Non-Invasive Human Embryo Metabolic Assessment as a Developmental Criterion

Abstract

The selection of a highly-viable single embryo in assisted reproductive technology requires an acceptable predictive method in order to reduce the multiple pregnancy rate and increase the success rate. In this study, the metabolomic profiling of growing and impaired embryos was assessed on the fifth day of fertilization using capillary electrophoresis in order to find a relationship between the profiling and embryo development, and then to provide a mechanistic insight into the appearance/depletion of the metabolites. This unique qualitative technique exhibited the appearance of most non-essential amino acids and lactate, and depleting the serine, alanyl-glutamine and pyruvate in such a manner that the embryos impaired in their development secreted a considerably higher level of lactate and consumed a significantly higher amount of alanyl-glutamine. The different significant ratios of metabolomic depletion/appearance between the embryos confirm their potential for the improvement of the prospective selection of the developed single embryos, and also suggest the fact that pyruvate and alanyl-glutamine are the most critical ATP suppliers on the fifth day of blastocyst development.

Capillary electrophoresis–mass spectrometry as a tool for the noninvasive target metabolomic analysis of underivatized amino acids for evaluating embryo viability in assisted reproduction

“…Another significantly increased concentration was found for Gln, which was associated with higher development stages, differences were found between unfertilized oocytes compared to well‐developing embryos up to 8‐cell embryos or embryos that reached the morula or blastocyst stage: (4)–(2), (4)–(1); and also between embryos that failed to develop or well‐developing embryos up to 8‐cell embryos compared to embryos that reached the morula or blastocyst stage: (3)–(1), (2)–(1). Elevated Gln levels were reported in the literature [7,12,27,33,34]. On the other hand, Gln consumption was also reported [35].…”

“…Moreover, the combination of CE with MS detection offers the definitive identification of metabolites and also the identification of new metabolic targets. So far CE has been used for the analysis of lactate, pyruvate, and AAs in spent media with conductivity and LIF detection [7,26,27]. Besides this, CE-MS was used for the single-cell metabolomic analysis of frog Xenopus laevis embryos [28] and there were recently published several reviews on CE-MS for metabolomics [29,30].…”

Amino Acids and the Early Mammalian Embryo: Origin, Fate, Function and Life-Long Legacy

“…However, as a precaution against possible toxicity, glutamine is almost universally added to embryo culture media in the form of a dipeptide; usually, alanyl glutamine or glycyl glutamine, which can replace glutamine in [ 70 , 71 ]. Motiei et al [ 72 ] recently reported that these dipeptides are depleted from the culture medium of viable embryos. It is presumed that they are taken up intact by the embryo and hydrolysed intracellularly to provide glutamine and the companion amino acid, though some may be broken down by extracellular, vesicle-derived peptidases released by the embryo.…”

The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?

“…Until the morula stage, cell divisions are said to be reductive because they take place at constant embryonic volume within the zona pellucida (around 120 µm). From day 4, embryo metabolism switches towards the consumption of glucose and amino acids [ 71 , 72 ].…”