Biomimetic 3D mammary duct models of healthy and tumoral tissues engineered by a co-extrusion microfluidic based technology

Engineering the human breast in 3D physio-mimetic models is challenging due to its complex multilayered tubular organization, where milk is produced in acini and transported through ductal structures. These functions rely on a highly organized architecture comprising stromal, epithelial, and extracellular matrix compartments. The dysregulation of this architecture perturbs mammary gland homeostasis and promotes the emergence of diverse breast cancer subtypes, from frequent in situ luminal to rarer metastatic basal-like tumors. Despite this knowledge, conventional anti-cancer drug testing still primarily employs high-throughput 3D spheroid models that account for diffusion but lack stromal components, thereby failing to capture stroma-driven treatment resistance. With a unique microfluidic co-extrusion platform, we have developed 3D tubular tissues anchored on a porous and biocompatible alginate shell. Using a one-step protocol, we have bioengineered six relevant ductoid models of healthy and tumoral mammary ducts, most notably a multi-layered model comprising a lumen, mammary epithelium, and stromal compartment made of fibroblasts and matrixes. These new models offer limitless applications in tissue engineering including the characterization of an epithelium and its secretory function, and the identification of the stromal influence on healthy and tumoral mammary gland tissue. Finally, by releasing mechanical constraints, we scale-up the tubular duct model into a mammary assembloid that exhibits branching and budding of acini-like structures from the original duct. We envision that this modular design will broadly impact breast basic and clinical research by opening new experimental avenues toward more physio-mimetic tools through the integration of stromal compartments.