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 are 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 synthesize TIMP-2 in addition to TIMP-1 and progelatinase-A. Previously we found that human osteoblasts produced only low levels of TIMP-2 under any conditions. We also show that stimulated rabbit osteoblasts can degrade a type I collagen film even though both TIMPs are being synthesized.