Thesis presented November 13, 2024

Abstract:
Diabetes mellitus is a chronic disease affecting 61 million people living in Europe, or 1 in 11 adults. In type 1 diabetes an autoimmune mediated destruction of insulin-producing beta cells leads to hyperglycaemia. The only treatment for patients consists of multiple daily insulin injections to control their blood glucose level, without curing them. These patients are in desperate need of long-lasting treatment that will improve their quality of life. One possibility is the transplantation of pancreatic islets from a brain-dead donor, thereby restoring control of the normal blood sugar. There are several limitations to this cell replacement therapy, including the number of diabetic patients which is much higher than the number of donors. Thus, a new source of beta cells is needed so that transplantation can be available to all patients. Stem cells have the potential to provide an unlimited source of new insulin-producing cells. Several teams have successfully obtained these cells in a Petri dish by exposing the stem cells to a succession of different molecule combinations that mimic the development of the human pancreas. However, since these cells are grown in a petri dish, they lack the pancreatic microenvironment that plays an important role during their development. The aim of my thesis is to produce beta cells derived from human induced pluripotent stem cells (hiPSC) and provide them with a human microenvironment and vascularization. To achieve this, first we used an organoid-on-a-chip model that mimics key features of the native pancreas microenvironment: islet vascularization by endothelial cells for improved oxygen and nutrient delivery in a perfusable microfluidic chip. We showed biocompatibility of our microfluidic platform that demonstrated possibility to vascularize hiPSC-derived beta cell organoids with continuous media perfusion at controlled flow rate and microenvironment with supporting hydrogel enriched with fibroblasts and endothelial cell. In the second strategy, we have fused and vascularized islets and blood vessel organoids derived from hiPSC for improved insulin response over time. We have shown that islet and blood vessel organoid co-culture has a positive effect on islet functionality with maintained beta cell glucose responsiveness over prolonged culture. Overall, this study explores novel in vitro strategies for islet vascularization using organoid-on-a-chip and human induced pluripotent stem cell technologies, opening the path for their future use in personalized and regenerative medicine.

Keywords:
diabete, organoid-on-chip, regenerative medicine