Scalable and transplantable pancreatic islet organoids with engineered oxygenation

PROJECT SUMMARY Pancreatic islet transplantation is a therapeutic option for type 1 diabetes (T1D), providing glycemic control and eliminating the need for insulin injections. It offers the advantage of a less invasive, catheter-assisted procedure compared to another surgical intervention, whole pancreas transplantation, which carries high surgical complication risks. However, the long-term success of islet transplantation is limited, with the insulin independence rate dropping to ~10% of patients after five years. This is in contrast to whole pancreas transplantation, which achieves higher insulin independence rates of >70% at five years post-transplant. The key difference lies in the loss of the islet microenvironment during isolation for islet transplantation; disrupting vasculature and extracellular matrix support leads to significant graft attrition. This underscores the need for creating an islet-supportive microenvironment. Fabricating an islet organoid in vitro-with interactions between islets and supporting cells prior to transplantation-is a promising solution. However, fabricating a clinically scalable organoid has been challenging due to the insufficient oxygen supply to the organoid core. Our longterm goal is to develop clinical-scale transplantable islet organoids that incorporate an islet-supportive microenvironment to improve islet engraftment efficiency in T1 D patients. In this application, we propose a practical approach to deliver oxygen to the diffusion-limited organoid core. We engineered oxygen-transporting microcapillary mesh made from clinically proven parylene material. Oxygen is delivered through the ultra-thin 25-μm microcapillary mesh via passive diffusion from the surrounding environment. This achieves a uniform and self-sustaining oxygenation throughout the organoid. We hypothesize that establishing an islet-supportive microenvironment within an islet organoid, prior to transplantation, will improve post-transplant engraftment. We will test this through the following Specific Aims: Aim 1: Fabricate scalable human islet organoids using oxygen transport from culture media in a dynamic culture system. Aim 2: Fabricate scalable human islet organoids using oxygen transport from ambient air in a static culture system. We will fabricate human islet organoids of 5 mm in thickness that far exceed the general oxygen diffusion limit of ~50-100 μm. The organoids will be integrated with multiple layers of our oxygen-transporting mesh to deliver continuous oxygen to the core. We will use human cadaveric and stem cell-derived islets as potential insulin-producing cell sources and transplant these organoids under the skin in diabetic immunodeficient animals to assess the therapeutic benefits compared to conventional islet transplantation. These aims share the same concept-delivering oxygen into the organoid core through the oxygen-transporting mesh-but employ distinct oxygen sources with mesh modifications. Successful completion will demonstrate a scalable solution in large organoid fabrication. This research aligns with the mission of the NIDDK by integrating cross-cutting science in biology, physiology, and engineering using a unique device to address a critical gap in T1D treatment, with implications for multiple organoid-based therapies.