HUGE! thing in the medical world.

this is the story.

It's the stuff of sci-fi and really crappy awesome horror films, but now it looks like regrowing damaged skin and limbs isn't so far-fetched -- in fact, it's already happening. A certain 69 year old Lee Spievak lost half an inch of finger to an aggressive model plane blade, and doctors had little hope for the appendage. Lucky for Lee, his brother Alan works in the field of regenerative medicine, and sent him some powder (which lee calls "pixie dust") to apply to the finger.

Four weeks later Lee had grown back the entire finger, as good as new. The pixie dust is actually modified cells scraped from the lining of a pig's bladder cleaned into a general-purpose tissue generator -- the cells basically tell the body to grow instead of scar. Doctors have high hopes for the cells, for everything from amputees to burn victims to cancer patients. We're just waiting until they can program these cells to grow that third arm we always wanted.

full link
http://www.switched.com/2008/05/01/biomagic-pixie-dust-regrows-mans-lopped-off-finger/