VEGF参与低氧预适应对移植肝肝内胆管上皮细胞的保护作用

目的 探讨低氧预适应(hypoxic preconditioning,HP)对移植肝肝内胆管上皮细胞的保护作用及血管内皮生长因子(VEGF)在其中的作用.方法 建立大鼠自体原位肝移植模型,实验大鼠被分为3组: 自体原位肝移植组(AT组)、HP后行自体原位肝移植组(HP组)和假手术组.各组于术后6、12、24和48 h检测血清总胆红素(TBIL)、直接胆红素(DBIL)及碱性磷酸酶(ALP)水平,免疫组织化学法检测肝内胆管上皮细胞中VEGF的表达,光镜下观察肝内胆管上皮细胞的病理变化.结果 AT组术后血清TBIL、DBIL及ALP水平持续高于HP组(P＜0.05);各时相HP组VEGF的表达均明显高于AT组(P＜0.05);光镜下,HP组各时相肝内胆管上皮细胞损伤及炎症细胞浸润程度均较AT组明显减轻.结论 HP对移植肝肝内胆管上皮细胞有保护作用,VEGF可能在其中发挥着重要作用.     

Life-Threatening Portal Flow Steal Reappearing Under Increased Intrahepatic Vascular Resistance After Living Donor Liver Transplantation

Maintenance of adequate portal inflow is crucial for graft regeneration in adult living donor liver transplantation (ALDLT) to allow the recipients to meet their early metabolic demands. A persistent large spontaneous portosystemic shunt can divert portal flow away from the liver graft, leading to impaired or delayed graft regeneration and subsequent graft failure. The importance of obliterating huge portosystemic shunt during liver transplantation is obvious for successful ALDLT. However, in partial liver graft with a relatively small graft-to-recipient weight ratio (GRWR) (compared with deceased donor whole graft liver transplantation), even the persisting small portosystemic shunt may result in repeated portal flow steal when a liver graft faces increased intrahepatic vascular resistance caused by rejection or graft congestion with hepatic venous outflow stenosis. We present 2 complicated cases of reappearing portal flow steal that were derived from the remaining small portosystemic shunt under the increased vascular resistance of the liver graft, even after interruption of a large portosystemic shunt during ALDLT. Because ALDLT is always a partial liver graft, even when GRWR is over 1%, it is much more vulnerable to hemodynamic changes in portal flow by rejection or graft congestion by hepatic venous outflow obstruction. Therefore, a comprehensive understanding of complex portosystemic shunt and complete reinterruption of reappearing portosystemic shunt, even though small and insignificant, during ALDLT is important for graft salvage procedures before irreversible liver graft damage.     

The Effect of Normothermic Recirculation is Mediated by Ischemic Preconditioning in NHBD Liver Transplantation

We have evaluated the involvement of hepatic preconditioning mediators (adenosine, adenosine A1 and A2 receptors) during normothermic recirculation (NR) in a model of liver transplantation from non-heart-beating donor (NHBD) pigs. Application of NR after 20 min of warm ischemia (WI) reversed the lethal injury associated with transplantation of NHBD livers (achieving 5-day survival and diminishing glutathione S-transferase (GST), aspartate aminotransferase (AST) and hyaluronic acid (HA)). Adenosine administration prior to WI simulated the effect of NR. Measuring adenosine, we found that during NR, hepatic adenosine levels increased and xanthine levels decreased. Then when we blocked A2 receptors the effect of NR was abolished, whereas the blocking of A1 receptors further protected the liver. Furthermore, A2 blocking improved hepatic perfusion during NR whereas A1 blocking reduced it. The study suggests that NR has a preconditioning effect by maintaining adequate adenosine and xanthine levels. During NR, adenosine protects the liver through A2 activation and damages it through A1 activation although simultaneous stimulation of both receptors exerts a clear beneficial effect. The possible relation of NR mechanism with other preconditioning mediators such as cAMP and nitric oxide synthesis are discussed.     

Role of Ischemic Preconditioning in Liver Surgery and Hepatic Transplantation

Introduction  

The purpose of this review is to summarize intraoperative surgical strategies available to decrease ischemia–reperfusion injury associated with liver resection and liver transplantation.     

Prognostic Significance of c-erbB-2 and Vascular Endothelial Growth Factor in Colorectal Liver Metastases

Background  

The prognostic value of c-erbB-2 and vascular endothelial growth factor (VEGF) expression in colorectal liver metastases (CLM) is unclear. The purpose of this study was to clarify the relationship of c-erbB-2 and VEGF with the clinicopathological parameters and the survival results in CLM.     

Role of Peritubular Capillaries and Vascular Endothelial Growth Factor in Chronic Allograft Nephropathy

Objective

To investigate the role of peritubular capillary damage and vascular endothelial growth factor (VEGF) in chronic allograft injury and to evaluate their correlation with clinical factors.

Patients and Methods

The study included 56 patients who underwent transplantation between 1987 and 2004 and experienced chronic graft dysfunction. CD34 (peritubular capillaries) and VEGF were evaluated at histologic analysis. Patients were classified into 3 groups: 47 with chronic allograft injury, 9 with pure cyclosporine toxicity, and 26 who served as the control group (time 0 biopsy).

Results

Compared with the control group, CD34 total expression in chronic nephropathy was indirectly proportional to Banff stage (P < .05), and VEGF was increased in chronic allograft injury grade I or II or nephrotoxicity (P < .05). CD34 expression was correlated with age (P < .007) and number of acute rejection episodes (P = .005). A negative correlation was observed between expression of CD34 and of VEGF (P < .001). Low expression of CD34 was associated with risk of graft loss of 1.45 (95% confidence interval, 1.15-7.24; P = .04).

Conclusion

Peritubular capillaries decreased progressively with development of chronic allograft injury. The VEGF demonstrated a bimodal behavior, increasing at the onset of nephropathy and decreasing in the final stages. Loss of peritubular capillaries was associated with worse graft survival and overexpression of VEGF.     

Immunohistochemical Analysis of Vascular Endothelial Growth Factor and Hepatocyte Growth Factor,and Their Receptors,in Transplanted Islets in Rats

Purpose. Our previous studies showed that transplanted islets increasingly express a marker of neovascularization, platelet endothelial cell adhesion molecule-1 (PECAM-1), as well as vascular endothelial growth factor (VEGF). Hepatocyte growth factor (HGF) is another stimulator of neovascularization. In this study, we examined the expression of these growth factors and their receptors; fetal liver kinase-1 (Flk-1) for VEGF and c-Met for HGF, to acertain whether VEGF and HGF play a role in the neovascularization of transplanted islets. Methods. Islets were isolated from male Lewis rats by collagenase digestion and the discontinuous dextran gradient method, then transplanted into the bilateral subnephrocapsular space. The kidneys were excised 1–28 days after transplantation, then fixed in formaldehyde and embedded in paraffin. Serial slices were immunostained for VEGF, HGF, Flk-1, or c-Met, respectively. Results. Islets in the normal pancreas were positively stained for VEGF, HGF, and c-Met; however, Flk-1 was only stained at the periphery of the islets. In the transplanted islets, staining for VEGF, HGF, and c-Met was positive, but Flk-1 was not stained. Moreover, staining for HGF and c-Met became stronger in the transplanted islets with time. Conclusion. These results suggest that HGF, rather than VEGF, may play a role in the neovascularization of transplanted islets.     

Impact of Donor Age on the Growth of Young Recipient Rats After Liver Transplantation

Purpose We studied the age-related changes in graft livers, and their impact on post-transplantation liver function and the growth of young recipient rats. Methods Rats aged 11–68 weeks old were studied as controls to assess liver histology, liver function, and body weight. We performed orthotopic liver transplantation using Kamada's cuff technique without arterial reconstruction. Young rats aged 11 weeks were randomized to receive livers from either 11-week-old donors (YD group) or 52-week-old donors (OD group). Recipient rats were killed 0, 8, or 16 weeks after surgery and we assessed the same variables as in the controls. Results We confirmed an age-related increase in the average size of hepatocytes and their nuclei. These age-related changes persisted and progressed in the graft liver after transplantation. There were no significant differences in the levels of serum transaminases or total bilirubin between the YD and OD groups, but the serum albumin level was significantly lower in the OD group. The YD group grew normally, whereas the OD group recipients lagged significantly in gaining body weight. Conclusion We found that 52-week-old grafts transplanted into 11-week-old recipients resulted in deficient growth and a decline in serum albumin, suggesting that grafted old livers fail to produce enough protein to meet the demands of growth adequately.     

Prognostic Significance of Vascular Endothelial Growth Factor,Basic Fibroblast Growth Factor,and Angiogenin in Patients With Resectable Hepatocellular Carcinoma After Surgery

Background: Hepatocellular carcinoma (HCC) is a hypervascular malignancy. Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and angiogenin (ANG) are important angiogenic factors of neoangiogenesis. This study investigated the predictive value of serum VEGF, bFGF, and ANG in tumor recurrence, disease-free survival (DFS), and overall survival (OS) in HCC patients.Methods: Preoperative serum VEGF, bFGF, and ANG were measured in 98 patients with resectable HCC and in 15 healthy controls. The median follow-up time was 43 months.Results: Preoperative serum VEGF was increased in patients with resectable HCC compared with healthy controls (P < .05). Increased serum VEGF was correlated with tumor recurrence (P = .001). Univariate analysis showed that serum VEGF, tumor-node-metastasis stage, tumor size and number, macroscopic portal vein invasion, and microscopic vascular invasion were correlated with OS and DFS. Serum bFGF and ANG were not associated with survival. Multivariate analysis showed that serum VEGF was the most significant predictor of DFS (relative risk, 2.35; 95% confidence interval, 1.26–4.39; P = .007) and OS (relative risk, 3.44; 95% confidence interval, 1.81–6.57; P < .001) in HCC patients after surgical resection.Conclusions:Preoperative serum VEGF is a significant independent predictor of tumor recurrence, DFS, and OS in patients with resectable HCC.     

VEGF mRNA在预测肝癌肝移植术后肿瘤复发和转移中的应用价值

目的 探讨血管内皮生长因子（vascular endothelial growth factor，VEGF）mRNA作为肝癌游离癌细胞标志物在预测肝癌肝移植术后复发和转移中的应用价值。方法 以2002年4月至2003年12月期间的53例原发性肝癌肝移植患者为研究对象（肝癌肝移植组），通过建立稳定可靠的实时荧光定量RT—PCR检测方法来定量检测肝癌患者外周血中VEGFmRNA在整个肝移植术围手术期的动态变化情况，并与术后复发和转移进行相关分析；同时，为了解VEGFmRNA表达的特异性，分别设立了进展期肝癌组（n=8）、良性肝病组（n=26）和正常对照组（n=10）。结果 VEGFmRNA可以作为肝癌游离癌细胞的标志物，具有较好的特异性。进展期肝癌组和肝癌肝移植组VEGFmRNA的表达阳性率明显高于良性肝病组和正常对照组（75．0％、37．7％vs11．5％、10．0％），P〈0．01；术前VEGFmRNA的阳性表达和术后出现2次以上持续性的VEGFmRNA阳性表达与移植术后肝癌复发与转移相关（P〈0．01）。结论 术前检测VEGFmRNA阳性表达和术后持续的VEGFmRNA标志物检测表达阳性可以有效预测肝癌肝移植术后肿瘤复发和转移。     

Tubulovascular Cross-Talk by Vascular Endothelial Growth Factor A Maintains Peritubular Microvasculature in Kidney

Vascular endothelial growth factor A (VEGFA) production by podocytes is critical for glomerular endothelial health. VEGFA is also expressed in tubular epithelial cells in kidney; however, its physiologic role in the tubule has not been established. Using targeted transgenic mouse models, we found that Vegfa is expressed by specific epithelial cells along the nephron, whereas expression of its receptor (Kdr/Vegfr2) is largely restricted to adjacent peritubular capillaries. Embryonic deletion of tubular Vegfa did not affect systemic Vegfa levels, whereas renal Vegfa abundance was markedly decreased. Excision of Vegfa from renal tubules resulted in the formation of a smaller kidney, with a striking reduction in the density of peritubular capillaries. Consequently, elimination of tubular Vegfa caused pronounced polycythemia because of increased renal erythropoietin (Epo) production. Reducing hematocrit to normal levels in tubular Vegfa–deficient mice resulted in a markedly augmented renal Epo production, comparable with that observed in anemic wild-type mice. Here, we show that tubulovascular cross-talk by Vegfa is essential for maintenance of peritubular capillary networks in kidney. Disruption of this communication leads to increased renal Epo production and resulting polycythemia, presumably to counterbalance microvascular losses.     

Selective Blockade of Vascular Endothelial Growth Factor Receptor 2 With an Antibody Against Tumor-Derived Vascular Endothelial Growth Factor Controls the Growth of Human Pancreatic Adenocarcinoma Xenografts

Background Vascular endothelial growth factor (VEGF), a key regulator of angiogenesis, is critical for growth of human pancreatic adenocarcinoma. Preclinical studies demonstrate that blockade of VEGF activity can control the growth of pancreatic tumors in mice. In this study, we evaluated the efficacy of 2C3, an antibody that inhibits VEGF receptor 2 activation by human VEGF, to inhibit the growth of human pancreatic adenocarcinoma in mice. Methods Human pancreatic cancer cell lines (MiaPaca-2, Panc-1, and Capan-1) were used to establish xenografts in nu/nu mice. The expression of VEGF and its receptors was determined in each cell line. Proliferation of tumor cells in vitro and tumor growth in vivo in the presence of 2C3 or a control antibody was evaluated. The effect of 2C3 on tumor weight, total vessel density, number of pericyte-associated vessels, and tumor perfusion was determined, and the level of 2C3 in the serum of animals was measured by enzyme-linked immunosorbent assay. Results 2C3 did not affect the proliferation of cells in culture. 2C3 was present and active in the serum of tumor-bearing animals treated with 2C3, and these animals showed a decrease in tumor burden compared with control-treated mice. Therapy with 2C3 resulted in reduced vascular function, measured by a decrease in vessel density and in the percentage of vessels associated with pericytes. Furthermore, tumors derived from Capan-1 cells demonstrated decreased perfusion after treatment with 2C3. Conclusions Blockade of VEGF receptor 2 activation by tumor-derived VEGF decreases tumor vessel function and growth of some human pancreatic adenocarcinoma cell lines in mice. Presented at the 57th Annual Meeting of the Society of Surgical Oncology, New York, New York, March 2004. Dr. Brekken is a paid consultant for, receives research support through a sponsored research agreement with, and has an equity interest in Peregrine Pharmaceuticals Inc., a company that has licensed the exclusive rights to 2C3 from the University of Texas.     

Prognostic Significance of Vascular Endothelial Growth Factor D in Gastric Carcinoma

The angiogenic factor called vascular endothelial growth factor (VEGF)-D is a ligand for VEGF receptor-2 (VEGFR-2/KDR) and receptor-3 (VEGFR-3/Flt-4). It is implicated in the development of lymphatic vessels and promotion of lymphatic metastasis. The purpose of this study was to investigate the prognostic significance of VEGF-D expression in patients with gastric carcinoma. We assessed the expression of VEGF-D in gastric carcinoma by immunohistochemistry on 143 consecutive patients’ stored sections and evaluated the lymphatic vessel count (LVC) in tumors using the novel selective lymphatic endothelium marker D2-40. VEGF-D expression was observed in 55 (39%) tumor sections. The expression of VEGF-D correlated significantly with tumor size, T of the TNM classification, lymphatic and venous system invasion, LVC, lymph node metastasis, M of TNM, and pTNM stage. Multivariate analysis indicated that VEGF-D expression was an independent prognostic factor for both relapse-free survival (RFS) and overall survival (OS). Our data indicate the involvement of VEGF-D in tumor progression via lymphoangiogenic pathways. Practically, VEGF-D expression can be useful for predicting RFS and OS in patients with gastric carcinoma.     

Intrahepatic Hepatic Vein Stenosis After Living-Related Liver Transplantation Treated by Insertion of an Expandable Metallic Stent

Although the incidence of stenosis and obstruction of the hepatic venous anastomosis after right hepatic living-related liver transplantation (LRLT) has been found to be higher than after orthotopic liver transplantation (OLT), to the best of our knowledge, intrahepatic stenosis of the venous trunk in the early period after right hepatic LRLT has never been reported in the literature. A 53-year-old man who underwent right hepatic LRLT, postoperatively, developed liver dysfunction and an increasing amount of ascites, and a Doppler sonogram showed a flat waveform and low-flow velocity in the hepatic vein. Based on these findings an outflow block was suspected, and a hepatic venogram and manometry revealed intrahepatic stenosis of a tortuous hepatic venous trunk and a pressure gradient of 14 mmHg at the site of the stenosis. We inserted an expandable metallic stent (EMS) at the site of intrahepatic venous stenosis, and its insertion was followed by a decrease in pressure gradient. Liver function recovered, and the volume of ascitic fluid decreased after placement of the EMS. The results of an analysis of the venogram and CT volumetric data suggested that the pathogenesis of the stenosis was twisting of the venous trunk during hypertrophy of the liver parenchyma.     

Clinical Relevance of Vascular Endothelial Growth Factor for Thyroid Neoplasms

Angiogenesis is of vital importance during the development and progression of solid tumors. Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis and could be produced by some cancer cells. To investigate the clinical relevance of VEGF in the tumorigenesis of human thyroid, an immunohistochemical study was performed on archival materials of follicular adenomas (n= 13), Hürthle cell adenomas (n= 6), papillary carcinomas (n= 76), follicular carcinomas (n= 12), Hürthle cell carcinomas (n= 2), and anaplastic carcinomas (n= 8). Patterns of VEGF expression were analyzed in relation to histologic subtypes of thyroid tumors and were correlated to biologic indicators of papillary carcinoma. All papillary carcinomas and Hürthle cell neoplasms revealed a strong, diffuse staining reaction, whereas anaplastic carcinoma usually exhibited weak and infrequent immunoreactivity. VEGF levels were usually higher in follicular adenomas than in follicular carcinomas. With regard to prognostic value, VEGF expression did not correlate with tumor size, extent of invasion, or scores on the AGES system (i.e., patient age, tumor size, histologic grade, tumor extent, distant metastasis) or the MACIS system (i.e., metastasis, age, completeness of resection, invasion, tumor size) for papillary carcinomas (p > 0.05, respectively). The results of the current study indicate that VEGF may play a role in the development of human thyroid cancer. Determination of the angiogenic phenotype may have limited prognostic value for patients with papillary carcinoma.     

Markedly Elevated Levels of Vascular Endothelial Growth Factor in Malignant Ascites

Background: Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that also has the ability to increase vascular permeability. Malignant ascites has significant morbidity, but the mechanism of its development is unknown. Because of the permeability-inducing properties of VEGF, we hypothesized that malignant ascites formation is associated with high levels of VEGF. The purpose of our study was to determine the role of VEGF in malignant ascites formation.Methods: Ascites from 25 patients with gastric (n = 6), colon (n = 7), or ovarian (n = 12) cancers was collected by paracentesis or surgery. VEGF protein levels were determined by enzyme-linked immunosorbent assay. The effect of ascites on endothelial cell permeability was assessed by evaluating propidium iodide uptake by human umbilical vein endothelial cells (HUVECs) exposed to ascites. Neutralizing antibodies to VEGF added to ascites were used to determine the causal effect of VEGF in permeability induction.Results: VEGF protein levels were markedly increased in malignant ascites compared with levels in nonmalignant cirrhotic ascites (controls). VEGF protein levels in ovarian, gastric, and colon cancer ascites were found to be increased 45, 23, and 12 times, respectively, compared with levels in cirrhotic ascites. Malignant ascites from patients with colon and gastric cancer caused an increase in permeability in HUVECs in all cases. Neutralizing VEGF activity in colon cancer ascites decreased in-vitro HUVEC permeability in three of four cases.Conclusions: VEGF protein levels are markedly elevated in malignant ascites. VEGF may play a role in malignant ascites formation by increasing endothelial cell permeability.