Preliminary Investigation on the Role of Vitrification in Pre-Implantation Genetic Diagnosis

Objective To investigate the feasibility of vitrification of blastocysts following blastomere biopsy. Methods Among patients undergoing pre-implantation genetic diagnosis （PGD）, artificial shrinkage of the blastocoelic cavity and subsequent vitrification of applicable surplus blastocysts after day-3 blastomere biopsy were performed. According to patient requirements, thawed blastocysts were transferred into patients due to pregnancy failure after fresh embryo transfer, ectopic pregnancy, ovarian hyperstimulation. Results Twenty-four PGD cycles were carried out. According to genetic diagnosis and the development of blastocysts, transfer was cancelled in 7 cycles due to absence of applicable embryos or ovarian hyperstimulation. In the remaining 17 cycles, 26 blastocysts were thawed and transferred, which resulted in 13 implanted （50.0%）. Clinical pregnancies were observed in 11 patients （64.71%）. Following transfer, 30 applicable blastocysts in 10 cycles were cryopreserved. Six patients received transfer of thawed blastocysts. All 8 thawed embryos survived and were transferred, and singleton pregnancies occurred in 5 patients. Two women delivered healthy infants and 3 pregnancies are ongoing. Conclusion Vitrification with artificial shrinkage is effective for preserving blastocysts following blastomere biopsy.

Noninvasive preimplantation genetic testing in assisted reproductive technology:current state and future perspectives

Invasive genetic screening of pre-implantation embryos via biopsied trophectoderm(TE)cells has been in use for more than 20 years,while its benefits in selecting euploid embryos remain controversial.Recent advances in the ability to process embryonic cell-free DNA(cfDNA)from blastocoel fluid(BF)and spent culture media(SCM)of blastocysts in a manner similar to that of a biopsied TE sample provide a potential alternative holding great promise for obtaining cytogenetic information of the embryos without intrusive biopsy of traditional biopsy-based pre-implantation genetic testing(PGT).Several studies have reported even higher diagnostic accuracy in non-invasive PGT(ni-PGT)than conventional PGT.However,there are still several technical challenges to be overcome before ni-PGT can be accepted as a reliable genomic information source of embryo.In this review,we have summarized the emergence and current state of ni-PGT,and discussed our own perspectives on their limitations and future prospect.There is still a long way to go before truly wide clinical application of ni-PGT.