(Agencies)
Updated: 2007-11-03 11:11

London - Scientists have found a key protein that helps newts regrow severed limbs and which may guide future research into human regenerative medicine.

An undated photo of a North American newt. Scientists have found a key protein that helps newts regrow severed limbs and which may guide future research into human regenerative medicine. [Agencies]

Biologists have long been intrigued by the ability of newts and salamanders to renew damaged body parts. But how they do it has been unclear.

Now new research by a British team published on Thursday shows that a protein called nAG, secreted by nerve and skin cells, plays a central role in producing a clump of immature cells, known as a blastema, which regrows the missing part.

The importance of nAG was demonstrated by the fact that even when a nerve was severed below the stump tip, which would normally prevent regrowth, the scientists were able to coax regeneration by artificially making cells produce the protein.

Anoop Kumar and colleagues from University College London (UCL), writing in the journal Science, said the finding "may hold promise for future efforts to promote limb regeneration in mammals."

David Stocum of Indiana University-Purdue University Indianapolis said it could help explain why mammals have limited regrowth abilities and thus help direct the field of regenerative medicine.

Important Step Forward

A clear understanding of the molecular signals involved in blastema formation and limb regeneration could eventually allow medics to program similar patterns into cells of non-regenerating body parts.

"How soon this might be possible, particularly in humans, is anyone's guess but the addition of nAG to the repertoire of necessary factors is an important step forward," Stocum said.

In effect, newts are able to manipulate their bodies by turning cells into undifferentiated stem cells and then back into mature tissue again.

It is a clever trick -- but understanding how they do it does not mean humans will necessarily be able to copy them and regrow lost arms or legs, according to Jeremy Brockes of UCL.

"It would be very desirable for regenerative medicine to understand the specification of the blastema and to try to recreate that in a mammalian context. But we are a long way away from being able to do that," he said in an interview.

Regenerative medicine is a growing area of research, with much of it centered on stem cells, the master cells that act as a source for various cells and tissues in the body.