Epigenotoxic Effect of Dimethyl Sulfoxide on Buffalo Somatic Cells and Buffalo-Bovine Interspecies Somatic Cell Nuclear Transfer Embryos

Objective: In the present study, we investigated the possible epigenotoxic effect of dimethyl sulfoxide (DMSO) on buffalo fibroblast cells and on reconstructed oocytes during buffalo-bovine interspecies somatic cell nuclear transfer (iSCNT) procedure and its effect on rate and quality of blastocyst which derived from these reconstructed oocytes. Materials and Methods: In this experimental study, cell viability of buffalo fibroblasts was assessed after exposure to various concentration (0.5, 1, 2 and 4%) of DMSO using MTS assay. The epigenetic effect of DMSO was also assessed in terms of DNA methylation in treated cells by flowcytometry. Reconstructed oocytes of buffalo-bovine iSCNT exposed for 16 hours after activation to non-toxic concentration of DMSO (0.5%) to investigate the respective level of 5-methylcytosine, cleavage and blastocyst rates and gene expression (pluripotent genes: OCT4, NANOG, SOX2, and trophectodermal genes: CDX2 and TEAD4) of produced blastocysts. Results: Supplementation of culture medium with 4% DMSO had substantial adverse effect on the cell viability after 24 hours. DMSO, at 2% concentration, affected cell viability after 48 hours and increased DNA methylation and mRNA expression of DNMT3A in fibroblast cells. Exposure of reconstructed oocytes to 0.5% DMSO for 16 hours post activation did not have significant effect on DNA methylation, nor on the developmental competency of reconstructed oocyte, however, it decreased the mRNA expression of NANOG in iSCNT blastocysts. Conclusion: Depending on the dose, DMSO might have epigenotoxic effect on buffalo fibroblast cells and reconstructed oocytes and perturb the mRNA expression of NANOG in iSCNT blastocysts.