P-759 Comparison of DNA methylation profiles of human embryo cultured in either uninterrupted or interrupted incubators

Abstract

Abstract Study question Are there are differences in the DNA methylation profiles of human embryos cultured in Time-lapse imaging (TLI) and standard incubators (SI)? Summary answer The genome-wide DNA methylation landscape was globally similar between the SI and TLI groups. What is known already Early embryonic development is a special biological process, along with dynamic changes of DNA methylation. In vitro culturing ensured the successful development of human embryo, and is the most important step of ART cycle. TLI is one type of newly developed ART embryo culture systems, which allows for continuous assessment of embryonic development. Our previous study performed transcriptome analysis to compare SI and TLI and found that the global transcriptomic profiles were similar between the two groups. However, whether there are differences in the DNA methylation profiles of human embryos cultured in TLI and SI still unknown. Study design, size, duration This study was designed to explore the influence of SI and TLI incubator culturing on genome-wide DNA methylation of human eight-cell embryos. A total of 9 women who received IVF treatment, ≤ 30 years old (range: 20–30 years), without a history of genetic diseases or smoking were included in this study. Participants/materials, setting, methods Transvaginal oocyte retrieval was performed 36 h after HCG injection. Cumulus-enclosed oocytes were collected in 2.5 mL IVF medium and incubated in 5% O2, 6% CO2, and 37 °C incubators for insemination. The fertilized oocytes were transferred into pre-equilibrated Embryoslides. Then the embryoslides were cultured in either TLI or SI at 37 °C with 5% O2 and 6% CO2 until embryo transfer on Day 3. Samples were sequenced by the Illumina HiSeq 4000 with a 150-bp paired-end. Main results and the role of chance The genome-wide methylation patterns and CpG methylation levels in transposable elements and imprinting control regions of TLI-cultured embryos were similar to those of the SI-cultured embryos. However, a small number of differentially methylated regions (DMRs) were detected, and these DMRs mainly occurred in exons other than promoters. Functional annotation revealed that the genes in DMRs tended to execute functions such as cell cycle, DNA damage stimulus, histone modification, mitochondrial, glucose import, and MAPK signaling pathway. Limitations, reasons for caution Small sample size. Wider implications of the findings Evaluated the safety of TLI culture system from the perspective of DNA methylation at single-cell level, and provided an important reference for understanding the association between embryo culture condition and epigenetic regulation. Trial registration number not applicable