Cold plasma, paired with the immune system activator interleukin-2, may be the key to drug-free hair regrowth.

The treatment, which reactivates dormant hair follicles, could fill the gap for more effective alternatives to minoxidil and finasteride, the only two hair-loss drugs currently approved by the Food and Drug Administration. Neither drug was initially developed to treat hair loss, their efficacy varies from person to person, and various side effects have been reported.

Hair follicles are “complex mini-organs made of many different cell types, all of which are strongly influenced by their surrounding microenvironment,” explains Junho Byun, a professor at the College of Pharmacy at Sookmyung Women’s University in Seoul, Korea.

“Because of this complexity, simply trying to stimulate the follicles is often not enough,” adds Jaiwoo Lee, a professor at the College of Pharmacy at Korea University, who co-led the study. “New strategies need to reshape this microenvironment so that dormant follicles can restart and return to active growth.”

Byun explains that creating a healthy immune environment around the hair follicle would make it easier for dormant follicles to start growing again. “In hair loss, many hair follicles enter a long-term ‘resting’ state and fail to naturally return to the growth phase,” he elaborates. This resting state, called the “telogen phase” of the hair growth cycle, can be induced by stress, illness, or simply aging.

Waking up “sleeping” hair follicles

To “wake up” resting hair follicles, Byun, Lee, and their team designed a gel-forming treatment that can be injected specifically into the areas of the scalp with hair loss.

To make the liquid form of the gel, they mixed hyaluronic acid, a substance produced in our bodies that helps plump skin and lubricate joints, with interleukin-2, a protein secreted by white blood cells. Inteterleukin-2 promotes the production and survival of immune cells called regulatory T cells, or Tregs. These cells reduce inflammation and promote tissue repair when the immune system encounters a threat, such as a virus or bacteria.

The same mechanism can be tapped into to stimulate the cells that control hair growth but, without an immune system threat, the researchers had to activate the mechanism another way.

Cold atmospheric plasma, which appears as a glowing blue or purple mist at normal room temperature and pressure, provides the needed trigger.

“Plasma forms when a gas gets enough energy for some electrons to break free from their atoms, creating a mix of charged and neutral particles,” Byun explains. Unlike the superheated plasma that powers the universe—found in the sun, nebulae, and lightning—cold atmospheric plasma is much cooler and can be generated using a commercial handheld device.

A dynamic duo for hair regrowth

Byun says that cold plasma plays two roles in their treatment, which they tested on mice. 

“It first helps the injected liquid turn into a soft gel by providing reactive oxygen species that trigger the material to solidify under the skin,” he says. “It also supplies additional reactive oxygen species that become trapped inside the gel.”  

The hydrogel stays in the skin for several days and slowly releases interleukin-2 and reactive oxygen species, which together boost Treg cell production.

When the cells at the base of hair follicles, called the dermal papilla, are activated by Tregs, they stimulate hair follicles stuck in the telogen stage to enter the growth, or anagen, stage, resulting in stronger and faster hair regrowth.

Mice treated once every four days, for a total of four sessions over two weeks, showed better hair regeneration efficacy than those tested with minoxidil or finasteride. In their paper in Advanced Science, the researchers reported 100% fur coverage within 15 days of treatment, while daily topical application of 5% minoxidil has been reported to achieve only 35% fur regrowth after 14 days.

Although mouse models are typical for assessing hair regeneration, they do not capture all the factors that contribute to genetic hair loss, medically known as androgenic alopecia, so future studies on human hair follicles are needed before clinical trials.

“Even with these limitations, this approach may offer a new way to support hair regrowth by improving the immune environment around hair follicles, but more research is needed to understand it fully and confirm its safety in people,” Byun says.

Reference: Jung Suk Kim et al. Cold Atmospheric Plasma-Activated In Situ Hydrogel Induces Hair Regeneration Via Immune Microenvironment Remodeling. Advanced Science (2025). DOI: 10.1002/ advs.202511962

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