Which CAP components are relevant for enhancing dermal microcirculation in intact skin?

Abstract

Cold atmospheric plasma (CAP) has been shown to be beneficial in various medical fields such as wound healing, oncology or dentistry. A prominent effect induced by CAP is the boost of microcirculation in human skin tissue. Being a complex cocktail of physical and chemically reactive components, the mechanisms by which CAP enhances microcirculation still remain unclear. Thus, this study aims to identify relevant CAP components involved in stimulation of dermal microcirculation. In a comparative approach, the application of the same CAP source was modified in such a way that three different treatment modalities could be realized, each with a characteristic composition of electrical current flow and concentration of reactive species. Microcirculation parameters oxygen saturation (StO2), tissue hemoglobin index, near-infrared perfusion index and tissue water index were recorded before and after each treatment on the lateral proximal left arm of 10 healthy volunteers by means of hyperspectral imaging. The maximum microcirculatory response to CAP was observed when all components were allowed to interact with skin tissue (standard treatment). In contrast, no upregulation was found as soon as electric currents and fields had been removed from the effective component spectrum. Application of the CAP source at reduced concentrations of reactive species compared to standard treatment led to significant but less pronounced enhancement of dermal microcirculation. The findings of this study indicate that a synergistic interplay of all CAP components promotes microcirculation in dermal tissue most effectively. Moreover, the findings support the hypothesis that electric currents and fields play a key role in enabling microcirculation boost whereas availability of reactive species in the gas phase is associated with the intensity of the tissue response to CAP treatment.