Biocompatibility of magnesium particles evaluated by in vitro cytotoxicity and genotoxicity assays.

Mg is a biodegradable biomaterial which may release particles (MP) to the environment. The possible cyto- and genotoxic effects of MP derived from magnesium powder (mesh 325) were analyzed on rat osteosarcoma UMR106 cells in order simulate the effect of Mg debris. Neutral red (NR) incorporation and acridine orange/ethidium bromide (AO/EB) staining techniques were used as endpoints to analyze the cytotoxic effects at 25-1000 μg/mL concentration range. Genotoxicity was estimated according to micronucleus (MN) formation and the Comet assay (CA). Results showed that MP size changes with time due to corrosion. Changes in lysosomal activity were observed after 24 h only at 1000 μg/mL. Accordingly, AO/EB staining showed a significant decrease in the number of living cells at 500 μg/mL. Transmission electronic microscopy showed MP internalization (60 and 200 nm diameter) in cells after 2-h treatment, whereas no MP was detected after 24 h. A significant dose-dependent increase in MN frequencies was observed at 25-100 μg/mL range (nontoxic range). DNA damage induction was assessed by CA only at 500 μg/mL. Results showed dose-dependent cytotoxic and genotoxic effects of MP on UMR106 cells with different threshold values of MP concentration.