The influence of a systemic non‐steroidal anti‐inflammatory drug on growth factors and cytokines in equine plasma, solid platelet‐rich fibrin ( PRF ), and liquid PRF

BACKGROUND: Platelet-rich fibrin (PRF) is a second-generation platelet concentrate that contains growth factors and cytokines within a fibrin matrix, allowing prolonged release and supporting its use as a regenerative therapy for corneal wound healing. Horses with ulcerative keratitis are commonly treated with systemic NSAIDs; therefore, it is clinically important to determine whether prolonged flunixin meglumine alters the composition of PRF or plasma. OBJECTIVES: To evaluate the effects of systemic NSAID administration on bio-analyte concentrations in equine plasma, solid PRF, and liquid PRF, and to compare these concentrations among blood products. STUDY DESIGN: Prospective, cross-sectional study. METHODS: Horses were enrolled into two groups: horses treated with systemic full-dose flunixin meglumine (1.1 mg/kg BID) for three or more days (NSAID group) and horses without NSAID exposure for three or more months (control group). Plasma and PRF preparation followed standard protocols and concentrations for growth factors and cytokines were quantified using multiplex immunoassay or ELISA. Flunixin meglumine concentrations in plasma were measured via LC-MS/MS. Differences between treatment groups (NSAID vs. control) and between analyte concentrations were statistically compared across blood products; p < 0.05 was considered significant. RESULTS: NSAID group: n = 12 horses and control group: n = 12 horses. Solid PRF from the control group had significantly higher concentrations of TGF-β1, PDGF, and VEGF-A compared to the NSAID group. Analysis across the three blood products showed plasma had significantly higher concentrations of TGF-β1 and TGF-β2, whereas solid PRF had significantly higher concentrations of PDGF, IL-1β, IL-4, and TNF-α. MAIN LIMITATIONS: Small sample size and incomplete characterisation of horses' metabolic and endocrine status. CONCLUSIONS: Systemic NSAID administration appears to reduce concentrations of key growth factors in solid PRF. Combined use of plasma and solid PRF may maximise delivery of evaluated growth factors and cytokines.