HUVECs were seeded in 6-well plates (2 × 105/well) and treated with 10 μg/ml of PF/plasma exosomes or exosome-depleted PF/plasma for 24 hr in hypoxia, then detached using Accutase (Innovative Cell Technologies) and plated (104/well) in a flat-bottom 96-well plate or μ-Slide Angiogenesis (Ibidi), coated with Growth Factor Reduced Matrigel (Corning). For mirVana miRNA mimic or mirVana miRNA inhibitor experiments, HUVECs were seeded at a concentration of 7 × 103/well. After 6 hr, HUVECs were stained with Calcein AM (Biotium), and network formation was quantified by calculating the length of the cellular network on images captured using an objective magnification of 5× or by Angiogenesis Analyzer for ImageJ using a fluorescence objective magnification of 2.5×.