Rapid hepatic cell attachment onto biodegradable polymer surfaces without toxicity using an avidin–biotin binding system

Efficient cell attachment to biodegradable polymer scaffolds is a necessary prerequisite in tissue engineering. However, it is difficult to evenly cover scaffold surfaces with cells because scaffolds are generally highly porous, with complex three-dimensional (3D) surfaces. In this article, we demonstrate the efficiency of avidin–biotin binding systems (ABBS) for the initial attachment of biotinylated Hep G2 cells to avidin adsorbed flat, two-dimensional (2D) and highly porous 3D poly l-lactic acid (PLLA) surfaces. The potential toxicity of biotinylation and/or strong ABBS binding forces was also investigated. ABBS assisted Hep G2 cells to adhere to a flat PLLA surface within 10 min; the proliferation of these attached cells was comparable with control intact cells cultured on collagen. Hepatic functions of the attached cells, such as albumin secretion, induction of CYP1A1 and CYP1A2 genes, and metabolic capacity of CYP1A1/2 as measured by the ethoxyresorufin O-deethylase assay, were not significantly changed. Also, a stimulus of a cytokine: oncostatin M (OSM) phosphorylated an intracellular signaling molecule, extracellular signal-related kinase 1 (ERK1) via transmembrane receptor complex, at 24 h after inoculation by ABBS. In addition, efficient attachment of Hep G2 cells to a highly porous PLLA 3D scaffold was demonstrated. These results clearly show that ABBS is useful for rapidly trapping cells in both biodegradable, polymer-based, flat 2D surfaces, and in highly porous 3D scaffolds. Furthermore, binding hepatic cells by this technique has only small effects on liver-specific functions, or on signal transfer ability of transmembrane receptor complexes.