Fabrication of topographically patterned hydrogel substrates and their influence on cell morphology

Cell behavior is influenced by a multitude of extracellular factors including chemistry, mechanics, and geometry. Engineered microenvironments can be used to assess a wide range of such influences on cell behavior and identify parameters for future implementation into tissue engineered scaffolds. The first goal of this work was to develop a new method for fabricating topographically patterned hydrogels for use as engineered microenvironments for cells. Polyacrylamide gels were cast from silicon masters by a process that involved ultrasonically vibrating the master during polymerization. Gels were then covalently modified with an even coat of collagen. The second goal of this work was to use combinatorially patterned hydrogels to demonstrate the influence of topography, in the form of arrays of micron-scale posts, on several quantitative measures of cell morphology. Square post patterning was shown to be the most influential for directing cell orientation. Narrow gaps between posts had the greatest influence on elongation and on directing the placement of cell extensions. When seeded on substrates with gaps larger than 10 ??m, cells were found in the quasi-three dimensional environment between posts rather than on top. The cell morphology results provide parameters for the design of substrates and scaffolds intended for influencing cell-cell communication, directing extracellular matrix deposition, and for extending cell mechanics studies into three dimensions, while the methods presented can be extended to design engineered microenvironments with precisely controlled chemistry, mechanics, and geometry