Derivation of Euploid Human Embryonic Stem Cells from Aneuploid Embryos

Abstract

Human embryonic stem cells (HESCs) are pluripotent cells derived from the inner cell mass of preimplantation embryos. In this study, to isolate new lines of HESCs, we used blastocyst-stage embryos diagnosed as aneuploid in preimplantation genetic screening (PGS). During in vitro fertilization treatments, PGS is widely applied to identify chromosomal aneuploidies, especially in cases of advanced maternal age. Embryos that are detected as carrying aneuploidies are destined to be discarded unless donated for research. From 74 fresh PGS-defined aneuploid embryos, we derived seven HESC lines. Most of the embryos were left to hatch spontaneously through the hole created for blastomere biopsy and further treated by immunosurgery. The seven HESC lines exhibited morphology and markers typical of HESCs and the capacity for long-term proliferation. The derived HESC lines manifested pluripotent differentiation potential both in vivo and in vitro. Surprisingly, karyotype analysis of the HESC lines that were derived from these aneuploid embryos showed that the cell lines carry a normal euploid karyotype. We show that the euploidy was not achieved through chromosome duplication. Alternatively, we suggest that the euploid HESC lines originated from mosaic embryos consisting of aneuploid and euploid cells, and in vitro selection occurred to favor euploid cells. We assume that aneuploid HESC lines could be isolated mostly from embryos that are uniform for the aneuploidy. These results led us to conclude that the aneuploid mosaic embryos that are destined to be discarded can serve as an alternative source for normal euploid HESC lines.

Derivation and Characterization of New hESC Lines from Supernumerary Embryos, Experience from Turkey

“…In consistent with the previous results, in which it was aimed to derive chromosomally abnormal hESC lines for investigation of various aspects of early embryonic development, all our hESC lines derived from those embryos had normal karyotypes (Munne et al, 2005;Lavon et al, 2008). As stated in these studies, this unexpected result has been suggested to self correction of embryos during long-term in vitro culture (Hazan et al, 2008;Lavon et al, 2008).…”

“…After diagnosis, abnormal embryos were used to derive hESC lines with specific single gene mutation. In the second group of PGD cycles, embryos belonging to couples with advanced maternal age, a history of recurrent miscarriages and repeated implantation failures are destined to chromosomal screening (Kahraman et al, 2000Lavon et al, 2008;Munne et al, 2005;Verlinsky et al, 2005). Following PGD, chromosomally abnormal embryos were subjected to derivation of hESC lines having chromosomal aneuploidies.…”

Cytogenetic analysis of human embryos and embryonic stem cells derived from monopronuclear zygotes

“…Suss-Toby et al also reported a hESC coming from 1PN embryos with normal diploid karyotype (46, XX) [21]. However, the embryo development maybe differ from hESCs in-vitro, as suggested by Lavon et al that the mosaic could be corrected to normal karyotype in hESCs by faster proliferating of normal cells than abnormal cells during the growth of the hESCs, and then took over the culture, whereas the mosaic ICM of blastocyst only divided a few times in-vivo, which may lead to a mosaic fetus [22]. Although most of the 1PN hESCs were normal diploid, one aneuploid hESC line with trisomy 16 (47, XY, +16) was still observed.…”

Screening of human pluripotent stem cells using CGH and FISH reveals low-grade mosaic aneuploidy and a recurrent amplification of chromosome 1q

“…Our observation of aneuploidy rate that increases over time supports this possibility. Lavon et al 36 demonstrated the possibility that mosaicism may lead to one cell population, by the derivation of euploid hESCs from monosomy 21 embryos, which were in fact mosaic. They detected high rate of monosomy 21 mosaicism in early passages of hESCs and concluded that in higher passages the euploid cells took over the culture.…”