Migration assay
After 7 days of culture, the cells were detached, and 5×104 cells were resuspended in the upper chamber of a Transwell chamber (pore size 8 µm, Corning) with 200 µl EBM-2 basal medium (Lonza), while 500 µl EGM-2-BulletKit containing 10% FBS was added to the lower chamber[23-27]. After 24 hours, cells that migrated from the upper chamber to the lower surface of the membrane were fixed and stained as previous protocols[23-27]. For quantification, the stained cells were observed and counted manually in 3 random views per well with a phase-contrast microscope (Olympus).