Figure 15: Model II. PNIPAM aqueous solution (15 wt%) was injected onto photocured ST-gelatin gel (operational parameters: pressure, 0.05 MPa; dispenser movement rate, 1 mm/s; valve-opening ratio, 33%) at 37°C and overlayered with photocured ST-gelatin at a thickness of 1 thickness. Upon immersion in cold PBS, precipitated PNIPAM was dissolved, leaving tunnellike structures in the gel (B, C). Fluorescently labeled ECs (1×107 cells/ml in medium) were then inoculated into the tubules using a syringe, and cultured for one day (D).