Opposing effects of bisphosphonates and advanced glycation end-products on osteoblastic cells

Abstract

Patients with long-standing Diabetes mellitus can develop osteopenia and osteoporosis. We have previously shown that advanced glycation endproducts reduce the bone-forming activity of osteoblasts. Bisphosphonates are used for the treatment of various bone disorders, since they reduce osteoclastic function and survival, and stimulate osteoblastic bone-forming capacity. In this work we have investigated whether bisphosphonates are able to revert advanced glycation endproducts-induced deleterious effects in osteoblasts. MC3T3E1 and UMR106 osteoblastic cells were incubated with control or advanced glycation endproducts-modified bovine serum albumin, in the presence or absence of different doses of the bisphosphonates Alendronate, Pamidronate or Zoledronate. After 24-72 h of culture, we evaluated their effects on cell proliferation and apoptosis, type-1 collagen production, alkaline and neutral phosphatase activity, and intracellular reactive oxygen species production. Advanced glycation endproducts significantly decreased osteoblast proliferation, alkaline phosphatase activity and type 1 collagen production, while increasing osteoblastic apoptosis and reactive oxygen species production. These effects were completely reverted by low doses (10 − 8 M) of bisphosphonates. High doses of bisphosphonates (10-10 − 5 M) were toxic for osteoblasts. Nifedipine (L-type calcium channel blocker) did not affect the advanced glycation endproducts-induced decrease in osteoblastic proliferation, although it blocked the reversion of this effect by 10 − 8 M Alendronate. Both advanced glycation endproducts and Alendronate inhibited the activity of intracellular neutral phosphatases. In conclusion, we show that bisphosphonates revert the deleterious actions of advanced glycation endproducts on osteoblastic cells, and that these effects of bisphosphonates depend on: (a) Ca 2+ influx through L-type voltage-sensitive channels, and (b) blockage of advanced glycation endproducts-induced reactive oxygen species generation.

In vitro evaluation of the effects of risedronate associated with cobalamin on osteoblastic cells

“…Thus the statistical significance which was only found at 48 hours represents an isolated piece of information and does not modify the results observed in the study. Stability with the formation of calcium nodules was nondescript for the administration of the drug, in agreement with the reports by Gangoiti et al 5 , Graham et al 2 , Dane et al 3 , Qiu et al 6 and Ferrari et al 7 .…”

“…This demonstrates that this drug apparently does not possess cytotoxic action nor does it interfere with cell proliferation. Gangoiti et al 5 obtained similar results to this study using the same type of MC3T3 cells and bisphosphonates.…”

“…Gangoiti et al 5 demonstrated, in a study carried out using osteoblastic cells, that bisphosphonates do not cause cytotoxic action when administered to the cell culture in the period between 24 and 72 hours, and are capable of reversing the harmful effects of glycation in osteoblasts in patients with osteoporosis and diabetes mellitus. Its effectiveness in reducing bone resorption has been proven in comparative clinical studies after a period of 24 months administering the drug [6][7] .…”

Morphological changes induced by advanced glycation endproducts in osteoblastic cells: Effects of co-incubation with alendronate

“…AGEs-modified bovine serum albumin was prepared by incubation of 10 mg/ml bovine serum albumin (BSA) with 33 mM d-glycolaldehyde in 150 mM phosphate-buffered saline pH 7.4 at 37 • C for 3 days under sterile conditions, as previously described (Gangoiti et al, 2008). d-Glycolaldehyde was used as the glycating sugar instead of glucose to speed up non-enzymatic glycosylation.…”

“…In a recent study we showed that low doses (10 −8 M) of BP completely prevented the AGEs-induced alterations in osteoblast proliferation, differentiation, apoptosis and reactive oxygen species production (Gangoiti et al, 2008). However, high doses of BP (10 −4 -10 −5 M) were toxic for osteoblasts.…”