Endosteal human bone cells (EBC) show age-related activity in vitro

Based on the hypothesis that decreasing osteoblastic function is one of the reasons for the development of osteoporosis, we have studied the proliferation and protein production of isolated bone cells of young and old human donors. The isolation procedure for bone cells is based on a combined mechanical and enzymatical treatment of human trabecular bone. Endosteal bone cells (EBC) obtained by this method developed typical osteoblast-like characteristics in culture. The most important functional feature was the dose-dependent increase of osteocalcin production following stimulation with 1.25(OH)2D3. Growth of EBC (measured as emigration time after plating of trabecular bone fragments) was equal in premenopausal women and men aged under 40 years, but was impaired in EBC of men aged over 50 years. The production of osteocalcin after stimulation with 1.25(OH)2D3 was about 60% lower in older donors (> 50 years) than in younger ones (< 40 years), regardless of gender. According to our results osteoblastic function is reduced with increasing age in human EBC of both genders as clearly shown by a diminished protein production. However, the anticipated depressive effect of age on growth of bone cells was obvious in males only. So called age related osteoblastic insufficiency does exist but it has to be considered differently for bone cell function and bone cell growth. The limited data shown in this study should enhance understanding of age and sex related changes in the EBC metabolism.