Human gingival fibroblasts secrete non‐dialyzable, prostanoid‐independent products which stimulate bone resorption in vitro

Conditioned media from human gingival fibroblasts stimulate release of radioactive calcium, stable calcium and inorganic phosphate from mouse calvarial bones in organ culture. In addition, human gingival fibroblast‐conditioned media decrease the hydroxyproline content in the bones. Stimulation of mineral mobilization could be reduced by calcitonin, bisphosphonates and glucocorticoids, but not by cyclooxygenase inhibitors. The production of stimulating factors by fibroblasts was unaffected by indomethacin, meclofenamic acid and naproxen. Dialysis of human gingival fibroblast‐conditioned media showed that the product(s) had a molecular weight larger than 3000 daltons. Bone resorbing activity in human fibroblast‐conditioned media was heat‐labile. These data show that human gingival fibroblasts can secrete non‐prostanoid products with the ability to stimulate osteoclastic bone resorption in vitro .