- Video report by ITV News Science Correspondent Alok Jha
The reality of pigs becoming human organ donors has moved a step closer after a breakthrough study successfully removed potentially hazardous viruses from the animals' DNA.
US scientists used advanced gene editing to remove porcine endogenous retroviruses (Pervs), a virus that is permanently embedded in the pig genome, but could be potentially dangerous to humans.
Genetically modified pigs are being engineered to grow human transplant organs, but the existence of Pervs has been a major stumbling block in the development.
But according to new research in the journal Science, this hurdle has been overcome, representing a "promising first step" in the prospect of pigs as human organ donors.
Dr Luhan Yang, co-founder and chief scientific officer at the biotech company eGenesis, said: "This is the first publication to report on Perv-free pig production.
"This research represents an important advance in addressing safety concerns about cross-species viral transmission."
British expert Professor Ian McConnell, from Cambridge University, said the research was a "promising first step".
He added: "The safe use of pig organs such as kidneys in xenotransplantation has been seen as an approach which could be used to overcome the shortage of donor organs in human transplantation.
"The problem is that all pig cells carry cancer viruses embedded in their DNA. These are known as endogenous retroviruses which, although normally silent, can be activated to become fully infectious for human cells when pig cells carrying these retroviruses are co-incubated with human cells."
Genetics expert Professor Darren Griffin, from the University of Kent, said: "This represents a significant step forward towards the possibility of making xenotransplantation a reality.
"The chance of transmitting Perv from the pig organ to the human cells was a significant barrier and the study shows yet another application of the Crispr-Cas9 system."