The secret powers of frogs are being exploited by scientists to create drugs that will correct disfiguring facial scars and could one day help in the regrowth of amputated arms and legs

The secret powers of frogs are being exploited by scientists to create drugs that will correct disfiguring facial scars and could one day help in the regrowth of amputated arms and legs.

Manchester University researchers are exploiting the ability of some amphibians to regrow limbs. 'Human and amphibian proteins are very similar,' said one of the researchers, Professor Enrique Amaya. 'That means the lessons you learn from frogs and salamanders are applicable to humans. Their embryos - spawn - are also easier to study.'

The Manchester work on tissue regeneration began 10 years ago, when Professor Mark Ferguson discovered most animals' embryos recover more fully from cuts than adult animals. The latter are often left scarred, but not embryos.

'The protein responsible for this recovery is known as Transforming Growth Factor Beta 3,' said Ferguson. 'It is present in small amounts in adults, but in large amounts in embryos, where it plays a key role in helping skin to multiply inside in a rapidly growing embryo.' Ferguson's team has since isolated the protein, TGF Beta 3, and has developed ways to manufacture it artificially. The result is a drug called Juvista. Its development has been taken over by a university spin-off company, Renovo, which is now in phase two clinical trials. Juvista could soon be used as a treatment for alleviating scarring during surgery, added Ferguson. 'After surgery for really severe accidents, patients can be left with disfiguring scars. Using Juvista, which you inject into the skin during the operation, we've found we can reduce scarring by a significant amount.'

Researchers at both centres are now working on ways to make further improvement in drugs to help scars heal after surgery. 'We are not doing this to help women who want to remove bags from under their eyes,' said Amaya. 'We want to help people who suffered really nasty facial deformities after accidents.'

A key to this work is Manchester's research on amphibians. Spawn - usually from the genus Xenopus - is used to search for other biochemical agents that aid scar recovery. In addition, some species of amphibians, mainly salamanders, are known to grow replacement limbs.

If the biochemical agents and growth factors involved in limb growth can be discovered, then it could have profoundly important medical implications, said Professor Cay Kielty. 'Limb regrowth involves blood, bone and muscle tissue growing in a very ordered manner. If you can learn how that it happens in amphibians, you could think of replicating it in humans.'

Researchers envisage erecting bio-degradable scaffolding on a limb site, lacing these with a patient's stem cells and then adding biochemical agents developed from their amphibian work. The stem cells would evolve into blood, muscle and bone under the direction of these agents, while the scaffold disintegrates slowly - to form a new limb.

'It is encouraging, but it will take many years to realise,' added Ferguson. 'However, we are close to getting medicines that will reduce scars in accident victims.'