Effects of pH-neutral, super-oxidised solution on human dermal fibroblasts in vitro

For the past 20 years, super-oxidised solutions (SOSs) have been shown to be potent antimicrobials and disinfectants via oxidative damage. However, the potential toxicity of SOSs on eukaryotic cells has not been documented in vitro. This is relevant because oxygen and chlorine reactive species may possibly induce ageing and irreversible cellular dysfunctions that eventually produce cell death. The present study investigates the cytotoxicity and oxidative stress induced by a novel, pH-neutral SOS (i.e. Microcyn, MCN) on young, primary diploid - human dermal fibroblast (HDF) cultures. For this purpose, hydrogen peroxide (HP) was used as a positive control of oxidative damage. When these solutions were used at concentrations indicated for wound care (i.e. undiluted MCN or 880 mM HP), HP was significantly more toxic than MCN. After 5 and 30 minutes of exposure, cell viability was 38% and 5%, respectively, in 880 mM HP-treated cells versus 75% and 70% in MCN-treated populations, respectively. HP induced both apoptosis and necrosis, whereas MCN induced only necrosis. Genotoxic and ageing studies were then conducted at sublethal HP concentrations as previously reported in the literature. Cellular DNA and RNA were partially degraded only in HDFs exposed to 500 microM HP for 30 minutes but not in those exposed to undiluted MCN. At this same concentration, HP induced the formation of 8-hydroxy-2'deoxyguanosine adducts in HDFs but this effect was neither observed in control- nor observed in MCN-treated cells. HDFs were further exposed to 5 microM HP or 10% MCN for 1 month. The expression of senescence-associated-beta-galactosidase was only significantly elevated in cells chronically exposed to 5 microM HP. Altogether, these results show that MCN is significantly less cytotoxic than antiseptic HP concentrations (i.e. 880 mM) and that, in vitro, it does not induce genotoxicity or accelerated ageing.