High albumin production by multicellular spheroids of adult rat hepatocytes formed in the pores of polyurethane foam

Adult rat hepatocytes formed spherical multicellular aggregates (spheroids) when they were cultured in the pores of polyurethane foam (PUF). The diameter of the spheroids was within the range 100-200 μm. These spheroids partly attached and immobilized in the PUF pores for at least 2 weeks. The albumin production rate by the spheroids increased up to 17.0 μg/10⁶ nuclei per day during the first 6 days and maintained at a high level for 2 weeks. In contrast, the albumin production rate by the monolayer markedly decreased after 3 days. The spheroid culture using PUF seems to be a convenient and simple method for maintaining some differentiated functions of hepatocytes and for making a bioreactor using the function of spheroids.