Culture medium and protein supplementation affect sensitivity of the mouse embryo assay in detecting Triton X-100

Abstract

Research question: To what extent does the type and concentration of protein and the type of culture medium affect the sensitivity of Mouse Embryo Assays (MEAs) to detect Triton X-100 (TX-100) in culture media?Design: The effect of bovine (BSA) and human serum albumin (HSA) concentration was assessed by supplementing media with 0.5 or 5mg/ml. KSOM and HTF were used as complex and simple-formulation media, respectively. Variables were combined forming study groups where embryos were cultured in tested media spiked with a sublethal TX-100 concentration. The conditions of greatest sensitivity were determined by statistically comparing blastocyst formation rates and total cell counts between groups.Results: Although all the study groups showed an equal capacity of sustaining a proper embryo development, the reported sensitivity of the MEA differed between groups when subjected to TX-100. HTF significantly conferred greater sensitivity than KSOM regardless of the amount/type of protein used, whereas medium supplementation with 5mg/ml BSA rather than 0.5mg/ml also resulted in significantly higher sensitivity regardless of the type of medium used. This increase in concentration also resulted in a higher sensitivity when supplementing HTF with HSA. BSA groups provided more sensitivity than its HSA-counterparts except for the group 0.5mg/ml-KSOM. Cell counting analysis did not provide further significant conclusions.Conclusions: For TX-100 detection within culture medium, the concentration and type of protein supplementation and the culture medium type impact directly on MEA sensitivity. These results could help to standardize MEA protocols and increase their ability to detect sublethal amounts of embryotoxic substances, especially TX-100, avoiding possible clinical harmful effects.