(635b) Developing Islet-on-Chip Model Towards T2D Disease Modeling

In therapy development, inadequate animal models have remained a constant obstacle due to their inaccuracy in representing human physiology and disease, causing many treatments to fail in clinical trials after success in the animal studies. The human-on-a-chip model has become a promising new approach for aiding in treatment testing by mimicking the biochemical and mechanical environment of organs to more efficiently transition from initial testing to clinical trials. This project seeks to use this technique to develop a diabetic islet-on-a-chip model. Diabetes is a widespread disease that develops after the decreased function of pancreatic islets, which produce insulin for blood glucose regulation. The decreased function of islets can stem from an autoimmune elimination of the insulin producing beta cells (Type 1) or a toxic environment damaging the beta cells (Type 2). The current project aims to develop an islet-on-chip model using human induced pluripotent stem cells (hiPSC) that can be used to understand and treat type 2 diabetes (T2D).

The islet-on-chip platform was developed with a modification of a commercially available Micronit microfluidic device, which utilizes three glass slides to form a 2-chamber system partitioned by a customizable middle membrane layer. Both chambers can be individually accessed by a dedicated perfusion channel, which allows the flexibility of multiple flow configurations through the system. The parent design allows for culturing adherent cells on the middle membrane layer, with the flexibility of cell seeding either through perfusion flow or system disassembly and reassembly. Pancreatic islets, on the other hand, lose their function and phenotype upon adherent culture and require retaining 3D conformation. Alternate seeding and culture strategies were investigated to culture primary human islets in the Micronit device, leading to the development of a novel hydrogel-supported islet micropatterning technique on the membrane. The design of the micropatterning was informed by modeling the flow field through the device using COMSOL modeling software. Our islet-on-chip system could retain high viability and glucose stimulated insulin secretion (GSIS) of primary human islets for over 4 weeks of perfusion culture under normal ‘fasting’ condition. Towards disease modeling of Type 2 Diabetes, islet glucotoxicity was simulated by long term exposure to pathological glucose levels, lipotoxocity by elevated free fatty acids (oleate and palmitate) and glucolipotoxocity by combinations of the two. Extended exposure to cytokines (TNF-alpha, IL-1 beta, IFN-gamma) alone and in combination was used to mimic the complexity of T2D disease condition. Such simulated disease conditions could reproduce many of the known aspects of type 2 diabetes. In parallel, islet organoids are being derived from hiPSCs to replace the primary human islet with a regenerative cell source. Similar to primary islets, the microfluidic culture system could maintain survival, phenotype, and function of the hiPSC-derived islets over extended culture period. Further steps are for inducing the diseased state in the hiPSC-based chip model. These models can be further used to test T2D treatments to determine the reversibility of the toxic states and ability to simulate treating the disease in patients.