Endocytosis of sialic acid Neu5Gc and elevated p53 contributes to preimplantation embryonic arrest during in vitro fertilization.

The persistently low success rate of human in vitro fertilization (IVF) remains a major clinical challenge, despite significant technological advancements. While culture media composition is known to influence outcomes, the specific components affecting embryonic development are poorly understood. In this study, we identify N-glycolylneuraminic acid (Neu5Gc), a foreign sialic acid contaminant prevalent in animal-derived IVF media components, as a micro-environmental factor triggering developmental arrest. We demonstrate that Neu5Gc accumulates in arrested human embryos via endocytosis and upregulates p53, leading to caspase-3/PARP -dependent apoptotic pathways. This mechanism was validated in human embryonic stem cells (hESCs) and zebrafish embryos, with antibody-mediated Neu5Gc neutralization rescuing developmental defects. Our findings not only elucidate a novel pathway contributing to IVF inefficiency but also provide actionable insights for optimizing culture media formulations.