[Apr. 24, 2023: JD Shavit, The Brighter Side of News]
George Clooney at the Oscars. (CREDIT: Getty Images)
NYU Grossman School of Medicine Researchers have discovered that certain stem cells in mouse and human skin, called melanocyte stem cells (McSCs), have a unique ability to move between different compartments within hair follicles. However, as people age, these cells get stuck in a compartment, lose their ability to mature and retain hair color. The study was published in the Nature magazine.
Hair color is controlled by the fact that pools of non-functional but continually multiplying McSCs in the hair follicles are signaled to become mature cells which render the protein pigments responsible for the color.
During normal hair growth, McSCs continuously move back and forth on the maturity axis as they transit between compartments of the developing hair follicle. It is within these compartments that McSCs are exposed to different levels of protein signals influencing maturity.
According to the research team, as hair ages, falls out, and then repeatedly regrows, an increasing number of McSCs get stuck in the stem cell compartment called the hair follicle bulge. There they remain, do not mature into the transit amplification state, and do not return to their original location in the germinal compartment, where WNT proteins would have driven them to regenerate into pigment cells.
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“Our study adds to our basic understanding of how melanocyte stem cells work to color hair,” said study lead researcher Qi Sun, PhD, postdoctoral fellow at NYU Langone Health. “The new mechanisms raise the possibility that the same fixed positioning of melanocyte stem cells may exist in humans. If so, it presents a potential pathway to reverse or prevent graying of human hair by helping blocked cells to moving again between the developing hair follicle compartments.”
The researchers found that McSC plasticity is not present in other self-regenerating stem cells, such as those that make up the hair follicle itself, which are known to move in a single direction along a timeline established as they mature. For example, hair follicle cells that amplify transit never return to their original stem cell state. This helps explain in part why hair can continue to grow even when its pigmentation fails.
Previous work by the same research team at NYU showed that WNT signaling was required to stimulate McSCs to mature and produce pigment. This study had also shown that McSCs were billions of times less exposed to WNT signaling in the hair follicle bulge than in the hair germ compartment, which is located directly below the bulge.
Hair coloring stem cells (left, in pink) must be in the germinal compartment of the hair to be activated (right) to develop into pigment. (CREDIT: SPRINGER-NATURE PUBLISHING)
In the latest experiments on mice whose hair was physically aged by plucking and forced regrowth, the number of hair follicles with McSCs lodged in the follicle bulge increased from 15% before the plucking to almost half after the hair removal. forced aging. These cells remained unable to regenerate or mature into pigment-producing melanocytes.
In contrast, other McSCs that continued to cycle back and forth between the follicle bulge and the hair germ retained their ability to regenerate as McSCs, mature into melanocytes, and produce pigment throughout the period. two-year study.
“It is the loss of chameleon function in melanocyte stem cells that may be responsible for graying and loss of hair color,” said study lead researcher Mayumi Ito, PhD, a professor in the department. of Ronald O. Perelman Dermatology and the Department of Cell Biology at NYU Langone Health.
HG McSCs possess a self-renewing ability. (CREDIT: Nature)
“These results suggest that motility and reversible differentiation of melanocyte stem cells are essential for maintaining healthy, colorful hair,” said Ito, who is also a professor in the Department of Cell Biology at NYU Langone.
Ito says the team intends to investigate ways to restore the motility of McSCs or physically return them to their germinal compartment, where they can produce pigment.
The potential applications of this research are significant. Graying hair affects a large percentage of the population, and although it is often considered a natural part of aging, it can have a significant impact on a person’s self-esteem and confidence. If the NYU Grossman School of Medicine research team is successful in their efforts to restore the motility of McSCs, it could pave the way for new treatments to prevent or reverse graying hair.
The study’s findings could also have implications beyond hair color. According to Ito, “The plasticity of McSCs suggests that similar mechanisms may exist in other types of stem cells that are responsible for the maintenance and regeneration of tissues throughout the body. Understanding how stem cells move and differentiate in different contexts could lead to new insights into the mechanisms of aging and the development of new therapies for a wide range of diseases.”
The next steps for the research team will be to further investigate the mechanisms that control the motility of McSCs and develop strategies to restore their plasticity. They will also explore the potential of using small molecules or other agents to promote the return of McSCs to their germinal compartment.
Study co-authors include Minwoo Kim, Bo Zhang, Vivian Lee, Bin Wu, Zhiwei Ma, Michael Peckerar, Luiza Baptista, Sadegh Davari, David R. Drummond, Jessica G. Yeh, and Elsa Quintana-Bustamante.
The work of the NYU Grossman School of Medicine research team on McSCs is just one example of groundbreaking research being conducted in the field of stem cell biology. Stem cells have the potential to revolutionize medicine by offering new ways to treat a wide range of diseases and injuries. They have previously been used to treat conditions such as leukemia, lymphoma and some forms of anemia.
Stem cells are unique in their ability to grow into many different cell types in the body. This makes them useful for repairing or replacing damaged tissue. Stem cells can be found in many different tissues in the body, including bone marrow, blood, and fat. In recent years, scientists have been able to produce stem cells in the laboratory, which has opened up new possibilities for research and treatment.
Although stem cell research is very promising, it is also controversial. Some people have ethical concerns about using embryonic stem cells, which are taken from human embryos. There are also safety issues associated with the use of stem cells in medical treatments. However, many scientists believe that with proper regulation and oversight, stem cell research can be conducted safely and ethically.
The work of the NYU Grossman School of Medicine research team on McSCs is an exciting advance in the field of stem cell biology. By uncovering the mechanisms that control the motility of McSCs, they have opened up new possibilities for treating graying hair and other aging-related conditions. As they continue their research, they may discover new insights into the mechanisms of aging and the development of new therapies for a wide range of diseases.
For more scientific news, see our New discoveries section on The bright side of the news.
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