ENDOGENOUS BMP-4 AND BMP-7 GENE EXPRESSION IN CD-1 MOUSE DURING CHONDROGENESIS INDUCED BY BOVINE BONE MORPHOGENETIC PROTEIN IMPLANTATION

The osteoinductive activity of bone morphogenetic proteins can be demonstrated by implantation into the muscle pouch in the mouse to induce ectopic cartilage and bone. To study endogenous BMP expression after implantation of 2 mg of native bovine BMP, cDNA clones of the chondroinductive factors BMP-4 and BMP-7 were constructed and used as probes. The investigation concentrated on the early phase of regeneration three and seven days after implantation. Expressions of the endogenous BMP-4 and BMP-7 genes during chondrogenesis was observed. Both BMP-4 and BMP-7 genes were significantly expressed as early as seven days after implantation. The results suggest that ectopic implanted bovine BMP can induce chondrogenesis and that BMP-4/7 participated in this process. This observation could be applied clinically to the repair of damaged cartilage.