Figure 5.

Primary ccRCC cells but not normal-adjacent renal cortex–derived cells induce HUVEC sprouting in a flow-directed 3D microphysiological system. (A-F) Confocal z-stack projections (400-μm total thickness) of vessels formed from HUVECs in the presence of collagen only, collagen containing clusters of normal-adjacent renal cortex cells (normal), or ccRCC cells (tumor). HUVECs are labeled with the endothelial marker CD31, and the normal and tumor cells are labeled with the epithelial cell marker EPCAM. The white arrow represents the direction of flow through the lumen, which is in the same direction in all panels. Flow was maintained for 5 days. Scale bar, 100 μm. The enlarged inset in panel A is 100 μm wide. (G) 3D surface rendering of tumor-induced sprouting in a chip exposed to flow for 7 days. Each line in the grid of boxes represents 100 μm. (H) Quantification of the region containing sprouting from HUVEC vessels grown in the presence of collagen only (−), normal-adjacent renal cortex (N), or ccRCC tumor cells (T). The number of chips for which confocal staining and quantification were performed for each condition is shown below the graph. Error bars are the average deviation. The P value is < .01 for the comparison of sprouting between tumor versus normal across all patients.