Hepatocyte spheroid formation on a titanium dioxide gel surface and hepatocyte long-term culture

The cell morphology and expression of differentiated functions of primary rat hepatocytes on a titanium dioxide (TiO2) gel surface were investigated. Polystyrene culture dishes were coated with TiO2 gel by spin-coating an ethanol solution of titanium n-butoxide, hydrolyzing in a humidity chamber and drying with nitrogen gas. The TiO2 gel layer formed on the polystyrene dishes was transparent and robust, and its surface was quite flat. Rat hepatocytes inoculated on the TiO2 gel-coated polystyrene dishes gradually accumulated with increasing culture time, and then spontaneously formed many hepatocyte spheroids at 90 +/- 21 mu m diameter from about 3 days of culture. The diameter of the spheroids increased during the culture, and was 151 +/- 43 mu m at 14 days of culture. Ammonia removal and albumin secretion by hepatocytes on the TiO2 gel-coated polystyrene dishes were maintained at a high level for at least 14 days of culture compared with on a type I collagen-coated dish and a non-coated polystyrene dish. These results indicate that TiO2 gel is an adequate material for hepatocyte spheroid formation and long-term culture of spheroids.