Alendronate alters osteoblast activities.

OBJECTIVE: Due to accumulation in the bone matrix and a half-life of at least 10 years, it is important to understand the cellular impact of bisphosphonates (BPs). This study assessed the effects of alendronate (ALN) on human primary osteoblasts.

MATERIAL AND METHODS: Osteoblasts were incubated with ALN (5, 20 and 100 μM), and both cells and cell culture media were harvested after d 1, 3, 7 or 14. Proliferation was evaluated by 3 H-thymidine incorporation and tetrazolium dye (MTT) colorimetric assay, and viability by the lactate dehydrogenase (LDH) activity in the medium. Differentiation was evaluated using protein Luminex multiplex assays and RT-PCR.

RESULTS: ALN had no significant effects on cell viability. The lower concentrations enhanced the proliferation, whereas 100 μM diminished the proliferation. mRNA expression of osteocalcin (OC), alkaline phosphatase (ALP) and α-1 type 1 collagen were reduced, whereas ALN enhanced the expression of leptin mRNA and the secretion of interleukin-8 (IL-8) and regulated on activation normal T cell expressed and secreted (RANTES).

CONCLUSIONS: ALN enhanced the secretion of immune factors from human osteoblasts. Combined with a lower rate of proliferation and a decline in differentiation, this indicates that higher dosages or accumulation may cause undesirable local changes in bone.