Three-dimensional intestinal tube with a crypt-like uneven inner wall fabricated using electrolysis-generated microbubbles

We present a three-dimensional intestinal hydrogel tube with a crypt-like uneven inner wall fabricated using electrolysis-generated microbubbles. The uneven structure observed in crypt and villus intestinal epithelial tissue <i>in vivo</i> serves as crucial geometry for forming hierarchical tissue consisting of stem cells localized in the crypts and various differentiated cells located in the villi. Our approach utilizes electrically generated microbubbles on a wire mold during the fabrication of the hydrogel tube, resulting in the formation of crypt-like cavities on the inner wall. We fabricated the hydrogel tube with various sizes of crypt-like cavities by changing the voltage-applied time. Caco-2 cells were cultured in the fabricated tubes for over 7 d, and it was observed that they maintained the crypt-like structure. Furthermore, we used immunofluorescence staining to successfully observe the polarity of the intestinal epithelial cells and the unique cell morphology with a specific cell shape and height in response to the crypt-like structure. This specific cell morphology suggests the potential of the tube model to generate hierarchical intestinal tissue. With its highly biomimetic and high-throughput fabrication capabilities, our model will serve as a platform for intestinal models.