Chemokine gradient formation in microfluidic devices to investigate prostate cancer cell migration

Metastasis of cancer requires adhesion and migration of cells. The effect of chemokine gradient on prostate cancer cells (PCC) is not well understood. A poly-dimethylsiloxane (PDMS) microfluidic device that enables time-lapse study of cell migration is presented. Photolithography and soft lithography processes were used to fabricate the PDMS devices from SU-8 molds. The device has two inlets, a cell reservoir and an outlet channel with a depth of 100μm. The microfluidic device is configured to provide fluid mixing leading to a gradient across the outlet channel. The inlets allow for introduction of different chemokines at different concentrations and flow rates. The cell migration in the presence of chemokine gradient and flow rate can thus be monitored in a time-lapse fashion. The gradient formations at different flow rates over different lengths of time have been analyzed. Flow rates of 2, 3, 6, 8, 10, 20 μl/min at 5-minute intervals for over an hour were monitored to determine optimum flow rates and times required to produce desired gradient profiles. Results suggest that gradients formed at lower flow rates have less variation over time. Moreover, lower flow rates do not affect cell movement making observation of cell migration towards gradients possible. Higher flow rates have better gradient definition but cells tend to flow away with the fluid.