A direct simultaneous plate assay of proteoglycan and collagen degradation by cells in culture and its application to synovial cells.

1. A radiochemical plate assay is presented that allows a simultaneous evaluation of the capacity of cells in culture to degrade proteoglycan and collagen. Its principle consists of monitoring the release of soluble radioactive degradation products from Multiwell culture plates coated with dried reconstituted 3H-labelled-proteoglycan/14C-labelled-collagen mixed gels. The plates can also be used for the assay of proteolytic activities within enzyme solutions. 2. When cultured on the plates, rabbit synovial cells degrade collagen and proteoglycan almost simultaneously, owing to the secretion of collagenase and of a proteoglycan-degrading metal-dependent neutral proteinase.