Variability in protein quality used for embryo culture: Embryotoxicity of the stabilizer octanoic acid

Objective: To screen human serum albumin (HSA) preparations for toxicity and investigate causes of variation. Design: Experimental laboratory study. Setting: University-based laboratory. Animal(s): FVB and CF1 mice crossed to create embryos used in experiments. Intervention(s): Mouse embryo assay performed with 5% or 15% HSA (100 mg/mL albumin) from three samples from three separate manufacturers (A, B, C). Main Outcome Measure(s): Blastocyst rates calculated at 96 hours of culture (experiments repeated in triplicate). Result(s): The HSA preparations were desalted to remove stabilizers added during HSA processing, then mass spectrometry was used to determine the relative variation in stabilizer concentrations; the effect of the stabilizer octanoic acid on embryo development was tested. At 5% HSA, all samples had blastocyst rates ≥70%; at 15% HSA, the blastocyst rates for samples B and C were <50%. Desalting did not affect sample B but did improve the blastocyst rates of sample C. Mass spectrometry revealed high levels of octanoic acid in sample C compared with sample A. The addition of octanoic acid to sample A produced toxicity similar to sample C. Conclusion(s): The stabilizer octanoic acid varies by lot and inhibits embryo development. Because octanoic acid is known to cause disruptions in mitochondrial bioenergetics, reduce intracellular pH, and induce oxidative damage in peripheral tissues, its use in embryo culture should be monitored and limited.