Bioengineering Approaches to Improve Islet Transplantation Outcomes for the Treatment of Type One Diabetes Mellitus

Abstract

Type one diabetes mellitus is a chronic disease that results in the dysregulation of blood glucose levels. Current therapeutic approaches for patients with type one diabetes include continuous monitoring of blood glucose levels and self-administration of exogenous insulin. Islet or β-cell transplantation allows for insulin-independency and doesn’t pose the risk of the patients under- or over-medicating themselves. With increasing studies understanding the human pancreas during development and as an adult, the field of islet transplantation has progressed greatly over the last decades with specific interest in the areas of enhancing donor islet survival, improving stem cell-derived β-cell differentiation protocols, and protecting islet transplants from the immune system. In this thesis, the different aspects of islet transplantation and cell monitoring modalities were addressed from a bioengineering perspective to improve transplant outcomes. We investigated the use of lentiviral forward programming protocols to improve the efficiency of β-cell differentiation, emphasizing the importance of recapitulating the temporal expression of the mature β-cell markers as in development. Further, to support the β-cells post-transplantation, we moved towards re-establishment of the human adult pancreatic environment using extracellular matrix proteins strongly associated with insulin-producing cells within the islets of Langerhans, decorin and nidogen-1. Interestingly, supplementation of these recombinantly-produced proteins to our immortalized β-cell line pseudo-islet model and isolated human donor islets improved glucose-responsiveness, and protected them under hypoxic conditions as experienced in a post-transplantation environment. Furthermore, decorin was observed to reduce the expression of fibrotic ECM proteins, suggesting a role in preventing fibrotic capsule formation surrounding the transplant which would otherwise render it ineffective. We also demonstrated the use of FLIM to non-invasively monitor the metabolic response of the β-cells to glucose stimulation and changes in oxygen levels in its environment in real-time. Altogether, this thesis highlights the importance of recapitulating the signals and cues β-cells experience in vivo to best improve islet transplantation outcomes.