Researchers Develop Haploid Embryonic Stem Cells

The ‘half strength’ genome of the haploid stem cell line could help researchers better understand the function of genes.

AsianScientist (May 23, 2016) – Researchers in China have successfully developed human haploid embryonic stem cells (ESCs). This new type of ESC holds a single copy of the human genome instead of the normal two; yet, they are capable of cell division. Their work was published in Cell Research.

Mammalian haploid ESCs can be derived from androgenetic or parthenogenetic embryos of different species, including mice, rats and monkeys. However, whether haploid ESCs can be generated from humans was previously unknown.

The team of researchers, led by Professor Li Jinsong of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences at the Chinese Academy of Sciences, used two different methods to generate human haploid embryos. Firstly, they obtained parthenogenetic (PG) haploid blastocysts by chemical activation of human oocytes. From these PG blastocysts, they derived three ESC lines. However, no haploid cells could be enriched in these cells.

The second method they used relied on removing the male pronucleus from the zygotes and produced PG haploid blastocysts. From here, they derived four ESC lines, two of which contained haploid cells. The haploidy could be well maintained in these cells for over 30 passages.

These PG haploid ESCs expressed classical human ESC markers and could differentiate into various cell types of all three embryonic layers in vitro and in vivo. Interestingly, human PG haploid ESCs—different from mouse PG haploid ESCs, in which DNA methylation was quickly lost at maternally-imprinted loci—stably sustained maternal imprinting state during cell proliferation.

The generation of human haploid ESCs provides a novel tool for genetic analysis in humans. In normal diploid cells, mutation of one copy of a gene may not reveal the gene’s function as it is compensated for by the other copy. Haploid cells would allow researchers to understand the function of each gene without this interference.

The article can be found at: Zhong et al. (2016) Generation of Human Haploid Embryonic Stem Cells from Parthenogenetic Embryos Obtained by Microsurgical Removal of Male Pronucleus.


Source: Shanghai Institutes for Biological Sciences.
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