A Droplet Microfluidic System to Fabricate Hybrid Capsules Enabling Stem Cell Organoid Engineering

Organoids derived from self-organizing stem cells represent a major technological breakthrough with the potential to revolutionize biomedical research. However, building high-fidelity organoids in a reproducible and high-throughput manner remains challenging. Here, a droplet microfluidic system is developed for controllable fabrication of hybrid hydrogel capsules, which allows for massive 3D culture and formation of functional and uniform islet organoids derived from human-induced pluripotent stem cells (hiPSCs). In this all-in-water microfluidic system, an array of droplets is utilized as templates for one-step fabrication of binary capsules relying on interfacial complexation of oppositely charged Na-alginate (NaA) and chitosan (CS). The produced hybrid capsules exhibit high uniformity, and are biocompatible, stable, and permeable. The established system enables capsule production, 3D culture, and self-organizing formation of human islet organoids in a continuous process by encapsulating pancreatic endocrine cells from hiPSCs. The generated islet organoids contain islet-specific α- and β-like cells with high expression of pancreatic hormone specific genes and proteins. Moreover, they exhibit sensitive glucose-stimulated insulin secretion function, demonstrating the capability of these binary capsules to engineer human organoids from hiPSCs. The proposed system is scalable, easy-to-operate, and stable, which can offer a robust platform for advancing human organoids research and translational applications.