The microvasculature is an immense organ that defines the environmental conditions within tissues in both health and disease, and is vital for the proper functions of all tissues. Here, we describe existing tools to study vascular cell function and our work using one platform of in vitro microvessels, which we employed to study vessel structure and remodeling, endothelial barrier function, angiogenesis, interactions between endothelial cells and perivascular cells, interactions between blood cells and the endothelium, and microvascular thrombosis. We also briefly discuss the potential future applications of these platforms in biology and medicine.