The Effect of Clodronate on Antigenic Profile, Growth and Differentiation of Osteoblast-Like Cells

Abstract Purpose To evaluate the role of osteoblasts in bisphosphonate-related osteonecrosis of the jaw (BRONJ) by studying the effects of different concentrations of clodronate, a non-nitrogen-containing bisphosphonate, on osteoblast growth, differentiation, and antigenic profile. Materials and Methods Osteoblasts-like cells (MG63) were incubated in culture medium with different doses of clodronate. Their proliferative capacity was determined with a spectrophotometric technique (MTT). Flow cytometry was used to study the antigenic profile. Cell differentiation was evaluated by the study of nodule formation and alkaline phosphatase (ALP) activity was measured by spectrophotometric assay. Results Clodronate had a significant stimulatory effect on osteoblast-like cells (MG63) proliferation ( p< 0.05). A significant decrease in the expression of CD54, CD80, CD86 and HLA-DR membrane antigens versus controls was observed after 24 h of treatment with the different clodronate doses assayed ( p< 0.05). A significant decrease ( p =0.004) in ALP activity was found after 24h of treatment with the lowest dose (10-9 M), and a significant decrease in calcium deposition was found after 15 and 21 days of treatment ( p< 0.05). Conclusion Clodronate increases the proliferation of MG-63 osteoblast-like cells and decrease their differentiation capacity, generally at low doses, and modulate the expression of co-stimulatory molecules associated with immune function. Clodronate exerts its effect on osteoblasts by altering their physiology and impairing their repair capacity, which may be related with the development of bisphosphonates-related osteonecrosis of the jaw (BRONJ). However, further research in this line is warranted to fully elucidate the mechanisms by which bisphosphonates can produce this disease.