New signaling molecule discovered that may stimulate hair growth

The University of California, Irvine-led researchers have discovered that a signalling molecule called SCUBE3 potently stimulates hair growth and may offer a treatment for androgenetic alopecia, a common form of hair loss in women and men.

The study, published online today in Developmental Cell, determined the precise mechanism by which the dermal papilla cells—specialised signal-making fibroblasts at the bottom of each hair follicle—promote new growth. Although it's well known that dermal papilla cells play a pivotal role in controlling hair growth, the genetic basis of the activating molecules involved has been poorly understood.

"At different times during the hair follicle life cycle, the very same dermal papilla cells can send signals that either keep follicles dormant or trigger new hair growth," said Maksim Plikus, PhD, UCI professor of developmental & cell biology and the study's corresponding author. "We revealed that the SCUBE3 signalling molecule, which dermal papilla cells produce naturally, is the messenger used to 'tell' the neighbouring hair stem cells to start dividing, which heralds the onset of new hair growth."

The production of activating molecules by the dermal papilla cells is critical for efficient hair growth in mice and humans. In people with androgenetic alopecia, dermal papilla cells malfunction, significantly reducing the usually abundant activating molecules. A mouse model with hyperactivated dermal papilla cells and excessive hair, which will facilitate more discoveries about hair growth regulation, was developed for this research.

"Studying this mouse model permitted us to identify SCUBE3 as the previously unknown signalling molecule that can drive excessive hair growth," said co-first author Yingzi Liu, a UCI postdoctoral researcher in developmental & cell biology.

Further tests validated that SCUBE3 activates hair growth in human follicles. Researchers microinjected SCUBE3 into mouse skin where human scalp follicles had been transplanted, inducing new development in the dormant human and surrounding mouse follicles.

"These experiments provide proof-of-principle data that SCUBE3 or derived molecules can be a promising therapeutic for hair loss," said co-first author Christian Guerrero-Juarez, a UCI postdoctoral researcher in mathematics.

Currently, the Food and Drug Administration approves two medications on the market—finasteride and minoxidil—for androgenetic alopecia. Finasteride is only approved for use in men. Both drugs are not universally effective and need tomusten daily to muster their clinical effect.

"There is a strong need for new, effective hair loss medicines, and naturally occurring compounds normally used by the dermal papilla cells present ideal next-generation candidates for treatment," Plikus said. "Our human hair transplant model test validates the preclinical potential of SCUBE3."

Stay Tuned; more research and human trials are to come.