Human assembloid of human blood vessel organoids with pancreatic islets improves insulin secretion over time ex vivo.

Pancreatic islet transplantation is a promising treatment strategy for type 1 diabetes patients; however, there are still major challenges to overcome, including vascularization. Despite a substantial need to understand the islet graft decline observed in patients 5-10 years post transplantation, clinical translation remains challenging, probably because of species-specific features and the lack of in vitro vascularized models. Here, we report results of a human assembloid composed of self-organizing 3D blood vessel organoids (BVOs) with human pancreatic islets. We demonstrate that co-culture of islets and BVOs ex vivo leads to an auto-organized assembloid (by light-sheet fluorescence microscopy) and improves insulin secretion over time (functionality assays) on 5 independent human islet donors (from 3 different hospital facilities). Taken together, this study could accelerate our understanding of type 1 diabetes and facilitate therapeutic development for type 1 diabetes patients.