In a groundbreaking development for androgenetic alopecia, a common form of hair loss affecting both men and women, researchers led by the University of California, Irvine (UCI), have identified how senescent pigment-making cells in the skin can stimulate significant hair growth. This unexpected finding could generate a new wave of therapies to tackle hair loss in the future.
Hair follicle stem cells play a crucial role in hair growth, activating in cycles to allow new hair production. After each growth cycle, these stem cells become dormant. Although senescent cells are typically associated with aging and viewed as harmful for tissue regeneration, the UCI research team has discovered a positive side to cellular senescence.
“We found that senescent pigment cells produce large quantities of a specific signaling molecule called osteopontin, which activates dormant hair follicles. This instigates robust growth of long and thick hairs,” explained lead author Maksim Plikus, UCI professor of developmental and cell biology. These findings unearth a novel insight into the regenerative properties of senescent cells as beneficial components in tissue maintenance and growth.
The team’s study involved mouse models with pigmented skin spots that exhibited accelerated hair growth, bearing resemblance to human clinical observations of hairy skin nevi—moles or other marks such as birthmarks. An in-depth analysis of the interaction between senescent pigment cells and nearby hair stem cells revealed an abundance of the osteopontin molecule. Hair stem cells have a matching receptor molecule for osteopontin, known as CD44. When these two molecules interact, hair stem cells get activated, stimulating hair growth.
Recording slower hair growth in mice lacking either osteopontin or CD44 genes further confirmed their central role in hair growth. The effect of osteopontin on hair growth was also validated with human hairy skin nevi samples.
“Our findings provide qualitatively new insights into the relationship between senescent cells and tissue’s own stem cells, revealing the positive effects of senescent cells on hair follicle stem cells,” said Xiaojie Wang, UCI associate specialist in developmental and cell biology and first co-corresponding author of the study.
Understanding more about senescent cells could potentially lead to the development of new regenerative therapies for common hair loss, among other disorders. The research exemplifies a paradigm shift in the perceptions of senescence, suggesting that old cells can serve a regeneration purpose and may not be solely harmful.
The global research team, including healthcare professionals and scientists from the U.S., China, France, Germany, Korea, Japan, and Taiwan, are expanding their search into other molecules present in hairy skin nevi that might induce hair growth. “It’s likely that our continued research will unearth additional potent activators,” Plikus noted.
In addition to this groundbreaking discovery, a significant number of studies have contributed valuable information in the field of tissue regeneration and hair growth. Researchers have examined various aspects, such as the viability of tissue constructs, the effects of different substances on hair growth, and the role of specific genes and molecules. These studies aim to develop effective regenerative therapies for common hair loss and improve our overall understanding of the hair growth process.
For example, one study explored the use of liver organoids in a printed chip and found high cell viability, increased organoid size, consistent ATP production, and an increase in albumin production. This provides promising evidence for the development of tissue-engineered approaches to enhance hair growth.
Another study investigated the effects of different hydrogels on tissue regeneration and found that certain hydrogels, such as GelMA and HA hydrogels, showed significant improvements in hair growth. These hydrogels contain specific molecules that promote the activation of hair stem cells, leading to robust hair growth.
Furthermore, researchers have identified specific genes and molecules, such as BRAF mutations and SCUBE3, that play crucial roles in the hair growth process. Understanding the functions of these genes and molecules provides valuable insights into potential targets for regenerative therapies for hair loss.
Despite the advancements in hair growth research, there is still much to be explored. Studies have shown that factors like cell viability, extracellular matrix composition, and age-related changes can affect the success of regenerative therapies. Continued research in these areas will contribute to the development of more effective treatments for hair loss.
Overall, the discovery of the regenerative properties of senescent cells in stimulating hair growth is a major breakthrough in the field of hair loss research. Combining this knowledge with the insights gained from various studies on tissue engineering, hydrogel technology, and gene analysis, researchers are moving closer to developing innovative regenerative therapies for hair loss. These advancements bring hope to the millions of people affected by baldness and provide a new direction for future research in the field of hair growth.
The study Signalling by senescent melanocytes hyperactivates hair growth was published in the journal Nature.
FAQs
What treatments are currently available for hair loss?
Currently, there are only a few FDA-approved treatments for hair loss, including minoxidil (Rogaine) and finasteride (Propecia). Minoxidil is a topical medication that promotes hair growth by increasing blood flow to the hair follicles, which stimulates hair growth and prolongs the growth phase of the hair cycle. Finasteride, on the other hand, is an oral medication that inhibits the activity of an enzyme called 5-alpha reductase, thus reducing the levels of dihydrotestosterone (DHT) in the scalp, a hormone responsible for shrinking hair follicles and leading to hair loss. By blocking DHT, finasteride helps reverse the miniaturization of hair follicles and promotes hair regrowth. For autoimmune hair loss specifically, JAK inhibitors like upadacitinib have shown even more dramatic results, with a recent trial achieving complete hair regrowth in up to 23 percent of severe alopecia areata patients.
What do dermatologists think of the potential cure for baldness?
Dermatologists are hopeful about the potential cure for baldness using the SCUBE3 signaling molecule. The experiments with the molecule have provided proof-of-principle data that suggest it could be a promising therapeutic for hair loss. However, further experiments and clinical trials are still needed to validate its effectiveness and safety.
What does this mean for hair loss treatments?
The discovery of the SCUBE3 signaling molecule and its potential effectiveness in promoting hair growth could lead to new and more effective treatments for hair loss. The molecule has shown promise in inducing hair growth in experiments with mice and human hair follicles, and further research and clinical trials are still needed before it can be applied to new treatments.
How do they know that the SCUBE3 signaling molecule is what grows hair?
The researchers discovered the SCUBE3 signaling molecule through genetic tweaks to hair follicles in mice. Injecting the SCUBE3 molecule near normal mouse hair follicles induced hair growth in the mice. The researchers also transplanted human hair follicles into mice and found that injecting the SCUBE3 molecule near those follicles resulted in faster hair growth compared to traditional transplants. Other molecules that were initially suspected to be involved with hair growth did not have the same effect.
How does hair growth work?
Hair growth is regulated by stem cells located in hair follicles. Hair follicles work like 3D printers, with stem cells acting as the “ink” to create individual hairs. Specialized fibroblast cells called dermal papilla control the molecular program that determines hair growth and appearance. The dermal papilla cells at the bottom of each hair follicle control whether hair grows, what it looks like (curly or straight, thick or thin, color), and when it falls out. Hair follicles need to constantly grow new hair to maintain thickness and density, as old hairs fall out fairly quickly after the follicle stops growing new strands.
Why does this new SCUBE3 signaling molecule matter?
The SCUBE3 signaling molecule is significant because it plays a role in hair growth. Hair loss occurs when the dermal papilla cells stop producing SCUBE3. The presence of SCUBE3 tells nearby hair follicles to divide and grow hair. The molecule has shown potential as a potent hair growth trigger in experiments with mice, and further research is needed to explore its potential for hair loss therapy.
