Abstract
Functional interaction between cancer cells and the surrounding
microenvironment is still not sufficiently understood, which motivates
the tremendous interest for the development of numerous in vitro and in
vivo tumor models. Diverse parameters, e.g., transport of nutrients and
metabolites, availability of space in the confinement, interaction with
scaffolds, etc. make an impact on the size, shape, and metabolism of the
tumoroids. Herein, we demonstrate the fluidics-based low-cost
methodology to reproducibly generate the alginate and alginate-chitosan
microcapsules and apply it to grow human hepatoma (HepG2) tumoroids of
different dimensions and geometries. Focusing specifically on the
composition and thickness of the hydrogel shell, permeability of the
microcapsules is selectively tuned. The diffusion of the selected
benchmark molecules through the shell has been systematically
investigated using both, experiments and simulations, which is essential
to ensure efficient mass transfer of small molecules and prevent large
substances from reaching the encapsulated cells. Depending on available
space, phenotypically different 3D cell assemblies have been observed
inside the capsules, varying in the tightness of cell aggregations and
their shapes. Metabolic activity of tumoroids in microcapsules was
confirmed by tracking the turnover of testosterone to androstenedione
with chromatography studies in a metabolic assay. Because of the high
reproducibility, compartmentalization, and facile tuning of the shell
thickness and permeability, our system is not only a great platform for
the formation of cancer tumoroids, but also a promising tool for the
design and engineering of other cells.