Human-pig 'chimera embryos' detailed

By James Gallagher Health and science reporter, BBC News website


26 January 2017

Embryos that are less than 0.001% human - and the rest pig - have been made and analysed by scientists.

It is the first proof chimeras - named after the mythical lion-goat-serpent monster - can be made by combining material from humans and animals.

However, the scientific report in the journal Cell shows the process is challenging and the aim of growing human organs in animals is distant.

It was described as an "exciting publication" by other researchers.

To create a chimera, human stem cells - the type that can develop into any tissue - are injected into a pig embryo. Image copyright Juan Carlos Izpisua Belmonte Image caption The spherical pig embryo is held in place while a tiny needle is used to inject human cells

The embryo - now a mix of human and pig - is then implanted into a sow for up to one month.

The process appears very inefficient - of the 2,075 embryos implanted only 186 continued to develop up to the 28-day stage.

But crucially there were signs that human cells were functioning - albeit as a tiny fraction of the total tissue - as part of a human-pig chimera.

"This is the first time that human cells are seen growing inside a large animal," Prof Juan Carlos Izpisua Belmonte, from the Salk Institute, told the BBC News website.

Continued