2.3. Ex Vivo Culture of Human Saphenous Vein

Human saphenous veins were cultured using a flow-through system established in our laboratory [15]. Vein segments were placed in the chamber filled with Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum. Segments from the same patient were connected to the perfusion system and cultured for 24 hours either under venous condition (flow: 5 mL/min) or arterial condition (flow: 50 mL/min, pressure: 80 mmHg). All culture solutions were purchased from Invitrogen (Thermo Fisher Scientific, Waltham, MA, USA).