Effects of PMA on endothelial cell vascularization in collagen gel.

<p>(A) Schematic diagrams of the experimental design. (B) Phase-contrast microscopy images of HUVECs exposed to various PMA concentrations. HUVECs did not sprout into the collagen gel in the absence of PMA, forming a monolayer on the surface. When exposed to 20–500 ng/mL PMA, HUVECs formed typical luminal structures. At 1000 ng/mL PMA, sprouting was inhibited and cells became detached. Scale bar, 1 mm.