Biophotonic tools to image cellular mechanics

Abstract

The mechanical interaction of cells with their environment, e.g. the application and sensing of forces by cells, is at the heart of many important phenomena in biology. While our understanding of biochemical signals in cellular function in- creases rapidly, many aspects of mechanical activity and interaction remain elusive, largely due to the lack of suitable tools to detect and image the small forces at play. The creation of new biophotonic tools and methods to fulfil this role has therefore become a topic of strong interest in recent years.

A recent innovation in cellular force measurement technology was ERISM (Elastic Resonator Interference Stress Microscopy), which uses interference within an elastic microcavity to provide widefield, label free measurements of cellular forces with piconewton precision. In addition to force imaging of cells, the relationship between cell force and mechanical stiffness is a topic of strong interest in mechanobiology. Brillouin microscopy uses laser light to provide non-contact, in-vivo imaging of tissue and cellular stiffness with a very high spatial and measurement resolution. I demonstrate here a combined ERISM and Brillouin instrument which images both cellular force and stiffness, in addition to innovations in both ERISM and Brillouin microscopy which were necessary for the integration of these technologies.

Furthermore, I have developed a new form of force imaging technique which evolved from ERISM. It provides the same non-invasive, high-resolution force images, but offers a 1000-fold improvement in speed and temporal resolution, along- side a radically simplified experimental setup. I show real-time force measurements of fibroblast focal adhesions and macrophage podosomes, and demonstrate force imaging of beating neonatal cardiomyocytes at ≈ 100 fps which resolves micro-contractions associated with spontaneous oscillatory contractions (SPOC waves).

Date of Award	1 Dec 2020
Original language	English
Awarding Institution	University of St Andrews
Supervisor	Malte Christian Gather (Supervisor)