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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. 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. [ABSTRACT FROM AUTHOR]

Simple Summary: Advanced platelet-rich fibrin (A-PRF) induces more migration and proliferation of fibroblasts compared with standard PRF, but it being freshly prepared prior to it being applied is necessary. To preserve its biological function, lyophilization, a freeze-drying method, has been developed to improve the stability and storage potential of PRF. This study aimed to determine the effect of lyophilized A-PRF on growth factor release and cell biological activity compared to fresh A-PRF. The results of the present study demonstrated that both formulations of canine A-PRF matrices, the fresh and lyophilized forms, were able to release various growth factors, promoting better wound regeneration than in instances without the A-PRF matrices. Lyophilization in canine A-PRF can mostly preserve the similar release of growth factors, and consequently has similar biological activities to a fresh preparation. Interestingly, lyophilized canine A-PRF demonstrated the tendency of larger releases of certain growth factors, including the significantly larger accumulated release of a growth factor named vascular endothelial growth factor-A (VEGFA). Based on these findings, it became clear that the lyophilization process can preserve growth factor release as well as the biological activity of canine A-PRF matrices, in addition to encouraging the use of canine lyophilized A-PRF as a biological material for promoting wound healing. Advanced platelet-rich fibrin (A-PRF) induces more proliferation and migration of fibroblasts compared with standard PRF, but it being freshly prepared prior to it being applied is necessary. Therefore, this study aimed to determine the effect of lyophilized A-PRF on growth factor release and cell biological activity. Blood samples were collected from six dogs and processed for fresh and lyophilized A-PRF. The growth factors released included transforming growth factor beta-1 (TGF-β1), vascular endothelial growth factor-A (VEGFA), and platelet-derived growth factor-BB (PDGF-BB), and the fibroblast proliferation as well as wound closure enhancement of both products were compared. The results showed that TGF-β1, PDGF-BB, and VEGFA were continually released from lyophilized A-PRF for over 72 h. Lyophilized A-PRF released significantly more accumulated VEGEA and a tendency to release more TGF-β1 at 72 h as well as VEGFA at 24 h and 72 h than fresh A-PRF. Moreover, lyophilized A-PRF increased fibroblast proliferation and induced a significantly faster wound closure than the control, while no significant difference between fresh and lyophilized A-PRF was found. In conclusion, the lyophilization of canine A-PRF can preserve the release of growth factors and has similar biological activities to a fresh preparation. This encourages the substitution of lyophilized A-PRF instead of fresh A-PRF in regenerative treatments in which the stability of the product is concerned. [ABSTRACT FROM AUTHOR]