Construction of a Duck Intestinal Organoid Culture System: From Crypt Isolation to Medium Optimization.

Intestinal organoids possess self-organizing capacity and recapitulate essential features of intestinal architecture and function, making them powerful models for investigating development, disease mechanisms, pharmacological testing, and host-microbe interactions. Although standardized protocols for chicken intestinal organoids have been established, a defined culture system for ducks has not been available. In this study, we optimized crypt isolation procedures and culture medium composition to establish a reproducible system tailored to duck intestinal stem cells. Among various digestive solutions, ethylene glycol tetraacetic acid (EGTA) achieved the highest crypt isolation efficacy and organoid survival. Suspension culture resulted in better survival, proliferation, and differentiation of intestinal stem cells than air-liquid interface and embedding methods (p < 0.05). Immunofluorescence and real-time PCR indicated the presence of multiple epithelial lineages, including stem cells, Paneth cells, enterocytes, goblet cells, and enteroendocrine cells. Media supplemented with CHIR99021 and LDN193189 (CL) supported growth comparable to that of media with EGF, Noggin, and R-spondin 1 (ENR). Duckling serum and specific factors, such as SB203580 and retinol, further improved organoid formation and promoted differentiation. While long-term passaging and expansion remain technically challenging, this work provides the first duck intestinal organoid model and lays the foundation for future applications in avian intestinal research, including nutrition, disease modeling, and intervention strategies.