Perfusion into the luminal structure constructed in a stacked cell sheet: (a) top view photograph of the perfusion device (scale bar is 10 mm). The right image is a schematic illustration of the perfusion device’s cross-section. The illustrations show the process of removing the titanium wire. (b) Perfusion of the black ink through lumen structure. The perfusion condition times shown in figures (i)–(iv) are 0, 30, 60, and 90 s, respectively. (c) Graph measuring perfusion pressure. It was measured by increasing the perfusion rate to 20, 25, and 30 μL/min. (d) Photographs of the long-term perfusions at 3 h and 6 h, respectively (scale bars, 5 mm). (e) OCT images after 6 hours in static culture (left) and perfusion culture (right) (scale bar, 200 μm). (f) HE-stained cross-section of the tissue with the lumen structure after 6 h perfusion (scale bar, 50 μm).