Osteoblast-osteoclast interaction in bone resorption. Preliminary results.

Osteoclastic bone resorption has been evaluated in vitro by release of tritiated collagen fragments from 3H-proline prelabeled bone particles incubated for 48 hours in presence of avian isolated osteoclasts. Cells were co-incubated with periosteum-free chick calvarial fragments by interposition of 0.4 micron millipore membrane transwells, in presence or absence of 10(-8) M 1.34 bovine parathyroid hormone (PTH). Results demonstrated that i) calvaria exert a stimulating effect over osteoclastic bone resorption which was 1.8 fold enhanced with respect to controls (p less than 0.001). ii) the stimulating effect is exerted by calvarium-derived soluble molecules capable of crossing the 0.4 micron millipore membrane interposed between calvarial fragments and osteoclasts, iii) in this experimental system no further enhancement of calvarial stimulating effect is operated by PTH treatment.