The effect of heparin on IL-11–induced osteoclast development and pit formation.

(A) Cocultures of murine calvaria and bone marrow cells were maintained in the absence or presence of 20 ng/mL IL-11 and increasing doses of heparin (10 or 25 μg/mL). Nine days later the cells were stained for TRAPase activity and the number of multinucleated TRAP⁺ cells per well was determined. (B) Cocultures of murine calvaria and marrow cells were cultured on top of 1.0 cm² smooth cortical bone slices in the absence or presence of 20 ng/mL IL-11 and increasing doses of heparin (10 or 25 μg/mL). Twenty-one days later the cells were solubilized and the bone slices examined by light microscopy for pit formation. Data are expressed as mean ± SEM. *P < .01 when compared with the number of TRAP⁺ cells counted in the presence of IL-11 alone.