The sonic hedgehog gene carries far greater responsibility than its playful name might suggest. Originally named so for its spiky resemblance to the video game character, the gene codes for a protein that is critical to embryonic development, the formation of the central nervous system and left and right sides of the brain, among other important duties. Scientists have now tapped into its unique properties to regrow hair on damaged skin thought incapable of doing so, opening up new research opportunities for drugs to restore hair growth in those with baldness.
Scientists know that the sonic hedgehog gene plays a very active role during early growth in the womb. Here, it gets in early to make sure limbs and organs form in the appropriate places and that our eyes grow as two separate organs rather than one. For these reasons, researchers have studied the sonic hedgehog gene to better understand birth defects, the formation of cancers, and how limbs and tissues might one day be regenerated in humans.
In a similar vein, scientists at the New York University had wondered if the sonic hedgehog gene could hold some secrets regarding hair regrowth. It is known that the gene is inactive in wounded skin on healthy adults, which may be the reason why follicles fail to form on scars from burns, surgeries or other injuries. But what happens if it is brought out of hibernation?
The team carried out experiments where they activated the sonic hedgehog gene in mice with skin wounds, using the signaling pathway to stimulate fibroblasts just beneath the skin's surface where hair roots usually begin to form. Fibroblasts were targeted for their capacity to secrete collagen, a protein central to the shape, strength and structural integrity of skin and hair.
Sure enough, the scientists observed hair regrowth on the wounds within four weeks, with the hair root and shaft structures taking shape after nine weeks. Meanwhile, no signs of hair growth were observed in a separate set of injured mice whose wounds were untreated.
"Our results show that stimulating fibroblasts through the sonic hedgehog pathway can trigger hair growth not previously seen in wound healing," says study senior investigator and cell biologist Mayumi Ito.
This is a promising finding on a few fronts. Previously, scientists had held the belief that hair was unable to grow on wounded skin due to a buildup of excess collagen, but they now have evidence that the dormant sonic hedgehog gene has a role to play. This could have real ramifications for burn victims, or those with skin damaged through other traumas that are unable to regrow hair in certain places.
And it is significant for all efforts to restore hair growth in people suffering any kind of baldness, as it provides a new target through which scientists might be able to prompt mature skin to return to its embryonic state and spawn new hair follicles. Ito and her team are now looking to investigate chemical and genetic stimulants that do just that.
The team has published its research in the journal Nature Communications.
Source: New York University
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