Multi-omics PGT: re-evaluation of euploid blastocysts for implantation potential based on RNA sequencing

Noninvasive Biomarkers of Human Embryo Developmental Potential

There are two types of noninvasive biomarkers of human embryo developmental potential: those based on a direct assessment of embryo morphology over time and those using spent media after embryo in vitro culture as source of information. Both are derived from previously acquired knowledge on different aspects of pre-implantation embryo development. These aspects include embryo morphology and kinetics, chromosomal ploidy status, metabolism, and embryonic gene transcription, translation, and expression. As to the direct assessment of morphology and kinetics, pertinent data can be obtained by analyzing sequential microscopic images of in vitro cultured embryos. Spent media can serve a source of genomic, metabolomic, transcriptomic and proteomic markers. Methods used in the early pioneering studies, such as microscopy, fluorescence in situ hybridization, autoradiography, electrophoresis and immunoblotting, or enzyme-linked immunosorbent assay, are too subjective, invasive, and/or time-consuming. As such, they are unsuitable for the current in vitro fertilization (IVF) practice, which needs objective, rapid, and noninvasive selection of the best embryo for uterine transfer or cryopreservation. This has been made possible by the use of high-throughput techniques such as time-lapse (for direct embryo evaluation), next-generation sequencing, quantitative real-time polymerase chain reaction, high-performance liquid chromatography, nanoparticle tracking analysis, flow cytometry, mass spectroscopy, Raman spectroscopy, near-infrared spectroscopy, and nuclear magnetic resonance spectroscopy (for spent culture media analysis). In this review, individual markers are presented systematically, with each marker's history and current status, including available methodologies, strengths, and limitations, so as to make the essential information accessible to all health professionals, even those whose expertise in the matter is limited.

Association between hatching status and pregnancy outcomes in single blastocyst transfers: a retrospective cohort analysis

OBJECTIVE

To examine the potential association between blastocyst hatching status and pregnancy outcomes following single blastocyst transfer.

METHODS

This is a retrospective cohort. We screened all frozen-thawed single blastocyst transfer cycles from January 1, 2020, to April 30, 2022, at the authors' center. The hatching status was graded into four categories: unhatched, early hatching (hatched portion < the diameter of zona pellucida), late hatching (hatched portion > the diameter of zona pellucida), and fully hatched. Multivariate logistic regression was used to examine the association between hatching status and pregnancy outcomes (clinical pregnancy and live birth).

RESULTS

The final analysis included 906 cycles. The hatching status was unhatched in 116 cycles, early hatching in 556 cycles, late hatching in 197 cycles, and fully hatched in 37 cycles. The clinical pregnancy rate was 54.3%, 63.3%, 74.6%, and 54.1%, respectively (p = 0.001) in the unhatched, early-hatching, late-hatching, and fully hatched groups, respectively. The live birth rate was 39.7%, 51.6%, 58.3%, and 40.5%, respectively (p = 0.008). In pairwise comparisons, the late-hatching group had significantly higher rates of clinical pregnancy and live birth versus the unhatched category (p = 0.001 and p = 0.008, respectively). In multivariate logistic regression analysis, embryo hatching status, the duration until blastocyst formation, the grading of blastocyst cells, and the thickness of the endometrium were associated with clinical pregnancy and live birth.

CONCLUSION

After adjusting for confounding factors, late-hatching status of the blastocysts was associated with a higher rate of clinical pregnancy and live birth.