Intraportal infusion of 99mtechnetium-macro-aggregrated albumin particles and hepatocytes in rabbits: assessment of shunting and portal hemodynamic changes

Abstract

Partial correction of metabolic liver disease by hepatocyte transplantation requires infusion of a large number of cells into the portal vein. Uncontrolled infusion of cells leads to extrahepatic shunting. Obstruction of the sinusoidal space may result in hemodynamic changes and impairment of liver function. Catheters connected to a port were placed into the caudal mesenteric vein of rabbits. After injection of 99mtechnetium-macroaggregated albumin (99mTc-MAA) surrogates or 99mTc-MAA/hepatocyte (Hc) mixtures (1:125), shunting into the lung was scintigraphically monitored. Volume flow (mL/min) and maximum velocity of the portal vein were recorded by color-coded Doppler ultrasound during intraportal application of 2.5 x 10(7) MAA particles, 2.5 x 10(7) isolated hepatocytes, and saline solution without particles or cells. 99mTc-MAA particles (2.5 x 10(7)) or equivalent MAA/Hc mixtures were completely retained in the liver. With additional application of 2.5 x 10(7) particles, shunting into the lung was observed in two animals of the MAA group. All animals in the hepatocyte group have received 5 x 10(7) MAA/Hc mixtures, and three of these received 10(8) mixtures without shunting. Maximum velocity and volume flow increased with saline infusion. Hepatocyte suspended in the same volume blunted the increase observed in the control group, but parameters remained normal. Liver enzymes increased after hepatocyte application but returned to normal values within 5 days. Sinusoidal uptake capacity for hepatocyte or MAA particles varies at a wide range in normal rabbits. Scintigraphic monitoring of transplanted cells allows efficient monitoring of cell translocation into the lungs. No significant impairments of portal hemodynamics and liver function were detected.