Discovery of chemicals that control life and death in hair follicles

Bald Man Head

New research into the factors that control the life and death of hair follicle cells could help people with baldness as well as wound healing.

The discovery could help end baldness and speed healing

Scientists have discovered that one chemical is key to controlling when hair follicle cells divide and die. This breakthrough could not only lead to effective treatment of baldness, but ultimately speed up wound healing as follicles are the source of stem cells.

In the human body, most cells have a specific shape and function determined during embryonic development that does not change. A blood cell, for example, cannot turn into a nerve cell, or vice versa. However, stem cells are like blank tiles in a game of Scrabble; they can turn into other types of cells.

The adaptability of stem cells makes them valuable for repairing damaged tissue or organs.

Cross section of a hair follicle

Cross section of a hair follicle. Credit: UCR

“In science fiction when characters heal quickly from injuries, the idea is that the stem cells allow that,” said Riverside mathematical biologist and study co-author Qixuan Wang of the University of California, San Francisco.

“In real life, our new research brings us closer to understanding stem cell behavior so we can control it and promote wound healing,” Wang said. This research is detailed in an article recently published in Biophysical Journal.

In response to wounds, the liver and stomach regenerate themselves. However, Wang’s research team studied hair follicles because they are the only organ in humans that regenerates automatically and periodically, even without injury.

Scientists have discovered how TGF-beta, a type of protein, controls the process by which cells in hair follicles, including stem cells, divide and form new cells, or orchestrate their own death – ultimately leading to the death of the entire hair follicle.

“TGF-beta has two opposing roles. “It helps activate some hair follicle cells to produce new life, and later, it helps orchestrate apoptosis, the process of cell death,” Wang said.

As with many chemicals, it is the quantity that makes the difference in the outcome. If a cell produces a certain amount of TGF-beta, it activates cell division. However, an excessive amount causes apoptosis.

No one is quite sure why hair follicles kill themselves. According to some hypotheses, it is an inherited trait from animals that lose their fur to survive hot summer temperatures or to try to camouflage themselves.

“Even when a hair follicle is killed, it never kills its reservoir of stem cells.” “When the surviving stem cells receive a signal to regenerate, they divide, make new cells and develop into a new follicle,” Wang said.

If researchers can determine more precisely how TGF-beta activates cell division and how the chemical interacts with other important genes, it may be possible to activate follicle stem cells and stimulate hair growth.

Since many animals, including humans, have hair-covered skin, perfect wound healing would require the regeneration of hair follicles. Being able to more precisely control TGF-beta levels could also cure baldness, which plagues millions of people worldwide.

“Potentially, our work could offer something to help people suffering from various problems,” Wang said.

Reference: “A Probable Boolean Model on the Regulation of Hair Follicle Cell Fate by TGF-ß” by Katherine Dean and Qixuan Wang, June 16, 2022 Biophysical Journal.
DOI: 10.1016/j.bpj.2022.05.035

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