MOSCOW, May 1, Vladislav Strekopytov. A new study shows that the preservation of natural hair color does not depend on the number of pigment-producing melanocytes, but on the activity of the original stem cells in the hair follicles. Over time, they become more passive, but if you find a way to make them move again, the gray hair will recede, scientists say.
Color fades, hair stays
Human and other mammalian hair is genetically programmed to constantly renew itself. Regeneration is supported by stem cells located in a special zone of each hair follicle — the tubercle area.
While they are active, the hairline is restored, completely replaced 24-25 times in a person's life. Gradually, the process slows down, hair falls out faster than new ones grow. Baldness begins.
In addition, with age or under the influence of external factors, the hair loses color — turns gray. This happens due to a violation of the production of melanin pigment by special cells — melanocytes, which are located at the base of the hair follicle, around the dermal papilla.
For a long time it remained a mystery why, even after the loss of pigmentation, gray hair continues to grow, because both keratinocytes — the cells from which the filamentous base of the hair is built, and melanocytes need active stem cells. It has been suggested that the cells that produce melanocytes end up in the tubercle before the others. As it turned out, this is not the case. crop-width=»600″ data-crop-height=»517″ data-source-sid=»istock-2023″ class=»lazyload» width=»1920″ height=»1654″ decoding=»async» />< br />
Lazy cells
Scientists from the United States and Japan, led by Mayumi Ito of New York University's Grossman School of Medicine, observed cellular processes in mouse hair follicles for two years.
The result was that pigmentation disappeared when melanocyte stem cells , known as McSC, stop moving between follicle compartments. Old melanocytes in the germinal zone of the hair are depleted, but there are no new ones.
In order for McSCs to reach maturity and produce pigment, they must receive a certain protein signal — when they move from one zone of the follicle to another, when the cells interact with proteins.
It turned out that melanocyte stem cells can be in the most primitive, germinal state or the next — transit-amplifying — depending on the position in the follicle. What's more, as hair ages, more cells get stuck between these two stages. This really sets McSC apart from the stem cells that inevitably go all the way.
That is, the germ cells of melanocytes do not disappear with age, but seem to fall asleep. This means that you can get rid of gray hair — if you figure out how to activate lazy McSCs.
«This is a really big step,» Mayumi Ito said in a press release. the key to maintaining the health and color of the hair.»
To confirm these findings, scientists deliberately plucked the fur from mice, stimulating acceleration hair growth cycle. The percentage of stuck McSC cells increased from 15 to 50 percent.
Interestingly, new hairs were gray due to a lack of pigment, while McSCs continued to move into the remaining cells, picking up protein signals and producing a rich brown pigment.
The experiment used 3D imaging of cells to track their aging and movement inside the hair follicle in real time.
«We were surprised to see one group of stem cells switch from young to mature and back. This is not consistent with the basic notions,” says first author of the study, Dr. Qi Sun of New York University, “If the same mechanism works in humans, it is possible to defeat gray hair and baldness.”
Stem cells have a unique ability to transform into cells of any tissues and organs. They — donor or own — can be transplanted into the deep layers of the skin on the head so that they restore the activity of hair follicles. Scientists suggest that this will improve hair quality, prevent hair loss, and restore healthy pigmentation.
“It sounds promising, but you need to understand that this is only a study on laboratory animals,” says Irina Kolesnikova, a geneticist at the Gemotest laboratory. “Perhaps in the future, drugs will be created to restore the resource of stem cells in the basal layer of the skin. But so far this approach seems inappropriate — this is the case when the treatment is more dangerous than the disease itself.
However, this is already being used to combat baldness.
“Stem cells are versatile and therefore popular in tissue repair therapy and surgical procedures,” says Ilya Almazov, Ph.D., plastic surgeon. “Stem cell treatment for baldness is less invasive compared to traditional transplantation, improves hair condition, makes weak hair follicles stronger and healthy».
Different reasons
Aging is the main, but not the only reason for the decrease in melanocyte activity. Cells stop producing pigment in certain diseases, such as vitiligo, and as a result of internal inflammation.
Melanocytes are harmed by direct sunlight, certain hormonal drugs, and stress. Much depends on genetics — a hereditary predisposition to early or late gray hair.
The US National Institutes of Health considers the appearance of the first gray hair between the ages of 45 and 65 to be normal.