One incredible ability that has long been a staple of science fiction, and particularly superhero comics and movies, is the power of rapid, complete regeneration, sometimes called a “healing factor." The ability to heal wounds and even regenerate limbs has featured widely in popular culture, most notably in the popular comic book characters Wolverine and Deadpool, but as cool as it all looks, is this something that lies totally within the realm of fiction or is it a potential reality? What if this power is already within us, and indeed within our reach, even within our lifetime? Such a fantastic medical breakthrough that would allow us to heal wounds and regrow organs remains one of the Holy Grails of the medical world, along with a cure for AIDS and cancer. Yet, as far-fetched as it may all sound, the day when we learn to harness the sheer healing potential within every one of us, this healing factor, is perhaps not too far off, and it highlights just how mysterious our bodies really are.
Such miraculous powers of spontaneous regeneration already exist within the natural world and even within us. Perhaps most famously, many types of newt and salamander can completely regrow missing limbs and even organs, including such essential parts such as the heart or brain. In particular, the the axolotl, or Mexican salamander, has the phenomenal ability to completely regrow whole organs, limbs, swaths of skin, and even a full spinal cord. Some species of lizards, as well as tadpoles, can grow back lost tails. Flatworms are able to to grow back a new head replete with brain if they are decapitated. The acorn worm, which inhabits the sand surrounding coral reefs and is rather astonishingly similar in its genetic makeup to ourselves, has been found to be able to fully regenerate its entire body, including the head, nervous system, and internal organs, from a mere fragment of itself, even able to form two fully functioning worms if cut in half. Mammals have this regenerative ability to some degree as well. Male deer lose their antlers on a regular basis only to totally regrow them, and young mice and rats can even regrow limbs.
Even human beings have shown this ability to some extent, especially when we are very young. For instance, a young child can regrow a missing fingertip without any one ever realizing it was ever gone. Although this ability to grow back fingertips typically disappears at around the age of 12, even adults have some degree of startling regenerative power. The human liver is able to regrow and repair even missing pieces, as is human skin to some extent. Human fetuses are also capable of dramatic healing without scarring. There is the potential for incredible feats of healing within us, it is just that it seems limited in the extent that it manifests itself, with our bodies, like those of many other animals lacking these extraordinary regenerative abilities, opting for the quick fix of stitching collagen together in a side by side pattern rather than its regular criss-cross arrangement to seal wounds rapidly but also cause scar tissue.
However, we also have the potential to exhibit more sophisticated regenerative abilities in some circumstances to some extent, and indeed research into creatures such as salamanders and flatworms have shown that their miraculous healing powers are not due to having something we lack, but rather they are able to activate this trait whereas we for some reason cannot. In effect, something is keeping us from realizing our true healing potential when we reach a certain age. When creatures such as salamanders, newts, flatworms, and acorn worms heal, rather than merely conjuring up collagen through cells called fibroblasts to seal wounds, as we do, the surrounding cells are instead stimulated to revert back to bundles of stem cells called blastema, rewinding their clocks in a sense. These stem cells essentially revert to a blank slate, a blank check so to speak, and can then be reprogrammed to take whatever form is required of them, becoming skin, bone, organs, and other tissues to great effect, all without any scarring at all. Many neonatal or very young animals, including humans, have this ability early in life, but lose it as they grow older, yet is there anyway to emulate this effect in adult human beings? There has been some research to suggest that the answer to this question is "yes."
One promising avenue of research has involved the effects of a mysterious gene that was discovered quite by accident by a Dr. George Daley, of the Children’s Hospital in Boston and Harvard Medical School. While experimenting on mice that had been genetically modified to exhibit a gene that helps them grow in the womb after birth, for the purpose of cancer research, Daley found that when these mice had holes bored into their ears for identification purposes, the wounds would rapidly heal. He experimented further by clipping off the tips of the mice’s toes, and these too grew back within a matter of days.
This ability was attributed to a gene called Lin28a, which is present in the early life of many animals and has the power to boost metabolism and revert cells to embryonic-like stem cells, which can then become whatever kinds of tissue they want. The problem is, this gene seems to become dormant as animals mature, but in these modified mice they were obviously retaining the positive benefits of the gene. Daley surmised that this effect could be activated through gene manipulation or drug cocktails. The only problem seemed to be that the effects of the gene could only be activated and prolonged so long after birth and that they oddly seemed to exclude the heart, with one article in Scientific American explaining thus:
The power of Lin28a appeared to only extend so far. When mice were no longer babies—at five weeks—the scientists were not able to regenerate their limbs, even if the gene was stimulated. And mice with Lin28a activation were never able to repair damage to the heart, suggesting that the protein is not equally effective everywhere in the body.
Other genes have been found to be linked to regenerative abilities as well. One such gene that has been discovered in recent years is one simply known as p21, which has been found to act as sort of a control mechanism to keep in check and subvert our natural healing abilities. By turning off this gene, it has been found that animal cells can revert back to stem cells to some degree, and mice that have been subjected to this treatment have shown an incredible power to heal grievous wounds or regrow lost limbs without any noticeable scar tissue. The only problem is that p21 seems to be linked to another gene called p53, which just so happens to be a cell-regulator that can cause cancer. In this case, p21 seems to keep p53 in check, and that by tampering with it we are inviting trouble in the form of cells replicating out of control. It was also found that mice who had had their p21 genes turned off had the propensity for developing a condition in which cells destroy themselves, called apoptosis. This is obviously a route that may be effective but also which requires a certain care and balance of these forces.
Besides delving into specific genes for the purposes of enhanced regeneration in humans, there have been other avenues pursued as well. One Michael Levin, director of Tufts University’s Center for Regenerative and Developmental Biology in Medford, Massachusetts, has spent years studying the effects of electrical signals within our bodies in relation to healing and regeneration, and thinks that manipulating these forces are the key. Levin has long thought that these electrical impulses are intrinsically tied to the forces which control our healing abilities, as well as their ability to influence cells and proteins, and have the ability to control our healing and development.
To this end, Levin has pursued experiments into the matter in order to prove his rather controversial theories, namely involving trying to enhance through electrical signals the healing abilities of certain animals already demonstrating this power. One such experiment involved the tadpoles of the African clawed frog, or Xenopus laevis. These tadpoles have the ability to completely regenerate lost tails, but at around 8 days of age lose this ability, until it is totally gone by 10 days of age. Levin postulated that this was due to some electrical signal that was being lost somehow, some signal that was able to instruct the cells in the tadpole’s tail to grow back being blocked. If this electrical signal could be emulated or turned back on, then Levin hypothesized that the cells could be switched back on in a sense to once again regrow the lost tissue. Other scientists agree that such miraculous healing abilities are within our reach, with author and University of Washington Biology Professor Billie Swalla saying:
I really think we as humans have the potential to regenerate, but something isn't allowing that to happen. I believe humans have these same genes, and if we can figure out how to turn on these genes, we can regenerate.
Levin painstakingly went through efforts to try and work backwards by trying to shut off particular electrical channels and actually stop the regenerative process in the tadpoles, from where he planned to then identify the ones that caused it. He would eventually home in on a drug called concanamycin, which showed the ability to disable the ability of young tadpoles to grow back their tails. Levin then concocted a cell wall pump, which he surmised would alter electrical signals and trick a tadpoles body into thinking it was still young enough to regenerate a tail. In 2005, he successfully was able to entice an older tadpole to fully regrow a tail though the use of this pump. It was a groundbreaking discovery to say the least. He and his team have gone on to use various methods to control the healing abilities of flatworms, and has managed to influence the regeneration of various frog embryos, speeding it up or slowing it down, through controlling electrical voltage through their cells. It is believed by Levin and his associates that certain voltages at certain times can trigger or turn off various healing potentials, and they have seen positive results through the use of liquids and pumps that regulate cellular voltages in frogs and mice. Levin has said of his research and its future thusly:
I don’t know too many works of science fiction that are as wild and out there as things that have been discovered by real science. The people who really think that it’s never going to work in humans don’t have a good grasp of how closely related we all are.
We are probably a long way off from replicating the regrowth of limbs and organs within human beings, but does any of this research hold promise? Is a Wolverine-like healing factor a realistic thing that looms on the horizon? One thing that we can be certain of is that our bodies seem to be capable of this. Somewhere deep down within every one of us lies this extraordinary capacity to heal, we only need to find the way to unlock it. Such a breakthrough would change life as we know it. Disease, cancer, horrific injuries, organ failure, you name it, these would all be simple annoyances rather than life-threatening afflictions. One wonders if we are ready for a world like this, but it seems that with such dogged pursuit of these secrets of the human body, this world is coming whether we are ready or not.