High-Dose Busulfan Administration stimulates Collagen type I and III Synthesis in Rat Hepatocytes

초록

The veno-occlusive disease(VOD) of the liver is one of the major regimen-related toxicities developing after high-dose cytoreductive chemotherapy. The pathophysiology of VOD, however, remains largely unknown while endothelial cell damage has been implicated in some studies. We observed the early pathologic changes in the rat liver. The Fisher 344 rats were sacrificed within 24 hours after intraperitoneal administration of 16 mg/kg of busulfan and the morphologic changes of the liver were examined under the light and electron microscopes. We also performed in vitro slice culture studies of the rat liver using Waymouth MB752/1-based media, 95%O2/5%CO2 gas mixtures. Immunohistochemical staining of the cultured rat liver tissues for collagens were carried out within 24 hours after treatment with 48 mg/kg wet liver of busulfan and the results were compared with those of the control experiments. The concentration of collagens in the culture media were determined using ELISA kits. Electron microscopic examination of the rat liver revealed numerous bundles of tubular structures resembling collagen as early as one hour after intraperitoneal busulfan administration. These findings were more prominent in the zone 3 hepatocytes than in zone 1 hepatocytes. Immunohistochemical staining was positive for type I and III collagen, but not for type IV collagen. Concentrations of type I and III collagen were increased in the culture medium of busulfan-treated rat liver tissues. Control liver tissues did not show these electron microscopic and immunohistochemical changes, but type III collagen level were increased in the culture medium. In conclusion, we observed that the collagen synthesis in the hepatocytes was one of the early events occurring in the rat liver after high-dose busulfan treatment. Further investigation is warranted for the role of the hepatocyte collagen synthesis in inducing the thrombotic and fibrous changes of VOD of the liver.