Agarose‐Based Core‐Shell Scaffolds Facilitate Mammary Epithelial Tubulogenesis

Three‐dimensional mammary epithelial cultures are important for modeling tissue organization and developing cell‐based milk technologies, yet conventional Matrigel systems provide limited control over geometry, confinement, and long‐range tissue remodeling. Here, we developed a Matrigel‐agarose core‐shell bio‐casting platform that separates biochemical and structural cues by confining MCF10A cells or MCF10A organoids‐laden Matrigel within a hollow agarose shell. This defined architecture supported the formation of elongated mammary epithelial mini‐tissues and induced dynamic morphological remodeling, including longitudinal compaction, lateral tissue reorganization, and budding‐like protrusions. Compared to MCF10A cultured in Matrigel without the agarose shell, agarose core‐shell constructs showed enhanced epithelial and lumen‐like organization, as indicated by increased Ep‐CAM and MUC1 expression and enlarged lumen‐like regions. Strikingly, core‐shell filaments developed a transparent tube‐like phenotype with visible internal structures and retained epithelial marker expression. Gene‐expression analysis showed increased expression of selected mammary‐ and lipid‐associated markers, including Perilipin‐2, fatty acid synthase, and casein, suggesting early mammary‐associated molecular expression. Together, these results established Matrigel‐agarose core‐shell bio‐casting as a modular culture strategy for guiding mammary epithelial tubulogenesis in vitro.