regenerating fingertips -- 6/27/14

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Today's selection -- from "Chopped" by Michaeleen Doucleff and The Spark in the Machine by Dr. Daniel Keown. Children can sometimes regrow the tip of their finger if it is cut off:

"When a kid lops off a fingertip with a cleaver or car door, there's a chance the end of the digit will grow back. The fingerprint will be gone, and the tip may look a bit strange. But the flesh, bone and nail could return.

"Now biologists at New York University have figured out just how this lizard-like regeneration happens in mice. There's some secret sauce at the nail cuticle that makes it possible, scientists report Wednesday in the journal Nature.

"Doctors have seen the effect in humans without quite understanding how it happens. 'Kids will actually regrow a pretty good fingertip, after amputation, if you just leave it alone,' says Dr. Christopher Allan, from the University of Washington Medicine Hand Center."

"Chopped: How Amputated Fingertips Sometimes Grow Back"
by Michaeleen Doucleff, NPR, June 12, 2013

"When I was three years old I caught my thumb in a folding chair. I cannot remember this episode, filled as it must have been with blood and pain, but my mother does. She packed the amputated tip of the thumb on ice and rushed me to the Emergency Department, where a surgeon sewed it back on again. I still have the scar on my thumb now, running parallel to the base of my nail.

"What my mother didn't know, and what most doctors still don't, is that my thumb would almost certainly have grown back perfectly without any treatment. It would have regenerated in the same way as some amphibians can grow back their tails or legs. Bone, nail, nerves, blood vessels, the whole lot. All it needed was a gentle clean, a non-adherent dressing, and a lollipop to soothe my frayed, three-year-old nerves.

"It turns out humans can regenerate, but only the very tips of their fingers and only [some] children. In the 1970s a Sheffield paediatrician even published a paper on this effect in the Journal of Paediatric Surgery. Her results were unequivocal: amputations above the last joint in children under six left to heal naturally would regrow, the entire finger, without a scar or deformity!

"It is somewhat amazing that this fact is so little known in the medical community."