Blood coagulation equilibrium in rat liver microcirculation as evaluated by endothelial cell thrombomodulin and macrophage tissue factor

Clinical practice guidelines for management of disseminated intravascular coagulation in Japan 2024: part 4-trauma, burn, obstetrics, acute pancreatitis/liver failure, and others

Disseminated intravascular coagulation (DIC) is a complex condition with diverse etiologies. While its association with sepsis has been widely studied, less focus has been given to DIC arising from other critical conditions, such as trauma, burns, acute pancreatitis, and obstetric complications. The 2024 Clinical Practice Guidelines, developed by the Japanese Society on Thrombosis and Hemostasis (JSTH), aim to fill this gap and offer comprehensive recommendations for managing DIC across various conditions. This study, Part 4 of the guideline series, addresses DIC management in trauma, burns, obstetric complications, acute pancreatitis/liver failure, viral infections, and autoimmune diseases. For trauma-associated DIC, early administration of fresh-frozen plasma (FFP), coagulation factor concentrates such as fibrinogen and prothrombin complex concentrates, and tranexamic acid is recommended. The guidelines also highlight DIC in obstetrics, which is associated with massive bleeding, and recommend the administration of fibrinogen concentrate, antithrombin concentrate, and tranexamic acid. Through a systematic review of the current evidence, the guidelines provide stratified recommendations aimed at improving clinical outcomes in DIC management beyond sepsis, thereby serving as a valuable resource for healthcare providers globally.

Advances in Understanding Lipopolysaccharide-Mediated Hepatitis: Mechanisms and Pathological Features

Lipopolysaccharide (LPS), a key component of Gram-negative bacterial membranes, plays a central role in the pathogenesis of inflammatory liver diseases. In this review, we aimed to explore the role of LPS in hepatic injury. Upon hepatic infiltration, LPS activates Kupffer cells via toll-like receptor 4 (TLR4) signaling, inducing proinflammatory cytokines such as tumor necrosis factor-α and interleukin-1β. These mediators amplify hepatocyte apoptosis, endothelial damage, and platelet aggregation, thereby contributing to sinusoidal thrombosis and tissue ischemia. Pathological features, such as hepatocyte shrinkage, sinusoidal expansion, and fibrin deposition, are hallmark indicators of LPS-induced hepatic inflammation. Therapeutically, aspirin shows promise for attenuating cytokine release, protecting endothelial integrity, and reducing thrombogenesis. Emerging strategies include targeting TLR4 pathways, modulating the gut-liver axis, and utilizing biomolecular approaches such as RNA interference for LPS suppression. The integration of public health interventions, such as dietary optimization and microbiome regulation, offers additional preventive measures. In this review, the dual roles of LPS in inflammation and thrombosis have been emphasized. Advancing our understanding of LPS-driven mechanisms and enhancing treatment strategies are pivotal for managing hepatic inflammation and its systemic implications. Future research should focus on refining biomarkers, optimizing therapeutic efficacy, and addressing safety concerns for clinical applications.

Loss of RAR-α and RXR-α and enhanced caspase-3-dependent apoptosis in N-acetyl-p-aminophenol-induced liver injury in mice is tissue factor dependent

Tissue factor (TF) activates the coagulation system and has an important role in the pathogenesis of various diseases. Our previous study stated that retinoid receptors (RAR-α and RXR-α) are released as a lipid droplet in monocrotaline/ lipopolysaccharide-induced idiosyncratic liver toxicity in mice. Herein, the interdependence between the release of retinoid receptors RAR-α and RXR-α and TF in Nacetyl-p-aminophenol (APAP)-induced mice liver toxicity, is investigated. Serum alanine transaminase (ALT) level, platelet and white blood cells (WBCs) counts, protein expression of fibrin, TF, cyclin D1 and cleaved caspase-3 in liver tissues are analyzed. In addition, histopathological evaluation and survival study are also performed. The results indicate that using of TF-antisense (TF-AS) deoxyoligonucleotide (ODN) injection (6 mg/kg), to block TF protein synthesis, significantly restores the elevated level of ALT and WBCs and corrects thrombocytopenia in mice injected with APAP. TF-AS prevents the peri-central overexpression of liver TF, fibrin, cyclin D1 and cleaved caspase- 3. The release of RXR-α and RAR-α droplets, in APAP treated sections, is inhibited upon treatment with TF-AS. In conclusion, the above findings designate that the released RXR-α and RAR-α in APAP liver toxicity is TF dependent. Additionally, the enhancement of cyclin D1 to caspase-3-dependent apoptosis can be prevented by blocking of TF protein synthesis.

Antisense Tissue Factor Oligodeoxynucleotides Protected Diethyl Nitrosamine/Carbon Tetrachloride-Induced Liver Fibrosis Through Toll Like Receptor4-Tissue Factor-Protease Activated Receptor1 Pathway

Tissue factor (TF) is a blood coagulation factor that has several roles in many non-coagulant pathways involved in different pathological conditions such as angiogenesis, inflammation and fibrogenesis. Coagulation and inflammation are crosslinked with liver fibrosis where protease-activated receptor1 (PAR1) and toll-like receptor4 (TLR4) play a key role. Antisense oligodeoxynucleotides are strong modulators of gene expression. In the present study, antisense TF oligodeoxynucleotides (TFAS) was evaluated in treating liver fibrosis via suppression of TF gene expression. Liver fibrosis was induced in rats by a single administration of N-diethyl nitrosamine (DEN, 200 mg/kg; i. p.) followed by carbon tetrachloride (CCl4, 3 ml/kg; s. c.) once weekly for 6 weeks. Following fibrosis induction, liver TF expression was significantly upregulated along with liver enzymes activities and liver histopathological deterioration. Alpha smooth muscle actin (α-SMA) and transforming growth factor-1beta (TGF-1β) expression, tumor necrosis factor-alpha (TNF-α) and hydroxyproline content and collagen deposition were significantly elevated in the liver. Blocking of TF expression by TFAS injection (2.8 mg/kg; s. c.) once weekly for 6 weeks significantly restored liver enzymes activities and improved histopathological features along with decreasing the elevated α-SMA, TGF-1β, TNF-α, hydroxyproline and collagen. Moreover, TFAS decreased the expression of both PAR1 and TLR4 that were induced by liver fibrosis. In conclusion, we reported that blockage of TF expression by TFAS improved inflammatory and fibrotic changes associated with CCl4+DEN intoxication. In addition, we explored the potential crosslink between the TF, PAR1 and TLR4 in liver fibrogenesis. These findings offer a platform on which recovery from liver fibrosis could be mediated through targeting TF expression.

Silencing of tissue factor by antisense deoxyoligonucleotide mitigates thioacetamide-induced liver injury

BACKGROUND

Retinoid receptors (RRs), RAR-α and RXR-α, work as transcription factors that regulate cell growth, differentiation, survival, and death. Hepatic stellate cells (HSCs) store retinoid and release its RRs as lipid droplets upon their activation.

PURPOSE

We test the hypothesis that loss of retinoid receptors RAR-α and RXR-α from HSCs is dependent on tissue factor (TF) during thioacetamide (TAA)-induced liver injury.

METHODS

Liver toxicity markers, TF, fibrin, cleaved caspase-3, and cyclin D1 as well as histopathology were investigated.

RESULTS

Increased TF, fibrin, cleaved caspase-3, and cyclin D1 protein expression is seen in zone of central vein after TAA injection compared with vehicle-treated mice. A strong downregulation of RAR-α and RXR-α is seen in TAA-induced liver injury. In addition, histopathological obliteration and pericentral expression of cleaved caspase 3 and cyclin D1 are observed after TAA injection compared with the normal vehicle-treated mice. No changes have been seen in TAA/TF-sense (SC) in whole parameters compared with TAA-treated animals. TAA/TF-antisense (AS)-treated mice show normal expression of all parameters and normal histopathological features when compared with the control mice. In conclusion, this study declares that the strong downregulation of RAR-α and RXR-α may cause liver injury and particularly activation of HSCs in TAA-induced toxicity. TF-AS treatment not only downregulates TF protein expression but also alleviates loss of liver RAR-α and RXR-α and suppresses the activated apoptosis signals in TAA-induced liver toxicity. Finally, TF and RAR-α/RXR-α are important regulatory molecules in TAA induced acute liver injury.

Absence of functional compensation between coagulation factor VIII and plasminogen in double-knockout mice

Plasminogen deficiency is associated with severely compromised fibrinolysis and extravascular deposition of fibrin. In contrast, coagulation factor VIII (FVIII) deficiency leads to prolonged and excessive bleeding. Based on opposing biological functions of plasminogen and FVIII deficiencies, we hypothesized that genetic elimination of FVIII would alleviate the systemic formation of fibrin deposits associated with plasminogen deficiency and, in turn, elimination of plasminogen would limit bleeding symptoms associated with FVIII deficiency. Mice with single and combined deficiencies of FVIII (F8^-/-) and plasminogen (Plg^-/-) were evaluated for phenotypic characteristics of plasminogen deficiency, including wasting disease, shortened lifespan, rectal prolapse, and multiorgan fibrin deposition. Conversely, to specifically examine the role of plasmin-mediated fibrinolysis on bleeding caused by FVIII deficiency, F8^-/- and F8^-/-/Plg^-/- mice were subjected to a bleeding challenge. Mice with a combined deficiency in FVIII and plasminogen displayed no phenotypic differences relative to mice with single FVIII or plasminogen deficiency. Plg^-/- and F8^-/-/Plg^-/- mice exhibited the same penetrance and severity of wasting disease, rectal prolapse, extravascular fibrin deposits, and reduced viability. Furthermore, following a tail vein-bleeding challenge, no significant differences in bleeding times or total blood loss could be detected between F8^-/- and F8^-/-/Plg^-/- mice. Moreover, F8^-/- and F8^-/-/Plg^-/- mice responded similarly to recombinant FVIII (rFVIII) therapy. In summary, the pathological phenotype of Plg^-/- mice developed independently of FVIII-dependent coagulation, and elimination of plasmin-driven fibrinolysis did not play a significant role in a nonmucosal bleeding model in hemophilia A mice.

Sphingosine 1-phosphate has anti-apoptotic effect on liver sinusoidal endothelial cells and proliferative effect on hepatocytes in a paracrine manner in human

AIM

Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid metabolite released from erythrocytes and platelets, and is a potent stimulus for endothelial cell proliferation. However, the role of S1P on human liver sinusoidal endothelial cells (LSEC) remains unclear. The proliferation and inhibition of apoptosis in LSEC are involved in the promotion of liver regeneration and the suppression of liver injury after liver resection and transplantation. The aim of this study is to investigate the role of S1P on human LSEC and the interaction between S1P and LSEC in hepatocyte proliferation in vitro.

METHODS

Immortalized human LSEC were used. LSEC were cultured with S1P, and the cell proliferation, anti-apoptosis, signal transductions and production of cytokines and growth factors were subsequently examined. To investigate the interaction between S1P and LSEC in hepatocyte proliferation, primary human hepatocytes were cultured with the supernatants of LSEC with and without S1P. DNA synthesis and signal transductions in hepatocytes were examined.

RESULTS

S1P induced LSEC proliferation through activation of Akt and extracellular signal-related kinase pathways and suppressed LSEC apoptosis by affecting the expression levels of Bcl-2, Bax and cleaved caspase-3. S1P promoted interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) production in LSEC. The supernatants of LSEC cultured with S1P enhanced hepatocyte DNA synthesis more strongly than the supernatants of LSEC cultured without S1P through activation of the signal transducer and activator of transcription-3 pathway.

CONCLUSION

S1P has proliferative and anti-apoptotic effects and promotes the production of IL-6 and VEGF in human LSEC, thereby promoting hepatocyte proliferation.

Effective control of relapsing disseminated intravascular coagulation in a patient with decompensated liver cirrhosis by recombinant soluble thrombomodulin

A 70-year-old Japanese man was hospitalized for expanding purpura and chronic disseminated intravascular coagulation (DIC) caused by decompensated liver cirrhosis. As there are no effective treatments for chronic DIC caused by liver cirrhosis, we decided to administer recombinant human soluble thrombomodulin (rhsTM) after he provided informed consent. The DIC was rapidly improved; however, the purpura and coagulopathy recurred after two months, and repeated rhsTM treatments were required. The rhsTM treatment sufficiently controlled the coagulopathy for two years, without any complications, including bleeding. This is the first report demonstrating that rhsTM can be administered safely and repeatedly to a patient with decompensated liver cirrhosis, and that it appears to be associated with a favorable outcome.

Antithrombin III injection via the portal vein suppresses liver damage

AIM: To investigate the effects of antithrombin III (AT III) injection via the portal vein in acute liver failure.

METHODS: Thirty rats were intraperitoneally challenged with lipopolysaccharide (LPS) and D-galactosamine (GalN) and divided into three groups: a control group; a group injected with AT III via the tail vein; and a group injected with AT III via the portal vein. AT III (50 U/kg body weight) was administrated 1 h after challenge with LPS and GalN. Serum levels of inflammatory cytokines and fibrin degradation products, hepatic fibrin deposition, and hepatic mRNA expression of hypoxia-related genes were analyzed.

RESULTS: Serum levels of alanine aminotransferase, tumor necrosis factor-α and interleukin-6 decreased significantly following portal vein AT III injection compared with tail vein injection, and control rats. Portal vein AT III injection reduced liver cell destruction and decreased hepatic fibrin deposition. This treatment also significantly reduced hepatic mRNA expression of lactate dehydrogenase and heme oxygenase-1.

CONCLUSION: A clinically acceptable dose of AT III injection into the portal vein suppressed liver damage, probably through its enhanced anticoagulant and anti-inflammatory activities.

Tissue factor antisense deoxyoligonucleotide prevents monocrotaline/LPS hepatotoxicity in mice

Tissue factor (TF) is a membranous glycoprotein that functions as a receptor for coagulation factor VII/VIIa and activates the coagulation system when blood vessels or tissues are damaged. TF was upregulated in our monocrotaline (MCT)/lipopolysaccharide (LPS) hepatotoxicity model. We tested the hypothesis that TF-dependent fibrin deposition and lipid peroxidation in the form of oxidized low-density-lipoprotein (ox-LDL) accumulation contribute to liver inflammation induced by MCT/LPS in mice. In the present study, we blocked TF using antisense oligodeoxynucleotides against mouse TF (TF-ASO). TF-ASO (5.6 mg kg(-1) ) was given i.v. to ND4 male mice 30 min after administration of MCT (200 mg kg(-1) ) p.o. followed after 3.5 h by LPS i.p. (6 mg kg(-1) ). Blood alanine aminotransferase (ALT), TF, ox-LDL, platelets, hematocrit and keratinocyte-derived chemokine (KC) levels were evaluated in different treatment groups. Fibrin deposition and ox-LDL accumulation were also analyzed in the liver sections using immunofluorescent staining. The results showed that TF-ASO significantly restored blood ALT, hematocrit and KC levels, distorted after MCT/LPS co-treatment, as well as preventing the accumulation of ox-LDL and the deposition of fibrin in the liver tissues, and thereby inhibited liver injury caused by MCT/LPS. In a separate experiment, TF-ASO administration significantly prolonged animal survival. The current study demonstrates that TF is associated with MCT/LPS-induced liver injury. Administration of TF-ASO successfully prevented this type of liver injury.

Roles of vascular endothelial growth factor and endothelial nitric oxide synthase during revascularization and regeneration after partial hepatectomy in a rat model

PURPOSE

Angiogenesis is an essential process in liver regeneration. Nitric oxide (NO) and vascular endothelial growth factor (VEGF) are the main regulators of normal and pathological angiogenesis. This study aimed to determine the roles of NO derived from endothelial nitric oxide synthase (eNOS) and VEGF in sinusoidal endothelial cell (SEC) proliferation during liver regeneration.

METHODS

Sprague-Dawley rats underwent a 70% partial hepatectomy (PHx), and were euthanized 0, 24, 48, 72, or 168 h later. Liver regeneration and SEC proliferation were evaluated. The protein expression of VEGF and eNOS was examined by a Western blot analysis. The rats were also treated with the NO synthase inhibitor N (G)-nitro-L-arginine-methyl ester (L-NAME) to examine its effects on liver regeneration and SEC proliferation.

RESULTS

The proliferating cell nuclear antigen (PCNA) labeling index of hepatocytes was significantly increased at 24 h after PHx. The eNOS protein expression and NO production were significantly increased from 72 to 168 h. The expression of VEGF protein was significantly increased at 72 h. L-NAME significantly inhibited the increases in the liver mass and decreased the PCNA labeling index of hepatocytes at 24 h. L-NAME also inhibited the induction of VEGF protein at 72 h.

CONCLUSIONS

Endothelial NOS and VEGF coordinately regulate SEC proliferation during liver regeneration. Sinusoidal endothelial cell proliferation is necessary and is an important step in liver regeneration.

Protease-activated receptor 1 and hematopoietic cell tissue factor are required for hepatic steatosis in mice fed a Western diet

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of obesity and metabolic syndrome and contributes to increased risk of cardiovascular disease and liver-related morbidity and mortality. Indeed, obese patients with metabolic syndrome generate greater amounts of thrombin, an indication of coagulation cascade activation. However, the role of the coagulation cascade in Western diet-induced NAFLD has not been investigated. Using an established mouse model of Western diet-induced NAFLD, we tested whether the thrombin receptor protease-activated receptor 1 (PAR-1) and hematopoietic cell-derived tissue factor (TF) contribute to hepatic steatosis. In association with hepatic steatosis, plasma thrombin-antithrombin levels and hepatic fibrin deposition increased significantly in C57Bl/6J mice fed a Western diet for 3 months. PAR-1 deficiency reduced hepatic inflammation, particularly monocyte chemoattractant protein-1 expression and macrophage accumulation. In addition, PAR-1 deficiency was associated with reduced steatosis in mice fed a Western diet, including reduced liver triglyceride accumulation and CD36 expression. Similar to PAR-1 deficiency, hematopoietic cell TF deficiency was associated with reduced inflammation and reduced steatosis in livers of low-density lipoprotein receptor-deficient mice fed a Western diet. Moreover, hematopoietic cell TF deficiency reduced hepatic fibrin deposition. These studies indicate that PAR-1 and hematopoietic cell TF are required for liver inflammation and steatosis in mice fed a Western diet.

Modelo de suplementação nutricional com fatores hepatotróficos aumenta proliferação celular em fígado de ratos sadios

Foram avaliados dois protocolos de administração, em ratos sadios, de uma solução de fatores hepatotróficos (FH), composta por aminoácidos, vitaminas, sais minerais, glicose, insulina, glucagon e triiodotironina (T3). A solução foi administrada durante 10 dias, 40mg/kg/dia, i.p., em duas, grupo 2xFH (n=15), ou três doses, grupo 3xFH (n=15), diárias. Foram observados os efeitos na proliferação celular dos hepatócitos, na angiogênese e na matriz extracelular hepática, assim como as possíveis reações adversas. Os animais dos grupos 2xFH e 3xFH apresentaram aumento da massa hepática de 30,1% e 22,5%, respectivamente, em relação ao grupo-controle (CT; n=15). O índice de proliferação hepatocelular foi maior nos grupos 2xFH (1,4%) e 3xFH (1,2%) em relação ao grupo CT (0,53%), e a densitometria relativa do fator de crescimento do endotélio vascular pelo imunoblot não revelou diferença estatística entre os três grupos. Nos grupos 2xFH e 3xFH, houve redução do colágeno intersticial em relação ao grupo CT. A solução de FH estimulou o crescimento hepático e reduziu o volume de colágeno perissinusoidal. A administração em três doses diárias resultou em mortalidade de 26,7%, possivelmente pelo excessivo estresse da manipulação e pela menor adaptação fisiológica dos ratos, o que não ocorreu nos grupos 2xFH e CT. Para esse tipo de abordagem em ratos, o procedimento experimental mais apropriado, seguro, com melhor chance de adaptação dos animais e com resultados significativos é a aplicação dos FH em duas doses diárias.

Biomolecular surface engineering of pancreatic islets with thrombomodulin

Islet transplantation has emerged as a promising treatment for Type 1 diabetes, but its clinical impact remains limited by early islet destruction mediated by prothrombotic and innate inflammatory responses elicited upon transplantation. Thrombomodulin (TM) acts as an important regulator of thrombosis and inflammation through its capacity to channel the catalytic activity of thrombin towards generation of activated protein C (APC), a potent anticoagulant and anti-inflammatory agent. We herein describe a novel biomolecular strategy for re-engineering the surface of pancreatic islets with TM. A biosynthetic approach was employed to generate recombinant human TM (rTM) bearing a C-terminal azide group, which facilitated site-specific biotinylation of rTM through Staudinger ligation. Murine pancreatic islets were covalently biotinylated through targeting of cell surface amines and aldehydes and both islet viability and the surface density of streptavidin were maximized through optimization of biotinylation conditions. rTM was immobilized on islet surfaces through streptavidin-biotin interactions, resulting in a nearly threefold increase in the catalytic capacity of islets to generate APC.

Thrombomodulin improves early outcomes after intraportal islet transplantation

Primary islet nonfunction due to an instant blood mediated inflammatory reaction (IBMIR) leads to an increase in donor islet mass required to achieve euglycemia. In the presence of thrombin, thrombomodulin generates activated protein C (APC), which limits procoagulant and proinflammatory responses. In this study, we postulated that liposomal formulations of thrombomodulin (lipo-TM), due to its propensity for preferential uptake in the liver, would enhance intraportal engraftment of allogeneic islets by inhibiting the IBMIR. Diabetic C57BL/6J mice underwent intraportal transplantation with B10.BR murine islets. In the absence of treatment, conversion to euglycemia was observed among 29% of mice receiving 250 allo-islets. In contrast, a single infusion of lipo-TM led to euglycemia in 83% of recipients (p = 0.0019). Fibrin deposition (p < 0.0001), neutrophil infiltration (p < 0.0001), as well as expression TNF-alpha and IL-beta (p < 0.03) were significantly reduced. Significantly, thrombotic responses mediated by human islets in contact with human blood were also reduced by this approach. Lipo-TM improves the engraftment of allogeneic islets through a reduction in local thrombotic and inflammatory processes. As an enzyme-based pharmacotherapeutic, this strategy offers the potential for local generation of APC at the site of islet infusion, during the initial period of elevated thrombin production.

Tissue factor-dependent coagulation contributes to alpha-naphthylisothiocyanate-induced cholestatic liver injury in mice

Separation of concentrated bile acids from hepatic parenchymal cells is a key function of the bile duct epithelial cells (BDECs) that form intrahepatic bile ducts. Using coimmunostaining, we found that tissue factor (TF), the principal activator of coagulation, colocalized with cytokeratin 19, a marker of BDECs in the adult mouse liver. BDEC injury induced by xenobiotics such as alpha-naphthylisothiocyanate (ANIT) causes cholestasis, inflammation, and hepatocellular injury. We tested the hypothesis that acute ANIT-induced cholestatic hepatitis is associated with TF-dependent activation of coagulation and determined the role of TF in ANIT hepatotoxicity. Treatment of mice with ANIT (60 mg/kg) caused multifocal hepatic necrosis and significantly increased serum biomarkers of cholestasis and hepatic parenchymal cell injury. ANIT treatment also significantly increased liver TF expression and activity. ANIT-induced activation of the coagulation cascade was shown by increased plasma thrombin-antithrombin levels and significant deposition of fibrin within the necrotic foci. ANIT-induced coagulation and liver injury were reduced in low-TF mice, which express 1% of normal TF levels. The results indicate that ANIT-induced liver injury is accompanied by TF-dependent activation of the coagulation cascade and that TF contributes to the progression of injury during acute cholestatic hepatitis.

Urokinase-type plasminogen activator gene therapy in liver cirrhosis is mediated by collagens gene expression down-regulation and up-regulation of MMPs, HGF and VEGF

Human urokinase-type plasminogen activator (uPA) gene administration via an adenoviral (Ad)-vector induced cirrhosis regression and ameliorated hepatic dysfunction in a model of experimental liver cirrhosis. The administration of a single dose of 6 x 10(11) viral particles per kilogram of a clinical-grade Ad-vector was evaluated after the onset of rat liver cirrhosis via degradation of deposited collagen and a substantial decrease of alpha-sma-positive cells. Also, gene expression for pro-fibrogenic molecules (Col I, III, IV, TIMP-1 and PAI-1) was clearly down-regulated. In contrast, gene expression for collagen-degrading enzymes such as MMP-13 and MMP-2 was up-regulated. These events correlated with increased amounts of proteic free-TIMP-1, i.e. non-complexed with metalloproteinases (MMPs), indicating the presence of higher amounts of active MMPs inside the liver of cirrhotic animals treated with Ad-huPA. The harmonized and concerted expression of HGF and c-met resulted in exacerbated hepatocyte proliferation, although these events did not induce an abnormal liver growth. Angiogenesis, i.e. formation of new blood vessels, was evaluated by vascular endothelial growth factor (VEGF) expression which was notably detected to be 10 times higher during the first 6 days after Ad-huPA-treatment in cirrhotic animals as compared with controls. These events provide a clearer rationale as to how Ad-huPA-induced liver regeneration on CCl(4)-induced liver fibrosis takes place.

Hyperbaric oxygen induces vascular endothelial growth factor and reduces liver injury in regenerating rat liver after partial hepatectomy

BACKGROUND/AIMS

The aim of this study was to investigate the effect and the mechanism of hyperbaric oxygen treatment on regenerating rat liver after partial hepatectomy (PH).

METHODS

Wistar rats underwent a 70% PH, followed by treatment with hyperbaric oxygen starting 8 h after PH. The regenerated liver weight and serum parameters were compared. Proliferation of both hepatocytes and sinusoidal endothelial cell (SEC) was also monitored by evaluating the proliferating cell nuclear antigen (PCNA) labeling index. Furthermore, the hepatic adenosine triphosphate levels and vascular endothelial growth factor (VEGF) protein expression were analyzed at different times.

RESULTS

Hyperbaric oxygen treatment significantly reduced the serum alanine aminotransferase levels at 24 h, total bilirubin and total bile acid levels at 48 and 72 h, respectively. No significant differences in the hepatic adenosine triphosphate levels, the restitution of liver weight, or PCNA positive hepatocytes were observed between the two groups. The PCNA positive SEC, in contrast, was significantly increased in the hyperbaric oxygen group at 48h, furthermore, the hyperbaric oxygen treatment significantly increased the expression of VEGF protein in the regenerating liver at 24 and 48 h.

CONCLUSIONS

Hyperbaric oxygen treatment can be considered as a therapeutic modality after massive PH.

A protein C deficiency exacerbates inflammatory and hypotensive responses in mice during polymicrobial sepsis in a cecal ligation and puncture model

During the systemic inflammatory state induced by sepsis, the potential for coagulopathy exists because of up-regulation of natural procoagulants and anti-fibrinolytics, and down-regulation of natural anti-coagulants, with protein C (PC) being a critical example of the latter case. PC functions as an anti-coagulant, profibrinolytic, and anti-inflammatory agent, and, thus, its administration or deficiency may affect the course and outcome of sepsis in patients. In this study, a cecal ligation and puncture model of septic peritonitis was applied to wild-type mice and littermates with a targeted heterozygous deficiency of PC (PC(+/-)) to characterize the importance of a PC-deficiency on polymicrobial sepsis. An enhanced mortality rate was found to accompany a PC deficiency. Plasma cytokines, as well as organ-specific expression of cytokine transcripts, were elevated in PC(+/-) mice. No signs of severe disseminated intravascular coagulation (DIC) were observed in wild-type or PC(+/-) mice, as indicated by an increase in fibrinogen levels and the invariability of platelet counts after cecal ligation and puncture. Consumption of coagulation factors was similar in both genotypes and a decrease in the PC mRNA and protein levels was more prominent in PC(+/-) mice. Renal and organ muscle damage was enhanced in PC(+/-) mice, as shown by increases in plasma blood urea nitrogen, creatinine, and creatinine kinase. Hypotension and bradycardia were more enhanced in PC(+/-) mice than in wild-type mice, thus provoking a more severe septic shock response. Thus, the hemodynamic role of PC during sepsis is of critical importance to the outcome of the disease.

Dietary effect of different high-fat diet on rat liver stereology

BACKGROUND/AIMS

Dietary habits are considered to be responsible for a fatty liver. The aims of this work are to study the effects of different lipid sources on rat hepatic structure.

METHODS

Twenty 21-day-old to 18-month-old male rats were fed one of the following diets: soybean oil, canola oil, lard and egg yolk (LE), or canola oil+lard and egg yolk (CA+LE). The blood serum triglyceride samples were analyzed. The following hepatic biometry and the stereology parameters were determined: densities of volume (V(v)) and surface (S(v)), absolute volume (V) and surface (S) of the hepatocytes (h), fat globules (g), and hepatic sinusoids (s), and numerical density of the hepatocytes (N(v)[h]).

RESULTS

The largest values of V(v)[h], S(v)[h], V[h], and S[h] were found in the LE group. However, the largest values of V(v)[g], S(v)[g], and S[g] were found in the CA+LE group, and the smallest values of those parameters were found in the LE group. On the other hand, V[g] was larger in the CA+LE group. V(v)[s] and V[s] were larger in the LE group and smaller in the CA+ LE group.

CONCLUSION

Long-term administration of canola oil or soybean oil resulted in similar effects on hepatocytes, hepatic sinusoids, and fat globules. Long-term administration of lard and egg yolk attenuates hepatic fat accumulation and increases hepatic sinusoids. The administration of the canola oil and lard and egg yolk mixture increases hepatic fat accumulation, reducing the hepatic sinusoids.

Association between anatomopathologic graft disorders during reperfusion and vena cava sIL-2r in orthotopic liver transplantation

Graft ischemia-reperfusion injury during orthotopic liver transplantation (OLT) is associated with anatomic and pathologic disorders in the graft, which may cause initial dysfunction. The object of this paper was to evaluate sIL-2r as an indicator of liver damage during graft reperfusion.

MATERIAL AND METHODS

Blood samples were drawn from 20 consecutive patients who required OLT secondary to chronic end-stage insufficiency various sites (portal vein, vena cava, pulmonary artery) and during different surgical phases. Following centrifugation and storage at -70 degrees C, sIL-2r was quantitated by chemiluminescence (Immulite, EURO/DPC). In addition biopsies were graded from 0 to III according to the anatomic and pathologic findings. Base excess and ammonia were measured to evaluate the function of the new liver.

STATISTICAL ANALYSES

Parameter associations were explored using Spearman's Rho and Kendall's Tau-b methods.

RESULTS

There was a correlation between the degree of graft preservation and sIL-2R both during vena cava reperfusion (r=.0591, P=.05) and for the initial 2 hours after reperfusion (r=0.61, P=.062).

CONCLUSION

sIL-2r levels drawn from the vena cava after graft reperfusion are associated with its degree of injury.

Indications and criteria for liver transplantation for fulminant hepatic failure

Liver transplantation is the only effective treatment for potentially fatal cases of fulminant hepatic failure. However, it is very difficult to predict which cases will be fatal. The mortality may depend on alternative medical therapies. According to a nationwide survey of patients with fulminant hepatic failure presenting with encephalopathy of a coma grade greater than II within 8 weeks from the first symptoms of illness with a prothrombin time less than 40% of normal value, there were 93 patients in 311 hospitals between January and December 1998 in Japan. During this period, there were 11 patients with late-onset hepatic failure. The etiology was HAV infection in 4%, HBV infection in 44%, and nonA-nonB in 41%. Specific therapies were intensively used in all patients. The mean survival rate was 41%, with differences depending on the etiology. Six patients underwent liver transplantation, and 5 survived. In animal experiments, sinusoidal fibrin deposition caused massive liver necrosis. Activation of Kupffer cells and hepatic macrophages was a major contributing factor of this development. There were different mechanisms of such fibrin deposition. Tumor necrosis factor-alpha and superoxide anions released from hepatic macrophages after endotoxin administration destroyed endothelial cells, and then coagulopathy occurred in the sinusoids in rats given Propionibacteriom acnes, while a tissue factor from Kupffer cells played that role in rats undergoing partial hepatectomy. The prognosis of fulminant hepatic failure may depend on the etiology. The indication for liver transplantation for this disease must be carefully decided by analyzing the etiology, pathological conditions, and response to therapies in each case.

Vascular endothelial growth factor secreted by replicating hepatocytes induces sinusoidal endothelial cell proliferation during regeneration after partial hepatectomy in rats

BACKGROUND

The aim of this study was to investigate regulatory mechanisms of sinusoidal endothelial cell (SEC) proliferation after hepatectomy in rats.

METHODS

We investigated expressions of vascular endothelial cell growth factor (VEGF) and its receptors, flt-1 and KDR/flk-1, in regenerating liver after 70% hepatectomy. Proliferation of both hepatocytes and SECs was also monitored by evaluating the proliferating cell nuclear antigen (PCNA) labeling index. Furthermore, VEGF production by cultured hepatocytes isolated at different times after hepatectomy was measured in vitro.

RESULTS

The expression of VEGF mRNA was increased markedly between 48 and 72 h after hepatectomy, and thereafter decreasing gradually. The immunohistochemical staining revealed that expression of VEGF started to increase 24 h after hepatectomy, with a peak at 72 h, and the majority of the VEGF-positive cells were hepatocytes located in periportal areas. Meanwhile, expression of flt-1 and KDR/flk-1 was observed along the sinusoids even before hepatectomy, but was increased between 72 and 120 h. Furthermore, VEGF production by cultured hepatocytes isolated 72 h after hepatectomy was significantly increased. The PCNA labeling index of the SECs exhibited a delayed and slower regenerative response in comparison to the hepatocytes, reaching a peak at 72 h.

CONCLUSIONS

These data strongly suggest that VEGF secreted by proliferating hepatocytes may represent an important stimulator of SEC proliferation.

The endothelial cell protein C receptor (EPCR) functions as a primary receptor for protein C activation on endothelial cells in arteries, veins, and capillaries

Plasma protein C functions as an anticoagulant when it is converted to the active form of serine protease. Protein C activation has been found to be mediated by the endothelial cell surface thrombin/thrombomodulin (TM) complex. In addition, we recently identified the endothelial cell protein C/activated protein C receptor (EPCR) which is capable of high-affinity binding for protein C. In this study, we established monoclonal antibodies (mAbs) against EPCR including several function blocking antibodies. Immunohistochemical analysis using these mAbs demonstrated that EPCR is widely expressed in the endothelial cells of arteries, veins, and capillaries in the lung, heart, and skin. Function blocking anti-EPCR mAbs strongly inhibited protein C activation mediated by primary cultured arterial endothelial cells which express abundant EPCR. Anti-EPCR mAbs also prevent protein C activation mediated by microvascular endothelial cells. These results indicate that EPCR functions as an important regulator for the protein C pathway in various types of vessels.

Elimination of Kupffer cells and nafamostat mesilate rinse prevent reperfusion injury in liver grafts from agonal non-heart-beating donors

BACKGROUND

We hypothesized that microcirculatory disturbance was an obstacle to liver transplantation (LTx) from non-heart-beating donors (NHBDs) and that it was attributed mainly to a deterioration of sinusoidal endothelial cells (SECs) and sinusoidal narrowing. This study was designed to examine porcine orthotopic LTx using livers obtained from pretreated agonal NHBDs, and to determine whether the maintenance of the liver microcirculation would result in successful LTx from agonal NHBDs.

METHODS

Pigs were allocated to five groups: (i) control group; (ii) NM group, in which grafts were rinsed with nafamostat mesilate (NM) rinse; (iii) LD group, in which Kupffer cells in grafts were eliminated by liposome-encapsulated dichloromethylene diphosphonate (L-DMDP); (iv) LDNM group, in which grafts pretreated with L-DMDP were rinsed with NM rinse; (v) heart-beating donor (HBD) group. In all groups, but the HBD group, the livers were pretreated with FK506 and prostaglandin I2 analogue, and were preserved in University of Wisconsin solution after cardiac arrest. Thereafter orthotopic LTx was performed.

RESULTS

After reperfusion, it was histologically demonstrated that elimination of Kupffer cells prevented SECs deterioration and NM rinse prevented sinusoidal narrowing. The hepatic energy charge recovered in all groups except the control group. In the LDNM group, three of four recipients survived more than 7 days.

CONCLUSIONS

For a successful LTx from agonal NHBDs, it is important to prevent microcirculatory disturbance caused by SEC deterioration and sinusoidal narrowing after reperfusion. Combination therapy consisting in the elimination of Kupffer cells and NM rinse prevented primary graft non-function in liver grafts from agonal NHBDs.

Effect of vascular endothelial growth factor on hepatic regenerative activity following partial hepatectomy in rats

BACKGROUND/AIMS

Vascular endothelial growth factor (VEGF) is an angiogenic factor with a growth-promoting effect that is thought to be restricted to vascular endothelial cells. Its essential role during liver regeneration has yet to be determined. The aim of this study was to document the effect of exogenous VEGF administration on liver regeneration in rats undergoing submaximal hepatic resections.

METHODS

Adult male Sprague-Dawley rats (n = 4/group) undergoing 30% partial hepatectomy were administered 200 ng VEGF165 intravenously and were sacrificed at 24, 36, and 48 h postoperatively. Liver regeneration was monitored by measuring the restituted liver mass, proliferating cell nuclear antigen (PCNA) immunostaining, and hepatic PCNA protein by Western blot.

RESULTS

Changes in restituted liver mass 48 h postsurgery were more prominent, but did not differ statistically between VEGF-treated and control rats (47% vs. 29%; p<0.06). Nevertheless, PCNA immunostaining showed increased labeling index of hepatocytes, apparent at 36 and 48 h after partial hepatectomy (38% vs. 18% [p<0.041 and 42% vs. 11% [p<0.021], respectively). Hepatic PCNA proteins measured by Western blot showed a 3-fold increase in VEGF-treated rats 48 h postsurgery compared with controls (p<0.01).

CONCLUSION

Exogenous VEGF administration early after partial hepatectomy stimulates liver regeneration in rats. Whether or not VEGF165 is a direct mitogen for hepatocytes remains to be determined.

Deranged blood coagulation equilibrium as a factor of massive liver necrosis following endotoxin administration in partially hepatectomized rats

Activated Kupffer cells provoke massive liver necrosis after endotoxin stimulation through microcirculatory disturbance caused by sinusoidal fibrin deposition in rats undergoing 70% hepatectomy. In these rats, serum activities of purine nucleoside phosphorylase (PNP) and alanine transaminase (ALT) were increased at 1 and 5 hours, respectively, following endotoxin administration. When 70% resected liver was perfused with Dulbecco's modified Eagle medium (DMEM) containing heat-inactivated fetal calf serum, the increase in both enzyme activities was not affected by addition of endotoxin during perfusion, suggesting that activated Kupffer cells injured neither sinusoidal endothelial cells nor hepatocytes. The activity of tissue factor, an initiator of blood coagulation cascade, was much higher in Kupffer cells isolated from partially hepatectomized rats than in those from normal rats. In contrast, mRNA expressions of tissue factor pathway inhibitor (TFPI) as well as thrombomodulin were almost undetectable in normal and partially resected livers. When recombinant human TFPI was injected intravenously in 70% hepatectomized rats, TFPI was markedly stained on the surfaces of sinusoidal endothelial cells and microvilli of hepatocytes on immunohistochemistry. In these rats, endotoxin-induced liver injury was significantly attenuated compared with rats given no TFPI. Similar attenuation was also found in rats receiving recombinant human thrombomodulin. These results suggest that fibrin deposition developing in 70% hepatectomized rats after endotoxin administration may be caused by deranged blood coagulation in the hepatic sinusoids through increasing tissue factor activity in Kupffer cells and minimal TFPI and thrombomodulin in endothelial cells. The destruction of sinusoidal endothelial cells as well as hepatocytes may occur as a result of microcirculatory disturbance caused by such sinusoidal fibrin deposition.

Expressions of vascular endothelial growth factor in nonparenchymal as well as parenchymal cells in rat liver after necrosis

Vascular endothelial growth factor (VEGF) can induce proliferation of sinusoidal endothelial cells. Its mRNA expression was increased in proliferating rat hepatocytes in primary culture. To clarify a role of VEGF in liver after necrosis, expressions of VEGF and its receptors were measured in the liver or liver cells isolated from rats after carbon tetrachloride intoxication. Hepatic VEGF mRNA expression increased later than 24 h after the intoxication and became prominent at 168 h when liver necrosis disappeared, while hepatic mRNA expressions of its receptors increased between 24 and 72 h. VEGF mRNA expression was increased in Kupffer cells, hepatic macrophages and stellate cells isolated from rats between 24 and 72 h after the intoxication and in hepatocytes at 168 h compared to those cells from normal rats. Immunohistochemical VEGF stains were comparable to such results. Vascular endothelial cells existed abundantly in the necrotic areas, and sinusoidal endothelial cells appeared following disappearance of the necrotic areas. VEGF mRNA expression in hepatocytes isolated from 70% resected liver was increased at 12 h after the operation and became marked between 72 and 168 h. Similar increase of hepatic VEGF expression was immunohistochemically seen. In conclusion, VEGF derives from nonparenchymal as well as parenchymal cells in rat liver after necrosis. The former might contribute to vascular endothelial cell proliferation and the latter to sinusoidal endothelial cell regeneration.

Effect of FK506 on the activation state of hepatic macrophages in Propionibacterium acnes-treated rats

Activated hepatic macrophages can provoke massive liver necrosis following endotoxin stimulation through microcirculatory disturbances due to sinusoidal fibrin deposition in rats pretreated with heat-killed Propionibacterium acnes. In these rats, FK506 (tachlorinus) administered 24 h before and at the time of endotoxin injection, significantly attenuated liver injury compared with the rats given no FK506. The effect of FK506 on hepatic macrophage activation and its action sites were studied in Propionibacterium acnes-treated rats. When rats received Propionibacterium acnes intravenously, hepatic-mRNA expression of interferon-γ-inducing factor and interleukin-2 and splenic-mRNA expression of interferon-γ were significantly increased compared with normal rats. Hepatic-mRNA expression of CD14, a receptor for lipopolysaccharide and its binding protein complex, was also increased preceding the expressions of the three cytokines in the liver and spleen. FK506 administration attenuated hepatic-mRNA expression of interleukin-2 and both superoxide anions as well as tumour necrosis factor-α production by hepatic macrophages, but did not change CD14-mRNA expression in Propionibacterium acnes-treated rats. It is suggested that a cytokine network through interferon-γ-inducing factor, interferon-γ and interleukin-2 may operate during activation of hepatic macrophages in rats treated with heat-killed Propionibacterium acnes, while CD14 expression on the cells may increase independently of this network. FK506 seems to attenuate such activation by suppressing hepatic interleukin-2 expression, without affecting CD14 expression on the cells.

The mechanisms of hepatic sinusoidal endothelial cell regeneration: A possible communication system associated with vascular endothelial growth factor in liver cells

Vascular endothelial growth factor (VEGF) has been shown to induce proliferation of sinusoidal endothelial cells in primary culture. To elucidate the mechanisms of sinusoidal endothelial cell regeneration in vivo, mRNA expression of VEGF and its receptors, flt-1 and KDR/flk-1, were studied in rat livers. Northern blot analysis revealed that VEGF-mRNA was expressed in hepatocytes immediately after isolation from normal rats. In contrast, non-parenchymal cells, including sinusoidal endothelial cells, expressed VEGF receptor-mRNA. Vascular endothelial growth factor-mRNA expression in hepatocytes was decreased during primary culture, but increased following a peak of DNA synthesis, induced by addition of epidermal growth factor or hepatocyte growth factor to the culture medium at 24 h of plating. In a 70% resected rat liver, VEGF-mRNA expression increased with a peak at 72 h after the operation, and mRNA expression of VEGF receptors between 72 and 168 h. In such a liver, mitosis was maximal in hepatocytes at 36 h and in sinusoidal endothelial cells at 96 h. Also, mRNA expression of both VEGF and its receptors was significantly increased in carbon tetrachloride-intoxicated rat liver compared with normal rat liver. Vascular endothelial growth factor expression was minimal in Kupffer cells isolated from normal rats, but marked in activated Kupffer cells and hepatic macrophages from the intoxicated rats. Vascular endothelial growth factor-mRNA expression was also increased in activated stellate cells from these rats and in the cells activated during primary culture compared with quiescent cells. We conclude that increased levels of VEGF expression in regenerating hepatocytes may contribute to the proliferation of sinusoidal endothelial cells in partially resected rat liver, probably through VEGF receptors up-regulated on the cells. Also, VEGF derived from activated Kupffer cells, hepatic macrophages and stellate cells may be involved in this proliferation in injured rat liver.

Contribution of CD14 to endotoxin-induced liver injury may depend on types of macrophage activation in rats

Activated Kupffer cells and hepatic macrophages can produce massive liver necrosis through microcirculatory disturbance due to sinusoidal fibrin deposition. This mechanism is involved in the development of liver injury after endotoxin administration in rats pretreated with heat-killed Propionibacterium acnes (P.acnes) or undergoing 70% liver resection. The significance of CD14, a receptor for lipopolysaccharide and its binding protein, was evaluated in both models in relation to the activation mechanisms of Kupffer cells and hepatic macrophages. Northern blot analysis revealed that CD14 mRNA expression was increased in the liver of rats following P.acnes administration. In these rats, hepatic macrophages immediately after isolation showed marked increased of CD14 mRNA expression compared to Kupffer cells from normal rats. In contrast, CD14 mRNA expression was minimal in partially resected liver. Interleukin (IL)-18 and IL-2 mRNA expression in the liver and interferon (IFN)-gamma mRNA expression in the spleen were significantly increased in P.acnes-treated rats compared to normal rats, while these increases were absent in partially hepatectomized rats. Thus, CD14 expressed on hepatic macrophages after activation through a cytokine network of IL-18, IFN-gamma, and IL-2 may contribute to endotoxin-induced liver injury in P.acnes-treated rats. In contrast, in partially hepatectomized rats, this network may not operate during Kupffer cell activation, and the liver injury might develop through endotoxin receptors other than CD14 on the cells.

Selective bowel decontamination of recipients for prevention against liver injury following orthotopic liver transplantation: evaluation with rat models

Gut-derived substances can activate Kupffer cells to provoke hepatic necrosis after partial hepatectomy in rats. A similar situation may occur during orthotopic liver transplantation (OLT), as congestion in the intestinal wall, caused by portal vein occlusion, is inevitable during the operation. The contribution of such substances to liver injury following OLT was investigated in rats. Oral administration of polymyxin B sulfate for 7 days significantly altered intestinal bacterial flora in rats; Enterobacteriaceae diminished and anaerobes such as Bifidobacterium , Lactobacillus, Bacteroides, and Eubacterium increased in number, compared with the control rats. Also, this treatment significantly reduced endotoxin concentration in the portal blood 30 minutes after blood reflow following portal vein occlusion. When OLT was performed in rats using the liver preserved in cold University of Wisconsin solution for 18 hours, tissue factor activity in Kupffer cells (KC) isolated from the transplanted liver 1 hour after the operation was significantly higher than in that of normal rats. This increase was significantly reduced by pretreatment of the recipients with polymyxin B sulfate. In these recipients, serum alanine aminotransferase activity, tumor necrosis factor alpha (TNF alpha) concentration, and histological extent of liver necrosis were significantly attenuated at 24 hours after the operation compared with those of control rats. We conclude that the substances derived from bacilli sensitive to polymyxin B sulfate in the gut may be a contributing factor to liver injury following OLT in rats; we feel that this probably occurs by entering of the substances into the portal blood during the ahepatic phase of the operation to activate KC. Selective bowel decontamination of recipients with polymyxin B sulfate would be a candidate for protection against early graft failure following OLT.

Recombinant human tissue factor pathway inhibitor as a possible anticoagulant targeting hepatic sinusoidal walls

The expression of tissue factor pathway inhibitor (TFPI) was investigated in sinusoidal endothelial cells in the liver and endothelial cells in the lung. Northern blot analysis revealed that TFPI mRNA was expressed in the lung, but minimal in the liver. Also, immunohistochemical examination showed that TFPI was not expressed on the sinusoidal endothelial cells in contrast to marked expression on endothelial cells in the lung, suggesting that anticoagulant activity to inhibit blood coagulation induced by tissue factor is reduced in the hepatic sinusoids compared to the microvessels of other organs. When recombinant human TFPI was intravenously injected in rats, it disappeared rapidly from the circulation, but was detected by electron microscopy on the surface of sinusoidal endothelial cells and microvilli of hepatocytes in the space of Disse. In these rats, the TFPI reappeared in the circulation following an intravenous injection of heparin sodium with reduced immunohistochemical staining of the TFPI on hepatic sinusoidal walls. It is concluded that exogenous TFPI can increase anticoagulant activity on the hepatic sinusoidal walls by binding to heparinoids on the cell surface. It may act effectively even in the hepatic sinusoids with damaged endothelial cells.

Blood coagulation in the hepatic sinusoids as a contributing factor in liver injury following orthotopic liver transplantation in the rat

Blood coagulation equilibrium in the hepatic sinusoids may be deranged after orthotopic liver transplantation, since tissue factor activity increases in Kupffer cells and thrombomodulin expression disappears in sinusoidal endothelial cells in orthotopically transplanted rat liver. The presence of sinusoidal blood coagulopathy and its contribution to the development of early graft failure following orthotopic liver transplantation were investigated in rats. Orthotopic liver transplantation was performed using livers preserved in cold UW solution, according to the method of Kamada, in rats. Abnormalities in the hepatic sinusoids were evaluated electron-microscopically. Anticoagulation therapy was done using antithrombin III concentrate infused immediately and 12 hr after operation. Fibrin deposition and endothelial cell destruction in the hepatic sinusoids were observed in transplanted rats 5 hr after operation. In these rats, plasma antithrombin III activity was decreased to less than 40%o of normal levels, and massive hepatic necrosis developed with increased plasma thrombin-antithrombin III complex concentration 24 hr after operation. Anticoagulation therapy significantly attenuated the extent of hepatic necrosis, with normalization of plasma antithrombin III activity and further increase in plasma thrombin-antithrombin III complex concentration. A hypercoagulative state exists after orthotopic liver transplantation in rats. Fibrin deposition in the hepatic sinusoids associated with this state may contribute to the development of early graft injury.