Effects of lysate/tissue storage at -80C on subsequently extracted EVs of epithelial ovarian cancer tissue origins

Small extracellular vesicles (sEVs) and large extracellular vesicles (lEVs), play vital roles in intercellular communication. We optimized a method that extracts EVs from epithelial ovarian cancer (EOC) tissues for the purpose of investigating whether cryopreservation of EOC tissues affects the phenotypes, contents, and bio-logical functions of extracted EVs. EV morphology, the number and size distribution of EVs, and EV-related markers were analyzed. Storage of lysates at -80 degrees C decreased lEV yield and increased sEV yield, whereas storage of tissues at -80 degrees C increased both sEV and lEV yields; neither changed the morphology or particle mass ratio of EVs. The two cryopreservation groups retained over 90% of proteins and 80% of miRNAs detected in the "fresh"group. EVs extracted following lysate/ tissue storage at -80 degrees C could also promote angiogenesis and invasive migration ability in human endothelial cells. Cryopreserved EOC tissue may benefit clinical ap-plications for studies of tissue-derived EVs, especially EV proteins-related ones.