Mechanical characterization of hydrogels and its implications for cellular activities

Hydrogels are viscoelastic materials routinely used for the development of culture models in tissue engineering and regenerative medicine. They act as a temporary matrix, providing topographical, biochemical, and biophysical cues which cells can remodel and develop into a tissue. The mechanical properties of the hydrogel mutually affect the construct and the cells alike. It is important to determine and monitor a construct's material properties in order to recapitulate the in vivo environment, which usually involves strategies aimed at improving the mechanical properties. The mechanical properties of soft tissues are closely related to their physiological function and so can act as cellular biomarkers. Time, culture, and conditioning environments can all influence the structural and biochemical aspects of the tissue, which are important to their performance and durability, ultimately dictating whether the construct will be successful or not in a given application. This chapter begins with the discussion of current characterization tools for hydrogel mechanical properties with the focus on non-destructive testing modalities. How mechanical properties can become a biomarker in regenerative medicine has been demonstrated through corneal stromal and ageing models. Various strategies for improving and tailoring the mechanical properties of hydrogels are discussed.