PERIPHERAL-BLOOD MONONUCLEAR-CELLS DEVELOP INTO MULTINUCLEATED OSTEOCLASTS IN TISSUE-CULTURE

Background: Previous studies have shown that osteoclasts are derived f rom mononuclear cells of hemopoietic bone marrow and peripheral blood. The purpose of this study was to demonstrate the presence of multinuc leated osteoclasts after adding mononuclear cells from peripheral bloo d into established explants of fetal mouse calvaria in vitro. Methods: In order to utilize osteoclast-free bone, the fetal calvariae were ob tained from 13-14-day pregnant Swiss Webster mice and cultured in BGJb medium for 9 days. At day 9, peripheral blood mononuclear cells were isolated as a light density layer from adult Swiss Webster mice with t he Ficoll-Paque density gradient separation method and co-cultured wit h the osteoclast-free, fetal mouse calvaria. Results: After 10 days of co-culture, multinucleated cells, which have all the characteristics of osteoclasts, were found in juxtaposition to seams of woven bone. Tw o multinucleated osteoclasts per one million light density peripheral blood mononuclear cells were found in the experimental group; none wer e found in the mononuclear cell-free control group. Conclusions: Perip heral blood mononuclear cells can give rise to multinucleated osteocla sts in developing bone in vitro but will not develop without bone. (C) 1996 Wiley-Liss, Inc.