Combination stiffness gradient with chemical stimulation directs glioma cells migration on microfluidic chip.

Tumor cells response actively to the extracellular microenvironment via biomechanical and biochemical stimulation. Micro-chip provides a flexible platform to integrate multifactors for cell research. In this work, we developed a subtle microfluidic chip that can generate controllable stiffness gradient and orthogonal chemical stimulation to study the behaviors of glioma cells. Fibronectin-conjugated polyacrylamide (PAA) hydrogel with longitudinal stiffness gradient ranging from about 1kPa to 40 kPa is integrated within the cell culture chamber while the lateral diffusion-based chemical stimulation is generated through the circumambient microchannel arrays. The synergistic effect of epidermal growth factor (EGF) stimulation and hydrogel stiffness gradient on U87-MG cells migration was studied. By tracing cells migration, we discovered that the hydro-gel stiffness can promote cell chemotaxis, while EGF gradient can accelerate the cell migration. In addition, the cell mor-phology showed typical cell spreadin...