Sprouting angiogenesis under a chemical gradient regulated by interactions with an endothelial monolayer in a microfluidic platform.

Microfluidic cell culture assays are versatile tools for studying cell migration, particularly angiogenesis. Such assays can deliver precisely controlled linear gradients of chemical stimuli to cultured cells in a microfluidic channel, offering excellent optical resolution and in situ monitoring of cellular morphogenesis in response to a gradient. Microfluidic cell culture assays provide a chemical gradient subject to molecular diffusion, although cellular metabolism can perturb it. The actual gradient perturbed by cells has not been precisely described in the context of regulated cellular morphogenesis. We modeled the chemical gradient in a microfluidic channel by simulating the analyte(VEGF) distribution during cellular interactions. The results were experimentally verified by monitoring sprouting angiogenic response from a monolayer of human umbilical vein endothelial cells (hUVECs) into a type 1 collagen scaffold. The simulation provided a basis for understanding a real distribution of the analyte interrupted by cells in microfluidic device. The new protocol enables one to quantify the morphogenesis of hUVECs under a flat, less-steep, or steep gradient.