Rat hepatocyte spheroids formed on temperature-responsive PIPAAm polymer- grafted surface maintain long-term differentiated hepatocyte function

Abstract

Background. Although the development of a practicable culture method to maintain long-term hepatocyte function is highly desirable, hepatocytes lose their liver-specific functions rapidly on regular collagen-coated dishes. In this study, we evaluated the effi cacy of a special cell culture dish coated with the temperature-responsive polymer poly(N-isopropylacrylamide) (PIPAAm), and observed the morphological and functional changes of hepatocytes on changing the amount of polymer. Methods. Culture plates with varying amounts of PIPAAm polymer (1.5〜3.5 times that in the commercially available temperatureresponsive polymer-containing dish (UpCell®, CellSeed, Tokyo, Japan)) were prepared. All dishes were enhanced by adding a layer of rat tail collagen I at a dose of 600 µg/dish for 3 hours. Hepatocytes isolated from Sprague-Dawley rats were cultured in these static culture systems. Morphologic changes and liver-specific functions were evaluated. Results. On day 7 of culture, spheroid formation of hepatocytes was observed in the high-polymer group, with the presence of glycogen and albumin in the spheroid. In the high-polymer group, the rate of albumin production was significantly higher than in the low-polymer group until day 14 of culture (P<0.001). Conclusion. The spheroid formation of hepatocytes cultured in the presence of a high level of PIPAAm showed the long-term maintenance of liver-specific functions in vitro.