Multislice Computed Tomographic Manifestation of Transient Hepatic Attenuation Difference in the Left Lobe of the Liver: A Retrospective Study.

INTRODUCTION: Transient hepatic attenuation differences (THAD) are areas of high parenchymal enhancement observed during the hepatic arterial phase on computed tomography (CT). THAD in the left lobe of the liver can lead to surgical complications. METHODS: A retrospective study was conducted on patients who underwent multislice computed tomography (MSCT) examination of the upper abdomen to understand the morphology, distribution, and causes of THAD and their correlation with hepatic artery variation. RESULTS: Among 179 cases, 65 and 114 belonged to diseased and normal groups, respectively. THAD as observed in MSCT demonstrated various shapes: lobe/segment (127 cases; 70.9%), irregular sheet (31; 17.3%), strip shape (9; 5.02%), arc/semicircle (7; 3.9%), and segment + flaky (5; 2.79%). THAD were found to be caused by liver tumor (32.3%), hepatic inflammatory lesions (6.15%), biliary tract diseases (13.8%), perihepatic disease compression (9.23%), portal vein obstructive disease (1.53%), and lesion in left hepatic lobe with hepatic artery variation (29.2%). THAD exhibited variation in distribution in the left lobe of the liver. Among 114 cases, THAD in 18 (15.7%) cases were observed in the S2 segment, six (5.26%) in the S3 segment, and 90 (78.9%) in multiple segments of the liver, that is, 50 cases in S2 and S3 segments and 40 cases in S2, S3, and S4 segments. The hepatic artery of 179 cases was of various types based on Hiatt classification: 57 cases of Hiatt I (31%), 65 cases of Hiatt II (37%), 11 cases of Hiatt III (6%), 17 cases of Hiatt IV (10%), 7 cases of Hiatt V (4%), 12 cases of large left hepatic artery (7%), 6 cases of right hepatic artery originating from the celiac trunk (3%), and 4 cases (2%) of superior mesenteric artery originating from the celiac trunk. CONCLUSION: THAD can occur as a result of specific pathological causes and hence should be considered as a diagnostic sign in liver pathologies.

Quantification of Hepatic Vascular and Parenchymal Regeneration in Mice.

BACKGROUND: Liver regeneration consists of cellular proliferation leading to parenchymal and vascular growth. This study complements previous studies on cellular proliferation and weight recovery by (1) quantitatively describing parenchymal and vascular regeneration, and (2) determining their relationship. Both together are needed to (3) characterize the underlying growth pattern. METHODS: Specimens were created by injecting a polymerizing contrast agent in either portal or hepatic vein in normal or regenerating livers after 70% partial hepatectomy. 3D image data were obtained through micro-CT scanning. Parenchymal growth was assessed by determining weight and volume of the regenerating liver. Vascular growth was described by manually determined circumscribed parameters (maximal vessel length and radius of right inferior portal/hepatic vein), automatically determined cumulative parameters (total edge length and total vascular volume), and parameters describing vascular density (total edge length/volume, vascular volume fraction). The growth pattern was explored by comparing the relative increase of these parameters to the increase expected in case of isotropic expansion. RESULTS: Liver volume recovery paralleled weight recovery and reached 90% of the original liver volume within 7 days. Comparing radius-related vascular parameters immediately after surgical resection and after virtual resection in-silico revealed a slight increase, possibly reflecting the effect of resection-induced portal hyperperfusion. Comparing length-related parameters between post-operative day 7 and after virtual resection showed similar vascular growth in both vascular systems investigated. In contrast, radius-related parameters increased slightly more in the portal vein. Despite the seemingly homogeneous 3D growth, the observed vascular parameters were not compatible with the hypothesis of isotropic expansion of liver parenchyma and vascular structures. CONCLUSION: We present an approach for the quantitative analysis of the vascular systems of regenerating mouse livers. We applied this technique for assessing the hepatic growth pattern. Prospectively, this approach can be used to investigate hepatic vascular regeneration under different conditions.

A pilot study of autologous CD34-depleted bone marrow mononuclear cell transplantation via the hepatic artery in five patients with liver failure.

BACKGROUND AIMS: Many rodent experiments and human studies on stem cell therapy have shown promising therapeutic approaches to liver diseases. We investigated the clinical outcomes of five patients with liver failure of various causes who received autologous CD34-depleted bone marrow-derived mononuclear cell (BM-MNC) transplantation, including mesenchymal stromal cells, through the hepatic artery. METHODS: CD34-depleted BM-MNCs were obtained from five patients waiting for liver transplantation by bone marrow aspiration and using the CliniMACS CD34 Reagent System (Miltenyi Biotech, Bergisch Gladbach, Germany), and autologous hepatic artery infusion was performed. The causes of hepatic decompensation were hepatitis B virus (HBV), hepatitis C virus (HCV), propylthiouracil-induced toxic hepatitis and Wilson disease. RESULTS: Serum albumin levels improved 1 week after transplantation from 2.8 g/dL, 2.4 g/dL, 2.7 g/dL and 1.9 g/dL to 3.3 g/dL, 3.1 g/dL, 2.8 g/dL and 2.6 g/dL. Transient liver elastography data showed some change from 65 kPa, 33 kPa, 34.8 kPa and undetectable to 46.4 kPa, 19.8 kPa, 29.1 kPa and 67.8 kPa at 4 weeks after transplantation in a patient with Wilson disease, a patient with HCV, and two patients with HBV. Ascites decreased in two patients. One of the patients with HBV underwent liver transplantation 4 months after the infusion, and the hepatic progenitor markers (cytokeratin [CD]-7, CD-8, CD-9, CD-18, CD-19, c-Kit and epithelial cell adhesion molecule [EpCAM]) were highly expressed in the explanted liver. CONCLUSIONS: Serum albumin levels, liver stiffness, liver volume, subjective healthiness and quality of life improved in the study patients. Although these findings were observed in a small population, the results may suggest a promising future for autologous CD34-depleted BM-MNC transplantation as a bridge to liver transplantation in patients with liver failure.

Evaluation of melphalan, oxaliplatin, and paclitaxel in colon, liver, and gastric cancer cell lines in a short-term exposure model of chemosaturation therapy by percutaneous hepatic perfusion.

BACKGROUND: The goal of this study was to determine whether liver, gastric, or colonic cancer may be suitable targets for chemosaturation therapy with percutaneous hepatic perfusion (CS-PHP) and to assess the feasibility of utilizing other cytotoxic agents besides melphalan in the CS-PHP system. MATERIALS AND METHODS: Forty human cell lines were screened against three cytotoxic chemotherapeutic agents. Specifically, the dose-dependent effect of melphalan, oxaliplatin, and paclitaxel on proliferation and apoptosis in each cell line was evaluated. These agents were also evaluated for their ability to induce apoptosis in normal primary human hepatocytes. A high-dose short-term drug exposure protocol was employed to simulate conditions encountered during CS-PHP. RESULTS: The average concentration of melphalan required for inducing significant apoptosis was 61 µM, or about 3-fold less than the theoretical concentration of 192 µM, achieved in the hepatic artery during CS-PHP dosing with melphalan. Additionally, we found that gastric cancer cell lines were 2-5 fold more sensitive to apoptosis than liver cancer cell lines to all three compounds, suggesting that in addition to colonic and gastric cancer metastases to the liver, primary gastric cancer may also be amenable to management by CS-PHP using an appropriate therapeutic agent. Significantly, at concentrations that are predicted using the CS-PHP system, these agents caused apoptosis of colonic, gastric, and liver cancer cells but were not toxic to primary human hepatocytes. CONCLUSION: The compounds tested are potential candidates for use in the CS-PHP system to treat patients with gastric and colonic metastases, and primary cancer of the liver.

A light and transmission electron microscope study of hepatic portal tracts in the rhesus monkey (Macacus rhesus).

This study reports on morphological features of hepatic portal tracts in the liver of a rhesus monkey. The light microscope shows that the number of each type of principal component comprising a portal tract varies but that there are usually one to five lymphatics, one bile ductule, one bile duct, one arteriolar and one arterial branch of the hepatic artery, and one hepatic portal vein. Bile ductules, in cross section, have 6-10 cells (mostly low pyramidal, but with a few cuboidal) bordering the lumen, an outside diameter of from about 20 to 25 microm, and a luminal diameter of from 2 to 10 microm. Bile ducts, in cross section, have more than 10 cells (about equal numbers of low pyramidal and cuboidal) bordering the lumen, an outside diameter greater than 25 microm and a luminal diameter of greater than 10 microm. The term "pyramidal" has not previously been applied to the cells of the ductules and ducts. The monkey tracts show several cytological features previously undescribed, viz., abortive cilia and basal bodies in the duct cells, abortive cilia in the ductule cells, and an occasional aggregation of ribosomes in arterial endothelial cells. They also show a major histological feature previously mentioned but not illustrated, viz., bundles of nerve processes which exhibit a preferential location, i.e., proximity to the arterioles and arteries.

Epithelial expression of angiogenic growth factors modulate arterial vasculogenesis in human liver development.

UNLABELLED: Intrahepatic bile ducts maintain a close anatomical relationship with hepatic arteries. During liver ontogenesis, the development of the hepatic artery appears to be modulated by unknown signals originating from the bile duct. Given the capability of cholangiocytes to produce angiogenic growth factors and influence peribiliary vascularization, we studied the immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietin-1, angiopoietin-2, and their cognate receptors (VEGFR-1, VEGFR-2, Tie-2) in fetal human livers at different gestational ages and in mice characterized by defective biliary morphogenesis (Hnf6(-/-)). The results showed that throughout the different developmental stages, VEGF was expressed by developing bile ducts and angiopoietin-1 by hepatoblasts, whereas their cognate receptors were variably expressed by vascular cells according to the different maturational stages. Precursors of endothelial and mural cells expressed VEGFR-2 and Tie-2, respectively. In immature hepatic arteries, endothelial cells expressed VEGFR-1, whereas mural cells expressed both Tie-2 and Angiopoietin-2. In mature hepatic arteries, endothelial cells expressed Tie-2 along with VEGFR-1. In early postnatal Hnf6(-/-) mice, VEGF-expressing ductal plates failed to incorporate into the portal mesenchyma, resulting in severely altered arterial vasculogenesis. CONCLUSION: The reciprocal expression of angiogenic growth factors and receptors during development supports their involvement in the cross talk between liver epithelial cells and the portal vasculature. Cholangiocytes generate a VEGF gradient that is crucial during the migratory stage, when it determines arterial vasculogenesis in their vicinity, whereas angiopoietin-1 signaling from hepatoblasts contributes to the remodeling of the hepatic artery necessary to meet the demands of the developing epithelium.

Influence of flow and addition of oxygen during porcine liver hypothermic machine perfusion.

INTRODUCTION: In contrast with kidneys, data on hypothermic machine perfusion (HMP) of livers remain scarce. Optimal liver HMP is poorly defined. Superiority of liver HMP over simple cold storage (SCS), the current standard preservation, must be proven before HMP is applied clinically. In this study, morphology and adenosine triphosphate (ATP) contents of HMP livers at different flows and with versus without O(2) studied in a porcine ex vivo model were compared to SCS. METHODS: Pig livers were procured, flushed with HTK and preserved via SCS or HMP at 3 HMP settings: high flow (HF); low flow (LF); low flow + O(2) (300 mm Hg) (LFO). HMP livers were perfused via the hepatic artery (HA) and portal vein (PV) with KPS-1 TM at 4 degrees C to 6 degrees C for 24 hours with HF: PV: 3 to 5 mm Hg, 1 mL/g liver/min for HA and 25 mm Hg; LF: PV: 3 to 5 mm Hg, 0.5 ml/g liver/min with HA: 20 mm Hg. Morphology and ATP levels were measured in preserved liver tissues. RESULTS: Throughout the SCS preservation, livers remained intact. In HMP livers, vacuoles appeared after 4 hours of preservation in the HF group and after 12 hours in the LF livers. LFO livers remained intact with limited vacuoles. Compared to SCS, HMP livers showed dilated sinusoids, particularly in the HF group. ATP remained relatively constant or even increased during HMP, particularly in the LF group, whereas ATP decreased after SCS. CONCLUSION: Among the various HMP settings, HMP with LFO was superior. ATP levels were the highest in LF. In contrast with all HMP groups, SCS showed the lowest ATP levels, indicating that HMP has the potential to better preserve energy stores.

Morphological changes in hepatic vessels during modeling of pulmonary trunk stenosis and after its elimination.

Experiments on dogs showed that pulmonary trunk stenosis increased the tone of arterial vessels in the liver and led to the development of veno-arterial and veno-venous reactions. The number of vessels with intimal musculature and myoelastic sphincters in the arterial bed increases, and muscle rolls in large hepatic veins are thickened. The walls are hypertrophic in all vessels. Elimination of the defect abolished the previously formed vascular adaptation reactions, the tone in afferent liver vessels decreased, which leads to regression of hypertrophic changes in their tunica media. The number of arteries with intimal musculature and sphincters decreases. Muscle rolls in the efferent hepatic veins are thinned.

Cholangiocytes and blood supply.

The microvascular supply of the biliary tree, the peribiliary plexus (PBP), stems from the hepatic artery branches and flows into the hepatic sinusoids. A detailed three-dimensional study of the PBP has been performed by using the Scanning Electron Microscopy vascular corrosion casts (SEMvcc) technique. Considering that the PBP plays a fundamental role in supporting the secretory and absorptive functions of the biliary epithelium, their organization in either normalcy and pathology is explored. The normal liver shows the PBP arranged around extra- and intrahepatic biliary tree. In the small portal tract PBP was characterized by a single layer of capillaries which progressively continued with the extrahepatic PBP where it showed a more complex vascular network. After common duct ligation (BDL), progressive modifications of bile duct and PBP proliferation are observed. The PBP presents a three-dimensional network arranged around many bile ducts and appears as bundles of vessels, composed by capillaries of homogeneous diameter with a typical round mesh structure. The PBP network is easily distinguishable from the sinusoidal network which appears normal. Considering the enormous extension of the PBP during BDL, the possible role played by the Vascular Endothelial Growth Factor (VEGF) is evaluated. VEGF-A, VEGF-C and their related receptors appeared highly immunopositive in proliferating cholangiocytes of BDL rats. The administration of anti-VEGF-A or anti-VEGF-C antibodies to BDL rats as well as hepatic artery ligation induced a reduced bile duct mass. The administration of rVEGF-A to BDL hepatic artery ligated rats prevented the decrease of cholangiocyte proliferation and VEGF-A expression as compared to BDL control rats. These data suggest the role of arterial blood supply of the biliary tree in conditions of cholangiocyte proliferation, such as it occurs during chronic cholestasis. On the other hand, the role played by VEGF as a tool of cross-talk between cholangiocytes and PBP endothelial cells suggests that manipulation of VEGF release and function could represent a therapeutic strategy for human pathological conditions characterized by damage of hepatic artery or the biliary tree.

Hepatic microcirculation and cholangiocyte physiopathology.

BACKGROUND: The peribiliary plexus (PBP) plays a fundamental role in supporting the functions of the biliary epithelium. After common bile duct ligation (BDL) progressive PBP proliferation is demonstrated. We have, recently, demonstrated that the biliary epithelium express Vascular Endothelial Growth Factor (VEGF), both subtype -A and -B and VEGF receptors. Taking in consideration the wide extension of PBP during BDL, aim of our study is to investigate the role of VEGF in stimulating angiogenesis and also in the modulation of epithelial cells proliferation. MATERIAL AND METHODS: Experimental studies were performed by evaluating the effects of: a) endogenous VEGF neutralization by chronic administration of anti VEGF-C antibody on cholangiocyte proliferation in BDL rats and; b) the hepatic artery ligation (HAL) immediately after BDL followed by treatment (7 days) with a recombinant of VEGF-A (administered through IP implanted minipumps) on cholangiocyte proliferative activities. RESULTS: Both administration of antiVEGF-C antibody and HAL decreases cholangiocyte proliferation. The decrease of cholangiocyte proliferation was associated with depressed VEGF-A protein expression. The administration of rVEGF-A to BDL, hepatic artery ligated rats prevented the decrease of cholangiocyte proliferation and VEGF-A expression as compared to BDL control rats. CONCLUSION: These data suggest that VEGF-C modulates the proliferative activities of cholangiocytes in experimental cholestasis and that circulating factors (i.e., VEGF) in the blood supply of the intra-hepatic biliary epithelium, play an important role in the balance between cholangiocyte proliferation/loss.

Glucose-dependent insulinotropic peptide: differential effects on hepatic artery vs. portal vein endothelial cells.

Glucose-dependent insulinotropic peptide (GIP) has been reported to have opposing effects on splanchnic blood flow. GIP infusion in dogs results in an increase in portal vein circulation but a drop in hepatic artery blood flow. In an effort to evaluate whether these different responses were related to intrinsic differences in GIP effects, we isolated canine hepatic artery (HAEC) and portal vein endothelial cells (PVEC). We report that there are differences in GIP activation of the signal transduction pathways in these two cell types. GIP stimulates secretion of endothelin-1 (ET-1), a potent vasoconstrictor, from HAEC (EC50 0.28 nM) but not from PVEC. This effect could be abolished by preventing a rise in intracellular calcium, demonstrating the calcium dependence of GIP-induced ET-1 secretion from HAEC. The GIP effect was specific, as a GIP receptor antagonist blocked it. In contrast, GIP stimulated nitric oxide production from PVEC (EC50 0.09 nM) but not from HAEC. Taken together, our data demonstrate distinct differences in GIP effects on HAEC from those on PVEC. We conclude that differences in GIP stimulation of ET-1 vs. nitric oxide production in different vascular beds may account for some of the observed differences in its physiological effects.

Comparative morphology of the hepatic and coronary artery walls. Part III. The insignificance of medial morphologic features in the determination of an autopsied unidentified subjects age.

Since hepatic arteries are free of atherosclerosis any possible wall structure change may be attributed to age. We determined the media of hepatic and coronary arteries in view of this assumption. We measured its thickness and myocytic density (per 1 mm2 of cross-section) from specimens collected from autopsied subjects, aged up to 90 years. The media gradually thickens with age, although values noted during particular decades remain statistically insignificant. The myocytic density (in 1 mm2) was almost constant throughout life. The latter observation is incompatible, in comparison with data reported by other authors (diminution was expected).

Further investigation of endothelium-derived hyperpolarizing factor (EDHF) in rat hepatic artery: studies using 1-EBIO and ouabain.

1. The characteristics of endothelium-dependent hyperpolarization in rat hepatic artery have been further investigated in the presence of inhibitors of cyclo-oxygenase and nitric oxide synthase. 2. Using sharp micro-electrodes, the smooth muscle hyperpolarization induced by acetylcholine, KCl or 1-ethyl-2-benzimidazolinone (1-EBIO) in intact hepatic arteries was abolished by 30 micronM barium plus 500 nM ouabain. 3. In vessels without endothelium, the smooth muscle hyperpolarization induced by KCl was not reduced by 30 micronM barium alone. However, in the presence of barium the effects of KCl were partially inhibited by 100 nM ouabain and essentially abolished by 500 nM ouabain. 4. Using sharp micro-electrodes, the hyperpolarization of both the smooth muscle and the endothelium induced by 1-EBIO or by acetylcholine was unaffected by 100 nM iberiotoxin. However, in the presence of 100 nM charybdotoxin, the effects of 1-EBIO were abolished whereas those of acetylcholine were only partially reduced. The hyperpolarization induced by levcromakalim was unaffected by either charybdotoxin or iberiotoxin. 5 Under whole-cell patch-clamp recording conditions, 1-EBIO induced a voltage-insensitive, charybdotoxin-sensitive K+ current in cultured endothelial cells but was without effect on K+ currents in smooth muscle cells isolated from hepatic arteries. 6 It is concluded that the endothelium-dependent hyperpolarization of smooth muscle induced by either acetylcholine or by 1-EBIO in rat hepatic artery is initially associated with the opening of endothelial calcium-sensitive K+-channels insensitive to iberiotoxin. The resulting accumulation of K+ in the myoendothelial space activates an isoform of Na+/K+-ATPase which is sensitive to low concentrations of ouabain.

Role of nitric oxide in porcine liver circulation under normal and endotoxemic conditions.

The role of nitric oxide (NO) in the liver vasculature during baseline and endotoxic shock states was evaluated in 17 anesthetized pigs. Mean systemic arterial pressure, pulmonary arterial pressure, and portal venous pressure and flow, hepatic arterial pressure and flow, and cardiac output were measured. Pressure-flow (P-Q) relationships defined resistances as a back pressure and a slope. Inhibition of nitric oxide synthase (NOS) with NG-nitro-L-arginine methyl ester (L-NAME) at baseline increased mean arterial pressure, pulmonary arterial pressure, hepatic arterial pressure, and the slopes of their P-Q relationships (P < 0.05) but had no effect on portal venous pressure or its P-Q relationship. After endotoxin (10 micrograms/kg iv), NO induced arterial dilation and attenuated increases in portal venous and pulmonary arterial resistances (P < 0.05) that were reversed by L-NAME. NOS inhibition was stereospecifically reversed by L-arginine. Local control of liver blood flow at baseline via the hepatic arterial buffer response and hepatic arterial autoregulation were increased in gain after L-NAME. Endotoxic shock ablated the hepatic arterial buffer response and autoregulation independent of either NO or an alpha-adrenergic-receptor agonist (P < 0.05). Under baseline conditions, NO modulates pulmonary, systemic, and hepatic arterial but not portal venous resistances. NO production during endotoxic shock induces arterial hypotension and hepatic arterial vasodilation and attenuates increases in both portal and pulmonary resistances. NOS inhibition in endotoxic shock could increase morbidity due to a loss of local control of liver blood flow and marked increases in resistance to venous return across both the liver and lungs.

Smooth muscle in the hepatic artery, portal vein and hepatic vein within the liver of the raccoon and guinea pig.

The amount and arrangement of smooth muscle in the intrahepatic vessels suggests that the guinea pig would be a good animal model for studying mechanisms controlling intrahepatic portal vein blood flow, while the raccoon would be good for studying hepatic vein mechanisms of control.