"Genetic instruction manual" may unlock human limb regeneration

Studying the genetics of how animals such as the axolotl regenerate their limbs has led to the discovery of a "genetic instruction manual" that may one day be used to improve human regeneration abilities(Credit: AJC1/Creative Commons)

Humans can regrow hair, nails, skin and some tissue after its cut or damaged, but we can only look on in envy as the humble axolotl fully regenerates its arms, legs, tail and even sections of its spinal cord. Scientists at MDI Biological Laboratory are studying the genetics of axolotls and other animals in order to learn more about the possibility of giving humans similar limb regeneration capabilities.

In addition to the axolotl, the study focused on the zebrafish and the bichir, all animals with the ability to regenerate lost body parts. The team discovered that all three species shared the same genetic regulators that control regeneration, despite branching apart from each other on the evolutionary tree some 420 million years ago. The fact that these regulators were exactly the same surprised the researchers, and suggested that limb regeneration may be possible in other animals as well.

"We didn't expect the patterns of genetic expression to be vastly different in the three species, but it was amazing to see that they were consistently the same," says Benjamin L. King, co-author of the study.

When a limb is lost, the animals form what's called a blastema, an area of dedifferentiated tissue that acts as a reservoir for the progenitor cells. The researchers set out to identify the genetic signature that accompanies blastema formation, and found a set of genes common to the three animals that are controlled by a shared network of microRNAs.

"Limb regeneration in humans may sound like science fiction, but it's within the realm of possibility," said Voot P. Yin, co-author of the study. "The fact that we've identified a genetic signature for limb regeneration in three different species with three different types of appendages suggests that nature has created a common genetic instruction manual governing regeneration that may be shared by all forms of animal life, including humans."

Growing a full, functional human arm back may not be on the immediate horizon, but the discovery will improve future studies into the genetic mechanisms involved in how animals regenerate, as well as why humans are so bad at it. Understanding that could open the door to improving our healing abilities in less extreme, but no less useful, ways.

The research could lead to new treatments that may allow tissue to heal faster, reducing pain along with the risk of infection and the recovery time for patients. And for those who do lose an arm or leg, better healing of the nerves around the amputation site could allow for neater integration of a replacement prosthetic.

Along with other research, including creating multipotent stem cells from human fat and bone cells, our chances of full limb regeneration abilities could one day come to pass.

The research was published in the journal PLOS ONE.

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