Researchers in China say they’ve bred healthy mice with two mothers using a new type of gene editing technology, a significant feat that may help researchers better understand mammalian reproduction but carries significant ethical and safety questions.
A total of 29 bimaternal mice were produced using 210 embryos in the study. They all were “normal, lived to adulthood, and had babies of their own,” though they showed “some defective features,” according to researchers at the Chinese Academy of Sciences.
This image shows a healthy adult bimaternal mouse who was born to two mothers with offspring of her own.
But not all the mice pups survived the experiment. Mice produced from two fathers only survived a couple of days after being born.
“This research shows us what’s possible,” Wei Li, one of the study’s co-authors, said in a news release.
“We saw that the defects in bimaternal mice can be eliminated and that bipaternal reproduction barriers in mammals can also be crossed through imprinting modification,” said Wei Li.
“We also revealed some of the most important imprinted regions that hinder the development of mice with same sex parents, which are also interesting for studying genomic imprinting and animal cloning.”
This image shows a bipaternal mouse pup born to two fathers.
The scientists conducting the study, published in the journal Cell Stem Cell Thursday, said they were interested in answering why some reptiles, fish and amphibians can reproduce with one parent of the same sex, but others cannot.
The genes were removed using CRISPR Cas9, a tool that experts say has the potential to save countless lives and billions of dollars but has raised serious ethical questions about the future of genetic research.
The idea of “designer babies” — in which parents can choose genetic traits — is one example, but some have warned that editing individual human genes could affect the gene pool in future generations and carry unintended consequences.
Scientists say that despite the potential of the latest study, the technology just isn’t ready for practical application.
“The tremendous amount of genetic modification needed in order to do what they (Chinese researchers) did, makes it implausible to use it in anything other than research,” said Dr. Tim Hore, an expert in epigenetics and development at the University of Otago.