Relationship between bisphosphonate concentration and osteoclast activity and viability

Abstract

Difluoromethylidene bisphosphonate (F2MBP) is one of the many bisphosphonates known to inhibit bone resorption in vitro and in vivo. We have developed an analytical method, employing anion exchange and postcolumn indirect fluorescence detection, by which F2MBP can be quantified in bone samples. The objective of this study was to relate the concentration of F2MBP in embryonic bones treated in organ culture to the physiological effects of the compound, such as bone resorption (i.e., the amount of 45Ca released into the medium from prelabeled bones) and viability of the osteoclast population (i.e., the incidence of abnormal osteoclasts). Osteoclasts in bones treated with F2MBP exhibited morphological features of apoptosis, such as nuclear fragmentation. Both the number and percentage of these abnormal cells increased with dose of F2MBP and duration of incubation. The decrease in normal osteoclasts was correlated with the decreased amount of 45Ca released into the medium. Bones treated with F2MBP for only the first 5 min of the 48-h incubation period had similar numbers of abnormal osteoclasts and amounts of 45Ca released, as had bones incubated with F2MBP continuously for 48 h. The uptake of F2MBP into the bone was rapid. Bones treated with F2MBP for 6 h were similar to bones treated with F2MBP for the entire 48-h incubation period, both in F2MBP concentration and the 45Ca release ratios. These relationships between concentrations of F2MBP within bone and osteoclast activity and viability implicate apoptosis in the mechanism by which this bisphosphonate inhibits bone resorption.

Cellular and molecular mechanisms of action of bisphosphonates

“…[21][22][23][24][25] All such bisphosphonates have been found to be of similar potency or less potent than clodronate. [21][22][23][24][25] All such bisphosphonates have been found to be of similar potency or less potent than clodronate.…”

Alendronate Affects Cartilage Resorption by Regulating Vascular Endothelial Growth Factor Expression in Rats

“…Bisphosphonates have a similar chemical structure (P‐C‐P) to endogenous inorganic pyrophosphate (P‐O‐P). They accumulate selectively in hard tissue and inhibit bone resorption by the chelation of Ca 2+ ions (Fleish,1998) and the direct inhibition of osteoclasts (Rowe et al,1999; Reinholz et al,2000; Rogers et al,2000). Many clinical applications of these properties have been attempted in the treatment of osteoporosis, Paget disease, bone metastasis of tumor cells, etc.…”

New trends in the treatment of bone metastasis

“…Bisphosphonates are a group of chemicals that inhibit osteoclast activity resulting in decreased bone resorption and thus have received much attention as inhibitors of clinical complications of bone metastases [Mundy, 1999; Diel et al, 2000; Major et al, 2000]. Bisphosphonates work directly on osteoclasts to induce their apoptosis [Fleisch, 1997; Rowe et al, 1999]. Animal studies have demonstrated that bisphosphonates can diminish tumor‐induced osteoclastogenesis and osteolysis [Hall and Stoica, 1994; Yoneda et al, 1997, 2000; Kurth et al, 2000; Clohisy et al, 2001].…”