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

PurposeTo 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 MethodsOsteoblast-like cells (MG63) were incubated in culture medium with different doses of clodronate. Their proliferative capacity was determined with a spectrophotometric technique (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium assay). Flow cytometry was used to study the antigenic profile. Cell differentiation was evaluated by nodule formation and alkaline phosphatase (ALP) activity was measured by spectrophotometric assay.ResultsClodronate had a significant stimulatory effect on osteoblast-like cell (MG63) proliferation (P < .05). A significant decrease in the expression of CD54, CD80, CD86, and HLA-DR membrane antigens versus controls was observed after 24 hours of treatment with the different clodronate doses assayed (P < .05). A significant decrease (P = .004) in ALP activity was found after 24 hours of treatment with the lowest dose (10−9 mol/L), and a significant decrease in calcium deposition was found after 15 and 21 days of treatment (P < .05).ConclusionClodronate increases the proliferation of MG63 osteoblast-like cells and decreases their differentiation capacity, generally at low doses, and modulates the expression of costimulatory molecules associated with immune function. Clodronate exerts its effect on osteoblasts by altering their physiology and impairing their repair capacity, which could be related to the development of BRONJ. However, further research is warranted to elucidate fully the mechanisms by which bisphosphonates can produce this disease.