Non-thermal Plasma Suppresses Bacterial Colonization on Skin Wound and Promotes Wound Healing in Mice

The present study evaluated the effect of non-thermal plasma on skin wound healing in BalB/c mice. Two 6-mm wounds along the both sides of the spine were created on the back of each mouse (n=80) by using a punch biopsy. The mice were assigned randomly into two groups, with 40 animals in each group: a non-thermal plasma group in which the mice were treated with the non-thermal plasma; a control group in which the mice were left to heal naturally. Wound healing was evaluated on postoperative days (POD) 4, 7, 10 and 14 (n=5 per group in each POD) by percentage of wound closure. The mice was euthanized on POD 1, 4, 7, 10, 14, 21, 28 and 35 (n=1 in each POD). The wounds were removed, routinely fixed, paraffin-embedded, sectioned and HE-stained. A modified scoring system was used to evaluate the wounds. The results showed that acute inflammation peaked on POD 4 in non-thermal plasma group, earlier than in control group in which acute inflammation reached a peak on POD 7, and the acute inflammation scores were much lower in non-thermal group than in control group on POD 7 (P<0.05). The amount of granular tissue was greater on POD 4 and 7 in non-thermal group than in control group (P<0.05). The re-epithelialization score and the neovasularization score were increased significantly in non-thermal group when compared with control group on POD 7 and 10 (P<0.05 for all). The count of bacterial colonies was 10(3) CFU/mL on POD 4 and <20 CFU/mL on POD 7, significantly lower than that in control group (10(9) CFU/mL on POD 4 and >10(12) CFU/mL on the POD 7) (P<0.05). It was suggested that the non-thermal plasma facilitates the wound healing by suppressing bacterial colonization.