In vitro rapid organization of endothelial cells into capillary-like networks is promoted by collagen matrices.

TLDR

The study introduces a simple in vitro model to investigate factors driving angiogenesis. Cloned capillary endothelial cells were cultured in a three‑dimensional collagen matrix, with surface monolayers overlaid by a second collagen layer. The cells reorganized into branching, anastomosing capillary‑like tubes with lumens lined by at least two cells and basal lamina, demonstrating their capacity to form polarized vessel‑like structures and indicating that collagen topology induces this potential.

Abstract

We have studied the behavior of cloned capillary endothelial cells grown inside a three dimensional collagen matrix. Cell monolayers established on the surface of collagen gels were covered with a second layer of collagen. This induced the monolayers of endothelial cells to reorganize into a network of branching and anastomosing capillary-like tubes. As seen by electron microscopy, the tubes were formed by at least two cells (in transverse sections) delimiting a narrow lumen. In addition, distinct basal lamina material was present between the abluminal face of the endothelial cells and the collagen matrix. These results showed that capillary endothelial cells have the capacity to form vessel-like structures with well-oriented cell polarity in vitro. They also suggest that an appropriate topological relationship of endothelial cells with collagen matrices, similar to that occurring in vivo, has an inducive role on the expression of this potential. This culture system provides a simple in vitro model for studying the factors involved in the formation of new blood vessels (angiogenesis).