High-throughput formulation of reproducible 3D cancer microenvironments for drug testing in myelogenous leukemia

Targeting cancer microenvironment is currently one of the major directions in drug development and preclinical studies in leukemia. Despite the variety of available chronic myelogenous leukemia 3D culture models, the reproducible generation of miniaturized leukemia microenvironments, suitable for high-throughput drug testing, has remained a challenge. Here, we use microfluidics to generate over ten thousand highly monodisperse leukemic-bone marrow hydrogel microbeads per minute. We employ gelatin methacrylate (GelMA) as a model extracellular matrix (ECM) and tune the concentration of the biopolymer, as well as other possible components of the ECM (fibrin, hyaluronic acid), cell concentration and the ratio of leukemic cells to bone marrow cells within the microbeads. This allows to achieve optimal cell viability and the propensity of the encapsulated cells to microtissue formation, while also warranting long-term stability of the microbeads in culture. We administer model kinase inhibitor, imatinib, at various concentrations to the microbeads and, via comparing mono- and co-culture conditions (cancer alone vs cancer-stroma), we find that the stroma-leukemia crosstalk systematically protects the encapsulated cells against the drug-induced cytotoxicity, confirming therefore that our system mimics the physiological stroma-dependent protection. We finally discuss applicability of our model to (i) studying the role of direct- or close-contact interactions between leukemia and bone marrow cells embedded in 3D ECM on the stroma-mediated protection, and (ii) high-throughput screening of anti-cancer therapeutics in personalized therapies. ### Competing Interest Statement The authors have declared no competing interest.