Electron microscopy imaging and mechanical characterization of T47D multicellular tumor spheroids-Older spheroids reduce interstitial space and become stiffer.

Multicellular cancer spheroids are an in vitro tissue model that mimics the three-dimensional microenvironment. As spheroids grow, they develop the gradients of oxygen, nutrients, and catabolites, affecting crucial tumor characteristics such as proliferation and treatment responses. The measurement of spheroid stiffness provides a quantitative measure to evaluate such structural changes over time.