Alveolar mononuclear cells can develop into multinucleated osteoclasts: Anin vitro cell culture model

Previous studies have shown that osteoclasts are derived from mononuclear c ells of hemopoietic bone marrow and peripheral blood. The purpose of this s tudy was to demonstrate the presence of multinucleated osteoclasts after ad ding alveolar mononuclear cells to new-born rat calvaria osteoblasts in vit ro. To utilize osteoclast-free bone, fetal calvariae were obtained from new born Wistar-rats and cultured in DMEM medium for 14 days. On the day of ost eoblast culture, alveolar mononuclear cells were isolated from newborn Wist ar rats with a serial washing method and then co-cultured with the calvaria l osteoblasts. Bone resorption characteristics were observed both with ligh t and scanning electron microscopy. When alveolar mononuclear cells were cu ltured for 14 days on the calvarial osteoblasts in response to 1 alpha, 25- dihydroxyvitamin D3, they formed tartrate-resistant acid phosphatase (TRAP) -positive mononuclear and multinucleated cells. Resorption pits were seen i n the 7-14 days long-term cultures. These results indicate that osteoclasts can be derived from alveolar mononuclear cells in vitro when a suitable mi croenvironment is provided by calvarial osteoblasts and vitamin D-3. (C) 20 00 John Wiley & Sons, Inc.