Fingernails reveal clues to limb regeneration

Digit tip including bone can regenerate by 5 weeks after amputation in normal mice (top). In contrast, mice that lack Wnt signaling in epithelium fail to regenerate the digit tip (bottom). Credit: Ito Lab

Mammals possess the remarkable ability to regenerate a lost fingertip, including the nail, nerves and even bone. In humans, an amputated fingertip can sprout back in as little as two months, a phenomenon that has remained poorly understood until now. In a paper published today in the journal Nature, researchers at NYU Langone Medical Center shed light on this rare regenerative power in mammals, using genetically engineered mice to document for the first time the biochemical chain of events that unfolds in the wake of a fingertip amputation.

The findings hold promise for who may one day be able to benefit from therapies that help the body regenerate lost limbs.

"Everyone knows that fingernails keep growing, but no one really knows why," says lead author Mayumi Ito, PhD, assistant professor of dermatology in the Ronald O. Perelman Department of Dermatology at NYU School of Medicine. Nor is much understood about the link between nail growth and the regenerative ability of the bone and tissue beneath the nail. Now, Dr. Ito and team have discovered an important clue in this process: a population of self-renewing stem cells in the nail matrix, a part of the nail bed rich in and blood vessels that stimulate nail growth. Moreover, the scientists have found that these stem cells depend upon a family of proteins known as the "Wnt signaling network"—the same proteins that play a crucial role in hair and —to regenerate bone in the fingertip.

"When we blocked the Wnt-signaling pathway in mice with amputated fingertips, the nail and bone did not grow back as they normally would," says Dr. Ito. Even more intriguing, the researchers found that they could manipulate the to stimulate regeneration in bone and tissue just beyond the fingertip. "Amputations of this magnitude ordinarily do not grow back," says Dr. Ito. These findings suggest that Wnt signaling is essential for fingertip regeneration, and point the way to therapies that could help people regenerate lost limbs. An estimated 1.7 million people in the U.S. live with amputations.

The team's next step is to zoom in on the molecular mechanisms that control how the interacts with the nail to influence bone and nail growth.

More information: dx.doi.org/10.1038/nature12214

Related Stories

New research provides clues on why hair turns gray

Jun 14, 2011

A new study by researchers at NYU Langone Medical Center has shown that, for the first time, Wnt signaling, already known to control many biological processes, between hair follicles and melanocyte stem cells can dictate ...

Do salamanders hold the solution to regeneration?

May 20, 2013

Salamanders' immune systems are key to their remarkable ability to regrow limbs, and could also underpin their ability to regenerate spinal cords, brain tissue and even parts of their hearts, scientists have ...

Ancient gene gives planarians a heads-up in regeneration

May 12, 2011

A seldom-studied gene known as notum plays a key role in the planarian's regeneration decision-making process, according to Whitehead Institute scientists. Protein from this gene determines whether a head or tail will regrow ...

Recommended for you

Better living through mitochondrial derived vesicles

18 hours ago

(Medical Xpress)—As principal transformers of bacteria, organelles, synapses, and cells, vesicles might be said to be the stuff of life. One need look no further than the rapid rise to prominence of The ...

Zebrafish help to unravel Alzheimer's disease

19 hours ago

New fundamental knowledge about the regulation of stem cells in the nerve tissue of zebrafish embryos results in surprising insights into neurodegenerative disease processes in the human brain. A new study by scientists at ...

Engineering new bone growth

22 hours ago

MIT chemical engineers have devised a new implantable tissue scaffold coated with bone growth factors that are released slowly over a few weeks. When applied to bone injuries or defects, this coated scaffold ...

User comments