USE OF MYOBLASTS IN ASSAYING THE OSTEOINDUCTIVITY OF BONE MORPHOGENETIC PROTEINS

A novel, time- and BMP-saving in vitro method for the detection and qu antitation of bone morphogenetic protein (BMP) activity was developed based on the measurable effects of BMP on rat skeletal muscle myoblast s (L6). Calcium incorporation, stimulation of alkaline phosphatase act ivity and production of osteocalcin were used as markers of bone cell metabolism and on-going morphogenesis. The morphological change was co nfirmed by Chlorantine fast red and von Kossa staining. The response o f various BMPs was purity-dependent and consistent with intramuscular implantations of the same materials. Neither TGF-beta 1 nor insulin co uld induce the same actions. The data from this study indicate that at least in part in vivo implantations of BMP extracts can be replaced b y in vitro measurement of osteoinductivity. Considerable saving of tim e, BMP and experimental animals can be achieved using cell culture con ditions for the determination of bone-forming activity.