Development of a Functional 3D Colon Model for the Induction and Monitoring of Diseases.

Conventional in vitro and animal models do not reproduce the geometry, mechanics, or transport physics of the human colon, limiting their fidelity for disease studies and drug screening. A patient-derived, freeform reversible embedding of suspended hydrogels bioprinted three-dimensional (3D) in vivo mimicking human-colon model (3D-IVM-HC) is reported whose micro-computed tomography (CT) profile deviates by less than 4% from the original computed tomography template and spontaneously forms crypt-like invaginations with a median depth of 65 µm. The dual-layer gelatin methacrylate (GelMA)/alginate matrix matches native colonic stiffness (9-65 kPa) and sustains >95% cell viability with a 14-fold metabolic increase over 14 days. Caco-2 epithelia polarize within the lumen, form continuous Zonula occludens-1 (ZO-1) belts, and reach a transepithelial electrical resistance (TEER) of 68 ± 4 Ω cm², values within the human ex vivo range. Finite-element simulations (FEM) parameterized with measured geometry and resistance predict water and nutrient fluxes within 80-99% of human explants. When HCT116 tumor spheroids are introduced, the construct yields a 5-fluorouracil (5-FU) half-maximal inhibitory concentration (IC₅₀) of 540 ± 30 µm, an order of magnitude higher than a matched two-dimensional (2D) monolayer (42 ± 5 µm), mirroring clinical chemoresistance. Together, these benchmarks establish the 3D-IVM-HC as a physiologically faithful, animal-free platform for probing colorectal biology and quantifying drug response.