Healthy mice have been born from same-sex parents in China. To investigate the ways that mammalian reproduction differs from other animals, researchers at the Chinese Academy of Sciences used stem cells and genetic manipulation to produce 29 live, healthy offspring from two female mice. The pups have since grown to adulthood and had babies of their own.
The results suggest that the biological barriers to same-sex mammalian reproduction can be circumvented. But the technique isn’t foolproof, it seems: pups from two fathers were also born but only survived for around 48 hours.
“The research shows us what’s possible,” said Wei Li, who took part in the research. “We saw that defects in bimaternal mice can be eliminated and that bipaternal reproduction barriers can also be crossed.”
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Bimaternal mice (mice with two mums) have been produced prior to this experiment, but were never healthy. To produce the healthy mice Li and his team had to get around the genomic imprinting barrier, in which certain maternal or paternal genes are imprinted (chemically tagged) and switched off during the initial stages of embryonic development. Since some genes imprinted in a mother’s genetic material aren’t imprinted in the father’s, and vice versa, a mammalian offspring needs material from parents of both sexes in order to get all of the necessary activated genes. In their new research, Li and his team used embryonic haploid stem cells (ESCs) from one female mouse. ESCs only contain half the normal number of chromosomes and DNA. By deleting three imprinting regions of the genome, they were able to make the female stem cells express a more ‘male’ pattern, then use them to fertilise an egg from another female.
The team hope to explore these techniques further with other research animals, but there are ethical and practical issues to address before it can be considered for humans.
This is an extract from issue 329 of BBC Focus magazine.
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