The Influence of Culture Medium and Protein Supplementation on the Sensitivity of the Mouse Embryo Assay to Detect Triton X-100

Research question: To what extent does the type and concentration of protein and the type of culture medium affect the sensitivity of the mouse embryo assay (MEA) to detect Triton X-100 (TX-100) in culture media? Design: The effect of the concentration of bovine serum albumin (BSA) and human serum albumin (HSA) was assessed by supplementing media with 0.5 or 5 mg/ml. Potassium-supplemented simplex optimized medium (KSOM) and human tubal fl uid (HTF) were used as complex and simple formulation media, respectively. Variables were combined, forming study groups where embryos were cultured in test media spiked with a sublethal TX-100 concentration. The conditions of greatest sensitivity were determined by statistical comparison of blastocyst formation rates and total cell counts between groups. Results: Although all of the study groups showed equal capacity for sustaining proper embryo development, the reported sensitivity of the MEA differed between groups when subjected to TX-100. HTF conferred significantly fi cantly greater sensitivity than KSOM regardless of the type and concentration of protein used, and medium supplementation with 5 mg/ml BSA rather than 0.5 mg/ml BSA resulted in significantly fi cantly higher sensitivity regardless of the type of medium used. This increase in concentration also resulted in higher sensitivity when supplementing HTF with HSA. The BSA groups provided more sensitivity than their HSA counterparts, except for the KSOM + 0.5 mg/ml BSA group. Cell count analysis did not provide further significant fi cant conclusions. Conclusions: For TX-100 detection within culture medium, the type and concentration of protein and the type of culture medium have a direct effect on MEA sensitivity. These results could help to standardize the MEA protocol, and increase its ability to detect sublethal concentrations of embryotoxic substances, especially TX-100, thus avoiding possible clinical harmful effects.