BACKSCATTERED ELECTRON IMAGE ASSESSMENT OF MINERAL DENSITY IN BONE FORMED IN-VITRO

Backscattered electron (BSE) image analysis was used to determine whet her mineral density profiles for bone formed in an in vitro bone forma tion model, the chick periosteal osteogenesis (CPO) system, could be q uantified. CPO cultures were treated with various regimens of bisphosp honates {1-hydroxyethane-1,1-bisphosphonate (HEBP), or um-1-hydroxy-2- aminopropylidine-1,1-bisphosphonate (APD)}. Some cultures were treated with HEBP (50 mu M) for the first 6 days of culture and then chased, without HEBP, for 6 more days to demonstrate ''recovery'' from HEBP-me diated blockage of mineralization. Since low-dose APD might increase m ineral uptake, other 12 day cultures were treated with this drug durin g the HEBP-recovery phase. Cultures (12 day) exposed to HEBP over the first 6 days only, demonstrated markedly increased mineral density (p < 0.0005) as compared to the 12-day controls. APD had no additional ef fect on mineral density in 12-day cultures when added during the HEBP- recovery period (p > 0.05). These findings suggest that BSE can be use d to assess mineral density of bone formed in vitro, and that bisphosp honates may influence bone mineral density directly.