Generation of Fetal Intestinal Organoids and Their Maturation into Adult Intestinal Cells.

During embryonic development, the gut tube undergoes massive morphological changes from the simple tube structure composed of the pseudostratified epithelium into the mature intestinal tract composed of the columnar epithelium and characterized by the unique crypt-villus structures. In mice, maturation of fetal gut precursor cells into adult intestinal cells starts around embryonic day (E) 16.5, during which adult intestinal stem cells and their differentiated progenies are generated. In contrast to adult intestinal cells that form budding organoids containing both the crypt-like and villus-like regions, fetal intestinal cells can be cultured as simple spheroid-shaped organoids that show a uniform proliferation pattern. The fetal intestinal spheroids can undergo spontaneous maturation into adult budding organoids that contain intestinal stem cells and differentiated cells, including enterocytes, goblet, enteroendocrine, and Paneth cells, recapitulating intestinal cell maturation in vitro. Here, we provide detailed methods for establishment of fetal intestinal organoids and their differentiation into adult intestinal cells. These methods enable in vitro recapitulation of intestinal development and would be useful to reveal mechanisms that regulate the transition from fetal to adult intestinal cells.