Dr. Qingling Yang
Dr. Qingling Yang received his Ph.D. in 2013 from the University of Science and Technology of China. He has since been working as a research assistant and clinical embryologist at the Reproductive Medical Center of the fi rst Affi liated Hospital of Zhengzhou University. His current research involves the study of genes involved in DNA damage and repair during spermatogenesis and early embryonic development.
Project: Telomere length test of cell-free genomic DNA in spent embryo medium
Assessment of embryos with optimum development potential is one of the major challenges in human IVF technology. Routinely, embryo selection for transfer is mainly based on morphological and developmental characteristics. However, embryo morphology does not necessarily reflect functional status, and previous studies showed that 30–50% of normal looking embryos are chromosomally abnormal (Capalbo, et al., 2014, Fragouli, et al., 2014, Munne, 2006). In terms of aneuploidy, which is believed to be the single biggest cause of embryo implantation failure and miscarriage, what advantages can indirect methods of detection confer? Telomeres are non-coding DNA sequences with hexa-nucleotide tandem repeats (5’TTAGGG3’) that cap chromosome ends (Chan and Blackburn, 2002). Our previous study showed that sperm telomere length is positively associated with the quality of early embryonic development, which was published on Human Reproduction (Yang, et al., 2015). Another study found that shorter telomere length is indeed associated with aneuploidy in oocytes and early pre-implantation stage embryos (Treff, et al., 2011). These results indicate that telomere DNA deficiency (shorter telomere length) may count partly for embryo aneuploidy and may serve as a marker for embryos. On the hand, recent studies showed that cell-free DNA (cfDNA) can be released into the culture medium (Stigliani, et al., 2013). So we hypothesized that early embryonic development is associated with changes in the amount of telomeric cfDNA that can be detected in the spent medium. The aim of this project is to determine the relationship between telomeric cfDNA levels in spent embryo culture medium and early embryonic development potential in clinical IVF-ET procedure. We use a novel, highly sensitive and specifi c quantitative PCR (qPCR) assay, termed telomeric cfDNA qPCR, as described previously with some modifi cation (Xi, 2015), to quantify telomeric cfDNA levels in embryo culture medium in pre-implanation genetic screening (PGS) cycles. Aneuploidy assignments of the embryos are based on single nucleotide polymorphism (SNP) microarray in our center. These data were compared with the IVF outcomes. The telomere length of cell-free DNA in spent medium may have the potential to be used as a marker for embryo selection.