Some mothers do 'ave 'em: Mice with two mums bred in China

Researchers unlock some of the mysteries of reproduction in an experiment that created healthy mouse pups from two female sources

PUBLISHED : Tuesday, 17 November, 2015, 11:34pm
UPDATED : Wednesday, 18 November, 2015, 12:00am

Scientists in Shanghai are rewriting the rules of reproduction with a groundbreaking experiment that combined genetic material from two female mice to create healthy offspring, according to a paper in Cell Research on Tuesday.

But the researchers said they strongly opposed using the technology to create humans, saying it would give rise to serious ethical and genetic problems.

The team, led by Professor Li Jinsong from the Chinese Academy of Sciences’ Institute of Biochemistry and Cell Biology, genetically modified ovum-derived embryonic stem cells to make them function like sperm, and injected the cells into ova to produce a batch of mouse pups with two genetic mothers.

“The entire process does not require any male involvement,” Li said.

“Sperm is replaceable – that’s clear from the experiment.

“All we need are a pair of eggs, and from these eggs we can create a family, a colony, even a kingdom of healthy pups.”

The researchers were initially interested only in examining the genetic similarities between stem cells derived from ova and sperm but, out of curiosity, injected an ovum-derived stem cell into a mature egg to see what would happen.

Sperm is replaceable – that’s clear from the experiment
Professor Li Jinsong

After many failures, the team discovered that two genes – H19 and Gtl2 – could affect the “bad impression” that two ova had on one another.

“The first impression is always important. Natural eggs have a bad impression on each other, so they never combine,” Li said.

The team suppressed the mechanism that controlled the two genes’ expression in the egg-derived stem cell and introduced it to another egg.

The trick worked and embryos were created.

But out of 100 artificially created embryos, only about 15 pups were healthy. Li said they hoped to increase the success rate to 20 per cent.

Read more: Chinese scientists edit genes to produce artificial sperm capable of creating ‘army of half-cloned mice’

“But however well we improve the technology, it cannot be 100 per cent safe,” he said.

“We should therefore never use it on humans.

“Nature has created men and women, and the difference must be for good reasons.

“Cheating on that will not only generate an ethical crisis but lead to unpredictable consequences such as bad mutations and diseases.”

The researchers also said it was impossible to use the method using only genetic material from two fathers.

“Two sperms will not create a baby. You always need an egg,” Li said.

“Sperm is much smaller and simpler than an egg. It is possible to turn an egg into sperm, but the opposite direction is much more difficult.”

Two sperms will not create a baby. You always need an egg
Professor Li Jinsong

The results generated other questions for the team to try to answer.

Li and colleagues hope further studies will unlock the mechanisms behind sexual reproduction.

They said the ultimate purpose of their research was to explore the fundamental issues of life.

“What happens at the very beginning of our life? Why does nature pull male and female together for a baby and through what mechanism is the law of sex enforced?” Li said.

“These questions are as intriguing to biologists as the big bang is to physicists. Our research may provide some clues to solve some of these mysteries.”

Read more: Genetic breakthrough prompts call for debate on ‘designer babies’

Asked if the technology would be of interest to lesbian couples on the mainland, Li Yinhe, a sexologist and retired professor with the Chinese Academy of Social Sciences, said that not all lesbian couples would want to have their own genetic children.

She also said the technology warranted a high degree of caution.

“We should be extremely careful when using this kind of technology on humans, if at all,” she said.

“The technology should stay in scientific laboratories for a long time until the safety and ethical issues are solved.”