Microvascular Oreintation During Angiogenesis: Effects of Mechanical Stretch and Boundary Conditions

Mechanical forces affect the behavior of a variety of cell types including fibroblasts, chondrocytes, osteoblasts, smooth muscle cells, and endothelial cells. In vitro cellular orientation is primarily achieved through cell-generated mechanical forces or contact guidance. Endothelial cell (EC) cords align both normal to the stretch direction as well as along pre-tensioned collagen matrices. Confluent ECs orient parallel to grooved surfaces while tractional forces generated by ECs contract the matrix aligning collagen fibers, which in turn are considered a guiding scaffold. The influence of mechanical forces and boundary conditions on the growth and proliferation of microvessels during the process of angiogenesis is unknown. A better understanding of these interactions is essential both from a basic science standpoint as well as in the engineering of artificial vascularized matrices with specific orientation of vessels and endothelial cells. The objective of this study was to examine the role of internal and external mechanical forces in microvessel orientation during angiogenesis using an in vitro model of angiogenesis.