Chinese researchers use embryonic stem cells and gene editing to produce mice born from two parents of the same sex.
For the animal world, creating new life doesn’t always require a male and a female. Just ask birds, bees, fish, reptiles, amphibians and even laboratory mice.
Now it has taken a considerable feat of genetic engineering to break the rules of reproduction and breed healthy mice with two mothers. The study, published in the journal ‘Cell Stem Cell’, explored what makes it so difficult for some animals to reproduce with same-sex parents. The findings suggest some obstacles to same-sex reproduction can be tackled with stem cells and targeted gene editing.
The bimaternal mice – mice with two mothers – appeared healthy and bore their own young. “This research shows us what’s possible,” said co-senior author Dr Wei Li from the Chinese Academy of Sciences (CAS) in an interview with ‘BBC’. “We saw that the defects in bimaternal mice can be eliminated and that bipaternal reproduction barriers in mammals can also be crossed.” Quoted in ‘CNN’, he added: “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.”
Breaking down barriers preventing genetic coupling between same-sex individuals
Dr Li and his colleagues at the CAS produced the healthy bimaternal mice by using haploid embryonic stem cells (ESCs). These cells contain half the normal number of chromosomes and DNA from only one parent. They believe the haploid ESCs were the key to their success.
The team created the bimaternal mice by deleting three imprinting regions of the genome from haploid ESCs containing a female parent’s DNA. Then, it injected them into eggs from another female mouse. This work resulted in 29 live mice from 210 embryos. The mice were normal, lived to adulthood and had babies of their own.
The study also marks the first time that offspring from pairs of male mice were carried to full term. The researchers used a similar but more complicated procedure. They injected the sperm and the haploid ESCs into an immature egg stripped of its nucleus, the part of a cell that carries the majority of its genetic material. However, the results weren’t promising. The mice from two fathers didn’t survive for long, and died soon after birth. Just 2 of the 12 survived more than 48 hours. No one knows why the male offspring died so quickly.
Can the researchers use these methods in other mammals? Several barriers make this prospect challenging, even with the help of fertilisation technology. And that doesn’t include the serious ethical and safety concerns. At this point in time, it also takes quite a reach of the imagination to think such findings could lead to the development of ways for human same-sex couples to reproduce healthy children of their own.
Cordis Source: Based on media reports