Microfludic Culture and Analysis of Endothelial Cells in Relation to Cardiovascular Disease and Cancer Metastasis.

Abstract

Endothelial cells comprise the inner lining of the entire circulatory system and are key mediators in many aspects of vascular biology. The interaction of endothelial cells with blood-borne constituents and the mechanical forces due to blood flow regulate a broad range of diseases that originate at the vasculature. The challenges of studying endothelial cell biology in vivo is that it is highly invasive to access, experimentally manipulate, and/or observe changes inside of blood vessels. Furthermore, current in vitro-based systems do not faithfully recreate the mechanical and chemical cellular environments with the proper length scales seen in physiology. Here we show examples of using the tools of microfluidics and microfabrication in developing perfusion-based in vitro systems that mimic the in vivo environments of endothelial cells. We describe a novel, reconfigurable micro-pumping and valving system that enables the delivery of a wide range of mechanical shear stress to multiple endothelial cell compartments simultaneously. We also utilized this pumping and valving system to culture endothelial cells under continuous recirculation of sub-microliter amounts of fluid. Finally, we engineered a compartmentalized endothelium to model the intravascular adhesion events of circulating cancer cells with endothelium at metastatic and non-metastatic sites. We determined that the endothelium regulates site-specific adhesion of circulating cancer cells that is independent of the predicted metastatic abilities of the cancer cells. Collectively, these results confirm that microfluidic technology can be used to properly mimic a broad range of the endothelial cell environments seen in physiology. Furthermore, we establish microfluidics as a platform for the development of systems that have the capabilities of advancing the understanding of endothelial cell biology as it relates to vascular diseases.