In the spirit of superheroes featured in some of this summer’s blockbuster films (I’m looking at you, Clark Kent!), I started thinking about why we’re actually not superhuman ourselves. Don’t get me wrong: We humans can do some amazing things. But one area where some of our least advanced neighbors beat us is the field of regeneration.
Unless you’re Wolverine, regeneration is something that has been left to starfish, zebrafish, and certain types of lizards. Rather than forming scar tissue where the limb was taken off, these animals are able to generate entirely new appendages complete with skeletal, muscular, and nervous support. Biologists refer to this process as epimorphic regeneration, which means that these animals convert previously undifferentiated cells into specific types of cells. These cells are called blastema, and most animals aren’t lucky enough to produce them.
Humans can’t quite regrow entire feet or hands, but it turns out that we’ve got the roots of the capability to do so in our fingernails, of all places.
In 2010, a California native named Deepa Kulkarni successfully regenerated her pinky tip after she lost it to an unfortunate door slam. Doctors used a powder made from ground up pigs’ bladder to act as a sort of scaffolding to attract stem cells from bone marrow, rather than forming scar tissue. Believe it or not, the biomedical company ACell has already begun manufacturing this product called MatriStem.
However, just as important as the MatriStem is the tiny bit of fingernail that remained on Kulkarni’s wound: NYU scientist Dr. Mayumi Ito researched the situation further, and discovered that fingernails contain a family of proteins that promote cell growth called Wnts (pronounced “wints") that are also found in mice. The MatriStem acted as a base to help these proteins function, but the Wnts found in the nail did the actual heavy duty building.
In theory, Wnts help normal cells function like blastema, and we'd just need an extra trigger to get the body to produce these proteins in areas other than fingernails. So far, genetic manipulation experiments have been successful in mice, where subjects have regrown bone, nervous tissue and muscles where there haven’t been any natural stem cells present before. If this technique could be perfected, it would have huge implications for amputees.
Right now, over 60% of lower limb amputations result from diabetes. Other common reasons people must have appendages usually result from trauma or infection. However, if biologists perfect Wnt technology, amputations and any remaining disabilities could become a thing of the past.
Of course, any sci-fi-sounding solution has its equally terrifying complications: right now, lizards that regrow their limbs aren’t able to regrow the exact same limb. Rather, they grow something that functions similarly, but is either shorter or longer. While it’s frightening to think of the implications of a regrown limb gone wrong, the fact that we could potentially regain functionality — like our reptilian friends — is incredible.