Transmission electron microscopic study of hepatocytes in bioartificial liver

A bioartificial liver (BAL) was prepared by simple inoculation of hepatocyt es into the inner space of hollow fibers of a hemodialyzer and it was maint ained in a closed circuit for in vitro culture. Morphology of hepatocytes i n the hollow fibers was studied in detail using transmission electron micro scopy (TEM). The hepatocytes formed three-dimensional, rod-shaped aggregate s of 200 mum in diameter throughout the whole dimension of the hollow fiber s after 1 day of culture. Approximately five hepatocyte layers existed from the surface to the center of the aggregate. The hepatocytes in the aggrega te displayed mostly polygonal shapes and were surrounded by five to six cel ls. Abundant bile canaliculi were formed between the hepatocytes and were s ealed by tight junctions. The distance between the adjacent hepatocytes exc ept the bile canaliculus domain was approximately 20 nm, and interdigitatio n was observed between some hepatocytes. These observations indicate that t he hepatocytes formed functionally associated aggregates, that is, organoid s. Although the cells facing the inner surface of the hollow fiber lost the ir polygonal shape and became flattened during the following several-day cu lture, no drastic change was observed in the morphology of the hepatocytes located inside the aggregate. After 14 days of culture, the number of livin g cells decreased and most of these had a deformed nucleus, few numbers of organelles, and intermittent lipid droplets.