Essential oil compound boosts wound healing in mice

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A chemical compound found in essential oils improves the healing process in mice when topically applied to a skin wound, a new study shows.

The finding could lead to improved treatments for skin injuries in humans.

Further, skin tissue treated with the chemical compound, beta-carophyllene—found in lavender, rosemary, and ylang ylang, as well as various herbs and spices such as black pepper—showed increased cell growth and cell migration critical to wound healing. Researchers also saw increased gene expression of hair follicle stem cells in the treated tissue. They found no involvement of the olfactory system in wound healing.

“This is the first finding at the chemical-compound level showing improved wound healing in addition to changes in gene expression in the skin,” says corresponding author Sachiko Koyama, who, at the time of the research, was an associate scientist at the Indiana University School of Medicine and is currently a visiting scientist in the biology department.

“The way gene expression changed also suggests not only improved wound healing but also the possibility of less scar formation and a more full recovery. It’s an example that essential oils work; however, it’s not through our sense of smell.”

Stages of wound healing

Essential oils are natural, concentrated oils extracted from plants. Humans have used them since the times of ancient Egypt, but the scented oils have experienced a resurgence in popularity in the US over the past few years, with many people using them for aromatherapy.

Koyama, who originally studied pheromones, says she had no interest in essential oils at first. The project started when she saw several students studying the wound healing process in mice in the Medical Sciences Program. Having previously worked in the psychological and brain sciences department, where scientists work with cannabinoid receptors, Koyama knew that beta-caryophyllene activates not only olfactory receptors but also cannabinoid receptor 2 (CB2), which has an anti-inflammatory effect when it is activated.

“In the wound healing process, there are several stages, starting from the inflammatory phase, followed by the cell proliferation stage, and the remodeling stage,” she says. “I thought maybe wound healing would be accelerated if inflammation was suppressed, stimulating an earlier switch from the inflammatory stage to the next stage.”

This accelerated the wound healing process, she says, but the resulting change in gene expression indicates there is more to the improved healing than just activating of the CB2 receptor.

“It’s possibly more complicated,” Koyama says. “Our findings suggest the involvements of some other routes in addition to CB2. I hope to clarify the mechanisms of action in the near future.”

Essential oils for drug delivery, too?

Although the study’s results are promising, Koyama says she wouldn’t recommend that people start treating their injuries with just any essential oils, as her research applies to a very specific chemical compound with known purity, diluted in a specific concentration.

“It’s not very precise to use the essential oils themselves because there are differences,” she says. “Even if you say you used lavender, when the lavender was harvested, where it was harvested, how it was stored—all of this makes a difference in the chemical composition.”

Koyama says further research is necessary to figure out how beta-carophyllene might be used to develop new treatments for skin wounds in humans.

She says she hopes to better understand the mechanisms that accelerate the healing process and to find a combination of chemical compounds that could combine to accelerate drug delivery and chemical stability, which is important for avoiding or suppressing allergic responses that oxidation of the chemical compounds may cause.

“We still need thorough scientific studies at the chemical-compound level and also to test the combinations of these chemical compounds,” she says.

“For example, there are studies showing that linalool—another compound found in lavender—can suppress anxiety through the olfactory system. There could be the best combinations of chemical compounds at specific ratios, and we might be able to do prescriptions of aroma chemical compounds, depending on the specific treatment goals.

“There are many things to test before we can start using it clinically, but our results are very promising and exciting; someday in the near future, we may be able to develop a drug and drug delivery methods using the chemical compounds found in essential oils.”

The study appears in PLOS ONE.

Additional coauthors are from Duke University and Indiana University.

Source: Indiana University