Hypoxia-induced factor-1 alpha upregulates vascular endothelial growth factor C to promote lymphangiogenesis and angiogenesis in breast cancer patients

Hypoxia-induced factor-1 alpha （HIF-1α） affects many effector molecules and regulates tumor lymphangio- genesis and angiogenesis during hypoxia. The aim of this study was to investigate the role of HIF-1α in the regu- lation of vascular endothelial growth factor C （VEGF-C） expression and its effect on lymphangiogenesis and an- giogenesis in breast cancer. Lymphatic vessel density （LVD）, microvessel density （MVD） and the expressions of HIF-1α and VEGF-C proteins were evaluated by immunohistochemistry in 75 breast cancer samples. There was a significant correlation between HIF-1α and VEGF-C （P = 0.014, r = 0.273, Spearman＇s coefficient of correlation）. HIF-1α and VEGF-C overexpression was significantly correlated with higher LVD （P = 0.003 and P = 0.017, re- spectively）, regional lymph nodal involvement （P = 0.002 and P = 0.004, respectively） and advanced tumor, node, metastasis （TNM） classification （P = 0.001 and P = 0.01, respectively）. Higher MVD was observed in the group expressing higher levels of HIF-1α and VEGF-C （P = 0.033 and P = 0.037, respectively）. Univariate analysis showed shorter survival time in patients expressing higher levels of HIF-1α and VEGF-C. HIF-1α was also found to be an independent prognostic factor of overall survival in multivariate analysis. The results suggest that HIF-1α may affect VEGF-C expression, thus acting as a crucial regulator of lymphangiogenesis and angiogenesis in breast cancer. This study highlights promising potential of HIF- 1α as a therapeutic target against tumor lymph node me- tastasis.

Insulin-like growth factor-1 induces lymphangiogenesis and facilitates lymphatic metastasis in colorectal cancer

AIM:To investigate the expression of insulin-like growth factor-1(IGF-1)/insulin-like growth factor-1 receptor(IGF-1R)in colorectal cancer(CRC)tissues and to analyze their correlation with lymphangiogenesis and lymphatic metastasis.METHODS:Immunohistochemistry was used to evaluate IGF-1 and IGF-1R expression and lymphatic vessel density(LVD)in 40 CRC specimens.The correlation between IGF-1/IGF-1R and LVD was investigated.Effects of IGF-1 on migration and invasion of CRC cells were examined using transwell chamber assays.A LoVo cell xenograft model was established to further detect the role of IGF-1 in CRC lymphangiogenesis in vivo. RESULTS:Elevated IGF-1 and IGF-1R expression in CRC tissues was correlated with lymph node metastasis(r=0.715 and 0.569,respectively,P<0.05)and tumor TNM stage(r=0.731 and 0.609,P<0.05).A higher LVD was also found in CRC tissues and was correlated with lymphatic metastasis(r=0.405,P<0.05).A positive correlation was found between LVD and IGF-1R expression(r=0.437,P<0.05).Transwell assays revealed that IGF-1 increased the migration and invasion of CRC cells.In vivo mouse studies showed that IGF-1 also increased LVD in LoVo cell xenografts.CONCLUSION:IGF-1/IGF-1R signaling induces tumorassociated lymphangiogenesis and contributes to lymphatic metastasis of CRC.

Lymphangiogenesis, Lymphatic Endothelial Cells and Lymphatic Metastasis in Head and Neck Cancer—A Review of Mechanisms

Lymphatic metastasis is a continuous and complicated process. The detailed mechanisms of lymphatic metastasis are still not very clear, despite considerable research efforts in recent years. Previously, it was commonly accepted that there were no lymphatic vessels in the primary tumor. However, recent studies have demonstrated that lymphatic vessels are detectable in certain types of cancer, and more and more evidence has shown that cancer cells invade into local lymph nodes mainly via peritumoral lymphatic vessels, Moreover, activated endothelial cells may also be important, having an influence on lymphatic metastasis of cancer cells. This article, based on recent research findings, provides an in-depth discussion of the relationship between lymphangiogenesis, tumor-derived lymphatic endothelial cells and lymphatic metastasis in head and neck cancer.

Lymphangiogenesis:A new player in cancer progression

Lymph node metastasis is the hallmark of colon cancer progression,and is considered one of the most important prognostic factors.Recently,there has been growing evidence that tumor lymphangiogenesis(formation of new lymphatic vessels) plays an important role in this process.Here,we review the latest f indings of the role of lymphangiogenesis in colorectal cancer progression,and discuss its clinical application as a biomarker and target for new therapy.Understanding the molecular pathways that regulate lymphangiogenesis is mandatory to pave the way for the development of new therapies for cancer.In the future,tailored treatments consisting of combinations of chemotherapy,other targeted therapies,and anti-lymphangiogenesis agents will hopefully improve patient outcomes.This progression to the clinic must be guided by new avenues of research,such as the identif ication of biomarkers that predict response to treatment.

A review on Eph/ephrin,angiogenesis and lymphangiogenesis in gastric,colorectal and pancreatic cancers

Erythroprotein-producing human hepatocellular carcinoma receptors （Eph receptors） compose a subfamily of transmembrane protein-tyrosine kinases receptors that takes part in numerous physiological and pathological processes. Eph family receptor-interacting proteins （Ephrins） are ligands for those receptors. Eph/ephrin system is responsible for the cytoskeleton activity, cell adhesion, intercellular connection, cellular shape as well as cell motility. It affects neuron development and functioning, bone and glucose homeostasis, immune system and correct function of enterocytes. Moreover Eph/ephrin system is one of the crucial ones in angiogenesis and lymphangJogenesis. With such a wide range of impact it is clear that disturbed function of this system leads to pathology. Eph/ephrin system is involved in carcinogenesis and cancer progression. Although the idea of participation of ephrin in carcinogenesis is obvious, the exact way remains unclear because of complex bi-directional signaling and cross-talks with other pathways. Further studies are necessary to find a new target for treatment.

Induced dural lymphangiogenesis facilities soluble amyloid-beta clearance from brain in a transgenic mouse model of Alzheimer's disease

Impaired amyloid-β clearance from the brain is a core pathological event in Alzheimer＇s disease.The therapeutic effect of current pharmacotherapies is unsatisfactory,and some treatments cause severe side effects.The meningeal lymphatic vessels might be a new route for amyloid-β clearance.This study investigated whether promoting dural lymphangiogenesis facilitated the clearance of amyloid-β from the brain.First,human lymphatic endothelial cells were treated with 100 ng/m L recombinant human vascular endothelial growth factor-C（rh VEGF-C） protein.Light microscopy verified that rh VEGF-C,a specific ligand for vascular endothelial growth factor receptor-3（VEGFR-3）,significantly promoted tube formation of human lymphatic endothelial cells in vitro.In an in vivo study,200 μg/m L rh VEGF-C was injected into the cisterna magna of APP/PS1 transgenic mice,once every 2 days,four times in total.Immunofluorescence staining demonstrated high levels of dural lymphangiogenesis in Alzheimer＇s disease mice.One week after rh VEGF-C administration,enzyme-linked immunosorbent assay results showed that levels of soluble amyloid-β were decreased in cerebrospinal fluid and brain.The Morris water maze test demonstrated that spatial cognition was restored.These results indicate that the upregulation of dural lymphangiogenesis facilities amyloid-β clearance from the brain of APP/PS1 mice,suggesting the potential of the VEGF-C/VEGFR-3 signaling pathway as a therapeutic target for Alzheimer＇s disease.

Effect of HIF-1αon VEGF-C Induced Lymphangiogenesis and Lymph Nodes Metastases of Pancreatic Cancer

The effect of hypoxia inducible factor-1 α （HIF-1 α） on vascular endothelial growth factor C （VEGF-C） and the correlation between HIF- 1 α and lymphangiogenesis and lymph nodes metastases （LNM） in pancreatic cancer were investigated. Immunohistochemical SP method was used to detect the protein expression of HIF-1 α and VEGF-C, and Lymphatic vessel density （LVD） was determined by stain of VEGFR-3, collagen type IV in 75 pancreatic head cancers from regional pancreatectomy （RP） during Dec. 2001 to Dec. 2003. The relationship between HIF-1α and VEGF-C, lymphangiogenesis, LNM was analyzed statistically. The results showed that the positive expression rate of HIF-1α and VEGF-C in pancreatic cancer tissues was 48.00 % （36/75） and 65.33 % （49/75） respectively. In positive group of HIF-1α, the positive rate of VEGF-C and LVD, and LVD rate was 80.56 % （29/36）, 13.22±3.76 and 88.89 % （32/36） respectively, and in negative group of HIF-10t, positive rate of VEGF-C and LVD was 51.28 % （20/39）, 5.98±2.17 and 66.67 % （26/39） respectively （P〈0.01 or P〈0.05）. It was suggested that HIF-1α could promote the expression of VEGF-C, lymphangiogenesis and LNM in pancreatic cancer.

KAI1 inhibits lymphangiogenesis and lymphatic metastasis of pancreatic cancer in vivo

BACKGROUND: Several studies have shown that KAI1 inhibits tumor metastasis, but its mechanism is not clear. The present study aimed to determine the role of KAI1 in lymphatic metastasis, specifically in pancreatic cancer. METHODS: The KAI1 gene was transfected into the pancreatic cancer cell line MIA PaCa-2 and PANC-1 by using liposomes and selected by G418, and the protein was measured by Western blotting. After successful infection, the cell growth curve was studied by MTT, vascular endothelial growth factor C(VEGF-C) secretion by pancreatic cancer cell were measured by ELISA. The KAI1 and pCMV transfected MIA PaCa-2 cells were renamed as MIA PaCa-2-K and MIA PaCa-2-p. These two kinds of cells were injected into the subcuticular layer of nude mice; both tumor growth and metastasis through the lymphatic nodes were assessed. Lymphangiogenesis in tumors was measured by immunohistochemistry. RESULTS: The VEGF-C secretion was significantly reduced in MIA PaCa-2 cells compared with PANC-1 cells after being transfected with the KAI1 gene. The growth rate of subcutaneous tumors was similar after the injection of MIA PaCa-2-K, MIA PaCa-2, and MIA PaCa-2-p. MIA PaCa-2-K tumors showed slower lymphangiogenesis and lymph node metastasis compared with MIA PaCa-2 and MIA PaCa-2-p tumors. CONCLUSION: The overexpression of KAI1 inhibits the lymphangiogenesis and lymph node metastasis of MIA PaCa-2 pancreatic tumors.

Metastasis-associated protein 1 induces VEGF-C and facilitates lymphangiogenesis in colorectal cancer

AIM:To study the correlation between high metastasisassociated protein 1(MTA1)expression and lymphangiogenesis in colorectal cancer(CRC)and its role in production of vascular endothelial growth factor-C(VEGF-C). METHODS:Impact of high MTA1 and VEGF-C expression levels on disease progression and lymphovasculardensity(LVD,D2-40-immunolabeled)in 81 cases of human CRC was evaluated by immunohistochemistry. VEGF-C mRNA and protein expressions in human LoVo and HCT116 cell lines were detected by real-time polymerase chain reaction and Western blotting,respectively,with a stable expression vector or siRNA. RESULTS:The elevated MTA1 and VEGF-C expression levels were correlated with lymph node metastasis and Dukes stages(P<0.05).Additionally,high MTA1 expression level was correlated with a large tumor size(P< 0.05).A significant correlation was found between MTA1 and VEGF-C protein expressions in tumor cells(r=0.371, P<0.05).Similar to the VEGF-C expression level,high MTA1 expression level was correlated with high LVD in CRC(P<0.05).Furthermore,over-expression of MTA1 significantly enhanced the VEGF-C mRNA and protein expression levels,whereas siRNAs-knocked down MTA1 decreased the VEGF-C expression level. CONCLUSION:MTA1,as a regulator of tumor-associated lymphangiogenesis,promotes lymphangiogenesis in CRC by mediating the VEGF-C expression.

VEGFR-3 ligand-binding and kinase activity are required for lymphangiogenesis but not for angiogenesis

Although VEGFR-3 deficiency disrupts blood vascular development during early embryogenesis, the underlying mechanism was not clear. To characterize its function in angiogenesis and lymphangiogenesis, we employed two genetically modified mouse models in this study, targeting the coding region for the ligand-binding domain （Vegfr△LBD） or the tyrosine kinase domain with an inactivation point mutation （Vegfr3^TKmat）. We show that lymphatic growth was disrupted in Vegfr3△LBD/△LBD and Vegfr3^TKmut3^TKmat mice, but blood vessels developed normally in both embryo and yolk sac. Interestingly, in Vegfr3△LBD/△LBD but not Vegfr3^TKmut3^TKmat mice, lymph sac was present but there was lack of iym- phangiogenic sprouting. We further demonstrate that both the wild-type and mutant forms of VEGFR-3 could form heterodimers with VEGFR-2, and decreased the level of phospho-VEGFR-2 and the downstream phospho-Erk1/2 in endothelial cells when they were treated with VEGF-A. These findings indicate that signaling mediated via VEGFR-3 activation by its cognate ligands （VEGF-C/-D） is not required for angiogenesis, and that VEGFR-3 may play a role in this process by modulating VEGFR-2-mediated signals.

Effect of Antisense Oligodeoxynucleotide of Vascular Endothelial Growth Factor C on Lymphangiogenesis and Angiogenesis of Pancreatic Cancer

In order to investigate the effect of antisense oligonucleotide （ASODN） of vascular endothelial growth factor C （VEGF-C） on lymphangiogenesis and angiogenesis of pancreatic cancer, antisense and scamble-sense oligonucleotide of VEGF-C were constructed, and the model of nude mice with orthotopically xenografied human pancreatic cancer cells （Panc-1） was established. Thirty nude mice were randomly divided into 3 groups： PBS control group （group A）, scramble-sense control group （group B） and antisense group （group C）. All nude mice were treated once every 2 days as 3 times per week, for 3 weeks （oligonucleotide 10 mg/kg every time）. After treatments were completed, ELISA method was used to examine the concentration of VEGF-C in plasma and immunohistochemical method to examine microvessel density （MVD）, lymphtic vessel density （LVD） of pancreatic cancer. The results showed that the expression of VEGF-C was inhibited significantly in group C. The concentrations were 237.5±41.5, 221.5±52.3 and 108.6±14.9 pg/mL in groups A, B and C respectively （P〈0.01）. LVD in groups A, B and C was 13.8±2.1, 12.4±1.9 and 4.2±1.6 respectively （P〈0.01）. MVD in groups A, B and C was 27.5±8.7, 25.9±4.2 and 19.4±5.6 respectively with no significant difference among the groups （P〉0.05）. It was suggested that VEGF-C ASODN decreased the expression levels of VEGF-C in nude mice with orthotopically xenografted human pancreatic cancer, and it could inhibit lymphangiogenesis, but had no significant effect on angiogenesis.

Anlotinib suppresses lymphangiogenesis and lymphatic metastasis in lung adenocarcinoma through a process potentially involving VEGFR-3 signaling

Objective:Lymphatic metastasis is one of the leading causes of malignancy dispersion in various types of cancer.However,few anti-lymphangiogenic drugs have been approved for clinical use to date.Therefore,new therapies to block lymphangiogenesis are urgently required.Methods:Immunohistochemistry,immunofluorescence,Western blot,migration assays,and lymphangiogenesis and lymphatic metastasis assays were used.Results:Anlotinib,a receptor tyrosine kinase inhibitor,suppressed the rate of new metastatic lesions(31.82%in the placebo arm and 18.18%in the anlotinib arm)in patients with advanced lung adenocarcinoma who were enrolled in our ALTER-0303 study.D2-40+-lymphatic vessel density was strongly correlated with disease stage,metastasis,and poor prognosis in 144 Chinese patients with lung adenocarcinoma.In mice bearing A549EGFP tumors,tumor lymphatic vessel density,tumor cell migration to lymph nodes,and the number of distant metastatic lesions were lower in the anlotinib group than in the controls.Anlotinib inhibited the growth and migration of human lymphatic endothelial cells(hLECs)and lymphangiogenesisin vitro andin vivo.Treatment of hLECs with anlotinib downregulated phosphorylated vascular endothelial growth factor receptor 3(VEGFR-3).Conclusions:Anlotinib inhibits lymphangiogenesis and lymphatic metastasis,probably through inactivating VEGFR-3 phosphorylation.The results indicate that anlotinib may be beneficial for treatment in avoiding lymphangiogenesis and distant lymphatic metastasis in lung adenocarcinoma.(Trial registration:ALTER0303;NCT02388919;March 17,2015.)

Gecko crude peptides inhibit migration and lymphangiogenesis by down regulating the expression of VEGF-C in human hepatocellular carcinoma cells and human lymphatic endothelial cells

OBJECTIVE To explore the role of gecko crude peptides(GCPs)in the proliferation,apoptosis,migration and lymphangiogenesis of human hepatocellular carcinoma cells(Hep G2)and human lymphaticendothelial cells(HLECs)in vitro.METHODS The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay was used to evaluate the anti-proliferative effect of GCPs and si RNA-VEGF-C on Hep G2 cells,Hoechst 33258 staining and flow cytometry were performed to analyze cycle and apoptosis.The migration and invasion ability of cells were assayed by transwell chamber experiment and wound-healing assay.The protein and m RNA expressions of vascular endothelial growth factor-C(VEGF-C)and CXC chemokine receptor-4(CXCR4)were detected by q-PCR,immunofluorescence,Western blot.The protein expressions of the extracellular signal regulated kinase(ERKI/2),c-Jun N-terminal kinase(JNK),p38-mitogen activated protein kinases(p38 MAPK),serine/threonine kinase(Akt)and phosphatidylinositol-3-kinase(PI3K)were detected by western blot.The anti-lymphangiogenesis effect of GCPs on the HLECs was analyzed using an in vitro tube-formation assay.The protein and m RNA expressions of vascular endothelial growth factor receptor-3(VEGFR-3)and stromal cell-derived factor-1(SDF-1)were detected by q-PCR,Western blot.RESULTS GCPs and si RNA-VEGF-C inhibited Hep G2 proliferation,invasion and migration,and the most obvious inhibitory effect was both synergistic effects.Thus,GCPs suppressed HLECs proliferation,migration and tubelike structure formationin a dose-dependent manner,and had inhibitory effect of tumor-induced lymphangiogenesis in vitro.Additionally,we found that GCPs and si RNA-VEGF-C decreased the expressions of MMP-2,MMP-9,VEGF-C,CXCR4,phospho-ERK1/2,phospho-P38,phospho-JNK and PI3K in Hep G2 cells.Moreover,GCPs had a dose-dependent depressive effecton the expressions of VEGFR-3,SDF-1 in HLECs.CONCLUSION The low expression of VEGF-C mediated by si RNA-VEGF-C and GCPs inhibit tumor proliferation,invasion and migrationby suppressing the MAPK signaling pathway through reduced levels of VEGF-C,and GCPs inhibit tumor lymphangiogenesis by suppressing the CXCR4/SDF-1 signaling pathway through suppressed VEGF-C/VEGFR-3.

Relationship between angiogenesis and lymphangiogenesis in recurrent pterygium

AIM: To examine the relationship between angiogenesis and lymphangigenesis in recurrent pterygia. METHODS: Tissues from 34 excised recurrent pterygia (including 12 Grade 1, 10 Grade 2, and 12 Grade 3) were involved in the study and tissues from 7 nasal epibulbar conjunctivae segments were used as controls. Sections from each pterygium were immunostained with CD31 and LYVE-1 monoclonal antibodies to evaluate lymphatic microvessel density (LMVD) and blood microvessel density (BMVD), and the relationship between LMVD and BMVD in the pterygium was examined. RESULTS: There was a large number of CD31(+) LYVE-1((-)) blood vessels but only a few CD31 (+)LYVE-1 ((+)) lymphatic vessels in grades 1 and 2 pterygium. However, lymphatic vessels were dramatically increased in grade 3 pterygium. LMVD correlated dosely with BMVD in all pterygia, including grades 1, 2 and 3 peterygium patients (all P values < 0.01). Although both the density of blood and lymphatic vessels increased in recurrent pterygia, lymphatic vessels developed much faster than blood vessels, especially in grade 3 pterygia. CONCLUSION: There is a significant but not parallel relationship between angiogenesis and lymphangiogenesis in recurrent pterygium. The outgrowth of blood and lymphatic vessels provide evidence that immunological mechanism may play a role in the development and recurrence of pterygium.

LRG1 promotes corneal angiogenesis and lymphangiogenesis in a corneal alkali burn mouse model

AIM:To investigate the potential effect and mechanism of leucine-richα-2-glycoprotein-1(LRG1)on corneal angiogenesis and lymphangiogenesis.METHODS:Corneal neovascularization and lymphatics were induced by establishing alkali burn mouse model.Immunofluorescence staining was performed to detect the location of LRG1 in cornea tissues and to verify the source of LRG1-positive cells.Corneal whole-mount staining for CD31(a panendothelial cell marker)and lymphatic endothelial hyluronan receptor-1(LYVE-1;lymphatic marker)was performed to detect the growth of blood and lymphatic vessels after local application of exogenous LRG1 protein or LRG1 si RNA.In addition,expressions of the proangiogenic vascular endothelial growth factor(VEGF)related proteins were detected using Western blot analysis.RESULTS:LRG1 was dramatically increased in alkali burned corneal stroma in both the limbal and central areas.LRG1-positive cells in the corneal stroma were mainly derived from Vimentin-positive cells.Local application ofexogenous LRG1 protein not only aggravated angiogenesis but also lymphangiogenesis significantly(P<0.01).LRG1 group upregulated the levels of VEGF and the vascular endothelial growth factor receptor(VEGFR)family when compared with the phosphate-buffered saline(PBS)control group.We also found that LRG1-specific si RNA could suppress corneal angiogenesis and lymphangiogenesis when compared with the scramble si RNA-treated group(P<0.01).CONCLUSION:LRG1 can facilitate corneal angiogenesis and lymphangiogenesis through heightening the stromal expression of VEGF-A,B,C,D and VEGFR-1,2,3;LRG1-specific si RNA can suppress corneal angiogenesis and lymphangiogenesis in corneal alkali burn mice.

Inhibition of lymphangiogenesis,nodal and lung metastasis by dihydroartemisinin in mice bearing Lewis lung carcinoma

Objective:To investigate the activity of anti-malarial dihydroartemisinin (DHA) on tumor growth, lymphangiogenesis, nodal and lung metastasis and survival in mice bearing Lewis lung carcimoma (LLC). Methods: The models of C57BL/6 mice transplantation tumors were established via subcutaneous injection of LLC cells and divided into 4 groups: control group, DHA group, DHA+ferrous sulfate (FS) group and FS group, with 25 mice in each group. Tumor volumes and weights, nodal and lung metastasis, and survival were monitored. Tumor lymphatic microvessel density (LMVD) was determined by lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) immnohistochemistry. After LLC cells were treated with DHA or DHA+FS, protein and mRNA levels of vascular endothelial growth factor (VEGF) -C were evaluated by Western blotting and real time quantitative RT-PCR, respectively. Results: Oral administration of DHA or DHA+FS inhibited lymph node and lung metastasis, and prolonged survival. However, no significant tumor growth retardation effect was observed when mice were treated with DHA alone. The inhibited tumor metastasis was related to the decreased LMVD in the peritumoral regions, but not in the intratumoral regions. DHA significantly down-regulated the expression of VEGF-C protein and mRNA in LLC cells. Conclusion: DHA effectively inhibits LLC transplantation tumor lymphangiogenesis, nodal and lung metastasis, and may be a promising chemotherapeutic agent for controlling lung cancer metastasis by decreasing VEGF-C expression.

Relationship between the Expression of Vascular Endothelial Growth Factor C and Lymphangiogenesis in Human Pancreatic Cancer

Objective： To investigate the role the vascular endothelial growth factor C （VEGF-C） expression in lymphangiogenesis and lymph node metastasis in pancreatic cancer. Methods： The expression of VEGF-C in pancreatic cancer tissue of 42 cases and normal pancreatic tissue of 10 cases was detected by using immunohistochemical S-P method. The microlymphatic vessel density （MLVD） of both tissues was measured by enzyme-histochemical method at the same time. Results： The VEGF-C positive expression rate was significantly higher in pancreatic cancer tissue （64.3%） than in normal pancreatic tissue （20%, P〈0.05）. The MLVD was significantly higher in pancreatic cancer tissue （21.93±6.39） than that in normal pancreatic tissue （4.40±2.07, P〈0.001）. The VEGF-C positive expression rate, MLVD and lymph node metastasis had a positive correlation. Conclusion： The VEGF-C may play an important role in the lymphangiogenesis and lymph node metastasis of pancreatic cancer.

Lymphangiogenesis Occurring in Transplanted Corneas

To study corneal lymphangiogenesis after corneal transplantation, corneal allogenic transplantation models were established in rats. 8 female Wister rats were used as donors, and 16 Sprague Dawley （SD） rats were used as recipients and 2 SD served as controls. Corneal lymphangiogenesis and hemangiogenesis was examined by electron microscopy 1 and 2 weeks after corneal penetrating transplantation, and the expression of lymphatic vessel endothelial receptor （LY- VE-1） was examined 1, 3, 7, 14 days after the transplantation respectively. In addition, 19 allograft failed human corneas were examined by 5＇-nase-alkaline phosphatase （5＇-NA-ALP） doubleenzyme-histochemistry staining to detect corneal lymphangiogenesis and hemangiogenesis. By immunohistochemistry for LYVE-1, it was found that blown lymphatics were localized in the stroma 3 days after the corneal transplantation. With electron microscopy, new lymphatic vessels and blood vessels were found 1 and 2 weeks after the corneal transplantation. By 5＇-NA-ALP enzyme-histochemistry, corneal hemangiogenesis was found in all allograft failed human corneas and 5 of 19 （26.3 % ） cases had developed corneal lymphangiogenesis. It is concluded that corneal lymphangiogenesis is present after corneal transplantation, which may play an important role in allograft rejection.

Establishment of Lymphangioma Model and a Study on the Promoting Effect of Murine Melanoma Cell B16-F1 on the Lymphangiogenesis In Vitro

To establish an animal model of benign lymphangiomas of C57BL/6 mouse in vitro and to observe the effect of mouse ascites melanoma cell B 16-F1 on the lymphangiogenesis, 16 C57BL/6 mice aged 8 weeks were given two intraperitoneal injections of incomplete Freund＇s adjuvant at a 15-day interval. The induced neoplasms were studied histopathologically and thhe neoplasms specimens were immunohistochemically examined for the expressions of VEGF-C （vascular endothelial growth factor-C） and Fit-4 （VEGFR-3, vascular endothelial growth factor receptor-3）. The neoplasms were harvested and embedded in fibrin gel for culture in conditioned medium of B 16-F1 cells in vitro and observed under inverted microscope. Our results showed that white solid tumor masses devel- oped in peritoneal cavity after the induction. The tumors were confirmed to he lymplaangioma by gross and histological examination. The tumor cells expressed both VEGF-C and Fit-4. Lymphatic capillaries coming from lymphangioma specimen grew into the gel and the conditioned medium of B16-F1 cells was found to he able to promote the growth of the vessels. It is concluded that intraperitoneal injection of incomplete Freund＇s adjuvant is a good method for inducing benign lymphangiomas in mouse and B 16-F1 cells can promote lymphangiogenesis.

A Combination of Antigen Retrieval Methods Significantly Enhances the Unmasking of Tedious Antigens of Lymphangiogenesis and Angiogenesis in Canine Mammary Tumour

The use of immunohistochemical techniques has enhanced the diagnostic intensities in pathology. The sensitivity and specificity of any immunohistochemical protocol mainly depends on the ability to unmask antigen from formalin fixed tissue. Various combinations of antigen retrieval protocols have been used to unmask antigen efficiently but none has been established as a flawless one. These protocols either have one or the other lacunae, lacking repeatability under same conditions. In our study, we tried to develop a standardized immunohistochemical protocol for the identification of blood and lymphatic vessels in tissue sections of canine mammary tumour (CMT) using recently identified markers. The combined effects of antigen retrieval (AR) methods including pH shock by Heat-induced epitope retrieval (HIER) and Protease-induced epitope retrieval (PIER) were found highly effective in retrieval of tedious antigens of lymphangiogenesis and angiogenesis. The use of combined antigen retrieval technique for the unmasking of antigens from over fixed, old formalin fixed paraffin embedded (FFPE) canine mammary tumour sections resulted in efficient unmasking of epitopes when compared with the individual antigen retrieval methods.