Telomere length in human blastocysts

Abstract

This is a retrospective study aiming to assess telomere length in human embryos 4days post fertilization and to determine whether it is correlated to chromosomal ploidy, embryo developmental rate and patient age. Embryos were donated from patients undergoing treatment in the assisted conception unit. Seven couples took part, generating 35 embryos consisting of 1130 cells. Quantitative fluorescent in-situ hybridization (FISH) measured the telomere length of every cell using a pan-telomeric probe. Conventional FISH on six chromosomes was used to assess aneuploidy in the same cells. Maternal and paternal age, referral reason, embryo developmental rate and type of chromosomal error were taken into account. Chromosomally abnormal cells were associated with shorter telomeres than normal cells for embryos that were developmentally slow. Cells produced by women of advanced maternal age and those with a history of repeated miscarriage tended to have substantially shorter telomeres. There was no significant difference in telomere length with respect to the rate of embryo development 5days post fertilization. Telomeres play an important role in cell division and shorter telomeres may affect embryonic ploidy. Reduced telomere length was associated with aneuploid cells and embryos from women of advanced maternal age.This study assessed telomere length in human embryos 5days post fertilization. Telomeres are found at the ends of chromosomes and protect them from degradation. Many embryos cultured in vitro are not able to implant to the maternal womb for reasons that are not always understood. We were, therefore, trying to determine whether the telomere length in each of the embryo cells affects its chromosomes and embryo development and/or is affected by patient age and reproductive history. Embryos were donated from patients undergoing treatment in the assisted conception unit. Seven couples took part, generating 35 embryos consisting of 1130 cells. The telomere length of all chromosomes was established in each embryonic cell. Six chromosomes mostly found abnormal in embryos that fail to implant, miscarriages and stillbirths were investigated in terms of whether they had the correct number. Maternal and paternal age, reproductive history, embryo developmental rate and type of chromosomal error were taken into account. Chromosomally abnormal cells had shorter telomeres than normal cells in embryos that were developmentally slow. Cells produced by women of advanced maternal age and those with history of repeated miscarriage tended to have substantially shorter telomeres. There was no significant difference in telomere length with respect to the rate of embryo development 5days post fertilization. Telomeres play an important role in cell division and shorter telomeres may affect embryo development and implantation. Reduced telomere length was associated with aneuploid cells and embryos from women of advanced maternal age.