Derivation and differentiation of haploid human embryonic stem cells [methylation array]

Diploidy is a fundamental genetic feature in mammals, in which haploid cells normally arise only as post-meiotic germ cells that serve to insure a diploid genome upon fertilization. Gamete manipulation has yielded haploid embryonic stem (ES) cells from several mammalian species, but as of yet not from humans. Here we analyzed a large collection of human parthenogenetic ES cell lines originating from haploid oocytes, leading to the successful isolation and maintenance of human ES cell lines with a normal haploid karyotype. Haploid human ES cells exhibited typical pluripotent stem cell characteristics such as self-renewal capacity and a pluripotency-specific molecular signature. Although haploid human ES cells resembled their diploid counterparts, they also displayed distinct properties including differential regulation of X chromosome inactivation and genes involved in oxidative phosphorylation, alongside reduction in absolute gene expression levels and cell size. Intriguingly, we found that a haploid genome is compatible not only with the undifferentiated pluripotent state, but also with differentiated somatic fates representing all three embryonic germ layers, despite a persistent dosage imbalance between the autosomes and X chromosome. We expect that haploid human ES cells will provide novel means for studying human functional genomics, development and evolution. Genome-wide DNA methylation profiling by Illumina Infinium HumanMethylation 450K Beadchip was performed on a total of 12 samples, including undifferentiated haploid and diploid human parthenogenetic embryonic stem cells in either G1 or G2/M, as well as 3 in vitro fertilization (IVF) control embryonic stem cell lines.