We're one step closer to not just treating baldness but preventing it, with scientists making an important discovery that offers keen insight into why hair growth comes to a screeching halt, offering new hope to millions of people across the globe.
In a new study led by Australia's Walter and Eliza Hall Institute of Medical Reesearch (WEHI) and Duke-NUS Medical School in Singapore, researchers have found that all-important hair follicle stem cells (HFSCs), which are in charge of hair growth, can't do their job without a certain "bodyguard" protein. This protein, MCL-1, is a powerful agent in regulating cell death – and if levels are lowered, by way of outside forces such as stress, aging, cancer drugs or genetics, HSFCs are left vulnerable and overworked as they try to produce new growth. This ultimately causes them to die off, too.
"This study advances our understanding of how stem cell survival and tissue regeneration are orchestrated," the researchers noted. "Our findings may have broader implications for controlling the survival of stem and progenitor cells in tissue regeneration and cancer."
Think of HFSCs as a team if builders erecting a house (aka, your hair) on a spot of land that's been cleared. But at the same time, a demolition crew rolls in and begins knocking down structures as soon as the builders make any progress, stressing them out to the point of complete exhaustion. While a passer-by might see no progress on the site and assume the builders are inept or lazy, they've simply been overpowered. But with adequate MCL-1 security on site, the demolishers are kept at bay and the builders are able to carry on undisturbed to complete the project.
Essentially, without adequate MCL-1 to safeguard the hardworking HFSCs, the stem cells become stressed to the point of self-destruction. Then, no hair will be produced. The researchers demonstrated this malfunction by switching off MCL-1 in mice and removing patches of existing hair. The team observed that the HFSCs were still alive for some time, but soon became overworked – which triggered a stress signal (P53) that ultimately killed the cells.
In 2022, another team of scientists found that the protein TGF-beta played a role in HFSC regulation (and cell death), but this latest research provides new insight into the behavior and vulnerabilities of the stem cells.
Until now, scientists didn't know that HFSCs, found deep beneath the surface of our skin, were so fragile and vulnerable to outside forces without the protection of the MCL-1 protein. And by blocking P53 or boosting MCL-1 levels, we might be able to safeguard these vital cells and in turn prevent hair loss.
And while programmed cell death (apoptosis) is a critical mechanism for deleting faulty and old cells in order for the body to regenerate new, more productive cells, HFSCs even at their most active will ultimately work themselves to death without adequate MCL-1 protection. The scientists observed this happening in just a few days in their mice model. This now opens new avenues of research to develop novel treatment for conditions like alopecia as well as broader hair-loss prevention.
“Importantly, our data highlight the interplay between P53 and MCL‑1, offering new insights into balancing proliferation stress and apoptosis during tissue regeneration," the researchers added.
The study was published in the journal Nature Communications.
