Baldness may soon become a thing of the past, Yale researchers hope.

Yale researchers have uncovered chemical triggers that could restore hair growth in bald men. Bald men have stem cells in their hair follicles, a known fact that the new Yale study, led by assistant biology professor Valerie Horsley, used to discover a way to reactivate these cells. After the team identified that a precursor to hair growth is the growth of a layer of fat in the scalp, they then identified the stem cell responsible for that fat growth.

The researchers found that when the hairs die, a layer of fat in the scalp shrinks. But when a new hair begins to grow, that same layer of fat expands in a process called adipogenesis. The stem cells that control that process are called precursor cells, the study explains.

“We are hopeful that in humans, adipocyte precursor cells will be a viable therapy to induce hair growth in these individuals,” Horsley said in an e-mail.

The team tested an injection of the precursor cells on mice who were unable to produce these fat cells. Before the injection, the follicles of the mice were unable to produce both hair and the fat tissue.

But two weeks after injection, the study found that hair follicles had begun to grow.

Moreover, scientists discovered that the precursor fat cells also produced a chemical, called platelet-derived growth factor (PDGF), that aids in hair growth 100 times faster than normal cells do. Up to 86 percent of hair follicle growth was restored in mice with the injection of this chemical.

But in order for the research to be relevant to the human population, scientists must prove that the cellular signaling in mice is the same as in humans.

Two cellular and molecular biologists from University of California, Los Angeles told the News that the research has promise in real life applications.

Priya Hays, staff research associate in the Berk Lab, said she believed the study was a good use of Yale’s scientific resources.

“Stem cell research has mostly been associated with life threatening diseases,” Nian Chen, researcher at the Chen Lab, said. “It’s fascinating to see it applied to male pattern baldness.”

The research appeared in the September issue of Cell.

Male pattern baldness affects roughly 40 million men in the United States.