Abstract: An in vitro microfluidic spheroid angiogenic vascularization system includes an optically transparent base; a reservoir adhered to the optically transparent base; a first media reservoir opening disposed along an external perimeter of the reservoir configured for receiving media; a first spheroid inlet configured to receive a cancer spheroid; a first cell inlet configured to receive an endothelial cell; a divider posed between the first spheroid inlet and the first cell inlet; a spheroid channel configured to transport the cancer spheroid from the first spheroid inlet to a central observation cavity; a cell channel configured to transport the endothelial cell from the first cell inlet to the central observation cavity; an outlet disposed along an end of the spheroid channel opposing the first spheroid inlet; and the central observation cavity filled with a volume of collagen into which the spheroid channel and the cell channel open.