Integrins are key cell surface receptors enabling cells to sense and respond to changes in their environment. Integrin signalling is crucial to many cellular processes such as migration, adhesion, proliferation and survival. Errors in signalling are implicated in many disease and injury states, hence understanding these molecular processes is crucial to directing treatment towards them.
Mesenchymal stem cells (MSCs) are extensively used in regenerative medicine, due in part in their ability to modulate the immune response. Their immunomodulatory abilities are not fully understood at the molecular level, yet it is thought integrins play a central role in this, particularly by clustering of these receptors.
Thus fundamental research into how integrins can control the ability of the MSCs to bring about repair processes is needed in order to inform the design of tissue engineered scaffold or drug delivery systems.
This thesis examines the role of integrin α5β1 clustering in MSC immunomodulation at the molecular level. In order to achieve single molecule resolution, the super-resolution microscopy technique, STORM, was optimised and utilised to analyse changes in the localisation of the receptor on the cell surface. The effect of the inflammatory cytokines, IL-1β and TNFα, on clustering and subcellular expression and localisation of α5β1 were investigated. Finally insights into predicted downstream signalling molecules linking integrin activation and inflammatory signalling are explored. This data demonstrates clustering of α5β1 in the presence of IL-1β and TNFα in a donor specific manner. This thesis importantly highlights the need to understand cell behaviour at a molecular level where it is thought modifying molecular spacing of ligands, whether in a drug or tissue engineering setting, could tune the cells response bringing about distinctive signalling cascades.