With the help of pink alien-looking salamanders about the size of a hot dog, scientists at a Bar Harbor laboratory are hoping to unlock secrets about how humans can regrow their limbs and bodily organs.
Used for the research at Mount Desert Island Biological Laboratory, the axolotl, pronounced “aksuh-lottle,” has an uncanny ability to regrow legs, or significant parts of its retinas, heart and brain, as well as other parts of its body. It’s native to Mexico.
If scientists at the lab can figure out how the aquatic axolotl’s regenerative abilities function, and whether that can be translated to human medicine, it could one day pave the way for humans to regrow tissue that might be damaged by a heart attack or in a fire, according to James Godwin, an assistant professor at the lab who also conducts immunology research a few miles away at The Jackson Laboratory.
“We know that in the animal kingdom, regeneration is possible,” Godwin said, pointing to a live axolotl in a clear water-filled plastic bin on his desk. “The proof is in front of you.”
Godwin recently made a discovery about axolotl blood cells that might eventually help humans regenerate parts of their bodies. He traced a type of white blood cell called macrophages that help axolotls avoid developing scar tissue to their livers — which is where humans also produce macrophages in their very early developmental stages.
Early on in embryonic development of humans, however, the production of white blood cells shifts from the liver to bone marrow, Godwin said, which appears to enable the creation of scar tissue in humans.
Axolotls macrophages are produced throughout their lives by their livers, which appears to help them regrow limbs and organs.
The scar tissue that results when humans suffer heart or lung damage, or if they are badly burned, is believed to be an inhibitor to the healthy regeneration of tissue, Godwin said. If scientists can figure out how to get humans to continue producing macrophages from their livers as they age, it could enable humans to regrow damaged heart or lung tissue, or maybe even one day a finger or ear, or even entire limb.
“What’s really fascinating is that it really doesn’t have to be that way,” Godwin said of having scar tissue grow over a wound, or of even requiring a transplant from a donor if an organ fails. “This cell type is somehow blocking the scarring process.”
In his research, Godwin found a way to temporarily block an axolotl’s production of macrophages in its liver and, when the axolotl lost a limb, it developed scar tissue instead of regrowing the limb. He said he then was able to restore the axolotl’s macrophage production in its liver and, after the scar tissue was manually cut away, the limb grew back.
Godwin said it is far too early in his research to know if such treatment is possible at the human level. He noted that injectable patches in development by other biomedical researchers that could help heart attack victims mitigate damage to their hearts could also be a delivery method for regeneration medicine.
If the chemical method he used to turn off liver macrophage production in axolotls can be reversed and applied to humans, Godwin said, that application might be possible with the same technology.
“We’ve just got to know what to fill the patches with,” he said. “I think the future is optimistic in that regard.”
Godwin’s research is but one way researchers at MDI Bio Lab are trying to learn more about how examples of regeneration or longevity in other organisms might be applicable to human medicine. These include studies of zebrafish, which can quickly regrow its tail with the help of medication, and a type of tiny worm called C. elegans which, with genetic alterations, can live 5 times longer than it normally would. Last year, the lab also hired Prayag Murawala, who also studies regeneration in axolotls.