Engineering of the alginate capsules for human hepatoma cell (HepG2) encapsulation

Liver cancer is the second most lethal malignancy worldwide. Recently, three-dimensional (3D) cancer organoids models have been constructed and applied to liver cancer research, to predict the therapy outcomes. However, there is still low success and reproducibility rate for generating patient-derived liver tumoroids due to limitations in current technologies. Herein, a high reproducible cross junction based microfluidic droplet generation system is applied for human hepatoma cell line encapsulation and organoids engineering. The fabrication of alginate and alginate-chitosan microcapsules is systematically studied, forming microcapsules with different shell thicknesses (~ 5 to 150 µm) and tunable permeability. In combination with a COMSOL model, the size selective permeability of different molecular complexes through the capsule membrane has been investigated, which is essential to ensure efficient mass transfer of small molecules, and prevent large substances from reaching the loaded cells. Finally, we demonstrate that the cells are prone to aggregate more tightly in capsules with a lower permeability, which causing more hypotonicity and lower viability. Because of the high reproducibility, compartmentalization, and easily permeability tuning, this system not only provides a great platform for liver patient-derived tumoroids forming, but also is promising for other cell organoids design and engineering.