Mechanical Properties of the Extracellular Matrix of the Aorta Studied by Enzymatic Treatments

The microarchitecture of different components of the extracellular matrix (ECM) is crucial to our understanding of the properties of a tissue. In the study presented here, we used a top-down approach to understand how the interplay among different fibers determines the mechanical properties of real tissues. By selectively removing different elements of the arterial wall, we were able to measure the contribution of the different constituents of the ECM to the mechanical properties of the whole tissue. Changes in the network structure were imaged with the use of two-photon microscopy. We used an atomic force microscope to measure changes in the mechanical properties by performing nanoindentation experiments. We show that although the removal of a key element of the ECM reduced the local stiffness by up to 50 times, the remaining tissue still formed a coherent network. We also show how this method can be extended to study the effects of cells on real tissues. This new (to our knowledge) way of studying the ECM will not only help physicists gain a better understanding of biopolymers, it will be a valuable tool for biomedical researchers studying processes such as wound healing and cervix ripening.