Early development of certain mammalian embryos is protected by complex checkpoint systems to maintain the genomic integrity. Several metabolic pathways are modulated in response to genetic insults in mammalian cells. The present study investigated the relationship between the genetic integrity, embryo metabolites and developmental competence in preimplantation stage mouse embryos with the aim to identify early biomarkers which can predict embryonic genetic integrity using spent medium profiling by NMR spectroscopy. Embryos carrying induced DNA lesions (IDL) developed normally for the first 2.5 days, but began to exhibit a developmental delay at embryonic day 3.5(E3.5) though they were morphologically indistinguishable from control embryos. Analysis of metabolites in the spent medium on E3.5 revealed a significant association between pyruvate, lactate, glucose, proline, lysine, alanine, valine, isoleucine and thymine and the extent of genetic instability observed in the embryos on E4.5. Further analysis revealed an association of apoptosis and micronuclei frequency with P53 and Bax transcripts in IDL embryos on the E4.5 owing to delayed induction of chromosome instability. We conclude that estimation of metabolites on E3.5 in spent medium may serve as a biomarker to predict the genetic integrity in pre-implantation stage embryos which opens up new avenues to improve outcomes in clinical IVF programs.

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This study aims to investigate the influence of two- (day 2) and six-to-eight-cell-stage (day 3) laser-assisted hatchings on the developmental potential and genetic integrity of the embryos. In this prospective experimental study, two- and six-to-eight-cell-stage mouse embryos were subjected to laser hatching using 1,480 nm diode laser, and then assessed for the developmental potential and DNA integrity in blastocysts. Similarly, four-cell-stage human embryos from 20 patients were also subjected to laser hatching, and then assessed for the developmental competence. Laser-assisted hatching in mouse embryos significantly enhanced the blastocyst hatching potential on day 4.5 (P < 0.0001). However, a significant decline in blastocyst total cell number (TCN) was observed in six-to-eight-cell-stage laser-hatched embryos (P < 0.001). Conversely, no significant difference in TCN was observed between laser-hatched and unhatched human four-cell-stage embryos after 24 h. Attempt to understand the genetic integrity in laser-hatched mouse blastocysts revealed significantly higher labeling index when hatching was done at two- (P < 0.01) and six-to-eight-cell stage (P < 0.05). DNA damage induced by the laser manipulation may affect implantation and postimplantation developmental potential of the embryos. However, further studies are required to elucidate the impact of laser-induced DNA damage on the reproductive outcome.