Avidin-biotin binding-based cell seeding and perfusion culture of liver-derived cells in a porous scaffold with a three-dimensional interconnected flow-channel network.

To engineer implantable liver tissues, we designed a novel scaffold with a three-dimensional (3D) branching and joining flow-channel network comprising multiple tetrahedral units (4-mm edge length). For the fabrication of this network, biodegradable polycaprolactone (PCL) and 80% (w/w) NaCl salt particles serving as porogen were thoroughly mixed and applied in a selective laser sintering (SLS) process, a technique adapted to rapid prototyping. We thus obtained a scaffold that had high (89%) porosity with a pore size of 100-200 microm and 3D flow channels. To evaluate its biocompatibility, human hepatoma Hep G2 cells were seeded into the scaffold using avidin-biotin (AB) binding and cultured in a perfusion system for 9 days. The results demonstrated that such 3D flow channels are essential to the cells' growth and function. In addition, the AB binding-based seeding remarkably improved the overall performance of the cell-loaded scaffolds. The fabrication of a much finer scaffold, having a 500 cm(3) scale, based on the same design and the use of human hepatocyte progenitors, may, in the near future, lead to the development of an implantable liver tissue equivalent for use in humans.