A recent imaging study questions long-held beliefs about how hair grows and may open the door to new hair-loss treatments.
Scientists have found that human hair doesn’t grow by being pushed up from the root. Rather, it is drawn along by forces from a newly identified network of moving cells. This discovery challenges long-standing biological assumptions and could reshape approaches to hair loss and tissue regeneration.
An Unseen Mechanism Powers Hair Growth
Researchers from L’Oréal Research & Innovation and Queen Mary University of London used advanced 3D live imaging to track individual cells inside human hair follicles maintained alive in laboratory cultures. Their Nature Communications study showed that cells in the outer root sheath—the layer surrounding the hair shaft—move in a downward spiral within the same region that generates the upward pulling force driving hair growth.
Dr. Inês Sequeira, a senior author, said: “Our findings reveal a remarkable choreography in the hair follicle.” For decades, scientists believed hair was pushed out by dividing cells in the hair bulb. Instead, we discovered it is actively pulled upward by the surrounding tissue, which acts like a tiny motor.
To test this mechanism, the researchers blocked cell division in the follicle, expecting hair growth to slow or stop. Surprisingly, growth continued at almost the same pace. In contrast, disrupting actin—a protein essential for cell contraction and movement—reduced hair growth by more than 80 percent. Simulations confirmed that coordinated pulling in the follicle’s outer layers drives hair movement.
Dr. Nicolas Tissot explained that real-time 3D time-lapse microscopy reveals the dynamic processes inside hair follicles that static images cannot. It shows cell movement, migration, and division rates, enabling modeling of the forces involved.
Rethinking Hair Disorders and Regeneration
Dr. Thomas Bornschlögl noted that hair growth is driven by the outer root sheath, not just cell division. This new view of follicle mechanics opens opportunities for studying hair disorders and developing therapies.
Although the experiments were performed on human hair follicles grown in laboratory culture, the findings provide valuable insights for hair research and regenerative medicine. The researchers suggest that understanding these mechanical forces could lead to treatments that address both the physical and biochemical environment of the follicle. In addition, the newly developed imaging approach will enable live testing of drugs and therapeutic strategies.
The study also underscores the increasing importance of biophysics in biology, demonstrating how tiny mechanical forces help shape the organs we encounter in everyday life.
Read the original article on: SciTechDaily
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