Posted on 04/24/2023 10:55:32 PM PDT by libh8er
A groundbreaking study from NYU Grossman School of Medicine has shed new light on the causes of gray hair. It also focuses on the unique properties of melanocyte stem cells (McSCs) found in hair follicles.
The study reveals that as people age, McSCs lose their ability to move between growth compartments in hair follicles. This ultimately affects hair color. The research improves our understanding of the mechanisms underlying hair pigmentation. It also opens up the possibility of developing treatments to reverse or prevent graying in humans.
Published in the journal Nature on April 19, the study focused on cells present in the skin of mice and humans, known as McSCs. The maturation of these cells determines hair color. They continually multiply but remain nonfunctional unless they receive a signal to transform into mature cells responsible for producing pigments.
The researchers discovered that McSCs exhibit remarkable plasticity. This means they can transition between different states of maturity as they move through the various compartments of a hair follicle.
Normal hair growth vs. maturing hair growth During normal hair growth, McSCs continually transition between their most primitive stem cell state and the next stage of maturation. The next stage is the transit-amplifying state, depending on their location within the hair follicle. The compartments within the follicle expose the McSCs to varying levels of protein signals that influence their maturation.
However, as hair ages, sheds, and regrows repeatedly, an increasing number of McSCs become trapped in a stem cell compartment called the hair follicle bulge. Here, they remain immobile and unable to mature into the transit-amplifying state. Consequently, they do not return to their original location in the germ compartment, where WNT proteins would have stimulated their regeneration into pigment cells.
“Our study adds to our basic understanding of how melanocyte stem cells work to color hair,” said study lead investigator Qi Sun, PhD, a postdoctoral fellow at NYU Langone Health. She further noted that these newly discovered mechanisms suggest that a similar fixed-positioning of melanocyte stem cells might occur in humans.
If this is the case, it could provide a potential pathway for reversing or preventing the graying of human hair. This would be accomplished by helping these “jammed” cells move again between developing hair follicle compartments.
Stem cells play a crucial role Researchers have discovered that the plasticity of melanocyte stem cells (McSCs) plays a crucial role in maintaining hair color. The findings suggest that the loss of McSCs’ unique ability to move back and forth between growth compartments in hair follicles could be responsible for hair graying.
The research team at NYU Langone Health found that other self-regenerating stem cells, such as those that make up the hair follicle itself, do not exhibit the plasticity observed in McSCs. These other cells typically move in only one direction along an established timeline as they mature.
“For example, transit-amplifying hair follicle cells never revert to their original stem cell state. This helps explain in part why hair can keep growing even while its pigmentation fails,” said study lead investigator Qi Sun, PhD, a postdoctoral fellow at NYU Langone Health.
The same research team had previously demonstrated that WNT signaling is necessary for stimulating McSCs to mature and produce pigment. They found that the hair germ compartment, located directly beneath the bulge, was exposed to WNT signaling at a rate many trillions of times higher than McSCs in the hair follicle bulge.
In their latest experiments, the researchers physically aged the hair of mice by plucking and forcing regrowth. They discovered that the number of hair follicles with McSCs trapped in the follicle bulge increased from 15% before plucking to nearly 50% after forced aging. These cells were unable to regenerate or mature into pigment-producing melanocytes.
The researchers determined that the stuck McSCs ceased their regenerative behavior due to the lack of exposure to WNT signaling. This impaired their ability to produce pigment in new hair follicles, which continued to grow.
Conversely, other McSCs that maintained their movement between the follicle bulge and hair germ retained their ability to regenerate as McSCs, mature into melanocytes, and produce pigment over the entire study period of two years.
“It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for graying and loss of hair color,” said study senior investigator Mayumi Ito, PhD, a professor in the Ronald O. Perelman Department of Dermatology and the Department of Cell Biology at NYU Langone Health.
“These findings suggest that melanocyte stem cell motility and reversible differentiation are key to keeping hair healthy and colored,” said Dr. Ito.
The research team plans to explore methods of restoring motility to McSCs or physically relocating them back to their germ compartment. There, they can produce pigment. For this study, the researchers employed cutting-edge 3D-intravital-imaging and scRNA-seq techniques. This allowed them to track cells in near-real-time as they aged and moved within each hair follicle.
This research contributes significantly to our understanding of the biology of hair pigmentation. It also holds promise for future therapeutic interventions to address hair graying, a common cosmetic concern for many individuals.
What we know about hair color The presence of pigments produced by cells called melanocytes determines hair color. These are located within hair follicles. There are two main types of pigments that contribute to hair color: eumelanin and pheomelanin.
Eumelanin is responsible for shades of brown and black hair, while pheomelanin produces yellow and red hues. The specific combination and concentration of these pigments determine an individual’s hair color.
Several factors influence hair color, including genetics, age, and environmental factors:
Genetics Genes play a significant role in determining hair color. The regulation of melanocyte function, melanin production, and pigment transfer to hair shafts involves multiple genes. The interactions between these genes and the expression of the relevant proteins determine the color, shade, and intensity of hair pigments.
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When I was working I consumed products from Mannatech. It’s a multi-level marketing company / home business, based on mannose from aloe vera. I got interested when I saw a participant nurse testify to her changes since enrolling, and her white hair with black roots was evidence enough for me. Kept me at work when others fell ill around me for decades.
I haven’t seen a woman under 70 with gray hair since the 1990s. Seriously... those little old grandmothers you remember from childhood? They were likely in their early 50s. As likely in their 40s as in their 60s.
The cast of Friends is now older than the cast of the Golden Girls was when that show started.
That’s a lost cause. Remember on Star Trek, LaForge’s blindness was remedied by a special visor, yet Picard’s baldness was still a hopeless condition.
"Science"!
I wish I had gray hair...
“might be caused by the same thing”
I think you’re on to something. It’s called “old age”.
There is a direct correlation between grey hair and cataracts
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and balding and heart disease
I’ve earned more than you.
Grew up with brownish/auburn hair and in another year or two, it’ll be white. Turning 61 this year & 95% of my hair is gray.
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