Rat regains nerves in spine after transplant from pig

A tissue transplant from the snout of a pig has restored the nerve impulses of a rat with a severed spinal cord in research that supports the potential use of pig organs in human transplant operations. Scientists from Yale University in New Haven, Connecticut, transplanted nerve cells from a pig's nose in an operation intended to mend the broken nerves of another species.

A tissue transplant from the snout of a pig has restored the nerve impulses of a rat with a severed spinal cord in research that supports the potential use of pig organs in human transplant operations. Scientists from Yale University in New Haven, Connecticut, transplanted nerve cells from a pig's nose in an operation intended to mend the broken nerves of another species.

The pig had been genetically engineered to produce a human protein designed to make the body's immune defences compatible with foreign tissue from another species. To lessen the risk of tissue rejection still further, the rat had a suppressed immune system.

The scientists, led by Toshio Imaizumi, a Yale neurologist, found that the rat's spinal cord regenerated because the pig cells regrew and rebuilt the outer protective sheath of nerve cells.

Being able to repair damaged spinal cords using xenografts - tissue transplants from other species - is one of the holy grails of medicine, which could lead to the restoration of paralysed limbs. The research, published in Nature Biotechnology, has not, however, resulted in any improvement in the symptoms of the damaged rats.

Professor Lars Olson, of the Karolinksa Institute in Stockholm, says in an accompanying editorial that many of the age-old beliefs in the inability of the nervous system to mend itself are being overturned. "Though unthinkable only a decade or two ago, it now appears that reparative treatment for spinal cord injury may be within reach," Professor Olson says.

The use of pig tissue and organs in human transplants is unlikely to go ahead until government ethical bodies are convinced that the risk to patients can be minimised. Scientists fear the introduction of a pig virus into people that will then be able to spread within the human population.