Control of oxidative stress by an amino-acid derivative

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This project tested the protective potential of N-acetyl cysteine, an antioxidant, amino acid derivative(AAD), in controlling oxidative stress against osteoblasts. Osteoblastic cells extracted from rat bone marrow were cultured. Oxidative stress was induced by adding H2O2 into the culture media. Then, some H2O2-treated cultures were cotreated with AAD. Addition of H2O2 decreased the number of cells to 50% of untreated cultures at days 2. Addition of AAD into H2O2 cultures resulted in a dose-dependent increase in the number of cells, with the cell number being 50% greater than that in the H2O2 culture. The gene expression levels of type I collagen, osteopontin, and osteocalcin were downregulated threefold by H2O2 on day 7. The H2O2-suppressed gene expression was fully recovered by AAD cotreatment. The mineralizing capability, assessed by Von Kossa staining on day 15, were approximately 1. 8 times greater in the AAD+H2O2 cotreated group than in the culture with H2O2 alone. These AAD-mediated restorations were associated with an AAD dose-dependent increase of intracellular glutathione and a AAD dose-dependent decrease of intracellular reactive oxygen species. In conclusion, oxidative stress induced by H2O2 substantially impairs the proliferation, differentiation, and mineralization of osteoblasts. More importantly, the addition of AAD into the culture was found to restore these damages to a near normal level due to the improved redox balance, warranting further in vivo studies to test its therapeutic potential as a local antioxidative stress drug.