Relative Stiffness Measurements of Cell-embedded Hydrogels by Shear Rheology .

Hydrogel systems composed of purified extracellular matrix (ECM) components (such as collagen, fibrin, Matrigel, and methylcellulose) are a mainstay of cell and molecular biology research. They are used extensively in many applications including tissue regeneration platforms, studying organ development, and pathological disease models such as cancer. Both the biochemical and biomechanical properties influence cellular and tissue compatibility, and these properties are altered in pathological disease progression (Cox and Erler, 2011; Bonnans , 2014 ). The use of cell-embedded hydrogels in disease models such as cancer, allow the interrogation of cell-induced changes in the biomechanics of the microenvironment ( Madsen , 2015 ). Here we report a simple method to measure these cell-induced changes using a controlled strain rotational rheometer.