Shawn Luttrell: Getting a Head with Regeneration
|Figure 1. Ptychodera flava, a hemichordate|
from Honolulu, Hawaii.
Regenerating missing and damaged tissue may seem like it’s straight out of science fiction, but this superpower is completely real and quite common in the animal kingdom. Just as the fictional character Wolverine can heal nearly every wound, some real, living animals can not only heal wounds, but many can even regrow missing appendages and organs and multiple lineages can regenerate an entirely new animal from just a small piece of tissue. If you cut sponges, planarian worms, and hydra into pieces, they will regrow complete and normal animals from most, if not all, of the pieces. Nearly every major animal group has members that are able to regenerate to some degree. It is likely that the common ancestor of all animals was able to regenerate and this remarkable characteristic has been highly conserved in many lineages.
|Figure 2. Deuterostome phylogeny. Humans are|
vertebrates, to the right. Hemichordates are a
sister group to the well known echinoderms.
Millions of people suffer from neurodegenerative diseases, spinal cord injuries, and limb amputations. Furthermore, aging and age related diseases affect every person on the planet. Regeneration may slow the aging process and regenerative stem cells present feasible ways to combat a multitude of diseases and injuries. If regeneration is a conserved ancestral trait, it is likely that humans possess many, if not all, of the genetic switches controlling regeneration, but those switches have been modified or inactivated in some way over evolutionary time. It may therefore be possible to re-activate those pathways in humans using genetic models made from animals with extensive regenerative capabilities. Understanding the morphological and genetic mechanisms for regeneration in P. flava may yield clues to unlocking more extensive neural regeneration in humans.
|Figure 3. Ptychodera flava collection sites. |
A) Tetiaroa, French Polynesia. B) Paiko Bay, Honolulu, Hawaii.
|Figure 4. Bisected Ptychodera flava. The boxed area |
indicates the regeneration site of the
posterior half of the animal.