In a new study, researchers have discovered a previously unknown smooth muscle that surrounds hair follicles.
The finding may help develop a new treatment for baldness.
The research was conducted by a team at the Icahn School of Medicine at Mount Sinai.
According to the team, in the life cycle of each human hair, a new hair shaft is created by so-called dermal papilla cells.
These specialized cells begin at the base of growing hair follicles, but then move slowly upwards toward stem cells that are found at the follicle’s tip.
These stem cells receive signals from the nearby dermal papilla cells “to start the next growth phase and make a new hair shaft, while the previous hair shaft is shed.
However, sometimes this cell-to-cell partnership gets interrupted. And that could play a role in hair loss.
In the study, the team aimed to find out how the dermal papilla cells travel up towards the stem cells.
Working with mice, they found an answer for how this works by discovering that the dermal sheath surrounding growing hair follicles is a smooth muscle, whose function is to contract and push up the hair shaft and pull up the dermal papilla.
Further experiments suggest that human hairs follow a similar mechanism.
And in the hair “destruction” phase of the hair-growth cycle, the dermal sheath contracts, allowing for existing hair strands to fall out.
This happens naturally in full heads of hair, but when it occurs too often, baldness can begin to set in.
The team says the new insight into how the dermal sheath works could re-focus research into hair loss.
Blocking the newly discovered muscle and its contraction cannot cure baldness caused by those processes.
Instead, blocking contraction and arresting the destruction phase of the cycle has the potential to retain the existing hair shaft that is otherwise lost when a new hair shaft is produced.
That means men might someday have a treatment that simply allows them to maintain the head hair they have now, instead of slowly losing it.
The lead author of the study is Dr. Michael Rendl. He’s associate director of the Black Family Stem Cell Institute.
The study is published in Science.
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