A group of scientists have been involved in a recent study in researching how human limb regrowth could one day be applied with the help of the Acorn Worm. They are looking at how amputees could regrow limbs and for patients to regenerate the spinal cord after injury.
The Acorn Worm may at first glance seem to be not all that related to humans but when observing closer to its DNA, they are actually one of our closest invertebrate relatives.
This is because they share thousands of genes with humans.
Acorn worms are found in the sand and coral reefs where they burrow into. Their ancestral lineage chordates means that they have genetic building blocks that are very similar to ours.
A study that was led by the University of Washington (UW) and published shows that acorn worms can regrow every major body part – including the head, the internal organs, and their nervous system. In fact nothing will stop them from being regenerated.
If you slice them in half then within 15 days they have replaced their mouth, nose , heart and kidneys, along with having generated a new neural tube.
Initially, in around 4 days the worm will start to generate a proboscis and its mouth. In around 10 days, the heart and kidneys will appear, and then on the 15th day, these creatures will have completely regrown a new neural tube.
The neural tube would correspond to a human’s spinal cord and the brain.
The team of scientists in this project suggest that if they can unlock the genetic network pathways that controls the generation in the Acorn Worm, they might be able to regrow lost limbs in humans.
This can be done via manipulating our own similar genetic heritage.
The lead author on this project, Shawn Luttrell whom is a UW biology dortorial student stated:
“…We share thousands of genes with these animals, and we have many, if not all, of the same genes they are using to regenerate their body structures… “
He also pointed out that this could hold promising research for the central immune system in terms of human regeneration, if they could understand the mechanism used by the Acorn Worm to regenerate itself.
It is discovered that when the worms are cut in half, each half of the worm that was severed will continue to regenerate and self-heal. Producing a fully functional healthy worm once all of the body parts regrow.
The scientists point out that not only are the tissues lost, regrown, but they are regenerated in exactly the same way as if the injuries never occurred. So the end result is you cannot tell the creature that was injured compared to one that was never cut.
One of the things that was observed in this body of research is the gene expression patterns of the acorn worm that is used to regrow new body parts after injury.
This is believed to be a significant first stage into unraveling the puzzle of the mechanisms driving regeneration.
The researchers suspect a master gene or a ‘mother’ set of genes is responsible for initiating the pattern of genetic activity that stimulates tissue regrowth. Since when the regeneration process is started then the same kind of pattern is observed in every worm.
It is felt that when these genetic patterns are known and understood, then tissues can be collected from a human patient whom has suffered an amputation. The genes in those cells can then be activated leading the patient down a more regenerative pathway.
This would mean that perhaps under hospital conditions in the emergency ward, a tissue graft could be placed on the end of the lost limb at the injured area, and thus the arm or leg would then regrow to the appropriate size.
This sounds like straight from a science fiction movie but this is what the scientists are saying in this study in how they envision the treatment might operate and be applied to the patient.
In other words they are trying to see if the what the Acorn Worm does could be reverse engineered in humans.
Regeneration in our Species
In nature regeneration is common in many species, however, with vertebrates (including humans) it is most efficient with fish and amphibians, such as the Axolotl Salamander.
Now humans today can regrow aspects of organs along with skin cells up to a point, however, we have lost the ability of full regeneration of body parts.
There can be several reasons for this such as our immunue system in a way to protect the human body by scarring to prevent blood loss and infection.. Scientists think this might be hindering the regeneration process in humans.
However I would suggest when you understand certain DNA Code sequencing then it would be a matter of turning on the right DNA instructions to allow regrowth of lost body parts.
Planarian Worm Regeneration
I wrote an article back in September 2015 on the Planarian Flat Worm about its remarkable powerful regeneration abilities. They have the ability to clone themselves where they can recreate and their genome over and over again.
This gives them some kind of immortality and no-one really knows how old the Planarian Worm really is.
The flat worm can be cut up into little pieces and then each one will regenerate into a new worm.
Scientists are working on unlocking its secrets but one area of progress is where they have been able to manipulate non-regenerative worms to have regeneration abilities like the Planarian Worm.
This is based on the understanding how to turn on certain genetic switches resulting in a non-regenerating worm regrowing its head.
So there are other species of worm in nature that can regenerate and add value to ongoing research for human regeneration. However, the Acorn Worm is very significant because of its close genetic relationship with humans.
The Next Step Forward
The scientists are now trying to learn and understand what are the correct type of cells the Acorn Worm uses to regrow lost limbs and body parts. Perhaps stem cells could be used to promote regrowth of tissues, or may be commands are given to other cells for initiating regrowth.
The researchers are also hoping to activate genes that would stimulate complete regeneration in certain species that currently can not regrow all muscle and tissues, such as the Zebra Fish.
To summarize, scientists at UW are hoping by studying the Acorn Worm as a model because of its closeness to humans, then we can unlock human limb regrowth genetic potential in humans.