Mechanobiology

The Mechanobiology Group studies the signalling processes related to mechanical forces that are omnipresent and constantly changing in the heart. They shape life, acting either as crucial drivers for a wide range of physiological processes, or as potential threats to which cells have to adapt to survive in pathological conditions. How cells sense their environment and adapt their function to changes in mechanical states is the key question driving this group. Molecular mechanisms underlying this ability are poorly understood and we focus on mechano-sensitive channels, key players in Mechano-Electric Feedback (MEF).

Molecular identity and functions of cardiac mechano-sensitive channels

To unravel functions of these mechano-sensors, we combine the patch-clamp technique with equipment that allows:

acute mechanical stimulation of minute membrane areas, such as by high speed pressure clamp, to stretch patches of membrane inside a recording pipette;
chronic mechanical stimulation, such as using the Flexcell® system, to expose cells in culture to changes that mimic normal or diseased cardiovascular Function.

Using genetic tools, and pharmacological interventions we target individual channel candidates, and test their roles in cells ranging from cardiac muscle cells to connective tissue and heart valve endothelium.

Fig.1: Glass capillaries that will be sealed to the cell plasma membrane to record ion channel activity. Patch-clamp is one of the very few techniques that allow one to observe conformational changes of a single protein in real time.

Axial and radial forces in isolated cardiomyocytes

Combining our Carbon Fibre technique (see 4D Imaging page) and Atomic Force Microscopy (from AFM Workshop, Fig. 2) we can record both axial and radial forces from single isolated cardiomyocytes in different loading states. We use this to study acute mechanical effects on cell mechanical properties and, by combining this with fluorescent imaging and patch clamp investigations, we explore ionic mechanisms underlying observed behaviour.

Fig.2: A ventricular cardiomyocyte stretched by two carbon fibres (right) under the cantilever of an atomic force microscope (left). Carbon fibres allow one to prescribe and record axial force development, whilst the AFM cantilever records radial forces. Cells are paced, perfused and temperature-controlled. (Source: AFM Workshop)

In the long term, whilst modifying the loading state of single isolated cardiomyocytes, we plan to better understand the distribution of mechanical forces in the cytoskeleton and at the plasma membrane level. To do so, we will use fluorescent tension probes and fluorescent curvature-sensitive probes. This is anticipated to allow us to understand where and how changes in membrane curvature / cytoskeletal tension occur, and what impact they have on cellular mechano-sensing.