Study Uncovers Why Hair Grows & Shrinks in Different Areas of the Body

A team researching male pattern baldness has unveiled critical information about hair growth that could provide the foundation for revolutionary hair loss treatments.

Previous studies suggest that much of the body’s hair growth cycle is controlled by two proteins: Wnt proteins and bone morphogenetic proteins (BMPs). The former regulates cell proliferation during the development of embryos and other tissue while the latter drives development within the embryo and helps cells function properly.

In regards to hair growth, the two proteins are involved in what are known as “signaling pathways.” They pass signals into hair cells, causing the cellular function of hair growth to begin. When either pathway becomes defective, hair growth patterns across the body are said to be disrupted.

The University of California at Irvine (UCI) team designed their study to learn more about hair growth patterns across the entire body. They began by utilizing biological data and a mathematical model to create a map of these patterns. The model was engineered from a mouse to represent baldness, or simply poor hair growth within human skin. Study co-leader and professor of mathematics Qing Nie described the value of this tool:

"Our new mathematical model predicted details of signaling communications between hairs, otherwise difficult to reveal with standard biological experiments alone.”

Prior to the study, hair growth scientists were under the impression that Wnt proteins and BMPs signaling pathways are largely responsible for all hair growth. The team, however, found that different areas of the skin must “communicate” with each other to coordinate the growth of each area’s hair follicles.

This might explain why male pattern baldness only affects the front and top of the head and excludes the lower back of the head. It seems the hair follicles in this area did not receive the same signals as the other areas, allowing these follicles to grow without disruption.

The team also found that the regulation of Wnt and BMP signaling pathways facilitates the communication between the different areas of the skin.

"If communication between nonbalding and balding regions can be reactivated, hair growth signals can then start spreading across the entire head skin, preventing regional baldness," says Professor Plikus.

In other words, drug makers might be able to develop treatments that inhibit or activate Wnt and BMP signaling pathways, causing hair to start or stop growing.

The researchers were even able identify the levels of Wnt and BMP signaling that are “very favorable” for hair growth, and optimizing these levels even further could theoretically “achieve enhanced hair growth.”

"Just like scalp skin can show hair growth deficiency, skin in other body sites - such as the face, arms, and legs - can often show excessive hair growth that can be cosmetically undesirable. Our findings suggest that increased signaling crosstalk among hair follicles could be one major reason for this." added Professor Plikus.

Future studies will gauge the results of manipulating different factors that affect the two signaling pathways, which could stimulate hair growth and even prevent hair from growing in undesirable parts of the body.

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