Derivation of Euploid Human Embryonic Stem Cells from Aneuploid Embryos

¹ The International Stem Cell Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
² Department of Genetics, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel
³ ART Reproductive Center, Beverly Hills, CA.
⁴ The International Stem Cell Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA; Department of Genetics, The Institute of Life Sciences, The Hebrew University, Jerusalem, Israel

^* To whom correspondence should be addressed. E-mail: lavonn{at}cshs.org.

	Abstract

Human embryonic stem cells (HESCs) are pluripotent cells derived from the inner cell mass of pre-implantation embryos. In this study, to isolate new lines of HESCs, we used blastocyst-stage embryos diagnosed as aneuploid in pre-implantation 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 seventy four 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 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 aimed to be discarded can serve as an alternative source for normal euploid HESC lines.