Browsing by Author "Al-Ani, Abdullah"

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    Microscale Tissue Engineering and Contributors of the Cellular Niche
    (2019-05-31) Al-Ani, Abdullah; Ungrin, Mark D.; Biernaskie, Jeff A.; Kallos, Michael S.; Rancourt, Derrick E.; Hirota, Simon Andrew; Gratzer, Paul F.
    The behaviour of cells is modulated by their microenvironment or ‘niche’. While cellular therapies offer promising curative solutions for many diseases, the efficacy of transplanted cells is often hampered by a suboptimal microenvironment. One strategy to overcome this limitation is to reconstruct the niche of the cells of interest prior to transplantation. The central aim of this thesis is to develop novel tissue engineering approaches to further understand and reconstitute the cellular niche. While these approaches were specifically validated in the retinal and islet systems, they were also designed to be easily implemented in other biological systems. One project showcases a novel scaffold-free, scalable and injectable retinal pigment epithelium (RPE) microtissue for minimally-invasive transplantation. While RPE transplantation holds great potential to cure various retinal degenerative diseases, cells transplanted as cellular suspension exhibit suboptimal survival and function. Conversely, transplanting RPE as coherent cellular sheets has yielded better outcomes, but they are complex to transplant and produce at large scale. Our RPE microtissues were designed to capture the benefit of both approaches: namely, simplicity of production and transplantation, as well as enhanced performance. We found that our RPE microtissue exhibited superior cellular behaviour in terms of gene expression and in vitro function when compared to standard adherent culture. Another project presents a unique approach to produce transplants with a reconstituted cellular niche. This approach aims to repopulate the niche by incorporating finite amounts and proportions of niche cells into transplantable constructs. Using it enabled us to produce size-controlled pseudoislet constructs that contained various proportions of mesenchymal stem cells (MSCs), fibroblast and endothelial cells, and to quantitatively evaluate their in vitro performance. Further, applying this approach led us to discover more than one favourable condition that yielded improvements in islet cell performance in vitro. While the islets of Langerhans were used for biological validation, the approach was designed to be broadly applicable to various biological systems. In sum, this thesis offers several novel approaches for scientists to better understand and enhance the cellular niche. The simplicity, accessibility and scalability of these approaches render them suitable for both scientific applications and clinical translation.