Alteration of cell motility dynamics through collagen fiber density in photopolymerized polyethylene glycol hydrogels

Polyethylene glycol (PEG) hydrogels that have natural fibers mimicking extracellular matrix can be used as a model to understand the role of substrate properties on cell growth and migration. Due to the dependence of cell movement to adhesion, characterization of motility is needed to prepare biocompatible substrates. We demonstrated a method to encapsulate collagen into PEG hydrogel crosslinked via photopolymerization and studied the effect of fiber density on motility dynamics. Porous hydrogel immersed into collagen solution was coated with fibers after neutralizing solution. We provided a detailed study of cell instantaneous/average speed, total displacement, persistence and angular displacement. We found that cells demonstrated a biphasic motility where a maximum speed of 17.4 μm/h with a total distance of 215 μm and persistence of 0.43 were obtained at 1.2 mg/ml collagen. High occurrence of low angular displacement observed at intermediate fiber density suggests that cells tend to move forward along hydrogels. Increased anisotropy at low density was an indication of forward and backward movement. Finally, matrix deformation was determined in the absence of fluorescent beads by tracking fiber displacement at subpixel resolution. Our findings establish a method for preparation of collagen coated hydrogels and provide an insight into cell motility dynamics.