Collagen Hollow Microbeads for Engineered Hollow Organ Model in Vitro

We propose an in vitro model to mimic the hollow structure of biological tissues (e.g. heart or stomach) using hollow core-shell collagen microgel beads. By using collagen hydrogel as the shell of the microbeads, cells encapsulated inside of the collagen shell can proliferate and form a tissue structure with a hollow center. In this paper, as a first step toward engineered hollow structure tissue formation, we report a fabrication method for core-shell (hollow) alginate microgel beads by a simple droplet-dipping method using a two-layer coaxial nozzle device. To apply collagen hydrogel to this droplet-dipping method, we applied alginate cross-linking network as a template for creating collagen microgel beads and dissolved the alginate network after the collagen hydrogel was stabilized. By combining these techniques, we believe that hollow collagen microgel beads encapsulating cells can easily and massively be produced for reconstructing in vitro hollow organ models.