Investigation of the effect of external nitric oxide (NO) application on wound healing in rats

Objective: The aim of this preclinical, in vivo, and experimentally designed study conducted under laboratory conditions is to compare the effects of NO application (inhaler, topical, and inhaler+topical) on wound healing, promoting wound healing, and preventing wound deterioration in rats with wound models, compared to spontaneously healing wounds. Materials and Methods: Permission was obtained from the Local Ethics Committee for Animal Experiments at Süleyman Demirel University to initiate the study. A total of 28 rats were randomly divided into four groups. The first group received only inhaled NO (Group I), the second group received only topical NO applied to the wound (Group T), the third group received a combination of both inhaled and topical NO (Group I+T), and the fourth group served as the control group (Group K). Tissue samples were collected from all groups on days 5, 10, and 15, processed using optimal protocols, and histopathologically evaluated using Hematoxylin&Eosin (H&E) and Masson's Trichrome (MT) staining. The obtained data were also statistically analysed. Findings: Topical and combined NO applications were observed to facilitate earlier resolution of inflammation and significantly accelerate the regenerative/remodelling phases. The sequence of the healing process was determined as Group I+T > Group T > Group I > Group K. Conclusion: Although NO was found to have supportive effects on wound healing, it was also observed that this effect depends on the optimal dose and route of administration. In particular, topical and combined applications were found to be more effective in regenerative/remodelling processes. For the therapeutic potential of NO to be transferred to clinical applications, dosage, application duration, and pharmacokinetic parameters must be carefully evaluated.