Efeito do ranelato de estrôncio na proliferação, viabilidade e ativação de osteoblastos murinos in vitro

Abstract

The bone tissue is classified as a specialized connective tissue composed by organic and inorganic matrix, osteoclasts and osteoblastic lineage cells. In pathologic procedures, the bone tissue’s homeostasis can be reestablished with some pharmacological therapies, as strontium ranelate, widely used to treat osteoporosis post menopause, because of its inhibitory effects over the osteoclasts and the activation of the osteoblasts. The mechanisms involved, however, are still not completely clarified. OBJECTIVES: This paper has as objective to evaluate the direct effect of strontium ranelate in murine proliferation and activation of osteoblasts, and the possible mechanisms involved. METHODOLOGY: To evaluate the viability and cell proliferation were performed trials of MTT and immunolabeling with Ki67, respectively, after 24 and 48 hours of osteoblasts’ incubation with strontium ranelate. For the MTT, it was used different concentrations of ranelate (0,01; 0,1; 1; 10; 100 and 1000 mM), and by the obtained results, two concentrations (0,01 and 0,1 mM) were selected for the next trials: immunolabeling with Ki67, Western Blot to investigate the protein expression of BMP2, SMAD2/3OPG, RANKL, and alkaline phosphatase (FAO). It was still performed the quantification of the levels of FAO in a culture medium, using specific kits of LABTEST®, after 24, 48, 72 and 120 hours of incubation with strontium ranelate. The mineralization was evaluated by the von Kossa Staining Protocol for Calcium among 7, 14, and 21 days. RESULTS: A significant increase of the viability of osteoblasts was observed after these cells incubation with 0,01 and 0,1 mM of strontium ranelate for 24 hours. BMP2 increased significantly in these two concentrations of the drug used in the period of 24 hours by the Western Blot trial. In the trial to measure the FAO in culture medium, it was observed a significant increase of FAO after incubation with 0,1mM of ranelate for 24 hours. In the von Kossa trial, it was observed an increase and acceleration of mineralization in concentrations of 0,01 and 0,1 mM.CONCLUSION: The results suggest a positive effect of the strontium ranelate in proliferation, viability, and activation of osteoblasts, possibly because of the higher expression of BMP and FAO by osteoblasts. Therefore, promising studies can be performed with the strontium ranelate with its application in regenerating bone defects.