Extracellular matrix proteins give new life to cell culture

Under standard culture conditions, hepatocytes fail to proliferate or to maintain liver-specific functions (1, 2). Recent work, such as that reported by Ponce et al. in this issue of Hepatology and in an earlier article (3), suggests that the conditions used in the past to culture hepatocytes and other differentiated cells may be inappropriate or inadequate. This is part of an ongoing revolution in the way cells are cultured. The price of fetal calf serum, the elixir of cell culture, has undergone recent increases of a magnitude to whet the appetite of OPEC. Concomitantly, it has been realized that serum is not the physiological nutrient for all cells. In fact, while some cells grow in calf serum, they will grow and differentiate better when serum is replaced by various defined factors such as steroid hormones and other growth factors, transferrin, and proteins which stimulate cell attachment (4). Under these conditions, for example, neuroblastoma cells proliferate and maintain their cell-specific functions. Further, by eliminating serum, the overgrowth of slowly proliferating cells by fibroblasts may be prevented. Defined media have not yet been well developed for hepatocytes but efforts in this regard are underway (5).