Endothelial Cell Spreading Assay

Human umbilical vein ECs (HUVECs) and human dermal blood ECs (HDBECs) were purchased from PromoCell (Heidelberg, Germany). Cells were grown on gelatin-coated plates as previously described [18 (link), 26 (link)]. For spreading analyses, cells were detached from the culture plate by using enzyme-free cell dissociation buffer (Thermo Fisher Scientific, Waltham, MA, USA), plated on gelatin-coated coverslips, and allowed to spread for different times. Cells at specific phases of spreading were fixed, labeled, and imaged by microscopy. Transient transfection experiments were performed by electroporation as previously described [12 (link)].