Fat cells may hold the key to triggering hair growth, US researchers have found. They discovered that a layer of fat cells under the skin of mice sends chemical messages to stem cells, instructing them to grow hair.

Professor Valerie Horsley, a lead author on the paper said: 'If we can get these fat cells in the skin to talk to the dormant stem cells at the base of hair follicles, we might be able to get hair to grow again'.

Research showed that when hairs die, the layer of fat underneath them shrinks. When new hair grows, the layer of fat grows back. By using mice that were unable to produce these fat cells (and so having stunted hair growth) the scientists from Yale University, USAwere able to study the effect of the fat cells on the mice's ability to grow fur.

They injected these mice with fat cells derived from healthy mice, and discovered they could kick-start fur growth. Two weeks after the injection they could see hair follicles being reactivated, and the start of new hair growth.

They then isolated the chemical signal that they believe is responsible for stimulating hair growth – platelet derived growth factor (PDGF). The fat cells secrete PDGF at a level roughly 100 times higher than neighbouring cells do, and when the team injected PDGF directly into bald mice it was able to stimulate hair growth in 86 percent of follicles.

It has previously been shown that men suffering from male-pattern baldness still have the normal amount of stem cells required for hair growth but that these cells are dormant.

The researchers hope they may be able to use a similar signal to awaken the dormant stem cells in balding men, and encourage hair growth. However, further research is needed to determine if the signals involved in human hair growth are the same as in mice.

This research was published in Cell.