Vascular endothelial growth factor production by isolated rat hepatocytes after cold ischemia-warm reoxygenation

Inflammatory disturbances in the liver microcirculation have been associated with preservation injury of hepatic grafts. Vascular endothelial growth factor (VEGF), a proinflammatory growth factor released by hepatocytes, acts on sinusoidal endothelial cells, but its implication in graft injury is still unclear. We studied VEGF production by rat hepatocytes after cold ischemia and warm reoxygenation and compared the capacity of University of Wisconsin (UW) and sodium-lactobionate-sucrose (SLS) preservation solutions to maintain this hepatocellular function. Isolated hepatocytes were kept for 0, 24, and 48 hours at 4 degrees C in either solution (cold ischemia), then incubated for 1 to 24 hours at 37 degrees C (warm reoxygenation). We assessed cell viability and production of VEGF messenger RNA (mRNA) and protein. Cell viability decreased in a linear time-dependent fashion by 10% after 48 hours of cold preservation and by an additional 40% after 24 hours of warm culture. Very little VEGF mRNA could be detected after up to 48 hours of simple cold preservation in either solution. However, subsequent warm culture led to a robust and rapid increase in VEGF mRNA expression within the first hour, which declined to close to background levels within 8 to 12 hours in culture. This effect was more important in cells preserved in SLS than UW solution. Similarly, cold preservation alone did not trigger VEGF secretion. VEGF secretion was detected after culturing hepatocytes at 37 degrees C and reached a maximal secretion rate within 12 to 15 hours. However, VEGF production by preserved cells was reduced compared with unstored cells. In conclusion, cold ischemia and warm reoxygenation triggers VEGF mRNA expression by hepatocytes, but subsequent VEGF secretion is partially impaired, suggesting posttranslational defects.