Biliary copper excretion was examined in rats with acute, continuous and chronic copper loads. Copper was excreted into bile, and the concentration peaked 40 min after a venous injection of copper sulfate (127 ng/gm body weight). The excretion was significantly inhibited by colchicine. Therefore some copper may be transported in hepatocytes by a vesicular pathway and excreted into bile. Biliary copper output increased over time and reached a plateau 180 min after a continuous venous infusion of copper sulfate (318 ng/gm body weight/hr) had started, when the concentration of copper in bile was much higher than that in plasma; the bile/plasma ratio of copper concentrations was 4.32 +/- 0.46. These data support the idea that copper transport involves a specific uptake and transport system. In chronically copper-loaded rats, hepatic copper content was significantly increased compared with controls, and reaction products for copper were observed in hepatocyte granules by light microscopic examination with p-dimethylaminobenzylidene rhodanine stain. The number of lysosomes in hepatocytes increased and the shape changed. In chronically copper-loaded rats the number of tubular lysosomes was very high. However, other organelles appeared to be normal. In these rats biliary excretion of not only copper but also acid phosphatase, a lysosomal enzyme, was significantly greater than the control. Therefore hepatocyte lysosomes may play an important role in biliary copper excretion. Furthermore, when biliary lysosomal excretion increases, the tubular lysosomes actively participate in this excretion.

Patients with hepatocellular carcinoma sometimes have erythrocytosis and high plasma erythropoietin levels. However, previous studies have not revealed direct evidence that the carcinoma cells produce the erythropoietin. To address this question, we carried out light and electron microscopic immunohistochemical studies, using a human erythropoietin antibody to the liver in three male patients with hepatocellular carcinoma and erythrocytosis. alpha-Feto-protein localization was also examined in serial liver sections by light microscopic immunohistochemistry with an antibody to alpha-fetoprotein. All three patients demonstrated high hemoglobin levels (16.7, 17.6 and 18.1 gm/dl) and high plasma erythropoietin levels (227, 266 and 280 mU/ml). In one patient the plasma erythropoietin level in the hepatic vein was significantly higher than that in the hepatic artery. The levels of plasma erythropoietin, as well as such tumor markers for hepatocellular carcinoma as serum alpha-fetoprotein and plasma des-gamma-carboxyprothrombin, were significantly reduced after treatment with an anticancer drug, cisplatin. Light microscopic immunohistochemistry showed that erythropoietin was definitely present in the cytoplasm of the hepatocellular carcinoma cells, but not in normal hepatocytes around the carcinoma lesion or in other nonparenchymal cells such as vascular endothelial cells and Kupffer cells. In electron microscopic immunohistochemistry, reaction products for erythropoietin were revealed in the cisternae of the endoplasmic reticulum in the carcinoma cells, suggesting the production of erythropoietin by these cells. Light microscopic immunohistochemistry showed that alpha-fetoprotein was localized in the hepatocellular carcinoma cells that were erythropoietin positive in the serial sections. These findings indicated that hepatocellular carcinoma cells produced erythropoietin as well as alpha-fetoprotein in these cases, leading to the complication of erythrocytosis.

To determine the effects of extracellular matrices on the function and morphology of hepatic sinusoidal endothelial cells, isolated rat hepatic sinusoidal endothelial cells were cultured in three-dimensional fashion on collagen gel containing various extracellular matrix components. Cells cultured on type I collagen gel with or without type IV collagen formed a cobblestone appearance on the surface of the gel. Cells cultured on laminin-containing type I collagen gel invaded the gel and exhibited three-dimensional tube formation with a decreased number of characteristic endothelial pores. Morphometrically, there was a significant relationship between the length of the tube formed and the concentration of laminin in the type I collagen gel. Cells cultured on Matrigel, which contains high concentrations of laminin, type IV collagen, fibroblast growth factor, tissue plasminogen activator, and other growth factors, formed a great number of tubes into a network on the surface of the gel, as is observed in the situ hepatic sinusoidal endothelial cells. Ultrastructurally, tube-forming endothelial cells cultured on Matrigel had many endothelial pores on the cell surface, with tubes (approximately 10 microns in diameter) formed by two or three hepatic sinusoidal endothelial cells. These results indicated that extracellular matrix components, especially laminin, induced the formation of tubes in cultured rat hepatic sinusoidal endothelial cells. Tube-forming sinusoidal endothelial cells cultured on Matrigel could provide more advantages than the two-dimensional culture model for investigating the function and morphology of these cells in vitro.

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