Comparison of Cytotoxic Effects of Bisphosphonates In Vitro and In Vivo

Abstract

We compared the cytotoxic effects of alendronate (ALN) and incadronate (YM175) on isolated rabbit osteoclasts in vitro and on rats in vivo. In the in vitro experiment, each bisphosphonate was added to the culture of isolated osteoclasts at the final concentration of 3 x 10(-5), 3 x 10(-4), or 3 x 10(-3) M, and the amount of creatine phosphokinase (CPK) released into the medium was taken as an index of cytotoxicity at 5, 10, and 24 hours after the treatment. Also viability of osteoclasts, measured in terms of trypan blue exclusion, was assessed at 24 hours after the treatment. In YM175-treated groups, CPK activity in the medium increased in a concentration-dependent manner with time, and phase-contrast microscopic observation revealed damaged cell membranes and nuclear deterioration in YM175-treated osteoclasts. As a result, the viability of the osteoclasts was decreased at the concentrations of 3 x 10(-4) and 3 x 10(-3) M. However, in the ALN-treated groups, neither CPK activity nor viability of isolated osteoclasts changed significantly compared with control levels even at 3 x 10(-3) M for up to 24 hours. In the in vivo experiment, each bisphosphonate was administered separately to normal rats (7 weeks old, Sprague-Dawley) by intravenous injection at 1, 5, or 25 nmol/kg. Two days after the injection, the animals were euthanized, and the plasma Ca concentration and total CPK activity were measured. In YM175-injected rats, the CPK activity increased at 25 mmol/kg, and a slight decrease in the plasma Ca level was seen at this dose. In contrast, in ALN-injected rats, CPK activity did not increase even at 5 or 25 mmol/kg, and the plasma Ca level did decrease significantly compared with controls. Isozyme analysis revealed that, not only was CPK activity increased in the BB type in YM175-injected rats, it was also increased in the MB and MM types. In conclusion, alendronate, unlike YM175, does not have any cytotoxic effects on osteoclasts either in vitro or in vivo.

The cytotoxic effects of three different bisphosphonates in-vitro on human gingival fibroblasts, osteoblasts and osteogenic sarcoma cells

“…In addition the present study shows and describes the physiologically relevant doses. This confirms the use of 1, 5, 10 and 20 mM concentrations in the current work with its analytical aim, despite of earlier studies using higher concentrations and others suggesting even lower concentrations to be effective (Breuil et al, 1998;Ito et al, 1998;Wood et al, 2002;Im et al, 2004;Suzuki et al, 2007;Journé et al, 2008). Table 2 clearly shows the distinct reactions for the different concentrations for each BP.…”

Intermittent and Continuous Administration of the Bisphosphonate Ibandronate in Ovariohysterectomized Beagle Dogs: Effects on Bone Morphometry and Mineral Properties

“…(28) These in vivo observations are in contrast with in vitro data that point to bisphosphonates as inhibitors of the number of osteoclasts through decrease in osteoclast recruitment (71,72) or shortening of the osteoclast lifespan due to cytotoxicity (73) or apoptosis. (74) However, other in vitro studies showed that aminobisphosphonates such as alendronate are not cytotoxic (75) and do not alter osteoclast number. (76) These data, together with the histomorphometric findings, suggest that bisphosphonates act in vivo primarily on osteoclast activity.…”

Medicinal Surface Modification of Silicon Nanowires: Impact on Calcification and Stromal Cell Proliferation

“…As candidates, bisphosphonates such as alendronate are widely used for the treatment of a variety of bone diseases characterized by excessive bone resorption,16 including tumor-induced hypercalcemia,17 Paget’s disease,18 and osteoporosis 19. They have a strong affinity for calcium phosphate, the major mineral component of bone, and hamper osteoclastic bone resorption by inhibiting the key enzyme farnesyl pyrophosphate synthetase 20,21. Recently, the therapeutic value of bisphosphonates has also been expanded by the discoveries that alendronate is effective in the prevention of urolithiasis by inhibition of calcium stone formation,22 as well as inhibiting invasion of PC-3 prostate cancer cells by affecting the mevalonate pathway 23.…”