A simple approach for COnsumption and RElease (CORE) analysis of metabolic activity in single mammalian embryos

Non-invasive assay of the consumption and release of metabolites by individual human embryos could allow selection at the cleavage stage of development and facilitate Single Embryo Transfer in clinical IVF but will require simple, high throughput, sensitive methods applicable to small volume samples. A rapid, simple, non-invasive method has therefore been devised using a standard fluorescence plate reader, and used to measure the consumption of pyruvate and glucose, and release of lactate by single bovine embryos at all stages of preimplantation development in culture; amino acid profiles have been determined using HPLC. Early embryos with an 'intermediate' level (6.14±0.27 pmol/embryo/h) of pyruvate uptake were associated with the highest rate (68.3%) of blastocyst development indicating that a mid "optimum" range of pyruvate consumption correlates with high viability in this bovine model.