Sinusoidal Endothelial Cell Injury Research Articles

Correlation between nitric oxide production and preservation injury of sinusoidal endothelial cells during cold ischemia

Correlation between nitric oxide production and preservation injury of sinusoidal endothelial cells during cold ischemia

No attenuation of ischemic and reperfusion injury in Kupffer cell-depleted, cold-preserved rat livers.

Activated Kupffer cells (KC) have been implicated in the damage sustained by preserved liver grafts during ischemia and reperfusion. The aim of this study was to compare ischemia/reperfusion injury in preserved, KC-depleted rat livers and preserved control livers, with special regard to sinusoidal endothelial cell (SEC) injury. Wistar rats were injected with liposome-encapsulated dichloromethylene diphosphonate, 48 hr before hepatectomy, to eliminate KC, or were withheld this pretreatment (controls). Livers were flushed with cold University of Wisconsin solution and after 0, 8, 16, or 24 hr of storage at 4 degrees C, were reperfused in a recirculation system with 200 ml of oxygenated Krebs-Henseleit solution at 37 degrees C for 90 min. Damage to SEC was measured by the uptake of hyaluronic acid (HA) from the perfusate and release of purine nucleoside phosphorylase (PNP). Perfusate samples were, furthermore, analyzed for aspartate aminotransferase (AST) and tumor necrosis factor-alpha. Carbon particles were infused in the perfusate to determine the phagocytotic capacity of KC. Biopsies were taken for histological examination and sections were stained with ED2 monoclonal antibodies to confirm the absence of KC. After 90 min of reperfusion, immediately after cold flush (t0), the uptake of HA was 72.2+/-2.3% and 69.3+/-1.3% in KC-depleted livers and in control livers, respectively (n.s.). After 8 hr of storage, HA uptake was 21.6+/-4.5% and 34.6+/-8.0%, respectively (n.s.). After 16 and 24 hr of storage and reperfusion, no uptake of HA was found in either KC-depleted or control livers, indicating abolished SEC function. PNP activities in the perfusate were higher in control livers (after 8 and 24 hr of storage), presumably due to release from damaged KC. No difference was found in AST and no tumor necrosis factor-alpha was measured in the perfusates of normal and KC-depleted livers. Electron microscopic studies showed that after 8 and 24 hr of storage and reperfusion, KC were activated and were able to phagocytose colloidal carbon. Our conclusion was that the elimination of Kupffer cells did not result in reduction of ischemic and reperfusion damage in livers preserved up to 24 hr, as assessed in vitro by SEC uptake of HA, PNP release, and AST release.

Sinusoidal endothelial cell and parenchymal cell injury during endotoxemia and hepatic ischemia-reperfusion: protection by the 21-aminosteroid tirilazad mesylate

The early vascular injury in the liver was characterized in an experimental model of multiple organ failure (MOF). Significant increases of hyaluronic acid levels (660%) and plasma alanine aminotransferase activities (1050%) were observed after 20 min hepatic ischemia followed by 4 h reperfusion and injection of 0.5 mg/kg Salmonella enteritidis endotoxin at 30 min reperfusion. Morphological evaluation of sinusoids with transmission electron microscopy indicated neutrophil and Kupffer cell activation as well as damage or loss of sinusoidal endothelial cells. Hepatocellular injury was evident from fused microvilli and blebbed plasma membranes. Treatment with the 21-aminosteroid tirilazad mesylate (U-74006F) (2 × 3 mg/kg) reduced plasma hyaluronic acid levels by 61% and plasma transaminase activities by 69% suggesting a beneficial effect on sinusoidal endothelial cell and parenchymal cell injury. This was confirmed by morphology. Our data provide morphological and functional evidence for severe injury to sinusoidal endothelium and the vascular pole of hepatocytes in this model of MOF. U-74006F significantly protected the liver against this Kupffer cell- and neutrophil-mediated injury. Thus, U-74006F may be a promising therapeutic for liver dysfunction and failure during a local or systemic inflammatory response.

Mitochondrial dysfunction during anoxia/reoxygenation injury of liver sinusoidal endothelial cells

Sinusoidal endothelial cell injury plays a pivotal role in anoxia/reoxygenation liver damage. However, the mechanisms culminating in anoxia/reoxygenation endothelial cell injury remain unclear. Our aims were to determine whether anoxia/reoxygenation injury of sinusoidal endothelial cells causes mitochondrial dysfunction. In cultured rat liver sinusoidal endothelial cells, the mitochondrial membrane potential, cytosolic free calcium and cytosolic pH were quantitated by means of fluorescent probes and multiparameter digitized video microscopy. Cell viability was measured on the basis of lactate dehydrogenase release, and ATP was quantitated with a luciferin/luciferase assay. Mitochondrial membrane potential was stable during 90 min of aerobic perfusion. After 60 and 90 min of anoxia, mitochondrial membrane potential decreased gradually to 97% +/- 6% and 79% +/- 7% of the basal value, respectively. However, mitochondrial membrane potential decreased abruptly with reoxygenation after 60 min of anoxia to 45% +/- 12% of the basal value and did not recover over 30 min of aerobic perifusion. Loss of mitochondrial membrane potential could not be attributed to changes of cytosolic free calcium, cytosolic pH, nitric oxide generation or activity of poly(ADP-ribose) polymerase.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial dysfunction during anoxia/reoxygenation injury of liver sinusoidal endothelial cells.

Sinusoidal endothelial cell injury plays a pivotal role in anoxia/reoxygenation liver damage. However, the mechanisms culminating in anoxia/reoxygenation endothelial cell injury remain unclear. Our aims were to determine whether anoxia/reoxygenation injury of sinusoidal endothelial cells causes mitochondrial dysfunction. In cultured rat liver sinusoidal endothelial cells, the mitochondrial membrane potential, cytosolic free calcium and cytosolic pH were quantitated by means of fluorescent probes and multiparameter digitized video microscopy. Cell viability was measured on the basis of lactate dehydrogenase release, and ATP was quantitated with a luciferin/luciferase assay. Mitochondrial membrane potential was stable during 90 min of aerobic perfusion. After 60 and 90 min of anoxia, mitochondrial membrane potential decreased gradually to 97% +/- 6% and 79% +/- 7% of the basal value, respectively. However, mitochondrial membrane potential decreased abruptly with reoxygenation after 60 min of anoxia to 45% +/- 12% of the basal value and did not recover over 30 min of aerobic perifusion. Loss of mitochondrial membrane potential could not be attributed to changes of cytosolic free calcium, cytosolic pH, nitric oxide generation or activity of poly(ADP-ribose) polymerase.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitochondrial dysfunction is a key event in anoxia-reoxygenation injury of sinusoidal endothelial cells: Protection by the novel antioxidant tempo

Mitochondrial dysfunction is a key event in anoxia-reoxygenation injury of sinusoidal endothelial cells: Protection by the novel antioxidant tempo

Acidosis protects against lethal oxidative injury of liver sinusoidal endothelial cells

The purposes of this study were to determine the pH dependence of lethal endothelial cell injury during oxidative stress and the pH dependence of those cellular mechanisms proposed to result in endothelial cell killing. Oxidative stress was produced in rat liver sinusoidal endothelial cells with H2O2 (5 mmol/L). Cell survival was dependent on the extracellular pH. Indeed, after 180 min of incubation with H2O2, cell survival was only 27% at pH 7.4, 45% at pH 6.8 (p less than 0.05) and 62% at pH 6.4 (p less than 0.05). Despite improved cell survival at pH 6.4 compared with pH 7.4, the magnitude of ATP hydrolysis and glutathione depletion was similar. In contrast to cell survival, lipid peroxidation as measured by malondialdehyde generation was increased twofold at pH 6.4 compared with pH 7.4. A rapid and profound loss of the mitochondrial membrane potential occurred during oxidative stress at pH 7.4 that was delayed at pH 6.4 (0.3% vs. 20% of the initial value at 30 min, p less than 0.0001). After 60 min of incubation with H2O2, NAD(P)H oxidation was greater at pH 7.4 than at pH 6.4 (100% vs. 64%, p less than 0.05). The results indicate that the protective effect of acidosis against cell death during oxidative stress is associated with the inhibition of NAD(P)H oxidation and delayed loss of the mitochondrial membrane potential. Acidosis appears to maintain organelle and cell integrity during oxidative stress by influencing the redox status of NAD(P)H.