Time lapse phase contrast video microscopy of directed migration of human microvascular endothelial cells on matrigel

Migration of microvascular endothelial cells is an early and critical step in angiogenesis. Formation of branching and polygonal cellular aggregates b y endothelial cells on matrigel has often been considered to be an in vitro model for angiogenesis, although formation of lumens has not always been c onfirmed. The dynamics of migration of living cells of a human dermal micro vascular endothelial cell line (HMEC-1) on a reconstituted basement membran e matrix have been captured in real time using time lapse video microscopy. The cells exhibit periods of quiescence and directed rapid migration by fo rmation of extensions towards a specific target cell. Cells repeatedly exte nd flexible protrusions from the cell body both within the plane of the mat rix and out of the plane of the matrix into the incubation medium. Connecti ons between protrusions and target cells are made frequently, but not all c ells which start to form protrusions achieve connections with other cells. Some of these migrating cells which do not connect arrest before reaching t he target, or arrest and retract to their origin. After formation of multic ellular polygonal structures, the structures contract to form amorphous clu sters of fused cells without visible effects on the underlying matrix. The study demonstrates that time lapse video microscopy is a simple but very us eful approach to monitor the dynamics of movements which vary in speed and frequency during migration of living cells.