Cold atmospheric plasma (CAP) in wound healing: harnessing a dual-edged sword

Chronic wounds take longer to heal and, if left untreated, can result in severe repercussions such as sepsis, gangrene, and amputation. The current treatment procedures followed are wound cleaning and debridement, specialized dressings, antibiotics and antiseptics, hyperbaric oxygen therapy, and vacuum-assisted wound closure. Some of the limitations of these treatment options are multidrug resistance and tissue toxicity. Cold plasma is an emerging technology that has opened a new frontier in biomedical applications and is found to have great utility in wound healing. Cold plasma comprises reactive oxygen and nitrogen species (RONS) that can be targeted against bacterial inactivation and improve wound healing. The amount of RONS produced can be controlled by several parameters such as gas composition, flow rate, power, frequency, voltage, distance, and exposure time. The reactive species causes damage to the cell membrane as well as the intracellular components which ultimately lead to bacterial cell death. It can also accelerate wound healing by activating neutrophils, macrophages, endothelial cells, keratinocytes, and fibroblasts. These help in maintaining tissue oxygenation, initiating angiogenesis, collagen synthesis which aids in rapid wound closure. In this review, we summarize the various characteristics of cold plasma that can be optimized to produce an effective antimicrobial effect. The different mechanisms of bacterial inactivation and the stimulation of wound healing processes by the reactive species are discussed. Furthermore, numerous pieces of evidence from in vitro and in vivo experiments and clinical trials that prove that cold plasma is an effective approach are presented.