Faculty Bibliography

Uroplakin (UP) tetraspanins and their associated proteins are major mammalian urothelial differentiation products that form unique 2D-crystals of 16-nm particles ("urothelial plaques") covering the apical urothelial surface. Although uroplakins are highly expressed only in mouse urothelium and are often referred to as being urothelium-specific, they are also expressed in several nonurothelial cell types in stomach, kidney, prostate, epididymis, testis/sperms and ovary/oocytes. In oocytes, uroplakins co-localize with CD9 on cell surface and multivesicular body-derived exosomes, and the cytoplasmic tail of UPIIIa undergoes a conserved fertilization-dependent, Fyn-mediated tyrosine-phosphorylation that also occurs in Xenopus laevis eggs. Uroplakin knockout and antibody blocking reduce mouse eggs' fertilization rate in in vitro fertilization assays, and UPII/IIIa double-knockout mice have a smaller litter size. Phylogenetic analyses showed that uroplakin sequences underwent significant mammal-specific changes. These results suggest that, by mediating signal transduction and modulating membrane stability that do not require 2D-crystal formation, uroplakins can perform conserved and more ancestral fertilization functions in mouse and frog eggs. Uroplakins acquired the ability to form 2D- crystalline plaques during mammalian divergence enabling them to perform additional functions, including umbrella cell enlargement and the formation of permeability and mechanical barriers, in order to protect/modify the apical surface of the modern-day mammalian urothelium.

Aneuploid conceptions constitute the majority of pregnancy failures in women of advanced maternal age. The best way to combat age-related decline in fertility is through preimplantation genetic testing for aneuploidy (PGT-A). PGT-A allows for better embryo selection, which improves implantation rates with single embryo transfer and reduces miscarriage rates. Single embryo transfers decrease multiple gestations and adverse pregnancy outcomes such as preterm or low birth weight infants. Advancements in extended embryo culture, blastocyst biopsy techniques, and 24-chromosome aneuploidy screening platforms have made PGT-A safe and accessible for all patients who undergo in vitro fertilization. Improved genomic coverage of new sequencing platforms, such as next-generation sequencing, has increased the identification and diagnosis of mosaicism and partial aneuploidies in preimplantation embryos. Mosaic embryos have decreased viability compared to euploid embryos when transferred, but some mosaic embryos result in normal live births. Whole genome amplification artifacts may contribute to a misdiagnosis of mosaicism, or some mosaic embryos may self-correct to euploid after implantation. For this reason, patients without euploid embryos should be given the option of transferring mosaic embryos after genetic counseling. Further research is needed to characterize which mosaic embryos may be viable.

OBJECTIVE:To evaluate whether the use of next generation sequencing (NGS) for preimplantation genetic screening (PGS) in single thawed euploid embryo transfer (STEET) cycles improves pregnancy outcomes compared with array comparative genomic hybridization (aCGH). DESIGN/METHODS:Retrospective cohort study. SETTING/METHODS:Single university-based fertility center. PATIENT(S)/METHODS:A total of 916 STEET cycles from January 2014 to December 2016 were identified. Cases included 548 STEET cycles using NGS for PGS and controls included 368 STEET cycles using aCGH for PGS. INTERVENTION(S)/METHODS:Patients having a STEET after undergoing IVF and PGS with either NGS or aCGH. MAIN OUTCOME MEASURE(S)/METHODS:Primary outcomes were implantation rate, ongoing pregnancy/live birth rate (OP/LBR), biochemical pregnancy rate (PR), and spontaneous abortion (SAB) rate. RESULT(S)/RESULTS:The implantation rate was significantly higher in the NGS group compared with the aCGH group (71.6% vs. 64.6%). The OP/LBR was also significantly higher in the NGS group (62% vs. 54.4%), and there were significantly more biochemical pregnancies in the aCGH group compared with the NGS group (15.1% vs. 8.7%). After adjustment for confounding variables with a multiple logistic regression analysis, OP/LBR remained significantly higher in the NGS group. The SAB rate was not significantly different in the NGS group compared with the aCGH group (12.4% vs. 12.7%). CONCLUSION(S)/CONCLUSIONS:Preimplantation genetic screening using NGS significantly improves pregnancy outcomes versus PGS using aCGH in STEET cycles. Next-generation sequencing has the ability to identify and screen for embryos with reduced viability such as mosaic embryos and those with partial aneuploidies or triploidy. Pregnancy outcomes with NGS may be improved due to the exclusion of these abnormal embryos.