Allogenic platelet-rich plasma and platelet-rich plasma extracellular vesicles alter the proteome of tenocytes in an in vitro equine model of tendon inflammation: A pilot study

BackgroundTendon injuries are common in horses, often resulting in a high risk of reinjury. Hemoderivative therapeutics including platelet-rich plasma (PRP) show promise but outcomes vary due to inconsistent composition. PRP is rich in soluble growth factors and extracellular vesicles (EVs), the latter facilitate cell-to-cell communication by delivering biologically active cargo. This pilot study profiled the proteome of PRP and PRP-derived EVs and examined their effects on an equine tendon inflammatory model in vitro. MethodsPlasma was isolated via double centrifugation and PRP produced using a commercial filtration kit. EVs were isolated from PRP and plasma using differential ultracentrifugation and characterised with the Exoview Tetraspanin assay. Equine tenocytes were stimulated with interleukin 1{beta} and tumor necrosis factor , then treated with PRP or PRP-derived EVs. Proteomic analysis was conducted on cell lysates, PRP and PRP-EVs using data-dependent acquisition liquid chromatography-tandem mass spectrometry and the data analyzed using multivariate and univariate approaches. ResultsPRP contained 575 quantifiable proteins and PRP-derived EVs 209 proteins. When compared to plasma and plasma derived EVs respectively, PRP and PRP-EVs were enriched in proteins associated with cellular waste disposal and inhibition of lipid metabolism. Experimental factors (inflammatory stimulation and/or treatments) significantly affected the abundance of 18 proteins as expressed in equine tenocytes including col1a1 (col1a1) and sequestosome 1, associated with collagen metabolism and nuclear factor kappa B signaling. DiscussionThe findings from this study suggest PRP-derived EVs influence inflammatory tenocytes and may be crucial to the efficacy of PRP.