RABBIT CALVARIAL OSTEOBLASTS IN CULTURE CONSTITUTIVELY SYNTHESIZE PROGELATINASE-A, AND TIMP-1 AND TIMP-2

Defining the TIMPs (tissue inhibitors of metalloproteinases) produced by non-human bone cells is important because animal models and cells a re used extensively for research on bone resorption, and because TIMP- 2 can bind to and prevent activation of progelatinase-A. By zymography we show that rabbit calvarial osteoblasts in culture constitutively s ynthesize TIMP-2 in addition to TIMP-1 and progelatinase-A. Previously we found that human osteoblasts produced only low levels of TIMP-2 un der any conditions. We also show that stimulated rabbit osteoblasts ca n degrade a type I collagen film even though both TIMPs are being synt hesized.