Calcium alginate microcapsules with spherical liquid cores templated by gelatin microparticles for mass production of multicellular spheroids

Multicellular spheroids are important in biomedical applications, such as drug research and regenerative medicine. We developed microcapsules from sodium alginate and gelatin for mass production of size-controlled spheroids with diameters <200 μm. The microcapsules were composed of calcium alginate gels with spherical liquid cores (diameter ≈ 150 μm) for formation of spheroids. The spherical liquid cores were prepared by incubating calcium alginate microcapsules containing thermally gelled, cell-enclosing gelatin microparticles about 150 μm in diameter, at 37 °C. The gelatin microparticles were encapsulated within the microcapsules by dropping a sodium alginate solution containing suspended gelatin microparticles into 100 mM CaCl2. The enclosed feline renal fibroblast cell line, CRFK, cells showed 93.8% viability immediately after encapsulation, then grew and completely filled the spherical cores. Multicellular spheroids were collected within 1 min by soaking microcapsules in a medium containing alginate lyase.