In Vitro Antimicrobial Properties and Their Mechanisms in Relation to Reactive Oxygen Species of Canine Platelet-Rich Fibrin

Simple Summary Bacterial infections can often lead to complications in wound healing. The overuse of antimicrobial drugs can cause antimicrobial resistance, making it necessary to find alternative therapeutic options for wound care. Platelet-rich fibrin (PRF) has been used for tissue regeneration, but until now, its application for antimicrobial activity has been limited to periodontal pathogens. In this study, we aimed to determine the antimicrobial effects of canine PRF (cPRF) against bacteria from the clinical wound of a dog and to investigate the mechanism of its antibacterial activity, which involves the formation of reactive oxygen species (ROS). Our results showed that cPRF had a significant antimicrobial effect against Escherichia coli between 4 and 24 h, resulting from the release of ROS. Based on these findings, cPRF, a rich source of growth factors that accelerate the wound healing process, could be used as a biological material for wound infection treatment, benefiting veterinary medicine.Abstract Platelet-rich fibrin (PRF), which has been shown to promote wound and bone regeneration, has demonstrated antimicrobial properties against periodontal pathogens. However, in veterinary medicine, no study has determined the antimicrobial effects of canine platelet-rich fibrin (cPRF). Therefore, this study aimed to determine the antimicrobial effect of cPRF against E. coli and S. pseudintermedius found in dogs' wounds and against the standard strain S. aureus. Additionally, the mechanism of the existing antibacterial activity of cPRF, which involves the formation of reactive oxygen species (ROS), was tested. Blood samples from six dogs were processed for cPRF. The antimicrobial properties of three groups (growth control, cPRF, and drug control) were evaluated at 0.5, 4, 8, and 24 h using a time-kill assay. The killing mechanisms involving ROS were evaluated using horseradish peroxidase (HRP) to suppress ROS production in PRF (PRF-SR). Subsequently, tests for antimicrobial properties and ROS generation were compared to those of the growth control and cPRF groups. The results showed that cPRF had significant antimicrobial properties against E. coli but no antimicrobial properties against S. pseudintermedius. After the ROS suppression, PRF-SR did not show an antimicrobial property against E. coli. Moreover, cPRF-treated bacteria exhibited significantly greater intracellular ROS than PRF-SR. In conclusion, canine PRF showed an antimicrobial effect against E. coli, and its antibacterial mechanism was related to releasing ROS.