A high degree of aneuploidy in frozen-thawed human preimplantation embryos

Abstract

We have studied the chromosomal content in 68 normally fertilised freeze-thawed human embryos of good morphology from 34 patients with an average maternal age of 32,6 years. Forty embryos showed post-thaw cellular division and twenty-eight post-thaw cleavage arrest. After spreading of the embryos on microscope slides, analysis of chromosomes X, Y, 15, 16, 17 and 18 was performed using two rounds of fluorescent in situ hybridisation (FISH). According to the results, the embryos were divided into four groups: (I) normal, all nuclei uniformly diploid, (II) diploid mosaics, normal diploid blastomeres in combination with abnormal blastomeres, (III) abnormal, all nuclei abnormal, (IV) chaotic, the chromosome constitution varies randomly from cell to cell. Approximately 25% of the embryos had normal number of the chromosomes tested, while the majority of the embryos were abnormal. Most of the abnormal embryos were diploid mosaics (57%). This was true for the embryos showing cleavage division as well as the embryos showing cleavage arrest. Our data show a slightly higher incidence of abnormal embryos compared to those obtained with FISH in non-cryopreserved embryos and confirm that the majority of preimplantation embryos fertilised in vitro contain abnormal blastomeres. The results, mechanisms, significance and implications are discussed.

Asymmetric Aneuploidy in Mesenchymal Stromal Cells Detected by In Situ Karyotyping and Fluorescence In Situ Hybridization: Suggestions for Reference Values for Stem Cells

“…In addition, there was an MSC with high aneuploidy levels and loss of mitotic activity after cryopreservation. Considering that previous studies reported an increase in aneuploidy levels in ESCs after cryopreservation [42,43], we speculated that this MSC with high aneuploidy levels was damaged during storage or freezing and thawing and was senescent without mitotic activity when thawed for re-culture. The chromosomal abnormalities of this MSC can only be detected by interphase FISH analysis, and thus karyotyping was impossible.…”

The utility of embryo banking in order to increase the number of embryos available for preimplantation genetic screening in advanced maternal age patients

“…Our data shows that 16.5% of the frozen embryos were normal. This difference could be attributed to the number of chromosomes observed, Iwarsson and colleagues [16] utilized 5 probe FISH while we performed 9 or 12 probe FISH. We did not standardize based on either 9 probe or 12 probe FISH because it would decrease our numbers.…”

“…Iwarsson and colleagues [16] found a high degree of chromosomal abnormalities in frozen-thawed embryos (25% normal). Our data shows that 16.5% of the frozen embryos were normal.…”

IVF/ICSI with or without preimplantation genetic screening for aneuploidy in couples without genetic disorders: a systematic review and meta-analysis

“…Mosaicism may be a reason for the lack of pregnancy success. Apparently, most normal embryos with good morphology contain one or more chromosomally abnormal blastomeres [34][35][36]. Firstly, apoptosis in one cell line is not necessarily lethal for the embryo if a chromosomally normal core persists.…”