704 Background: In vitro models of cancer have led to significant therapeutic advances. Despite the widespread use of in vitro tissue culture, the ability to directly evaluate human biology is limited by the inability to model the complex, 3D nature of the TME. We introduce a novel, microfluidic-based system of 3D human micro-tumors perfused with a network of human micro-vessels which could overcome the shortcomings of current in vitro systems. Methods: The micro-device was created by casting polydimethylsiloxane (PDMS) onto master molds, which are then bonded to a flat PDMS sheet using air plasma. Normal human lung fibroblasts (NHLF) and GFP labelled endothelial colony forming cell derived endothelial cells (EC-FCECs) were loaded in a fibrin gel at a 1:2 ratio into the central tissue chamber. Media was introduced through the microfluidic lines. The vascular network was developed with complete EGM2 media under nominal interstitial flow. Colorectal tumor cell lines labelled with mCherry were loaded to the side chambers on the seventh day after NHLF and EC loading. Bevacizumab or TGF- β were added on the second day after tumor cell loading. Results: Micro-vessels formed in the central chamber in 5-7 days after loading. The vessels were perfused with 70KDa fluorescent (red) dextran, and displayed intact vessel wall barrier. A suspension of a colorectal tumor cell line was loaded into the device side chambers, next to a fully developed vasculature. The tumor cells drove angiogenesis into the side chambers, and at the same time tumor began to migrate into the central chamber and within the vessel lumen. The angiogenesis induced by tumor cells can be pharmacologically inhibited, and the migration/ intravasation of tumor cells can be stimulated by TGF-β. Conclusions: Our novel micro-device system can be used as a functional in vitro system that can model the tumor micro-environment. This system has the advantage over current in vitro and in vivo systems in that it is high-throughput, rapid, cost-effective, and recreates many features of the 3D TME. We are currently expanding the platform to incorporate immune cells and designing a completely autologous system to test cancer immunotherapeutics.
Aberrant methylation of the ATM promoter correlates with increased radiosensitivity in a human colorectal tumor cell line
