PPL Therapeutics, the Scottish biotechnology firm behind the creation of Dolly the sheep, has reported that it has produced four cloned piglets which may bring scientists a step closer to being able to use pig organs in human transplants.
On Christmas Day last year, a set of piglets was born in PPL's US laboratories with a 'knocked-out' copy of one of two genes which cause the rejection of pig organs by the human immune system. The scientists had used the 'knock-out' technique to inactivate a gene in the pigs that produces an enzyme called alpha 1,3 galactosyl transferase. This enzyme causes pig organs to be coated with a sugar that the human immune system recognises as foreign. Knocking out the gene therefore reduces the likelihood of the pig organs being rejected if transplanted into humans. The latest litter of piglets, born in July, has had a second copy of the gene 'knocked-out', meaning that none of the sugar can be produced by the pigs.
It is hoped that the technique will bring the possibility of xenotransplantation closer to reality, consequently providing some solution to the shortage of human organs and tissues available for transplant. But PPL acknowledges that there is still much research to be done before pig organs could be transplanted into people. Pigs carry certain viruses that may be transferred to the human population, and as well as 'knocking-out' genes that may cause organs to be rejected, making sure the viruses cannot be passed on is a high priority.
Sources and References
Cloned pigs bring new hope for transplants
Modified pigs are transplant 'breakthrough'
World's first cloned double knock-out pigs