Haploid cells represent an ideal tool for genetic analysis due to the presence of only one set of genetic materials. Two recent high-profile papers reported the generation of mouse haploid ESCs (haESCs) via parthenogenesis, and the use of such cells in cell-based genetic screens (Nature, 2011, 479: 131; Cell Stem Cell, 2011, 9: 563). An important limitation of the haploid ESCs in these two studies, however, is that successful conversion of the ESCs into live animals that would bear the ESC-carried trait, has not yet been demonstrated. Recently, a team of researchers, led by LI Jinsong and XU Guoliang, at the Institute of Biochemistry and Cell Biology (SIBCB), Shanghai Institutes for Biological Sciences, CAS, successfully generated haploid ESCs from androgenetic blastocysts (termed as AG-haESCs). These cells, partially maintain paternal imprints, can be used to generate live animals by injection into MII oocytes.
To generate AG-haESCs, YANG Hui, SHI Linyu, WANG Bangan and their colleagues, under the supervision of Drs. LI Jinsong and XU Guoliang, obtained haploid androgenetic blastocysts by nuclear transfer, in which a haploid sperm head instead of a somatic nucleus was injected into an enucleated oocyte. Some of the reconstructed embryos could develop to blastocyst stage, from which haploid ES cells were obtained. AG-haESCs express classical ESC markers, are pluripotent, and contribute to various tissues including the germline upon injection into diploid blastocysts. Importantly, live mice can be obtained upon injection of AG-haESCs into MII oocytes, and these mice bear the AG-haESC-carried trait and develop to become fertile adults. Finally, gene targeting via homologous recombination is feasible in these AG-haESCs, leading to successful generation of knock-out haESCs and a live-born F1 KO mouse. These results demonstrate that AG-haESCs can fertilize oocytes, providing a quick and reliable path to create genetically modified mice.
This work entitled “Generation of Genetically Modified Mice by Oocyte Injection of Androgenetic Haploid Embryonic
Stem Cells” was published in Cell as a Featured Article on Apr 27th, 2012.
This study was supported by grants from the Chinese Academy of Sciences, the Ministry of Science and Technology, National Natural Science Foundation of China and Shanghai Municipal Commission for Science and Technology.
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Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences , Chinese Academy of Sciences,
Models for AG-haESCs generation (top) and “fertilization” the oocytes with AG-haESCs (bottom).
(Image provided by Dr. Jinsong Li)