Single cell elastography from nanoindentation experiments

Cell mechanics is currently an exciting and active area of research, and it has great potential to provide a new and different outlook on pathologies and classical biological problems. It is known cells can actively sense and respond to a huge variety of mechanical signals. New different scientific branches are addressing the mechanisms underlying these processes of sens- ing and responding, called respectively mechanosensing and mechanotrans- duction. Mechanobiology is a novel field that stands at a meeting point among biology, bioengineering and physiscs and its purpose is to address these processes with a quantitative, model based approach. The increas- ing growth of mechanobiology has been supported by the advancement of new technologies, especially in measuring force. Indeed the exploitation of nanotechnology to the study of biological systems opened new avenues to- wards innovative approaches based on single cell mechanical characterization. Nanoindentation experiments played a major role in this process, and still do. This thesis aimed to find a simple and robust analytical procedure which can provide new insight in cell mechanical properties, starting from nanoin- dentation experiments, allowing to make inferences into the functional state of the cell. At the beginning the whole existing procedure was optimized to achieve a higher throughput. Then, an existing model, the most used in literature to describe cell mechanical properties, was extended, in order to increase and supplement the information gained from nanoindentation experiments. This new procedure, called Elastography, allowed to identify different stiffness layers into the single cell, putatively associated with inner components and compartments of the cell. The Elastography was tested and proved to work both simulating the system and in experimental tests. Then it was applied in many different biological problems, to several coltures of different cell lines, in order to address specific questions about changes in cell mechanical properties.