Vascular lumen formation from a cell biological perspective.

Endothelial cells are equipped with the intrinsic ability to form tubes and sprouts with a central lumen. However, the mechanisms that allow endothelial cells to form a lumen are largely unknown. We would like to discuss critically current models of vascular lumen formation and point to many unexplored and open questions. We briefly present what vascular researchers can learn from the formation of other cell systems with a lumen, such as cysts formed by Madin-Darby Canine Kidney (MDCK) cells as well as tracheae formed by Drosophila epithelial cells. In addition, we point to a number of questions that need to be addressed to understand better the cell biology that drives the formation of a vascular lumen.