Cytotoxicity and Genotoxicity Evaluation of Fluorapatite/bioactive Glass Nanocomposite Foams With Two Various Weight Ratios as Bone Tissue Scaffold: an in vitro study

The optimization of biomaterials biodegradation rate similar to tissue regeneration, is one of the main goals in the field of tissue engineering. However, the necessity to assess their possible toxicity is always considered. The aim of this study was cytotoxicity and genotoxicity evaluation of fluorapatite/bioactive glass (FA/BG) nanocomposite foams with two various weight ratios to determine the optimal composition. Nanocomposite foams were made by gel-casting method with FA and BG as precursors in two weight ratios (A and B). Nanocomposite foam extracts (CFEX) were prepared by shaking 100 mg/mL of each foam in a complete culture medium for 72 h in a shaker incubator at 120 rpm/37ºC. Saos-II cells were exposed to different concentrations of CFEXs for 24 and 48 h and then cytotoxicity and genotoxicity were evaluated by MTT and comet assay, respectively. Based on the MTT assay results after 24 h exposure, CFEX A at concentrations ≥75% and CFEX B at concentrations ≥50% had a cytotoxic effect, while after 48 h, both CFEXs showed similar cytotoxicity at concentrations ≥25%. According to the result of the comet assay, DNA damage increased with the increase of CFEXs concentration and exposure time. Both CFEXs showed significantly higher comet tails elongation scores at concentrations ≥50% and ≥25% after 24 and 48 h exposure, respectively. Both composite foams could be considered as a non-toxic candidate for tissue engineering at concentrations <25% which was less than FA50%/BG50% composite. Therefore, the composite with equal FA/BG proportion has priority if similar results are obtained in in vivo complementary experiments.