The mechanics of fibrillar collagen extracellular matrix

As a major component of the human body, the extracellular matrix (ECM) is a complex biopolymer network. The ECM not only hosts a plethora of biochemical interactions but also defines the physical microenvironment of cells. The physical properties of the ECM, such as its geometry and mechanics, are critical to physiological processes and diseases such as morphogenesis, wound healing, and cancer. This review provides a brief introduction to the recent progress in understanding the mechanics of ECM for researchers who are interested in learning about this relatively new subject of biophysics. This review covers the mechanics of a single ECM fiber (nanometer scale), the micromechanics of ECM (micrometer scale), and bulk rheology (greater than millimeter scale). Representative experimental measurements and basic theoretical models are introduced side by side. After discussing the physics of ECM mechanics, the review concludes by commenting on the role of ECM mechanics in healthy and tumorigenic tissues and the open questions that call for future studies at the interface of fundamental physics, engineering, and medical sciences.