Formation of cylindrical multicellular aggregate (cylindroid) and expression of liver specific functions of primary rat hepatocytes

In our studies of the development of a hybrid artificial liver, we investigated the formation of cylindrical multicellular aggregate (cylindroid) of primary rat hepatocytes on a pressed sheet of polyurethane foam (pressed-PUF) as a culture substratum. Hepatocytes formed cylindroids by attaching to a pressed-PUF surface, peeling off from the surface and aggregating. The diameter and length of most cylindroids were approximately 200-500 μm and 500 μm-2 mm, respectively. The activities of liver specific functions (albumin secretion and ammonia metabolism) of hepatocyte cylindroids were equivalent to or higher than those of hepatocyte spheroids. These results suggest that hepatocyte cylindroids can maintain highly differentiated functions longer than hepatocyte spheroids, and that a PUF/cylindroid culture may be effective to develop of a hybrid artificial liver.