Home About us Contact
|
Home About us Contact | ||
|
|
||
Lymphatic Endothelial Cells (lymphatic + endothelial_cell)
Selected AbstractsDevelopment of the avian lymphatic system,MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2001Jörg Wilting Abstract Recently, highly specific markers of the lymphatic endothelium have been found enabling us to reinvestigate the embryonic origin of the lymphatics. Here we present a review of our studies on the development of the lymphatic system in chick and quail embryos. We show that the lymphatic endothelium is derived from two sources: the embryonic lymph sacs and mesenchymal lymphangioblasts. Proliferation studies reveal a BrdU-labeling index of 11.5% of lymph sac endothelial cells by day 6.25, which drops to 3.5% by day 7. Lymphangioblasts are able to integrate into the lining of lymph sacs. Lymphatic endothelial cells express the vascular endothelial growth factor (VEGF) receptors-2 and -3. Their ligand, VEGF-C, is expressed almost ubiquitously in embryonic and fetal tissues. Elevated expression levels are found in the tunica media of large blood vessels, which usually serve as major routes for growing lymphatics. The homeobox gene, Prox1, is expressed in lymphatic but not in blood vascular endothelial cells throughout all stages examined, namely, in developing lymph sacs of day 6 embryos and in lymphatics at day 16. Experimental studies show the existence of lymphangioblasts in the mesoderm, a considerable time before the development of the lymph sacs. Lymphangioblasts migrate from the somites into the somatopleure and contribute to the lymphatics of the limbs. Our studies indicate that these lymphangioblasts already express Prox1. Microsc. Res. Tech. 55:81,91, 2001. © 2001 Wiley-Liss, Inc. [source] Decreased lymphatic vessel counts in patients with systemic sclerosis: Association with fingertip ulcersARTHRITIS & RHEUMATISM, Issue 5 2010Alfiya Akhmetshina Objective Systemic sclerosis (SSc) is a connective tissue disease that is characterized by microvascular disease and tissue fibrosis. Progressive loss and irregular architecture of the small blood vessels are well characterized, but the potential involvement of the lymphatic vessel system has not been analyzed directly in SSc. This study was undertaken to assess whether the lymphatic vascular system is affected in SSc, and whether changes to the lymphatic vessels are associated with dystrophic changes and tissue damage in patients with SSc. Methods Lymphatic endothelial cells in skin biopsy samples from patients with SSc and age- and sex-matched healthy volunteers were identified by staining for podoplanin and prox-1, both of which are specifically expressed in lymphatic endothelial cells but not in blood vascular endothelial cells. CD31 was used as a pan,endothelial cell marker. Statistical analyses were performed using Kruskal-Wallis, Mann-Whitney U, and Spearman's rank correlation tests. Results The numbers of podoplanin- and prox-1,positive lymphatic vessels were significantly reduced in patients with SSc as compared with healthy individuals. The number of podoplanin-positive lymphatic precollector vessels was significantly lower in SSc patients with fingertip ulcers than in SSc patients without ulcers. Moreover, the number of lymphatic vessels correlated inversely with the number of fingertip ulcers at the time of biopsy and with the number of fingertip ulcers per year. The inverse correlation between lymphatic precollector vessel counts and fingertip ulcers remained significant after statistical adjustment for the blood vessel count, age, and modified Rodnan skin thickness score. Conclusion These results demonstrate a severe reduction in the number of lymphatic capillaries and lymphatic precollector vessels in patients with SSc. Patients with decreased lymphatic vessel counts may be at particularly high risk of developing fingertip ulcers. [source] Anti-VEGF-A therapy reduces lymphatic vessel density and expression of VEGFR-3 in an orthotopic breast tumor modelINTERNATIONAL JOURNAL OF CANCER, Issue 10 2007Brandt Whitehurst Abstract Because metastasis contributes significantly to cancer mortality, understanding its mechanisms is crucial to developing effective therapy. Metastasis is facilitated by lymphangiogenesis, the growth of new intratumoral or peritumoral lymphatic vessels from pre-existing vessels. Vascular endothelial growth factor A (VEGF-A) is a well-known angiogenic factor. Increasing evidence implicates VEGF-A in lymphangiogenesis, although the mechanism of its pro-lymphangiogenic effect is poorly understood. We examined the effect of the anti-VEGF-A neutralizing antibody 2C3 on tumor lymphangiogenesis and metastasis in an orthotopic breast carcinoma model using MDA-MB-231 cells and its luciferase-tagged derivative, 231-Luc+ cells. Anti-VEGF-A antibody therapy reduced blood and lymphatic vessel densities by 70% and 80%, respectively, compared with the control antibody. Treatment with 2C3 antibody also decreased incidence of lymphatic and pulmonary metastases by 3.2- and 4.5-fold, respectively. Macrophage infiltration was reduced in 2C3-treated tumors by 32%, but VEGF-C expression was unchanged. In contrast, neoplastic cells and blood vessels in tumors from 2C3-treated mice expressed significantly less angiopoietin-2 (Ang-2) than tumors from control mice. The reduction in Ang-2 was associated with inhibition of VEGFR-3 expression in intratumoral lymphatic endothelial cells. Both VEGF-A and Ang-2 upregulated the expression of VEGFR-3 in cultured lymphatic endothelial cells. VEGF-A induced proliferation of lymphatic endothelial cells was reduced by 50% by soluble Tie-2, suggesting that Ang-2 is an intermediary of the pro-lymphangiogenic VEGF-A effect. These results suggest a novel mechanism by which anti-VEGF-A therapy may suppress tumor lymphangiogenesis and subsequent metastasis supporting the use of anti-VEGF-A therapy to control metastasis clinically. © 2007 Wiley-Liss, Inc. [source] The expression of E-selectin and chemokines in the cultured human lymphatic endothelium with lipopolysaccharidesJOURNAL OF ANATOMY, Issue 5 2008Yoshihiko Sawa Abstract This study investigated the expression of selectins and chemokines in cultured human lymphatic endothelial cells stimulated with lipopolysaccharides. In microarray, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 gene expressions in the lymphatic endothelium with lipopolysaccharides did not change at 0.5 h but increased two- to three-fold at 12 h, whereas E-selectin increased 10-fold at 0.5 h and 68-fold at 12 h compared with untreated cells. The E-selectin mRNA and protein increased in the lymphatic endothelial cells with lipopolysaccharides at more than two-fold levels compared with human umbilical vein endothelial cells. Induction of Cys-Cys chemokine ligand 2, 3, 5, 7, 8 and 20 mRNAs in the lymphatic endothelial cells with lipopolysaccharides was detected in microarray and real-time PCR. The Cys-Cys chemokine ligand 2, 5 and 20 mRNA amounts in cells with high concentration lipopolysaccharides were larger in the lymphatic endothelial cells than in human umbilical vein endothelial cells. The Cys-Cys chemokine ligand 3 and 8 mRNAs were not detected in human umbilical vein endothelial cells. Induction of Cys-X-Cys chemokine ligand 1, 3, 5, 6 and 8 mRNAs was detected in the lymphatic endothelial cells with lipopolysaccharides. The Cys-X-Cys chemokine ligand 3, 5 and 8 mRNA amounts in cells with high concentration lipopolysaccharides were larger in the lymphatic endothelial cells than in human umbilical vein endothelial cells. In conclusion, it was demonstrated that the cultured human lymphatic endothelial cells express E-selectin and phagocyte-attractive chemokine genes. [source] Histochemical analysis of lymphatic endothelial cells in lymphostasisMICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2001Rui-Cheng Ji Abstract The ultrastructure of endothelial cells of intestinal lymphatics and the thoracic duct (TD) and the relation to lymphostasis were examined in rats and monkeys. Localization of 5,-nucleotidase (5,-Nase) and endothelial nitric oxide synthase (eNOS) was studied. In normal lymphatic endothelial cells, 5,-Nase reaction product was evenly deposited on the cell surface in vivo and on cultured TD endothelial cells (TDECs), whereas eNOS was evenly distributed throughout the nucleus and cytoplasm. TDECs had a long filamentous process extending towards the subendothelial extracellular matrix but became flat and regular within 30,40 minutes after gastric perfusion with olive oil. According to their electron-density, two types of cells were found in the TD endothelial layer. The cells with low electron-density exhibited stronger 5,-Nase activity. Valves were bicuspid formations and the valvular endothelial surface of the convex side showed weaker 5,-Nase activity than the concave side. During TD blockage-induced lymphostasis in rats, the 5,-Nase product was almost not discernible in the TDECs within 2 weeks. Larger vesicles were found in the endothelial cytoplasm of the ligated TD. Their number decreased after 6,12 weeks. The small intestinal lymphatics in the mucosa and submucosa were dilated, with numerous open intercellular junctions. The endothelial lining appeared to have reduced activities for 5,-Nase and eNOS in 9 of 11 experimental animals. The results indicated that the inability of the open intercellular junctions, normally working as one-way endothelial flap valves, may be a key morphological feature after TD blockage. Reduced eNOS and 5,-Nase may functionally influence contractile activity and transport capability of the lymphatic vessels in the lymphostasis. Microsc. Res. Tech. 55:70,80, 2001. © 2001 Wiley-Liss, Inc. [source] Ultrastructure and Estrogen Regulation of the Lymphatic Stomata of Ovarian Bursa in MiceTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2007Meng Li Abstract The ovarian bursa is a key player in maintaining adaptive ovarian microenvironment for ovulation. The lymphatic stomata are believed to be a major contributor to execute the function of the ovarian bursa, whereas little is known about their ultrastructure and regulation. Here, we examined the ultrastructure of lymphatic stomata in mouse ovarian bursa by scanning electron microscopy and transmission electron microscopy and investigated its regulation by estrogen. We found that the mesothelium on the visceral layer of mouse ovarian bursa was composed of the cuboidal and flattened cells. The lymphatic stomata with round and oval shapes were mainly among the cuboidal cells. The particles, cells, and fluid passed through the stomata and entered into the lymphatic drainage unit composed of connective tissue and lymphatic endothelial cells beneath the stomata. We also used trypan blue as a tracer and found that the absorption of trypan blue through the lymphatic stomata was increased by estrogen that enlarged the average opening area of lymphatic stomata. Furthermore, we detected that there existed estrogen receptors in the nuclei of the mesothelial cells on the visceral ovarian bursa by using immunoelectron microscopy. Taken together, these data suggest that both the absorption and opening area of the lymphatic stomata in mouse ovarian bursa may be influenced by estrogen. Anat Rec, 290:1195-1202, © 2007 Wiley-Liss, Inc. [source] Prediction of lymphatic invasion by peritumoral lymphatic vessel density in prostate biopsy coresTHE PROSTATE, Issue 10 2008Kenji Kuroda Abstract BACKGROUND Lymphatic invasion in radical prostatectomy specimens has been suggested to be an unfavorable prognostic factor in clinically localized prostate cancer. Lymphangiogenesis detected by antibodies specific for lymphatic endothelial cells has been associated with lymphatic invasion and lymph node metastasis in prostate cancer. This study was designed to examine whether lymphangiogenesis in prostate biopsy could predict lymphatic spread in radical prostatectomy specimens. METHODS Paraffin-embedded positive biopsy cores obtained from 99 patients who underwent radical prostatectomy at our institution were immunostained with D2-40 monoclonal antibody, which specifically recognizes lymphatic endothelium. The association between lymphatic parameters in prostate biopsy and pathological parameters in radical prostatectomy specimens was analyzed. RESULTS Peritumoral and intratumoral lymphatic (ITL) vessels were observed in 90 (90.9%) and 23 cases (23.2%). Average and maximal peritumoral lymphatic vessel density (PTLD) and the presence of ITL in positive biopsy cores were significantly associated with positive biopsy core rates (P,=,0.0015 for average PTLD, P,<,0.0001 for maximal PTLD, and P,=,0.0038 for ITL) and lymphatic vessel invasion (P,<,0.0001 for average PTLD, P,<,0.0001 for maximal PTLD, and P,=,0.0322 for ITL). Among preoperative parameters, the biopsy Gleason score (P,=,0.0092, HR,=,6.108) and average PTLD (P,=,0.0034, HR,=,1.860) were significant predictors of lymphatic invasion in radical prostatectomy specimens in multivariate analysis. CONCLUSIONS PTLD in prostate biopsy specimens assessed by immunohistochemistry using D2-40 antibody could be a useful parameter for predicting lymphatic spread of clinically localized prostate cancer. Prostate 68:1057,1063, 2008. © 2008 Wiley-Liss, Inc. [source] Decreased lymphatic vessel counts in patients with systemic sclerosis: Association with fingertip ulcersARTHRITIS & RHEUMATISM, Issue 5 2010Alfiya Akhmetshina Objective Systemic sclerosis (SSc) is a connective tissue disease that is characterized by microvascular disease and tissue fibrosis. Progressive loss and irregular architecture of the small blood vessels are well characterized, but the potential involvement of the lymphatic vessel system has not been analyzed directly in SSc. This study was undertaken to assess whether the lymphatic vascular system is affected in SSc, and whether changes to the lymphatic vessels are associated with dystrophic changes and tissue damage in patients with SSc. Methods Lymphatic endothelial cells in skin biopsy samples from patients with SSc and age- and sex-matched healthy volunteers were identified by staining for podoplanin and prox-1, both of which are specifically expressed in lymphatic endothelial cells but not in blood vascular endothelial cells. CD31 was used as a pan,endothelial cell marker. Statistical analyses were performed using Kruskal-Wallis, Mann-Whitney U, and Spearman's rank correlation tests. Results The numbers of podoplanin- and prox-1,positive lymphatic vessels were significantly reduced in patients with SSc as compared with healthy individuals. The number of podoplanin-positive lymphatic precollector vessels was significantly lower in SSc patients with fingertip ulcers than in SSc patients without ulcers. Moreover, the number of lymphatic vessels correlated inversely with the number of fingertip ulcers at the time of biopsy and with the number of fingertip ulcers per year. The inverse correlation between lymphatic precollector vessel counts and fingertip ulcers remained significant after statistical adjustment for the blood vessel count, age, and modified Rodnan skin thickness score. Conclusion These results demonstrate a severe reduction in the number of lymphatic capillaries and lymphatic precollector vessels in patients with SSc. Patients with decreased lymphatic vessel counts may be at particularly high risk of developing fingertip ulcers. [source] | |||||||||||||