Nail stem cells are more versatile

Studying why nails grow back unlike many body parts, researchers have identified a new group of nail stem cells that perform dual roles - contribute to the growth of both the nails and the adjacent skin.

"That was a very surprising discovery," said principal investigator Krzysztof Kobielak from the University of Southern California in the US.

"The dual characteristic of these nail stem cells to regenerate both the nail and skin under certain physiological conditions is quite unique and different from other skin stem cells such as those of the hair follicle or sweat gland," Kobielak added.

For the study, the researchers attached fluorescent proteins and other visible labels to mouse nail cells.

Many of these cells repeatedly divided, diluting the fluorescence and labels among their increasingly dim progeny.

However, a few cells located in the soft tissue attached to the base of the nail retained strong fluorescence and labels because they either did not divide or divided slowly.

The researchers then discovered that these slow-dividing stem cells have the flexibility to contribute to the growth of both the nails and the adjacent skin.

The findings appeared in the journal Proceedings of the National Academy of Sciences.