Capillary morphogenesis during human endothelial cell invasion of three-dimensional collagen matrices

Here, we describe assay systems that utilize serum-free defined media to ev aluate capillary morphogenesis during human endothelial cell (EC) invasion of three-dimensional collagen matrices. ECs invade these matrices over a 1- 3-d period to form capillary tubes. Blocking antibodies to the alpha2 beta1 integrin interfere with invasion and morphogenesis while other integrin bl ocking antibodies do not. Interestingly, we observed increased invasion of ECs toward a population of underlying ECs undergoing morphogenesis. In addi tion, we have developed assays on microscope slides that display the invasi on process horizontally, thereby enhancing our ability to image these event s. Thus far, we have observed intracellular vacuoles that appear to regulat e the formation of capillary lumens, and extensive cell processes that faci litate the interconnection of ECs during morphogenic events. These assays s hould enable further investigation of the morphologic steps and molecular e vents controlling human capillary tube formation in three-dimensional extra cellular matrices.