Studying sprouting angiogenesis under combination of oxygen gradients and co-culture of fibroblasts using microfluidic cell culture model

Sprouting angiogenesis is an essential process for expanding vascular systems under various physiological and pathological conditions. In this paper, a microfluidic device capable of integrating a hydrogel matrix for cell culture and generating stable oxygen gradients is developed to study the sprouting angiogenesis of endothelial cells under combinations of oxygen gradients and co-culture of fibroblast cells. The endothelial cells can be cultured as a monolayer endothelium inside the device to mimic an existing blood vessel, and the hydrogel without or with fibroblast cells cultured in it provides a matrix next to the formed endothelium for three-dimensional sprouting of the endothelial cells. Oxygen gradients can be stably established inside the device for cell culture using the spatially-confined chemical reaction method. Using the device, the sprouting angiogenesis under combinations of oxygen gradients and co-culture of fibroblast cells is systematically studied. The results show that the oxygen gradient and the co-culture of fibroblast cells in the hydrogel can promote sprouting of the endothelial cells into the hydrogel matrix by altering cytokines in the culture medium and the physical properties of the hydrogel. The developed device provides a powerful in vitro model to investigate sprouting angiogenesis under various in vivo-like microenvironments.