Wasn't this proven many years ago by a random guy who used a "extra-cellular matrix" of stem cells to regrow his severed finger, nail and all?

Dude's brother had him throw his product on the finger as it did so, definitely an astute marketing trick. https://www.theguardian.com/science/2008/may/01/finger.claim

	▲	RajT88 an hour ago \| parent \| next [-]
		I recall reading a similar story with powdered lizard. Also just a fingertip.
	▲	ranger_danger 3 hours ago \| parent \| prev [-]
		"I don't know how it works, so it must be fake news." To be fair, the person being skeptical is just a surgeon, this is not a peer-reviewed study or anything actually scientific. Your NPR link even shows that scientists realize there are still unknowns: > "We think that nail stem cells may a have a special function to induce the whole regeneration process, including nerve attraction and growth of the bone," Ito say. A cursory search seems to say that typical regrowth of a nail takes 4-6 months, but Spievak claimed his only took 4 weeks. Can we say definitively that his "pixie dust" had nothing to do with it? I don't think so. Can we say it did have something to do with it? Also unknown... but the answer right now IMO certainly isn't a scientific "no."