Stem cell pluripotency: Impact of bio-inspired substrates on integrin-dependent signalling and force transmission

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Pluripotent stem cells (PSCs), such as embryonic stem cells and induced pluripotent stem cells, have the potential to generate any cell type in the adult body. This makes them important tools for investigating signalling mechanisms that regulate the differentiation of specific cell types during embryo development, and also means that they have huge potential as cell-based regenerative medicine therapies. However, for both of these applications, it is necessary to propagate the cells under defined culture conditions, which typically comprise recombinant human extracellular matrix (ECM) proteins and serum-free media; making it difficult to generate the quantities of PSCs required for research and medical applications. To address this, we have recently developed a novel molecularly-engineered nano-fibre PSC substrate. We have shown that this substrate can maintain PSCs in a pluripotent state over extended culture periods, and our data suggest that this is due to the activation of specific integrin receptors. The aim of this project is to determine the signalling pathways triggered by engagement of these integrins with our novel substrate and to explore how this signalling affects PSC self-renewal and differentiation. Integrin receptors sense and regulate the mechanical and biochemical properties of the ECM to maintain PSC self-renewal and pluripotency. Integrin-dependent adhesion complexes function as both physical links to the contractile cytoskeleton and dynamic signalling nexuses that regulate cell fate. Different integrins exhibit distinct biomechanical and signalling properties that directly influence cell proliferation and differentiation. As PSCs preferentially use specific integrins to engage the novel substrate, our major hypothesis is: Bio-inspired nanofibres trigger the formation of unique adhesion signalling complexes that promote pluripotency and modulate mechanical force transduction. To test this hypothesis, we will use a multi-disciplinary approach, incorporating proteomics, imaging, protein engineering and ultrastructural analysis to: 1) Define the integrin-dependent signalling networks established on PSC substrates; 2) Assess the impact of substrates and integrin signalling on mechanical force transduction; 3) Determine the role of integrin signalling modules on maintenance of pluripotency. Finally, in collaboration with Cell Guidance Systems, we will assess the commercial potential of the novel substrate.