Proteomic profiling reveals the potential role of allogenic equine platelet-rich plasma and extracellular vesicles in modulating tendon inflammation and repair.

Abstract

OBJECTIVE: To determine the protein composition of equine platelet-rich plasma (PRP) and PRP-derived extracellular vesicles (EVs) and evaluate their effects on tendon inflammation in vitro. As tendon injuries are common in horses and treatment with PRP derived from the horse's own blood shows promise, but outcomes vary due to inconsistent composition. PRP contains EVs that facilitate cell communication. METHODS: From December 2022 through May 2023, equine plasma (n = 3, adult) was isolated via double centrifugation and PRP produced using a commercial kit. Extracellular vesicles were isolated using differential ultracentrifugation and characterized with a tetraspanin assay. Equine tenocyte fibroblasts (n = 6) were stimulated with IL-1β and tumor necrosis factor-α for 24 hours to induce an inflammatory state simulating injury before treatment with PRP or PRP-derived EVs. Proteomic analysis employed data-dependent LC-MS-MS. RESULTS: Compared to plasma, PRP and PRP EVs were enriched in proteins related to cellular waste disposal and inhibition of lipid metabolism. Experimental conditions significantly influenced the levels of 18 proteins in tenocyte fibroblasts. Collagen type 1 α chain 1 abundance decreased with treatment of PRP and PRP EVs, with implications for collagen metabolism. An increase in sequestosome 1 was also observed, having the potential to enhance inflammation or resolve it through autophagy-mediated degradation. CONCLUSIONS: PRP EVs influence the proteome of inflammatory tenocyte fibroblasts and may contribute to PRP's therapeutic effects. CLINICAL RELEVANCE: Understanding the protein composition of PRP and PRP-derived EVs may help optimize PRP-based treatments for tendon injuries. Therapies could become more consistent and effective, reducing reinjury rates and improving tendon healing.