Deconstructing the Effects of Matrix Elasticity and Geometry in Mesenchymal Stem Cell Lineage Commitment.

A wide variety of environmental factors including physical and biochemical signals are responsible for stem cell behavior and function. In particular, matrix elasticity and cell shape have been shown to determine stem cell function, yet little is known about the interplay between how these physical cues control cell differentiation. For the first time, by using ultraviolet (UV) lithography to pattern poly(ethylene) glycol (PEG) hydrogels we are able to manufacture microenvironments capable of parsing the effects of matrix elasticity, cell shape, and cell size in order to explore the relationship between matrix elasticity and cell shape in mesenchymal stem cell (MSC) lineage commitment. Our data shows that cells cultured on 1,000 μm2 circles, squares, and rectangles were primarily adipogenic lineage regardless of matrix elasticity, while cells cultured on 2,500 and 5,000 μm2 shapes more heavily depended on shape and elasticity for lineage specification. We further went on to characterize how modifying the cell cytoskeleton through pharmacological inhibitors can modify cell behavior. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of cell shape and matrix elasticity in further understanding stem cell behavior for future tissue engineering strategies.