Skin inflammation can encourage hair growth in mice by activating fat cells. The serum derived from this process may also benefit humans without causing discomfort.

While hair loss is often addressed with medications or steroid injections, more effective solutions are being researched, including stem cell therapies and drugs that reactivate dormant hair follicles.

Songjian Lin, among researchers at National Taiwan University, became intrigued by how adipose tissue influences hair growth during experiments with mice. “Unexpectedly, we found changes in the size of fat cells following skin inflammation. [Fat cells] shrink quickly before hair starts to grow back. We proposed that fat cells could release fatty acids via lipolysis to spur hair regeneration,” Lin explains.

To explore this further, they repeated the study and examined the relevant cells more closely. They initially applied an irritant to a shaved section of the mouse’s back to simulate eczema. By day ten, they noted that the mice’s hair follicles were actively growing, resulting in visible hair growth in those regions. This effect was absent in other shaved areas without eczema, as well as in control mice.

The research team observed that this phenomenon appears to occur because immune cells called macrophages migrate to the fat layer beneath the mouse’s skin, signaling fat cells to release fatty acids. These fatty acids are then utilized by hair follicle stem cells, promoting increased mitochondrial production, which supplies energy and fosters hair growth. This aligns with past studies indicating that plucking hair can trigger immune responses in nearby hair follicles, stimulating their growth.

Though eczema isn’t typically linked to hair growth in humans, other forms of skin inflammation may play a role, such as those associated with casts for broken bones, which are connected to excess hair growth.

Next, Lin and his team sought to determine whether fatty acids alone could induce hair growth without prior irritation. They formulated a serum containing various fatty acids dissolved in alcohol. This serum was applied to non-irritated shaved mice, and the results were compared to untreated areas and control mice. “We discovered that only monounsaturated fatty acids, like oleic acid and palmitoleic acid—prevalent in adipose tissue—successfully induced hair regrowth when applied topically,” Lin notes.

The researchers, who have since patented the serum, also observed encouraging outcomes when tested on human hair follicles in the lab and now intend to evaluate different dosages on human scalps.

Lin does not anticipate any serious side effects from the treatment. “Oleic acid and palmitoleic acid are naturally occurring fatty acids. They are present in high quantities in our fat tissue and various vegetable oils, making them safe for use,” he states. “I applied a solution of these fatty acids mixed with alcohol to my thighs for three weeks and noticed it stimulated hair growth.”

However, he cautions that the treatment hasn’t yet undergone testing on human skin, and animal models may differ significantly, especially concerning hair follicle biology. Christos Tziotsios from King’s College London also points out that similar serums are under development, including one utilizing plant extracts that promote hair growth in a matter of weeks.

Nonetheless, Tziotsios affirms that the latest findings enhance our comprehension of hair growth and loss. “We were aware of fat cells’ involvement in hair follicle formation, but this is the first instance we’ve witnessed them playing a role in hair regeneration,” he remarks. It could also clarify why certain individuals experience hair growth post-microneedling treatments, which involve rolling fine needles across the scalp to create micro-injuries that elicit an immune response.