Characterisation of Equine Synovial Fluid Derived Extracellular Vesicles from Young and Old Horses.

Equine osteoarthritis is a disease that impacts the welfare and performance of horses from all disciplines. Similar to its effect on human joints, osteoarthritis in horses is a painful joint condition that leads to lameness and decreased range of movement. This study compared the lubricating synovial joint fluid from eight young and seven old horses, specifically looking for differences in the extracellular vesicles (EVs). EVs are small nanoparticles present in the joint synovial fluid. EVs contain a type of ribonucleic acid (RNA) called microRNAs (miRNA), which can alter expression of genes and therefore influence the environment of a joint as some gene changes may promote or prevent osteoarthritic changes. This study was investigating whether there was a difference in the miRNAs present between old and young horses, as well as whether other characteristics of the EVs differ. Our study aimed to add to ongoing research into the role of EVs in the progression of osteoarthritis, and whether they could be used as biomarkers to diagnose joint changes. Our study did not find any significant differences in the size, concentration or miRNA expression of three miRNAs tested which suggests that their characteristics remain similar as a horse ages. However, a trend of decreased expression of these miRNAs was found, and while not statistically significant, this suggests that older horses may have lower levels of expression of certain osteoarthritis and inflammation related miRNAs. Additional work is required to confirm these findings