A long-term goal of medicine in the big picture has been developing the field of regenerative medicine in order to work toward growing replacement organs for patients. This process has been decades in the making and, even today, can be finicky at best.
Regrowing Everything
Though researchers and doctors have begun succeeding more and more often with their organ regeneration attempts, it has remained slow going. But with the advent of gene editing and the possibility of housing these organs internally to grow within animals like pigs, the ability for humans to make replacement organs will only become more secure in the years to come.
However, organs are only one part of the whole picture. What about regrowing skin? Limbs? Perhaps even muscular or skeletal tissue? Cell growth experiments using stem cells and other materials have been ongoing in order to attempt these types of regeneration as well. Thus far, outside of skin reformation, there has been limited success.
Some researchers have taken this series of lacking results to mean that not enough is known about body regeneration in general and that more basic research needs to be conducted in order to expand the general knowledge base of the global scientific community.
The Regenerating Worm
To this end, scientists at Tufts University have been conducting tests again and again on the most simple of organisms used for regeneration research, the model organism or group of organisms known as planarians.
The term itself is somewhat vague and broad. In the most general sense, it applies to all the species of flatworms under the class Turbellaria, but this is a huge grouping that includes thousands of species. Many of these species have significant differences between each other in regards to size and even shape at times. For the purposes of regenerative medicine and any scientific research into their regenerative capabilities, the scientific community only refers to the genus Planaria or the genus Dugesia.
In this case, it is the latter and specifically the species Dugesia japonica. Planarians have the remarkable capability to regrow their bodies even when cut in half. This alone makes them useful test subjects for this kind of research. But there is another ability that is even more important for understanding how body structure, genetics, and regeneration are linked. Or not linked, as the case may be.
Bioelectricity and Body Patterns
The researchers had, in a prior experiment, shown that these planarians can, under the right conditions, regrow their body back not with their normal head, but two heads instead. During that test, they had been investigating the effects of bioelectricity. Bioelectromagnetism is an emerging field of study looking into the electrical networks of biological organisms, especially those that use more than the common amount for their size or use them in unique ways like as magnetic compasses.
In the new and recent study, the scientists decided to go even farther with their experiment to directly find out how bioelectricity played a role in this duplicative body mismatch. They cut the planarian specimens into fragments and, before they had begun regrowing, applied a chemical agent called octanol. This is known to interfere with the body’s electrical signals by blocking protein channels between cells that are used for cellular communication. Think of the connection point between neurons in the brain as an example.
By doing this, the scientists disrupted the planarians’ signals on how to regrow their missing body sections. What this resulted in was a fourth of them growing two heads and the rest growing back one head like normal. Originally, the researchers thought that the effects of octanol on the ones that didn’t change just hadn’t taken effect. But this wasn’t the case.
A Sustained Network
When cutting the one-headed planarians more without applying any octanol, they found that even the one-headed ones previously grew back at the same rate the original full group had: 25% with two heads and 75% with one (really 72%, as 3% did not develop back at all). This held true even with all of the continued one-headed flatworms, they kept the same ratio after the original application of octanol disrupting their bioelectric network.
Upon further investigation, the researchers found that they had permanently altered the bioelectric pattern memory of the planarians, changing their body morphology to encode a proper one-headed regrowth only three-fourths of the time. All without actual genetic changes to the genes controlling that morphology. In a manner of speaking, this can be considered an epigenetic effect.
Instead, this information is contained within the bioelectric network for each individual cell of the organism, whereby it directs the pattern for cell splitting to regrow the organism. This altered network could also be altered again back to its original formation if desired, making it reversible, but permanent without that active involvement.
New Avenues
This added understanding of how bioelectric networks work side by side with genetics and other systems opens up a new avenue of research for regenerative medicine. A combined method using genetic alteration and bioelectric pattern manipulation may finally hold the key to regrowing human limbs and other body parts.
There is clearly much more research to be done, however. Thus far, only a basic experiment in a microscopic species of flatworm has been done. Also, regrowing heads is probably not going to be a capability of humans any time soon, making this specific result not very transferable. But it’s a start. And often in science, that’s all you need.
Photo CCs: Dugesia japonica from Wikimedia Commons
