Characterization of human bone cells in culture.

Cultures of human bone cells were established, maintained, and characterized with respect to several metabolic parameters. These studies were undertaken with a view to using the bone culture system as a means of studying mechanisms of bone metabolism. The donor patients' ages ranged from 1 to 90 years and their disease states included congenital limb anomalies, exostosis, and osteo- and rheumatoid arthritis. Cultures were maintained up to 5 months. The osteoblast-like character of these cells was confirmed with the use of measurements applied to bone cells from other systems. Analyses showed that (a) the cells' appearance resembled that of cultured osteoblasts from other animal sources, b) intracellular cAMP was stimulated by human parathyroid hormone, c) osteocalcin was detected in the medium of all tested bone cell cultures and its production was found to be stimulated by 1,25-dihydroxycholecalciferol, and d) newly synthesized collagen was almost exclusively type I. In contrast, cultures of human fibroblasts, established in one instance from tissue specimens of the same donor patient, grew faster, reached a higher limiting density, and produced a greater proportion of type III collagen than the corresponding bone cells. Furthermore, fibroblasts did not accumulate osteocalcin in their culture medium. The conditions described in this report to maintain human bone cells in culture should provide a suitable test system to study the regulation of human bone metabolism.