*4.11. Tube Formation Assay*

The angiogenic potential of HUVECs was assessed by in vitro tube formation assays. Briefly, a 96-well plate was pre-coated with Matrigel (Corning®) substrate (50 µL/well) and then polymerized at 37 ◦C for 60 min. Approximately 3 <sup>×</sup> <sup>10</sup><sup>4</sup> HUVECs were seeded in each well and the plate was incubated in a CO<sup>2</sup> incubator for 6–8 h at 37 ◦C. Finally, the tubular structures formed by HUVECs in the 96-well plate were observed under an inverted microscope.
