Culture and behavior of osteoblastic cells isolated from normal trabecular bone surfaces

We report the characterization of human osteoblastic cells that were derived from the surface of trabecular bone fragments. After removal of bone marrow cells, the bone lining osteoblastic cells lining the bone surface were obtained by migration and proliferation from the trabecular surface onto a nylon mesh. The isolated population proliferated in culture and exhibited osteoblastic phenotype. Cultured cells show a regular arrangement in vitro and exhibited multiple interconnecting junctions on scanning electron microscopic examination. Immunocytochemical staining showed that the cells produced almost exclusively type I collagen. Bone-surface-derived cells responded to 1-34 human parathyroid hormone by increasing intracellular cyclic AMP. Cell cultures exhibited high alkaline phosphatase activity, which was unaffected by 1,25 (OH)2 vitamin D. Untreated cells produced high levels of osteocalcin, a bone-specific protein, and they responded to 1,25(OH) vitamin D by increasing osteocalcin synthesis in a dose-dependent manner. Although cells cultured for up to 5 mo. still produced osteocalcin, the response to 1,25(OH)2D decreased after multiple passages. This study shows that the bone cell populations isolated from trabecular bone surfaces are enriched in osteoblast precursors and mature osteoblastic cells.