal-derived tissues in vitro and in vivo. The chondrocytic phenotype is marked by an enhan ced expression of the collagen type-II gene. In this study, cultures g rown from explants of rabbit rib perichondrium were exposed to exogeno usly added transforming growth factor-beta 1 at concentrations of 0.1- 10 ng/ml of media. Cell proliferation and collagen gene expression wer e measured. The expression of types I and II collagen genes was analyz ed by Northern blot and reverse transcriptase-polymerase chain reactio n. The exogenous addition of transforming growth factor-beta 1 at a co ncentration of 0.1-10 ng/ml resulted in tritiated thymidine uptake by perichondrial cells, with optimum proliferative effects at 0.1 ng/ml. Transforming growth factor-beta 1 added at concentrations of 0.1 and 0 .5 ng/ml significantly upregulated the expression of type-II collagen mRNAs. The results suggest that, when the chondrocytic phenotype is de fined by markedly enhanced type-II collagen gene expression, the chond rocytic phenotype of explant cultures of perichondrium-derived cells i s enhanced by the exogenous addition of transforming growth factor-bet a 1.