COL-3 inhibition of collagen fragmentation in ruptured cranial cruciate ligament explants from dogs with stifle arthritis

Inhibition of collagen fragment generation in canine cranial cruciate ligament (CCL) explant cultures by the matrix metalloprotease inhibitor (6-demethyl)-6-deoxy-4-dedimethylamino tetracycline (COL-3) was studied. Cranial cruciate ligament specimens were collected from dogs with inflammatory stifle arthritis/CCL rupture and dogs with normal stifles. Explant cultures from each CCL specimen included one COL-3 treated explant and a baseline control; explants from 12 ruptured CCLs were prepared in triplicate and a protease inhibitor cocktail positive control was used. Explant supernatants were analyzed for generation of collagen fragments after two days. Treatment of ruptured CCL explants with 10−4 M COL-3 decreased generation of collagen fragments. The extent of this inhibition was increased in explants treated with a protease inhibitor cocktail. Generation of collagen fragments was increased in ruptured CCLs, when compared with intact CCLs. It is concluded that generation of collagen fragments was increased in pathological ruptured CCL explants. This degradation could be significantly inhibited in vitro by 10−4 M COL-3.