Assessment of the genotoxicity of three cryoprotectants used for human oocyte vitrification: Dimethyl sulfoxide, ethylene glycol and propylene glycol

Vitrification requires high concentrations of cryoprotectants that may induce long-term toxic effects on cells. The aim of this study was to evaluate the possible genotoxicity of three cryoprotectants extensively used for oocyte vitrification: dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PROH). For this purpose, a Chinese Hamster Ovary cell line (CHO), commonly used in genetic toxicology, was selected as an in vitro biological model to assess both the induction of DNA strand-breaks as identifiable by the alkaline comet assay and the persistence of chromosomal damages (micronuclei) as analyzed by the micronucleus assay. Results showed that DMSO was not genotoxic. EG did not exert direct genotoxic activity, however EG exhibited significant genotoxic and clastogenic activities in the presence of an external cytochrome-based P450 oxidation system (S9 Mix). PrOH produced in vitro DNA-damage leading to chromosome mutations in the presence and absence of the S9 Mix. These results showed that high concentrations of EG and PrOH could induce in vitro chromosomal damage in eukaryotic cells.