Effects of Cold Atmospheric Pressure Plasma on Accelerating Acute Wound Healing

Plasma is an ionized gas made up of free electrons and positively charged ions. For wound treatment, non-equilibrium atmospheric pressure plasma jets are generally made from noble gases like helium. Plasma treatment has been found to have properties that can accelerate wound healing and has been attracting attention with a rapid increase in the interest in medical devices based on cold atmospheric pressure plasma (CAP) in recent years.

Fractional CO₂ (FXCO₂) laser therapy has been used for skin resurfacing. However, the downtime after irradiation, such as the period with redness and/or pigmentation of the irradiated skin, is of concern. The aim of this retrospective clinical study was to evaluate and compare the effects of CAP on acute wounds created by a fractional CO₂ (FXCO₂) laser on four treatment groups.

This study was conducted between September 2017 and November 2018 to compare treatment outcomes of four identically-sized irradiated regions on the left forearm of healthy volunteer subjects. Twelve healthy volunteer subjects (9 women and 3 men) with a mean age of 34.3 ± 12.1 years old from the Tokyo City University and Clinic F in metropolitan Tokyo were enrolled. Each of the 12 subjects received irradiation on four areas of the same size (1.5 × 2.0 cm) on the medial side of the left forearm, making a total of 48 lesions. Each lesion was created using a FXCO₂ laser therapy device. Each region was then randomly assigned to one of four groups: 1) no treatment (control group), 2) irradiated CAP for 60 seconds (plasma group), 3) topical application of ointment containing betamethasone valerate (steroid group), or 4) two to three sprays of basic fibroblast growth factor (bFGF group).

The primary outcome of the skin was the change in absolute values of lightness index (L*), redness index (a*I) of L*a*b color space, arithmetical mean roughness (Ra), and mean melanin concentration. The secondary outcome was the clinical condition of the wounds, including inflammation, crust formation, and hyper/hypo-pigmentation on the recovering skin surface relative to the surrounding intact skin. Each item was evaluated at post-treatment 0, 1, 3, 7, 14, 28 days and 1 year.

The results revealed that the relative skin lightness index of the steroid group demonstrated the earliest improvement, and the other groups had almost equivalent improvement speed. At the end point of Day 28, all groups had skin lightness values higher than those before treatment. Although no significant difference was observed among all groups, the CAP group exhibited more rapid recovery regarding a*I and Ra. No side-effects were observed in the CAP group.

All in all, this study confirmed the effectiveness and safety of CAP, while avoiding the side-effects of conventional therapies; thus CAP may be a future treatment of choice in the field of medical plasma therapies.

Article by Akio Nishijima, et al, from Japan.

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