Abstract:
Heart function arises from the synchronous contraction of millions of individual cardiomyocytes. Despite their importance, the understanding of the underlying biomechanical properties of cardiomyocytes remains relatively limited owing to challenges associated with single-cell experimentation. Existing methods are not only highly inefficient, but also unrepresentative of in-vivo conditions. Nevertheless, the ability to characterise cell behaviour in healthy and diseased states would play a critical role in facilitating the development of treatments for cardiac disease. To address these challenges, a novel mechanical testing instrument that enabled testing of submillimetre-scale biomaterial samples suitable for the encapsulation of cardiomyocytes was developed. Recently, the use of gelatin methacryloyl (GelMA) as a hydrogel surrogate to the natural extra-cellular matrix has been highly promising in terms of enhancing cell viability after isolation. Accordingly, the design, manufacture and validation of the instrument were each carried out with the objective of quantifying the material properties of GelMA. The instrument incorporated a disposable optical flexure and portable mounting system compatible with standard microscope systems, which enabled the utilisation of a broad range of imaging modalities. Subsequent data capture, image processing and finite element modelling promoted an integration of experimental results, from which 3D mechanical analyses of hydrogel samples could be derived. Succeeding the conception of the device, a novel technique for embedding isolated single adult cardiomyocytes in GelMA using confocal microscopy onto an optical flexure was developed. It was thus possible to observe healthy cells demonstrative of normal contractile behaviour, which were axially aligned in cured GelMA constructs. Through this method, it was possible to create highly adaptable cell-gel constructs of arbitrary, unconstrained size and geometry. Outcomes from this thesis contribute towards to the development of a high-throughput cardiomyocyte testing platform.