Can Mechanical Stretch Induce Hair Regeneration？

“The advertising slogan ‘Pulling out a lion’s mane makes the hair grow back’ is actually about pulling a lion’s hair. Now, a research team has discovered that pulling your own hair can also promote hair growth! Facing the crisis of hair loss, we are usually very cautious about protecting every single strand of hair. But did you know? Properly pulling out hair can actually promote hair growth. This discovery comes from a research team at Taipei Veterans General Hospital, who found that pulling hair can induce the activation of hair follicle stem cells and promote hair regeneration.”

How does pulling hair promote hair growth?

The hair growth cycle is divided into the anagen (growth phase), catagen (regression phase), and telogen (resting phase). Under normal circumstances, about 80-90% of the hair on a human’s head is in the growth phase. Various factors that influence hair loss can prolong the resting phase of hair, leading to the crisis of baldness. Therefore, if external stimulation can help “awaken” hair follicle stem cells, it can induce a hair regeneration response.

The research team previously discovered that when 200 hairs within a 5mm diameter area were pulled from an animal, 1200 hairs could regenerate, which is equivalent to six times the original amount. This phenomenon is known as the “quorum sensing phenomenon.”

Mechanism of Promoting Hair Growth

Based on previous research results, the research team further explored ways to activate hair regeneration without having to pull out hair. They designed a special skin-stretching device to help stretch the skin on the backs of animals.

The experimental results showed that under conditions of stretching the animals’ skin for 7 days with an intensity of 33%, the maximum hair regeneration was induced. If the pulling force was insufficient or the duration was not long enough, the regeneration phenomenon did not occur.

When the skin is stretched, the hair growth inhibitor BMP-2 predominates, suppressing hair follicle stem cells. Once the skin is released, the expression of BMP-2 rapidly decreases. At this point, hair growth factors gain the upper hand, causing hair to enter the growth phase.

Conclusion

We already know that the body is more likely to produce activation responses when given appropriate stimulation. For example, the brain needs regular thinking to remain agile, and muscles will gradually atrophy when limbs are immobile. Based on this foundation, the research team has proven that appropriate scalp stimulation can promote hair regeneration. This is a very interesting study. If it can be applied clinically in the future, it is bound to bring new hope for improvement to those troubled by baldness.

Reference:

Nat Commun. 2019 Apr 3;10(1):1524. doi: 10.1038/s41467-019-09402-8.