A Multicellular 3D GelMA-Based Colorectal Cancer Model for Chemotherapeutic Responses.

Advanced biomaterials-based in vitro platforms are increasingly required to overcome the limited predictive power of conventional 2D cell cultures in colorectal cancer (CRC) drug screening. Herein, we report the development of a biomimetic, multicellular 3D CRC model based on gelatin methacrylate (GelMA) hydrogels, designed to recapitulate key structural and biological features of the tumor microenvironment. The platform integrates a vascularized hydrogel compartment with human endothelial cells, combined with cancer-associated fibroblasts and macrophages, enabling controlled tumor-stroma-vessel interactions within a physiologically relevant architecture. The GelMA hydrogels were comprehensively characterized, and their role in regulating endothelial viability, migration, and angiogenic marker expression was systematically evaluated. The drug screening capability of the platform was assessed using 5-fluorouracil (5-FU). Comparative analyses revealed that 3D cultures exhibited attenuated cytotoxicity, oxidative stress, and apoptotic responses relative to 2D monolayers, particularly at lower drug concentrations and prolonged exposure times. These findings demonstrate that GelMA-based microenvironment actively modulates cellular drug responses through multicellular interactions and diffusion-mediated effects, rather than acting as a passive scaffold. Overall, this study establishes a functional 3D in vitro platform that provides improved physiological relevance and predictive capability for preclinical CRC drug screening, while offering a human-relevant alternative aligned with the principles of the 3Rs.