Salamanders, Crocodiles, and the War

DARPA is good for something besides weapons of mass destruction, after all.

Funded by a million dollar DARPA grant, some scientists think they are well on their way to solve the problem of mammalian limb regeneration, perhaps within 10 years or so.

Salamanders can regrow limbs quite easily. And like mammals, these amphibians have limbs with complex joints, bones, cartilage, nerves and blood vessels similar to mammalian limbs. And before you pooh-pooh the idea because of the size differential, the authors point out that crocodiles can even regenerate whole tails, which are comparable to human limbs in girth.

According to the article in this month's Scientific American, one of the key differences that prevents us from regrowing limbs is that mammals have fibroblasts that promote fibrotic scarring instead of making a layer of regenerative cells.

So if we can trick our cells into bypassing this fibrotic scarring, and supply the severed area with enough nutrients, we should be able to someday restore all these poor soldiers who are coming back from Iraq with missing limbs.