Scientists Create Mice from Two Biological Fathers
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From there, the team converted the XX cells into primordial germ cells, the precursors of eggs and sperm, that were subsequently programmed with the signals to turn them into egg cells. Once fertilized with sperm and implanted into a mouse uterus, the eggs generated live offspring.
“This study is particularly neat because it takes advantage of errors that are known to occur during the culture of XY cells, which lead to loss of the Y chromosome and subsequent gain of a second X chromosome, resulting in XX cells that are capable of generating live offspring,” said Rod Mitchell, a professor of developmental endocrinology at the MRC Centre for Reproductive Health at the University of Edinburgh in Scotland, in a statement. He wasn’t involved in the research.
“However, its potential application for humans (e.g. for same-sex couples) remains to be seen. In the mouse study, very few of the embryos generated using mouse cells resulted in live offspring and the final steps required to convert germ cells into eggs have not been reliably reproduced using human cells,” added Mitchell.
Only 7 out of 630 implanted mouse embryos gave rise to mouse pups. Hayashi said this low success rate — around 1% — wasn’t down to the process of sex chromosome conversion but the reality that cells cultured in a lab are typically inferior to those in a living animal.
“This is due to the suboptimal condition of the culture system. Especially, if the culture period is long (in this case 5-6 weeks), then the cell potential is compromised,” Hayashi stated.