BASIC FIBROBLAST GROWTH-FACTOR INHIBITS OSTEOCLAST-LIKE CELL-FORMATION

Basic fibroblast growth factor (bFGF) inhibited osteoclast-like cell f ormation in co-cultures of mouse bone marrow cells either with the mou se stromal cell line, ST2, or with primary osteoblastic cells. Basic F GF significantly inhibited the osteoclast-like cell formation, induced by 1 alpha,25-dihydroxyvitamin D-3[1 alpha,25(OH)(2)D-3] when the cyt okine was added to the culture, at an intermediate stage, suggesting t hat bFGF inhibits the differentiation of the osteoclast progenitors. W ith regard to target cells, bFGF directly affected ST2; it increased [ H-3]thymidine uptake and decreased the number of alkaline phosphatase- positive cells. In contrast, bFGF had no inhibitory effect on the colo ny formation of bone marrow cells induced by macrophage colony stimula ting factor in methylcellulose culture. In addition, ST2 cells treated with bFGF produced similar amounts of colony forming activity to thos e without the cytokine. These findings indicated that the bFGF is not involved in the proliferation of progenitor cells even in the presence of ST2 cells. Furthermore, bFGF inhibited osteoclast-like cell format ion induced not only by 1 alpha,25(OH)(2)D-3, but also by prostaglandi n E(2) and by interleukin-11. These results suggest that bFGF inhibits the common site of osteoclast-like cell formation, as induced by diff erent mechanisms. Our data also indicated that the target cells for bF GF in inhibiting osteoclast formation are not osteoclast progenitors b ut stromal cells such as ST2 and osteoblastic cells, which support ost eoclast development. (C) 1996 Wiley-Liss, Inc.