New Study Reveals Hair Growth Mechanism Challenges Longheld Beliefs
A groundbreaking study from scientists at L’Oréal Research & Innovation and Queen Mary University of London has overturned traditional beliefs about hair growth. The research reveals that hair does not grow by being pushed out from the root, as long thought, but rather is actively pulled upward by coordinated movements of surrounding cells. This finding could reshape our understanding of hair biology and lead to innovative treatments for hair loss.
Utilizing advanced 3D live imaging, the team observed living human hair follicles in lab culture. The results indicate a significant shift in the mechanics of hair development. Professor Inês Sequeira, a co-author of the study, stated, “Our results reveal a fascinating choreography inside the hair follicle. For decades, it was assumed that hair was pushed out by the dividing cells in the hair bulb. Instead, we found that it’s actively being pulled upwards by surrounding tissue acting almost like a tiny motor.”
To validate their hypothesis, researchers conducted experiments that involved blocking cell division within the hair follicle. They anticipated that if hair growth relied on the traditional ‘pushing from below’ model, halting cell division would cease hair growth. Contrary to their expectations, hair growth persisted at nearly the same rate. In a subsequent experiment, when actin—a protein crucial for cell movement—was inhibited, the growth rate plummeted by over 80 percent.
The researchers employed computer dynamics simulations to reinforce their findings. Only models that integrated a pulling force from the outer sheath could accurately account for the speed at which hair ascends. Dr. Nicolas Tissot, the study’s lead author from L’Oréal’s Advanced Research team, emphasized the significance of their innovative imaging technique.
“We use a novel imaging method allowing 3D time-lapse microscopy in real-time,” he explained. “While static images provide mere isolated snapshots, this technique is essential for unraveling the intricate biological processes within the hair follicle, revealing crucial cellular kinetics, migratory patterns, and rates of cell division that would otherwise remain undetectable.”
These findings hold promise for the field of regenerative medicine. By focusing on the pulling mechanism rather than solely promoting cell division, future therapies may better support hair growth for individuals facing thinning or balding. This new perspective could lead to more effective treatments, enhancing the quality of life for those affected by hair loss.
The full study, titled “Mapping cell dynamics in human ex vivo hair follicles suggests pulling mechanism of hair growth,” is set to be published in Nature Communications in March 2025. As scientific understanding progresses, this research could pave the way for innovative approaches to hair regeneration, fundamentally altering the landscape of dermatological treatments.
