Cold Plasma Generates a Localized Inflammatory Response and Promotes Muscle Repair
The FDA-approved Renuvion cold plasma device is currently used for dermal skin tightening procedures and subdermal tightening after liposuction. Anecdotally, patients report improved tissue healing outcomes following treatment. The most likely explanation for this is plasma-generated reactive species which are inflammatory but also activate cellular signaling pathways, stimulate antioxidant responses, and activate immune cells. In this study, we aimed to determine the immediate and long-term molecular effects of a single plasma treatment on surgically injured muscle and the soft tissue envelope. We used RNA sequencing, histology, and immunohistochemistry to determine changes to the tissue following treatment. Neutrophils and mast cells rapidly mobilize 6 h after treatment in conjunction with an upregulated cellular antioxidant response. Additionally, genes identified by RNAseq indicate upregulated pro-regenerative muscle-tissue-protective gene transcripts and downregulated apoptotic pathway transcripts in the muscle tissue 6 h after treatment. The histology and RNAseq results from 4- and 14-days post plasma treatment indicate that these early inflammatory and antioxidant events drive muscle regeneration to skew toward myogenic differentiation over adipogenesis. Thus, we conclude that a single plasma treatment results in an immediate inflammatory and antioxidant response that enhances long-term muscle fiber repair through reduced adipogenesis. Overall design: Gene expression was compared between control and Renuvion treated surgical incisions in Sprague-Dawley rats at three different time points (6 hours, 4 days, and 14 days). The surgical incision was created on the same day as treatment for the 6 hour cohort. For the day 4 and day 14 groups, an initial surgery was done one week prior to the revision surgery with or without Renuvion treatment. The rats were euthanized at 4 and 14 days after the revision surgery. The biceps femoris was excised on the day of euthansia for each rat and snap frozen. The RNA was extracted from the tissue and sent to Novogene for sequencing.