A haploid cell with 23 chromosomes (left), and a diploid cell with 46 chromosomes (right). Credit: Columbia University Medical Center/Hebrew University
The stem cell carries a single copy of the human genome, instead of the two copies typically found in normal stem cells. These are the first human cells that are known to be capable of cell division with just 1 copy of the parent cell’s genome. Since the stem cells were a genetic match to the egg cell donor, they could also be used to develop cell-based therapies for diseases such as blindness, diabetes, or other conditions in which genetically identical cells offer a therapeutic advantage. Because their genetic content is equivalent to germ cells, they might also be useful for reproductive purposes.
Previous efforts to generate embryonic stem cells using human egg cells had resulted in diploid stem cells (23 pairs of chromosomes). In this study, the scientists triggered unfertilized human egg cells into dividing. They then highlighted the DNA with a fluorescent dye and isolated the haploid stem cells, which were scattered among the more populous diploid cells. These haploid stem cells were pluripotent (ie can differentiate).
By virtue of having just a single copy of a gene to target, haploid human cells may constitute a powerful tool for genetic screens. Being able to affect single-copy genes in haploid human stem cells has the potential to facilitate genetic analysis in biomedical fields such as cancer research, precision andr regenerative medicine. “One of the greatest advantages of using haploid human cells is that it is much easier to edit their genes,” explained Ido Sagi. In diploid cells, detecting the biological effects of a single-copy mutation is difficult, because the other copy is normal and serves as “backup.”
http://www.alphagalileo.org/ViewItem.aspx?ItemId=162173&CultureCode=en http://dx.doi.org/10.1038/nature17408
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