Intrinsic Optical Imaging of ECM Mechanics

© 2020, Springer Nature Switzerland AG. This chapter provides a comprehensive introduction to optical imaging in the context of extracellular matrix (ECM) mechanics. The goal is to address the critical aspects of optical microscopy so that researchers in the biomechanics research field are able to take full advantage of optical imaging technologies in their studies. Optics is of particular interest to answering questions of multiscale mechanics because of its multiscale nature; information can be obtained at the tissue, fiber, and even molecular levels. Revealing the microstructure of the load-bearing ECM constituents, elastin and collagen, and the interplay between ECM structure and mechanical loading is probably the area where optical microscopy has contributed the most to our understanding of ECM mechanics in recent years. The discussion is therefore confined to optical imaging technologies able to resolve ECM fibers using signals from molecules endogenous to tissue and emphasizes the importance of unbiased imaging and image analysis. Descriptions of polarimetric multiphoton microscopy and adaptive optics are also provided because of their potential for enabling discoveries in ECM mechanics. Although arteries are used here as an exemplar tissue, all concepts covered in this chapter are expected to be generalizable to other organs and tissues.