Branch Of Portal Vein Research Articles

Multimodality imaging of obliterative portal venopathy: what every radiologist should know.

Obliterative portal venopathy (OPV) is an important cause of non-cirrhotic portal hypertension, which is often erroneously misdiagnosed as cryptogenic cirrhosis. It has a worldwide distribution with majority of cases hailing from the Asian subcontinent. However, recently the disease has gained global attention particularly because of its association with human immunodeficiency virus infection and use of antiretroviral drug therapy (didanosine). As the name suggests, the disorder is characterized by sclerosis and obliteration of the intrahepatic portal vein branches (with attendant periportal fibrosis) leading to portal hypertension amid intriguingly little liver dysfunction. It primarily affects young adults who present with clinically significant portal hypertension in the form of episodes of variceal bleed; however, contrasting liver cirrhosis, the liver function and liver structure remain normal or near normal until late in the disease process. Radiological findings during advanced disease are often indistinguishable from cirrhosis often warranting a liver biopsy. Nevertheless, recent studies have suggested that certain imaging manifestations, if present, can help us to prospectively suggest the possibility of OPV. At imaging, OPV is characterized by a wide range of intrahepatic and/or extrahepatic portal venous abnormalities with attendant changes in liver and splenic volume and stiffness. We shall, through this pictorial review, appraise the literature and illustrate the germane radiological manifestations of OPV that can be seen using different imaging modalities including ultrasonography, CT, MRI, elastography and hepatic haemodynamic studies.

TorCH manoeuver: Toronto caudate process hepatotomy for laparoscopic exposure and division of the right portal vein branch

Although formal laparoscopic hepatic lobectomies are performed routinely, concerns including the risk of major intra-operative haemorrhage remain regarding such an approach.1,2 Control of the inflow vasculature prior to parenchymal transection reduces intra-operative blood loss during major hepatectomy3, and extra-hepatic dissection, ligation and division of the right hepatic artery and right portal vein (RPV) is effective in reducing intra-parenchymal haemorrhage. Laparoscopic exposure and stapled division of the RPV is limited owing to the weight of the liver and the RPV anatomical position. Excessive tension or torque on the vein while positioning the stapler can result in catastrophic consequences. A major impediment to smooth introduction of the stapler is the caudate process posterior to the RPV. This report and accompanying video describe the author's approach to address these issues. Specific gallbladder retraction and division of the caudate process after hepatic mobilization is crucial (Fig. 1). The approach is summarized as a checklist in Fig. 2. This method (TorCH manoeuver) is readily teachable and can be included in curricula for continuing medical education or for fellows and established surgeons learning laparoscopic techniques. Figure 1 Completed TorCH manoeuver with a stapler around the right portal vein. Illustrated by: Laura Maaske Figure 2 Checklist summarizing the steps of the TorCH manoeuver

Clinical studies in hepatocellular carcinoma.

According to clinicaltrials.gov (a clinical trials registration site), there are currently 31 trials that are evaluating selective internal radiation therapy (SIRT) in hepatocellular carcinoma (HCC; consisting of nine completed studies, 20 ongoing studies and two studies of unknown status). These studies reflect the considerable interest in the potential application of this procedure in not only advanced HCC, but also in intermediate HCC (with studies evaluating SIRT vs transarterial chemoembolization [TACE]), early HCC as a bridge to transplantation (based on retrospective studies and a new trial from a French institution that will evaluate SIRT vs TACE) and in the neoadjuvant treatment setting (presurgery). To date, the best published evidence for SIRT comes from retrospective and prospective cohort studies and case–control studies in advanced HCC [1–4]. One of the largest retrospective clinical case series evaluated 325 patients (from 2003 to 2009) with multinodular disease (75.9%) who had been treated with SIRT at eight European centers. The median duration of survival was 12.8 months (95% CI: 10.9–15.7) with elevated bilirubin reported as the main grade 3 adverse event in 5.8% of patients [2]. As discussed by Sangro in this supplement, SIRT (using either resin or glass microspheres) is effective across the spectrum of patients with earlyto advanced-stage HCC [3,5,6], including patients with main and branch portal vein thrombosis (PVT), who generally have a poor prognosis (Figure 1) [2,7]. As a consequence, a number of prospective Phase III studies are evaluating SIRT in advanced HCC (stratifying patients with or without PVT). Some of these studies are combining SIRT plus sorafenib, while others are comparing SIRT versus sorafenib (Table 1).

Efficacy and Safety of Percutaneous Transhepatic Portal Embolization with Dehydrated Ethanol

Purpose: The efficacy and safety of percutaneous transhepatic portal embolization (PTPE) with dehydrated ethanol was determined by measuring the liver lobe volume before and after the procedure. Materials and Methods: A total of 38 patients (25 men, 13 women; mean age: 62.0 ± 10.8 years) who underwent PTPE with dehydrated ethanol between April 2005 and March 2011 participated in this study. Dehydrated ethanol containing 17% lipiodol was injected into the target portal vein branch under balloon occlusion, and the portal vein was subsequently embolized. The liver lobe volume was measured via contrast-enhanced computed tomography, and the percent increase in the unembolized lobe volume was then calculated. In addition, PTPE-related complications were surveyed, and the procedural safety was evaluated. Results: The mean percent increase in the unembolized lobe volume after PTPE was 33.8% ± 20.2%. The procedure could not be completed in one patient because of an insufficient increase in the unembolized lobe volume. No serious post- PTPE complications were observed. Conclusion: These data suggest that PTPE with dehydrated ethanol is a safe and effective method for enlarging the planned residual liver volume before extensive liver resection.

Hepatopulmonary shunting in patients with primary and secondary liver tumors scheduled for radioembolization

PurposeIn patients undergoing transarterial radioembolization (RE) of malignant liver tumors, hepatopulmonary shunts (HPS) can lead to nontarget irradiation of the lungs. This study aims at analyzing the HPS fraction in relation to liver volume, tumor volume, tumor-to-liver volume ratio, tumor vascularity, type of tumor, and portal vein occlusion. Materials and methodsIn the presented retrospective study the percentage HPS fraction was calculated from SPECT/CT after infusion of Tc-99m macroaggregated albumin (Tc-99m MAA) into the proper hepatic artery of 233 patients evaluated for RE. ResultsHPS fractions correlate very weakly with liver volume (r=0.303), tumor volume (r=0.345), and tumor-to-liver volume ratio (r=0.340). Tumors with strong contrast enhancement (HPSmedian(range)=11.7%(46.3%); n=73) have significantly larger shunt fractions than tumors with little enhancement (HPS=8.3%(16.4%); n=61; p<0.001). Colorectal cancer metastases (HPS=10.6%(28.6%); n=68) and hepatocellular cancers (HPS=11.7%(39.4%); n=63) have significantly larger HPS fractions than metastases from breast cancer (HPS=7.4%(16.7%); n=40; p=0.012 and p=0.001). Patients with compression (HPS=13.9%(43.7%); n=33) or tumor thrombosis (HPS=15.8% (31.2%); n=33) of a major portal vein branch have significantly higher degrees of shunting than patients with normal portal vein perfusion (HPS=8.1% (47.0%); n=167; both p<0.001). The shunt fraction is largest in patients with HCC and thrombosis or occlusion of a major portal vein branch (HPS=16.6% (31.0%); n=32). ConclusionThe degree of hepatopulmonary shunting depends on the type of liver tumor, tumor vascularity, and portal vein perfusion. There is little to no correlation of HPS with liver volume, tumor volume, or tumor-to-liver volume ratio.

Transarterial radioembolization using yttrium-90 microspheres in the treatment of hepatocellular carcinoma: a review on clinical utility and developments.

A selective intra-arterial liver injection using yttrium-90-loaded microspheres as sources for internal radiation therapy is a form of transarterial radioembolization (TARE). Current data from the literature suggest that TARE is effective in hepatocellular carcinoma (HCC) and is associated with a low rate of adverse events; however, they are all based on retrospective series or non-controlled prospective studies, since randomized controlled trials comparing the other liver-directed therapies for intermediate and locally advanced stages HCC are still ongoing. The available data show that TARE provides similar or even better survival rates. TARE is very well tolerated and has a low rate of complications; these complications do not result from the embolic effects but mainly from the unintended irradiation to non-target tissue, including the liver parenchyma. The complications can be further reduced by accurate patient selection and a strict pre-treatment evaluation, including dosimetry and assessment of the vascular anatomy. First-line TARE is best indicated for intermediate-stage patients (according to the Barcelona Clinic Liver Cancer [BCLC] staging classification) who are poor candidates for transarterial chemoembolization or patients having locally advanced disease with segmental or lobar branch portal vein thrombosis. Moreover, data are emerging regarding the use of TARE in patients classified slightly above the criteria for liver transplantation with the purpose of downstaging them. TARE can also be applied as a second-line treatment in patients progressing to transarterial chemoembolization or sorafenib; a large number of Phase II/III trials are in progress in order to evaluate the best association with systemic therapies. Given the complexity of a correct treatment algorithm for potential TARE candidates and the need for clinical guidance, a comprehensive review was carried out analyzing both the best selection criteria of patients who really benefit from TARE and the new advances of this therapy which add significant value to the therapeutic weaponry against HCC.

A case of hospital-acquired GNB infection - P. aeruginosa meningoencephalitis post laparoscopic cholecystectomy for biliary pancreatitis, complicated with portal vein branch thrombosis and intracerebral ischemic and hemorrhagic lesions

Case report We present the case of a female patient admitted to our clinic with a suspicion of acute bacterial meningoencephalitis, one month after a laparoscopic cholecystectomy. During the first 48 hours she presented generalized seizures, 5-6 daily, with a duration that ranged from 30 to 60 seconds, that responded to medical therapy. The CSF cultures and the pulmonary tract secretions both tested positive for P. aeruginosa. The antibiotic regimen consisted of iv meropenem, colistin and ciprofloxacin for 7 days, then meropenem and ciprofloxacin for 21 days. The evolution and the treatment decisions were complicated by the discovery on the cerebral MRI of bilateral frontal ischemic and hemorrhagic lesions and a portal vein branch thrombosis. The patient registered almost complete cognitive and motor recovery, and is continuing the kinetotherapy.

Hepatic caudate lobe compensation function in rats

Objective To assess the safety and effectiveness of caudate lobe-sparing subtotal hepatoectomy after rapid hypertrophy of the caudate lobe following selective portal vein branches ligation except caudate lobe's in rats.Methods Forty SD rats were randomly divided into portal vein branches ligation group and sham group.Portal vein branches except caudate lobe's were ligated by laparotomy.Alanine transaminase (ALT),aspartate aminotransferase (AST),albumin,total bilirubin and direct bilirubin were assessed at 3rd,7th,14th and 21st day after portal vein ligation in 5 rats each day,followed by rats sacrifice.The morphological changes of both ligated and non-ligated liver lobes were observed by microscope.The expression of proliferation cell nuclear antigen (Ki-67) was detected by immunohistochemistry.Twenty-one days after the first operation,caudate lobe-sparing subtotal hepatoectomy was undertaken on other 20 rats of each group.Survival rate was assessed in both groups after the second operation.Results ALT levels were higher in experimental group than in control group on the 3rd,7th and 14th day [(57.28 ± 8.95) vs.(165.07±19.15)U/L,(67.03 ±13.46) vs.(131.24±9.51) U/L,and (67.03 ±13.46) vs.(100.16 ± 5.20) U/L,P ＜ 0.01].AST levels were also elevated on the 3rd,7th and 14th day [(148.89±37.64) vs.(853.61 ±276.33) U/L,(146.34 ±39.06) U/Lvs.(730.19 ±169.81) U/L,P ＜0.01 ; (143.13 ±23.30) vs.(129.82 ± 18.80) U/L,P ＜0.05].Albumin levels were only elevated at day 7 [(39.65 ± 2.49) vs.(25.91 ± 2.21) g/L,P ＜ 0.01].Total bilirubin and direct bilirubin showed no significant diffence between two groups.The hypertrophy rate of caudate lobe was very quick in former 3 days,and then got slower on the day 14.The experimental group had a higher survival rate of 10 days (16/20 vs.4/20,P ＜ 0.01).Conclusion It is safe and effective to undertake caudate lobe-sparing subtotal hepatoectomy after selective portal vein branches ligation in rats. Key words: Portal vein ligation; Caudate lobe; Hepatoectomy

Development of a fatal noncompressible truncal hemorrhage model with combined hepatic and portal venous injury in normothermic normovolemic swine.

Noncompressible truncal hemorrhage and brain injury currently account for most early mortality of warfighters on the battlefield. There is no effective treatment for noncompressible truncal hemorrhage, other than rapid evacuation to a surgical facility. The availability of an effective field treatment for noncompressible truncal hemorrhage could increase the number of warfighters salvaged from this frequently-lethal scenario. Our intent was to develop a porcine model of noncompressible truncal hemorrhage with a ∼50% one-hour mortality so that we could develop new treatments for this difficult problem. Normovolemic normothermic domestic swine (barrows, 3 months old, 34–36 kg) underwent one of three injury types through a midline incision: 1) central stellate injury (N = 6); 2) excision of a portal vein branch distal to the main PV trunk (N = 6); or 3) hemi-transection of the left lateral lobe of the liver at its base (N = 10). The one-hour mortality of these injuries was 0, 82, and 40%, respectively; the final mean arterial pressure was 65, 24, and 30 mm Hg, respectively; and the final hemoglobin was 8.3, 2.3, and 3.6 g/dL, respectively. Hemi-transection of the left lateral lobe of the liver appeared to target our desired mortality rate better than the other injury mechanisms.

Predictors of Thrombosis in Hepatic Vasculature during Microwave Tumor Ablation of an In Vivo Porcine Model

PurposeTo evaluate and model the risk of in vivo thrombosis in each hepatic vessel type during hepatic microwave ablation as a function of vessel diameter, velocity, and vessel-antenna spacing. Materials and MethodsA single microwave ablation antenna was inserted into a single porcine lobe (n = 15 total) adjacent to a hepatic artery, hepatic vein, or portal vein branch. Conventional ultrasound and Doppler ultrasound were used to measure the vessel diameter, blood flow velocity, and vessel-antenna spacing. A microwave ablation zone was created at 100 W for 5 minutes. Thrombus formation was evaluated on ultrasound performed immediately after the procedure. Logistic regression was used to evaluate the predictive value of vessel diameter, blood flow velocity, and vessel-antenna spacing on vascular thrombosis. ResultsThrombosis was identified in 53% of portal veins, 13% of hepatic veins, and 0% of hepatic arteries. The average peak blood flow rate of the hepatic artery was significantly greater than the average peak blood flow rate of the hepatic vein and portal vein. Peak blood flow velocity < 12.45 cm/s, vessel diameter < 5.10 mm, and vessel-antenna spacing < 3.75 mm were strong predictors of hepatic vein thrombosis. However, these individual factors were not predictive of the more common portal vein thrombosis. ConclusionsHepatic arteries do not appear to be at risk for thrombosis during microwave ablation procedures. Portal vein thrombosis was more common than hepatic vein thrombosis during microwave ablation treatments but was not as predictable based on vessel diameter, flow velocity, or vessel-antenna spacing alone.

Relationship between primary colorectal tumour and location of colorectal liver metastases.

There is conflicting evidence regarding whether streamlining of blood flow within the portal vein influences the anatomical distribution of colorectal liver metastases (CRLM). This study assesses the relationship between primary tumour location and metastases location. Patients were identified using a prospectively maintained database, and those with known site of primary colorectal tumour and hemiliver involvement were included. Site of metastases and segments affected were confirmed via review of the radiology reports. The location of primary colonic tumour was confirmed via review of clinical correspondence letters. A total of 2364 metastases were identified in 891 patients. Of these, 379 metastases were in the right lobe and 156 in the left lobe, with 356 having bilobar disease. There was no significant relationship between the distribution of CRLM and the site of primary disease (left colon versus right colon) (P = 0.819). However, when the segmental location of the metastases was considered, there is a statistically significant difference between the number of right-sided CRLM compared with left-sided CRLM (P < 0.001). Right-sided CRLM is more likely regardless of the primary location. Portal streaming may have an effect, although the natural anatomical 'angulation', particularly of the left portal vein branch is more likely to play a role.

Technical considerations of living donor hepatectomy of segment 2 grafts for infants

The selection of an adequate graft to mitigate the problems associated with a large-for-size graft is essential to ensure the success of liver transplantation for smaller children. Reduced left lateral segment (LLS) grafts have been introduced to overcome this issue. Five infants underwent living donor liver transplantation (LDLT) with segment 2 grafts. In the preoperative assessment, the graft-to-recipient weight ratio (GRWR) and the ratio of the thickness of the donor LLS were used as a reference index for graft size matching, and a 3-dimensional (3D) computer-generated model of the donor liver was used for the analysis of the intrahepatic vasculature. During the donor operation, the relevant portal vein branches feeding to the reduced part of segment 3 were first exposed and divided, and then the parenchymal transection was performed. Segment 2 grafts were selected in 3 cases and reduced segment 2 grafts were selected in the other 2 cases. The graft reduction was achieved with 46.6 ± 8.2% of the actual LLS, and thus the GRWR was reduced from 5.33 ± 2.09% to 2.70 ± 0.82%. The actual graft thickness was reduced by approximately half after the graft reduction. Primary abdominal closure was performed in all of the recipients. No surgical complications occurred in any of the donors or recipients. A segment 2 graft could be a valuable option for graft type selection in LDLT for smaller children. Precise planning using a 3D computer-generated model of the donor liver and meticulous operative procedures are necessary to obtain a viable graft.

Noncirrhotic intrahepatic portal hypertension.

Noncirrhotic intrahepatic portal hypertension.

Applied anatomy of small branches of the portal vein in transverse groove of hepatic hilum.

The objective of this study was to provide the morphological details on small branches of the portal vein in transverse groove of hepatic hilum. According to the surgery significance, the small branches of portal vein in transverse groove of hepatic hilum were named as "Short hepatic portal veins (SHPVs)". SHPVs were minutely dissected in 30 adult cadaveric livers. The number, diameter, length, origin points, and entering liver sites of SHPVs were explored and measured. There were 181 SHPVs in 30 liver specimens, including 46% (83/181) from the left portal vein, 31% (56/181) from the bifurcation, and 23% (42/181) from the right portal vein. At the entering liver sites of SHPVs, 22% (40/181) supplied for segment IV, 9% (17/181) for segment V, 4% (7/181) for segment VI, 23% (41/181) for segment VII, and 42% (76/181) for segment I (caudate lobe). There were 6.0 ± 2.4 branches per liver specimen with range 3-12. The mean diameter of SHPVs was 2.25 ± 0.89 mm. The average length of SHPVs was 4.86 ± 2.12 mm. SHPVs widely existed in each liver specimen. The detailed anatomical study of SHPVs could be useful to avoid damaging the short portal branches during hepatic operations, such as isolated or combined caudate lobectomy.

NF-E2-related factor 2 promotes compensatory liver hypertrophy after portal vein branch ligation in mice

Hepatectomy is a standard therapy that allows liver cancer patients to achieve long-term survival. Preceding hepatectomy, portal vein embolization (PVE) is frequently performed to increase the remnant liver size and reduce complications. Although the clinical importance of PVE is widely accepted, molecular mechanisms by which PVE leads to compensatory hypertrophy of nonembolized lobes remain elusive. We hypothesized that NF-E2-related factor 2 (Nrf2), a master regulator of cytoprotection, promotes compensatory liver hypertrophy after PVE. To address this hypothesis, we utilized three mouse lines and the portal vein branch ligation (PVBL) technique, which primarily induces the redistribution of the portal bloodstream in liver in a manner similar to PVE. PVBL was conducted in Kelch-like ECH-associated protein 1 (Keap1) conditional knockout (Keap1-CKO) mice in which Nrf2 is constitutively activated, along with Nrf2-deficient (Nrf2-KO) mice. We found that hypertrophy of nonligated lobes after PVBL was enhanced and limited in Keap1-CKO and Nrf2-KO mice, respectively, compared to wild-type mice. In Keap1-CKO mice, Nrf2 activity was increased, consistent with transient activation of the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway, and reactive hepatocyte proliferation was significantly prolonged after PVBL. Importantly, Nrf2 activation by a chemical inducer was also effective for enhancement of hypertrophy after PVBL. Nrf2 supports compensatory liver hypertrophy after PVBL. This finding is particularly intriguing, because the primary effect of PVBL is limited to the alteration of bloodstream; this effect is much milder than changes resulting from hepatectomy, in which intrahepatic bloodstream and bile production cease. Our results suggest that premedication with an Nrf2 inducer may be a promising strategy to improve the outcome of PVE; this approach expands the indication of hepatectomy to patients with poorer liver function.

Preliminary experience of a new perspective view technology for the detection of portal vein thrombus in hepatocellular carcinoma patients

To assess the feasibility and efficiency of a perspective view technology (Fly Thru) for the detection of portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) patients. Fly Thru was performed in 79 HCC patients. The images were reviewed off-site for evaluation of the imaging quality and diagnosis. Pathology and/or contrast-enhanced CT was used as the reference standard for PVTT. The diagnostic quality of the images, presences of PVTT, and patency of the target vessels were recorded by two-dimensional ultrasound (2DUS) and Fly Thru image. The diagnostic performances of resident and staff radiologists were compared between 2DUS with or without off-line Fly Thru. Fly Thru was performed successfully in 43 of 79 patients (54.4%). The Fly Thru Imaging quality was good in 30/43 patients (69.8%), suboptimal but diagnostic in 10/43 (23.2%), and non-diagnostic in the remaining 3/43 (7.0%). PVTTs were detected in 31 patients according to the reference standard, with 8 in the main portal vein, 15 in the first branch, and 8 in the second branch of the portal vein. The agreement was good between conventional 2DUS and Fly Thru (κ=0.783, p=0.000). There was a significant association between the quality and the ability of Fly Thru in the detection of PVTTs (p=0.001). The diagnostic performance for both readers between 2DUS with or without Fly Thru showed no statistically significant differences, except for the sensitivity for resident radiologist. The sensitivity of 2DUS (71.0%, 22/31) for resident radiologists was lower than that of Fly Thru as an adjunctive diagnostic tool (90.3%, 28/31) (p=0.041). Fly Thru is of diagnostic quality and can provide useful information for the detection of PVTT in HCC patients.

Hepatocellular Carcinoma with Portal Vein Tumor Thrombus: Treatment with Transarterial Chemoembolization Combined with Sorafenib—A Retrospective Controlled Study

To determine the safety and efficacy of transarterial chemoembolization (TACE) combined with sorafenib (hereafter, TACE-sorafenib) in patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombus (PVTT). This study was approved by the institutional review board, and the requirement for informed consent was waived. The medical records of consecutive patients with HCC and PVTT who underwent TACE-sorafenib or TACE alone from January 2010 to December 2012 were retrospectively evaluated. Sorafenib (400 mg) was administered twice daily. Outcomes of patients who underwent TACE-sorafenib were compared with outcomes of patients who underwent TACE by using the Kaplan-Meier method according to types of PVTT: PVTT in the main portal vein (type A), PVTT in the first-order portal vein branch (type B), and PVTT in second- or lower-order portal vein branches (type C). Ninety-one patients were included in the analysis; 46 patients underwent TACE-sorafenib and 45 underwent TACE. TACE-sorafenib showed significant survival benefits compared with TACE in patients with type B (median survival, 13 months vs 6 months; P = .002) or type C (median survival, 15 months vs 10 months; P = .003) PVTT. TACE-sorafenib and main PVTT were the independent prognostic factors for survival at uni- and multivariate analysis. Liver function after TACE-sorafenib worsened only in patients with main PVTT. Sorafenib-related adverse events of grade 3 or higher occurred in 16 patients (35%). TACE-sorafenib side effects were acceptable, and this treatment may improve overall survival in patients with HCC with first-order or lower-branch PVTT when compared with patients who underwent TACE alone.

Anatomy of hepatic arteriolo‐portal venular shunts evaluated by 3D micro‐CT imaging

The liver differs from other organs in that two vascular systems deliver its blood - the hepatic artery and the portal vein. However, how the two systems interact is not fully understood. We therefore studied the microvascular geometry of rat liver hepatic artery and portal vein injected with the contrast polymer Microfil(®). Intact isolated rat livers were imaged by micro-CT and anatomic evidence for hepatic arteriolo-portal venular shunts occurring between hepatic artery and portal vein branches was found. Simulations were performed to rule out the possibility of the observed shunts being artifacts resulting from image blurring. In addition, in the case of specimens where only the portal vein was injected, only the portal vein was opacified, whereas in hepatic artery injections, both the hepatic artery and portal vein were opacified. We conclude that mixing of the hepatic artery and portal vein blood can occur proximal to the sinusoidal level, and that the hepatic arteriolo-portal venular shunts may function as a one-way valve-like mechanism, allowing flow only from the hepatic artery to the portal vein (and not the other way around).

Epithelial VEGF signaling is required in the mouse liver for proper sinusoid endothelial cell identity and hepatocyte zonation in vivo

Vascular endothelial growth factor (VEGF) is crucial for vascular development in several organs. However, the specific contribution of epithelial-VEGF signaling in the liver has not been tested. We used a mouse model to specifically delete Vegf from the liver epithelial lineages during midgestational development and assessed the cell identities and architectures of epithelial and endothelial tissues. We find that without epithelial-derived VEGF, the zonal endothelial and hepatocyte cell identities are altered. We also find decreased portal vein and hepatic artery branching coincident with an increase in hepatic hypoxia postnatally. Together, these data indicate that VEGF secreted from the hepatic epithelium is required for normal differentiation of cells and establishment of three-dimensional vascular branching and zonal architectures in both epithelial and endothelial hepatic tissues.

Sequential embolization of the branches of the bile duct and portal vein to the targeted hepatic lobe in rats

The high recurrence rate of hepatolithiasis and the high operative risk of right posterior, caudate or multiple lobe hepatectomy are the unsettled problems in hepatobiliary surgery. The present study was to investigate the efficacy of chemical hepatectomy performed via applying sequential embolization of the branches of the bile duct and portal vein to the targeted hepatic lobe. The bile duct and portal vein branches of the median hepatic lobe of rats were treated with: 1) bile duct embolization followed by portal vein ligation (BDE+PVL) and 2) portal vein ligation followed by bile duct embolization (PVL+BDE). The efficacy of chemical hepatectomy in BDE+PVL and PVL+BDE groups was compared with that of sole BDE by histology and Western blotting analysis of collagen I expression. After six weeks of the chemical hepatectomy, rats in the BDE group showed hepatocyte damages, fibrosis and "self-cut" only in the periphery of the embolized lobe. In contrast, rats in the PVL+BDE and BDE+PVL groups exhibited complete necrosis of hepatocytes and replacement with proliferative ductules and collagen fibers, leading to complete fibrosis and "self-cut" phenomenon in the whole targeted lobe. Collagen I expression in the PVL+BDE group was slightly higher than that in the BDE+PVL group; however, no statistically significant difference was noted. The sequential embolization of the bile duct and portal vein branches to the targeted hepatic lobe may be a feasible and effective approach to acheive the ideal effect of chemical hepatectomy in a short period of time.