Scientists inch closer to ‘three parent babies’

Though they are yet to use the eggs to produce babies,they injected them with sperm to produce an early stage embryo in the laboratory.

Tanaka team removed the nuclei from 31 eggs collected from women undergoing IVF and injected them into enucleated eggs donated by women aged under 35. Of these,25 eggs looked viable.

When injected with sperm,7 eggs or 28 per cent formed early-stage embryos called blastocyts,compared with just 3 per cent of the unrepaired eggs,the ‘New Scientist’ reported on Thursday.

The research is likely to provoke an ethical outrage as critics believe it could lead to hybrid or genetically modified children.

“If we could transfer these constructed new embryos,I believe the success rate would be high,” Tanaka,the lead researcher was quoted as saying by the ‘New Scientist’.

Tanaka presented his results at the American Society for Reproductive Medicine meeting in Atlanta,Georgia last month. With colleagues in the US and Spain,he now plans to transfer embryos from repaired eggs into women.

IVF often fails in older women and one reason is thought to be abnormalities in the cytoplasm of their eggs.

Injecting the nucleus of one egg into an “enucleated” egg,was recently explored as a means of bypassing rare,inheritable diseases caused by faulty mitochondria,which are found in the cytoplasm.

Tanaka and colleagues used nuclear transfer to breathe new life into old eggs.

An outrage had been sparked in the US in 2001 when cytoplasm from young eggs was injected into older women’s eggs,to improve their quality.

Apart from the moral objections to “three-parent embryos” – created from eggs from two different women there were fears that children produced from eggs containing mitochondria from more than one woman might become ill.

Tanaka’s approach would reduce this risk,since the cytoplasm comes from one woman only. He underlined that 98 per cent of a cell’s DNA comes from the nucleus,which may allay moral unease.