Kazuyuki Mizunuma

Prevention of ischemia-reperfusion-induced hepatic microcirculatory disruption by inhibiting stellate cell contraction using rock inhibitor.

Background. We demonstrated that hepatic stellate cells (HSCs) isolated from rat livers exposed to warm ischemia are significantly contractile when compared with HSCs from intact rat livers. This suggests that ischemia-reperfusion (IR)-induced impairment of sinusoidal microcirculation results, at least in part, from contraction of HSCs. Methods. Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK) is one of the key regulators of HSCs motility. Therefore we investigated whether Y-27632, a p160ROCK-specific inhibitor, has beneficial effects on warm IR injury in an in vivo rat partial liver IR model and a rat orthotopic liver transplantation model. Results. After reperfusion following 90 min of warm ischemia, livers in untreated control rats had persistent congestion and impaired mitochondrial respiration, as demonstrated by increasing deoxy-hemoglobin and reduced cytochrome oxidase contents in the hepatic tissues using in vivo near-infrared spectroscopy. Serum levels of transaminase and endothelin (ET)-1 in these rats were markedly increased 1 hr after reperfusion. In contrast, when Y-27632 (3–30 mg/kg) was administered orally, hepatic tissue contents of deoxy-hemoglobin and cytochrome oxidase rapidly normalized. In such animals, the elevation of serum transaminase levels, but not that of ET-1 levels, was significantly suppressed. This is consistent with in vitro data demonstrating that Y-27632 causes HSCs to undergo relaxation even in the presence of ET-1. Moreover, in a rat orthotopic liver transplantation model, Y-27632 pretreatment dramatically improved the survival of recipients with liver grafts subjected to 45 min of warm ischemia. Conclusions. Y-27632 attenuates IR-induced hepatic microcirculation disruption by inhibiting contraction of HSCs.

Hepatocyte growth factor prevents chronic allograft dysfunction in liver-transplanted rats.

Background. Hepatocyte growth factor (HGF) is a growth factor with multiple biologic properties, including mitogenic, morphogenic, anti-apoptotic, and antifibrogenic activities. Long-term administration of the deletion variant of HGF (dHGF) might contribute to the prevention of chronic liver allograft dysfunction, which is attributed to immunologic and nonimmunologic reactions. Methods. Low-dose tacrolimus was administered to rat-liver recipients after transplantation. Effects of dHGF on transplanted livers treated with low-dose tacrolimus were investigated. Results. Rats receiving liver transplants treated with only low-dose tacrolimus administration showed chronic allograft dysfunction. Treatment with dHGF prolonged the survival time of rats that received liver allografts and suppressed fibrosis of liver allograft. Treatment with dHGF also suppressed the expression levels of interleukin (IL)-1&bgr;, caspase-1, and transforming growth factor (TGF)-&bgr; mRNAs in liver allografts. Conclusions. The findings indicate that dHGF may prevent chronic liver-allograft dysfunction and thus may become a novel treatment for chronic liver-allograft dysfunction.

Intraoperative near-infrared spectroscopy for evaluating hepatic venous outflow in living-donor right lobe liver

Background. This study was performed to determine the usefulness of intraoperative near-infrared spectroscopy (NIRS) for evaluating the extent of congestion in the anterior segment of the graft after living-donor liver transplantation using right lobe grafts that do not have the middle hepatic vein. Methods. Fifteen patients undergoing living-donor liver transplantation using a right lobe graft without the middle hepatic vein were enrolled in this study. During the course of harvesting and implantation, in vivo NIRS was performed on the liver grafts to determine hemoglobin (Hb) and cytochrome oxidase content in the hepatic tissues. Results. The 15 cases were divided into three groups according to the caliber of the middle hepatic vein tributaries in the right lobe grafts: the small group (<4 mm), the intermediate group (4–7 mm), and the large group (>7 mm). After implantation, congestion (increase in tissue Hb) in the anterior segment was more severe than that in the posterior segment in the intermediate and large groups. However, well-preserved mitochondrial cytochrome oxidase redox state was observed in both segments except for two cases in the large group with severe congestion in the anterior segment. The extent of postoperative congestion in the anterior segment was significantly correlated with the tissue content of remaining Hb in that segment after ex vivo flushing. Conclusions. Intraoperative NIRS enables quantification of the extent of congestion in the anterior segment after implantation of a right lobe liver graft and even enables prediction of such congestion at the phase of ex vivo perfusion.

Differential diagnosis between graft-versus-host disease and hemophagocytic syndrome after living-related liver transplantation by mixed lymphocyte reaction assay.

Graft-versus-host disease (GVHD) after liver transplantation is uncommon but is a serious complication that can be fatal. Hemophagocytic syndrome (HPS), which is caused by activation of autologous T lymphocytes, is also a serious complication that can occur after liver transplantation. Because these complications share the clinical triad of skin rash, marrow failure, and diarrhea, differential diagnosis is difficult. We describe a case of severe GVHD resembling HPS in clinical features that occurred after living-related liver transplantation. The patient who had undergone the transplantation had high fever, pancytopenia, and skin rash 3 wk after the operation. Examination of a bone-marrow biopsy sample revealed the presence of abundant monocytes with phagocytosis, suggesting either GVHD or HPS. Donor human leukocyte antigens were detected in the peripheral blood of the patient by polymerase chain reaction, but this finding is not specific for GVHD. A definitive diagnosis was made by demonstration of remarkable anti-self response and undetectable anti-donor response in a mixed lymphocyte reaction assay using carboxyfluorescein diacetate succinimidyl ester.

Beneficial effects of a Rho-associated coiled-coli forming protein serine/threonine kinase inhibitor, Y-27632, on survival of recipients in rat liver transplantation following warm ischemia.

LIVER transplantation, an established therapy for endstage liver diseases, is complicated in some cases by primary nonfunction due at least in some instances to ischemia-reperfusion injury. Hepatic stellate cells (HSCs) are readily activated by ischemia-reperfusion, and their contraction can result in impaired hepatic microcirculation. Recent studies have shown that Rho-associated coiled-coli forming protein serine/threonine kinase (ROCK) is one of the key regulators of the HSCs, motility, administration of Y-27632, a p160ROCK/Rho-kinase inhibitor, has been shown to suppress the activation of HSCs. The present study was undertaken to determine whether pre-administration of Y-27632 mitigates warm ischemia-reperfusion injury in liver transplantation.