Expression of long-term liver-specific function by adult rat hepatocytes cultured on microcarriers

The successful development of a bioartificial liver relies, in part, on the ability to maintain viability and differentiated function of a large number of hepatocytes in vitro for extended periods of time. Microcarriers have been widely used to scale up anchorage-dependent mammalian cell cultures. The goal of the present study was to seek optimal culture conditions for hepatocytes attached to microcarriers. Hepatocytes were seeded onto gelatin-coated polystyrene microcarriers, and the composite was cultured in suspension or embedded in an agarose or type I collagen gel for up to 14 days. We were able to seed up to 130 hepatocytes per microcarrier. Viability and function of hepatocytes on microcarriers cultured in suspension or in agarose decreased as a function of time. On the other hand, microcarriers embedded in a collagen gel exhibited specific albumin and urea secretion rates of approximately 3 mu g/h/10(6) cells and 10 mu g/h/10(6) cells during the second week of culture, respectively. These rates were similar to those obtained in control cultures of collagen-sandwiched hepatocytes in the absence of microcarriers. Thus, long-term liver-specific function can be induced by surrounding hepatocytes seeded on microcarriers with a collagen gel. This may be a viable approach to scale up the sandwich hepatocyte culture system.