The effects of "matrigenin" activity from bovine bone on the glycosaminoglycans of bovine articular cartilage in culture. A model for cartilage repair by bone derived factors.

A bovine articular cartilage longterm culture system was used to study proteoglycan synthesis by a pulse labeling technique. A brief preincubation of the cartilage slices with bacterial collagenase was found to be an effective method of depleting proteoglycan. The addition of a fraction from bovine bone that contained partially purified "matrigenin" activity to the cultures resulted in the stimulation of incorporation of radioactive precursors into cartilage chondroitin sulfate, suggesting increased proteoglycan synthesis. The stimulatory effect of matrigenin activity was observed earlier and was more sustained if the cartilage slices were preincubated with collagenase. The system appears to be useful for testing the hypothesis that bone derived factors stimulate the repair of damaged cartilage.