Vectorial control of cell movement by the design of microelasticity distribution of biomaterial surface

The understanding and realization of directional cell movement towards a harder region of a cell culture substrate surface, so-called mechanotaxis, may provide a solid basis for a functional artificial extracellular matrix, enabling manipulation and elucidation of cell motility. The photolithographic surface microelasticity patterning method was developed for fabricating a cell-adhesive hydrogel with a microelasticity-gradient (MEG) surface using photocurable styrenated gelatin to investigate the condition of surface elasticity to induce mechanotaxis as a basis for such substrate-elasticity-dependent control of cell motility. Patterned MEG gels consisting of different absolute surface elasticities, elasticity jumps and sharpness of elasticity were prepared by regulating the photoirradiation power, periods and positions. Surface elasticity and its two-dimensional distribution were characterized by microindentation tests using atomic force microscopy (AFM). From the analyses of trajectories of 3T3 cell movement on each prepared MEG gel, three critical criteria of the elasticity jump and the absolute elasticity to induce mechanotaxis were identified: 1) a high elasticity ratio between the hard region and the soft one, 2) elasticity of the softer region to provide medium motility, and 3) sharpness of the elasticity boundary. Design of these conditions was found to be necessary for fabricating an artificial extracellular matrix to control or manipulate vectorial cell movement.