In vitro microvasculature for studying cancer metastasis and angiogenesis

In vitro microvascular endothelial linings can be used to investigate biophysical and molecular mechanisms that play a role in circulatory disease phenomena such as inflammation, responses of the immune system and cancer cell attachment to the endothelium. In vivo, endothelial cells grow on the inner surface of blood vessels and are confined by its geometry. In the smallest vessels of the microvasculature, this confinement leads to a significant bend within each cell. To imitate these geometric constraints within an in vitro model of the endothelial lining, we have fabricated nearly round channels (70 µm wide, 50 µm high) and cultured human umbilical vein endothelial cells (HUVECs) within them. We have characterized the developed model and compared the results with those obtained with conventional microfluidic channels with square cross-sectional profiles. Our results indicate that shear stress is responsible for the conforming of HUVECs to the channel walls of square profile channels under fluid flow and cause the resulting square geometry of the in vitro endothelial lining.