2024-02-03 21:46:12
Hair graying is a common phenomenon observed in most humans and mice, often reflecting the premature aging of melanocyte stem cells (McSCs) compared to other adult stem cell populations. A recent study reveals that, contrary to popular belief, McSCs do not remain in an undifferentiated state in their follicular niche, but fluctuate between stem cell states and in-transit amplifying cell (AT) states for their self-renewal and production. of mature offspring. This finding suggests a fundamentally different model of melanocyte stem cell maintenance, where dedifferentiation plays a key role.
The mobility and plasticity of McSCs
Through live imaging and single-cell RNA sequencing, it was revealed that McSCs are mobile, moving between follicular stem cell compartments and TA compartments where they reversibly enter distinct differentiation states. These states are governed by local microenvironmental signals, such as WNT. Long-term lineage tracing showed that the McSC system is maintained by reverted McSCs rather than reserved stem cells, immune to reversible changes.
McSCs and hair pigmentation
Unlike the traditional hierarchical model of stem cell differentiation, which suggests a unidirectional process, this study indicates that most McSCs can alternate between transit-amplifying and stem cell states. This ability to switch between different states allows not only the self-renewal of McSCs but also the production of mature melanocyte progeny, essential for hair pigmentation.
A potential approach to graying hair
The accumulation of “failed” McSCs that do not contribute to the regeneration of melanocyte progeny during aging highlights a specific vulnerability in the long-term maintenance of McSCs. Modulating the mobility of McSCs might represent a new strategy for the prevention of hair graying, providing promising insight for future research in the field of tissue regeneration and treatment of visible signs of aging.
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Implications et perspectives futures
The discovery that dedifferentiation is integral to the homeostatic maintenance of stem cells opens new avenues of research for understanding stem cell niche dynamics in other tissue systems. Furthermore, understanding the mechanisms that enable the reversibility of McSCs might inform the development of innovative therapies for the repigmentation of gray hair and potentially influence the approach to treatments once morest various types of cancers, such as melanoma, which exhibit a similar retention capacity. of self-renewal despite extensive differentiation.
This study marks a turning point in our understanding of the biology of melanocyte stem cells, highlighting the importance of cellular plasticity in tissue maintenance and offering new perspectives for the treatment of pigmentary disorders and the prevention of hair aging.
Study source: Sun, Q., Lee, W., Hu, H. et al. Dedifferentiation maintains melanocyte stem cells in a dynamic niche. Nature 616, 774–782 (2023).
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