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PubMed2004

A method for the isolation of glomerular and tubulointerstitial endothelial cells and a comparison of characteristics with the human umbilical vein endothelial cell model.

BACKGROUND: Abnormalities in the structure and function of glomerular endothelial cells play a pivotal role in the development of progressive renal disease. The vascular abnormalities observed in the renal tubulointerstitium, however, correlate more strongly with progressive renal failure. Therefore, the successful isolation and culture of human renal microvascular endothelial cells from both the glomerulus and tubulointerstitium are paramount in studying renal disease models. METHODS AND RESULTS: This study describes a simple and reproducible method for the isolation of human tubulointerstitial and glomerular endothelial cells by using immunomagnetic separation with anti-platelet endothelial-cell adhesion (anti-PECAM-1) Dyna beads, followed by manual weeding of mesangial and fibroblast contamination. No significant changes in morphological or immunohistochemical characteristics were observed up to passage two of culture. The in vitro characteristics of the endothelial cells were compared to the renal cortical endothelial cells in vivo and the standard human umbilical vein endothelial cell model (HUVECs). Similar to HUVECs, both populations of renal microvascular endothelial cells had a classical cobblestone appearance, stained positively for von Willebrand Factor and PECAM-1 and negatively for antifibroblast surface antigen and anticytokeratin. Differences in the expression of von Willebrand Factor, Wiebel Palade bodies and Flk-1 staining were observed between glomerular and tubulointerstitial endothelial cells. These immunohistochemical characteristics suggested that tubulointerstital endothelial cells were more closely aligned to HUVECS than to the glomerular endothelial cells. This observation indicated that HUVECs may be a suitable model for determining the tubulointerstitial endothelial response to systemic injury. CONCLUSION: In conclusion, a unique and novel method for the differential isolation of both glomerular and tubulointerstitial endothelial cells has been developed. Significantly, characterization of these populations suggests a role for HUVECS in the study of renal tubulointerstitial disease.

Antigens, Surface↗

PubMed2001

Vascular endothelial growth factor and vascular endothelial growth factor receptor-2 expression in the chick embryo area vasculosa.

Vascular endothelial growth factor is an angiogenic factor in vivo and in vitro that plays a crucial role in the control of blood vessel development and in pathological angiogenesis. The vascularized extraembryonic membranes of the chick embryo include the area vasculosa and the chorioallantoic membrane. In this study, we investigated the expression of vascular endothelial growth factor and of its receptor-2, specifically expressed by the endothelial cells, in the chick area vasculosa at days 6, 10 and 14 of incubation. Our results indicate that, in all the three developmental stages examined, vascular endothelial growth factor is clearly expressed in the endodermal cells immediately adjacent to the mesodermal endothelial cells which, in turn, expressed vascular endothelial growth factor receptor-2. These observations suggest that during the development of the vascular system, endodermal cells, expressing vascular endothelial growth factor, initiate angiogenesis by stimulating directly mesodermal cells, which express vascular endothelial growth factor receptor-2. Moreover, our data demonstrate that vascular endothelial growth factor receptor-2 expression is also maintained by endothelial cells in the later stages of development, until day 14 of incubation. In accord with other literature data, this suggests that vascular endothelial growth factor is required not only for proliferation, but also for the survival of endothelial cells.

Allantois↗

PubMed1999

Role of endothelial nitric oxide synthase in endothelial cell migration.

Endothelium-derived nitric oxide (NO) and its precursor L-arginine have been implied to promote angiogenesis, but little is known about the precise mechanism. The inhibition of endogenous NO formation by Nomega-nitro-L-arginine methyl ester (L-NAME) (1 mmol/L) but not its inactive enantiomer D-NAME (1 mmol/L) inhibited endothelial cell sprouting from the scratched edge of the cultured bovine aortic endothelial cell monolayer. Inhibition of endogenous NO release by L-NAME was confirmed by amperometric measurement using an NO-specific electrode. In the modified Boyden chamber, L-NAME (1 mmol/L) significantly inhibited endothelial cell migration, whereas L-NAME did not affect endothelial DNA synthesis as assessed by analysis of [3H]thymidine incorporation. We then examined alteration of endothelial cell adhesion molecule expression after the inhibition of NO by L-NAME in cultured human umbilical vein endothelial cells. In both normoxic and hypoxic conditions, L-NAME (1 mmol/L) inhibited surface expression of integrin alphavbeta3, which is an important integrin facilitating endothelial cell survival and angiogenesis. However, L-NAME did not affect the expression of platelet endothelial cell adhesion molecule-1, intercellular adhesion molecule-1, vascular endothelial adhesion molecule-1, gap junction protein connexin 43, and VE-cadherin, which have been reported to potentially affect angiogenesis. In summary, inhibition of endothelial NO synthase by L-NAME attenuated endothelial cell migration but not proliferation in vitro. Furthermore, endogenous endothelium-derived NO maintains the functional expression of integrin alphavbeta3, a mediator for endothelial migration, survival, and angiogenesis. Endothelium-derived NO, thus, may play an important role in mediating angiogenesis by supporting endothelial cell migration, at least partly, via an integrin-dependent mechanism.

Animals↗

PubMed2000

The effects of vascular endothelial growth factor on endothelial cells: a potential role in preeclampsia.

OBJECTIVES: Preeclampsia is primarily a disorder of the maternal endothelium. An as yet unidentified circulating factor causes widespread alteration in endothelial function, and levels of vascular endothelial growth factor are elevated in preeclampsia. We hypothesized that vascular endothelial growth factor is involved in the alteration of endothelial function and set out to find further evidence for this contention. STUDY DESIGN: Bovine microvascular endothelial cells (B-88) were cultured in vitro. These cultured cells were then stimulated with vascular endothelial growth factor and with plasma from women with preeclampsia in the presence and absence of anti-vascular endothelial growth factor antibody. Prostacyclin, nitric oxide, and lactate dehydrogenase levels were measured. RESULTS: Vascular endothelial growth factor induced a significant concentration-dependent increase in prostacyclin production but not nitric oxide production. Cells stimulated with plasma from women with preeclampsia showed increases in production of both prostacyclin and nitric oxide. Vascular endothelial growth factor concentration in plasma was correlated with prostacyclin production by stimulated cells. The increase in prostacyclin production that usually followed the addition of plasma did not occur when anti-vascular endothelial growth factor antibody was present. CONCLUSIONS: Vascular endothelial growth factor has the ability to alter endothelial cell function in a manner analogous to that of plasma from women with preeclampsia.

Animals↗

PubMed2005

Potential autocrine function of vascular endothelial growth factor in head and neck cancer via vascular endothelial growth factor receptor-2.

Vascular endothelial growth factor is a peptide with well-defined actions on the vasculature and fundamental role in tumor angiogenesis. Its action in vascular endothelium is exerted in a paracrine manner. The immunohistochemical expression of this protein by cancer cells in head and neck squamous cell carcinoma was correlated with increased tumor aggressiveness and poor survival in previous studies. In the past years, an increasing amount of studies demonstrated potential autocrine action of vascular endothelial growth factor in various neoplasms. However, the existence and the impact of such autocrine action in head and neck cancer have not been demonstrated yet. In this retrospective study, we evaluated the expression of vascular endothelial growth factor and its receptors in neoplastic cells, in a cohort of patients with head and neck squamous cell carcinoma, and compared this expression with tumor aggressiveness, clinicopathologic parameters and outcome. High expression of vascular endothelial growth factor was strongly correlated with high expression of vascular endothelial growth factor receptor-2 (but not vascular endothelial growth factor receptor-1) on the cancer cells (P<0.001). The co-overexpression of both the protein and vascular endothelial growth factor receptor-2 was associated with higher tumor proliferation rate (P<0.001). The above co-overexpression also correlated with worse survival (log rank P<0.05) in patients with oral-larynx squamous cell carcinoma. Our results suggest that an autocrine vascular endothelial growth factor loop, mediated via vascular endothelial growth factor receptor-2, probably exists in head and neck squamous cell carcinoma. These observations support the hypothesis that the use of vascular endothelial growth factor receptor-2 inhibitors as adjuvant antiangiogenic therapy might have beneficial effects for these patients, by disrupting both paracrine (endothelial-dependent) and autocrine actions of vascular endothelial growth factor.

Adult↗

PubMed1996

Ultrastructural study of perivascular nerve fibres and endothelial cells of the rat basilar artery immunolabelled with monoclonal antibodies to neuronal and endothelial nitric oxide synthase.

The ultrastructural distribution of neuronal (type I) and endothelial (type III) isoforms of nitric oxide synthase in perivascular axons and endothelial cells was examined in the Wistar rat cerebral basilar artery, employing monoclonal antibodies specific either to type I or type III of nitric oxide synthase in pre-embedding peroxidase-antiperoxidase immunocytochemistry. Both neuronal and endothelial nitric oxide synthase were localized in similar proportions of perivascular axons (25.2% +/- 2.8 and 28.7% +/- 6.5, respectively) but in different proportions in vascular endothelial cells (6.2% +/- 0.9 and 27.1% +/- 2.4, respectively). The intracellular distribution of immunoreactivity to neuronal and endothelial nitric oxide synthase was similar both in axons and endothelial cells; e.g. the labelling of the membranes of mitochondria and synaptic/cytoplasmic vesicles. However, the intensity of immunoreactivity was most prominent in profiles positive for endothelial nitric oxide synthase. The neuronal and endothelial nitric oxide synthase-positive axon varicosities were characterized by the presence of small spherical agranular vesicles; agranular vesicles in nerve varicosities positive for neuronal nitric oxide synthase were significantly larger than those in nerve varicosities positive for endothelial nitric oxide synthase (43.2 nm +/- 0.5 versus 37.7 nm +/- 0.8; p < 0.001). Varicosities positive for endothelial nitric oxide synthase also contained large granular vesicles (116.6 nm +/- 5.9) with labelled cores. In conclusion, the present data demonstrate that monoclonal antibodies to neuronal and endothelial nitric oxide synthase immunoreact with subpopulations of both perivascular axons and endothelial cells of rat basilar artery. The significance of neuronal and endothelial isoforms of nitric oxide synthase for the basilar artery is discussed.

Animals↗

PubMed1992

Electrical method for detection of endothelial cell shape change in real time: assessment of endothelial barrier function.

We have developed an electrical method to study endothelial cell shape changes in real time in order to examine the mechanisms of alterations in the endothelial barrier function. Endothelial shape changes were quantified by using a monolayer of endothelial cells grown on a small (10(-3) cm2) evaporated gold electrode and measuring the changes in electrical impedance. Bovine pulmonary microvessel endothelial cells and bovine pulmonary artery endothelial cells were used to study the effects of alpha-thrombin on cell-shape dynamics by the impedance measurement. alpha-Thrombin produced a dose-dependent decrease in impedance that occurred within 0.5 min in both cell types, indicative of retraction of endothelial cells and widening of interendothelial junctions because of "rounding up" of the cells. The alpha-thrombin-induced decrease in impedance persisted for approximately 2 hr, after which the value recovered to basal levels. Pretreatment of endothelial cells with the protein kinase C inhibitor, calphostin C, or with 8-bromoadenosine 3',5'-cyclic monophosphate prevented the decreased impedance, suggesting that the endothelial cell change is modulated by activation of second-messenger pathways. The alpha-thrombin-induced decrease in impedance was in agreement with the previously observed increases in transendothelial albumin permeability and evidence of formation of intercellular gaps after alpha-thrombin challenge. The impedance measurement may be a valuable in vitro method for the assessment of mechanisms of decreased endothelial barrier function occurring with inflammatory mediators. Since the rapidly occurring changes in endothelial cell shape in response to mediators such as thrombin are mediated activation of second-messenger pathways, the ability to monitor endothelial cell dynamics in real time may provide insights into the signal-transduction events mediating the increased endothelial permeability.

Animals↗

PubMed1998

Neutrophil-derived 5'-adenosine monophosphate promotes endothelial barrier function via CD73-mediated conversion to adenosine and endothelial A2B receptor activation.

During episodes of inflammation, polymorphonuclear leukocyte (PMN) transendothelial migration has the potential to disturb vascular barrier function and give rise to intravascular fluid extravasation and edema. However, little is known regarding innate mechanisms that dampen fluid loss during PMN-endothelial interactions. Using an in vitro endothelial paracellular permeability model, we observed a PMN-mediated decrease in endothelial paracellular permeability. A similar decrease was elicited by cell-free supernatants from activated PMN (FMLP 10(-6) M), suggesting the presence of a PMN-derived soluble mediator(s). Biophysical and biochemical analysis of PMN supernatants revealed a role for PMN-derived 5'-adenosine monophosphate (AMP) and its metabolite, adenosine, in modulation of endothelial paracellular permeability. Supernatants from activated PMN contained micromolar concentrations of bioactive 5'-AMP and adenosine. Furthermore, exposure of endothelial monolayers to authentic 5'-AMP and adenosine increased endothelial barrier function more than twofold in both human umbilical vein endothelial cells and human microvascular endothelial cells. 5'-AMP bioactivity required endothelial CD73-mediated conversion of 5'-AMP to adenosine via its 5'-ectonucleotidase activity. Decreased endothelial paracellular permeability occurred through adenosine A2B receptor activation and was accompanied by a parallel increase in intracellular cAMP. We conclude that activated PMN release soluble mediators, such as 5'-AMP and adenosine, that promote endothelial barrier function. During inflammation, this pathway may limit potentially deleterious increases in endothelial paracellular permeability and could serve as a basic mechanism of endothelial resealing during PMN transendothelial migration.

5'-Nucleotidase↗

PubMed1996

Gamma interferon protects endothelial cells from damage by Candida albicans by inhibiting endothelial cell phagocytosis.

Once Candida albicans comes in contact with endothelial cells, it induces cellular injury. This endothelial cell injury may be a mechanism by which blood-borne organisms escape from the intravascular compartment and invade the tissue parenchyma during hematogenous infection. We have been investigating the ability of cytokines to modulate endothelial cell injury caused by C. albicans. Previously we reported that pretreatment of endothelial cells with gamma interferon (IFN-gamma) protects these cells from candidal injury in vitro. In the current study, we examined potential mechanisms of the cytoprotective effects of IFN-gamma. Time course experiments demonstrated that maximal reduction in candidal injury of endothelial cells occurred after the endothelial cells had been exposed to IFN-gamma for at least 72 h. In other studies, we determined that IFN-gamma reduced endothelial cell phagocytosis of C. albicans by 41.3% compared with that of untreated endothelial cells (P < 0.01). Since endothelial cell phagocytosis of C. albicans is required for damage to occur, inhibition of phagocytosis is likely a mechanism by which IFN-gamma protects endothelial cells from candidal injury. We also found that the cytoprotective effect of IFN-gamma is not mediated by reducing access of the organisms to intracellular endothelial cell iron or by upregulating the synthesis of reactive oxygen intermediates (which could potentially reduce the ability of C. albicans to injure endothelial cells). Thus, inhibiting endothelial cell phagocytosis of C. albicans may be a mechanism by which IFN-gamma augments the host defense against hematogenously disseminated candidal infections.

Antioxidants↗

PubMed1994

Lysophosphatidylcholine in oxidized low-density lipoprotein increases endothelial susceptibility to polymorphonuclear leukocyte-induced endothelial dysfunction in porcine coronary arteries. Role of protein kinase C.

We have shown that transferred lysophosphatidylcholine (lysoPC) from oxidized low-density lipoprotein (Ox-LDL) to endothelial surface membrane activates protein kinase C (PKC) in endothelial cells, suggesting that Ox-LDL could alter endothelial functions through PKC activation. The purposes of the present study were to examine whether the endothelial susceptibility to polymorphonuclear leukocytes (PMNs) may be altered in Ox-LDL-treated coronary arteries, which have properties closely resembling those observed in atherosclerotic arteries, and to determine the mechanism(s) by which Ox-LDL may affect the endothelial susceptibility to PMNs. Isolated porcine coronary arteries were cannulated and perfused with oxygenated culture medium with or without LDLs or lipids at a constant flow (37 degrees C, pH 7.4). The treatment of porcine coronary arteries with Ox-LDL increased endothelial adhesiveness to PMNs and augmented PMN-induced impairment of endothelium-dependent arterial relaxation (EDR). Furthermore, Ox-LDL stimulated the expression of intercellular adhesion molecule-1 (ICAM-1) in the porcine coronary arterial endothelium. These effects of Ox-LDL were not mediated by the scavenger-receptor-mediated process but were attributed to lysoPC in Ox-LDL. Blocking of the PMN adherence to endothelium by using anti-CD18 monoclonal antibody abolished the PMN-induced impairment of EDR. Coincubation with staurosporine or calphostin C, inhibitors of PKC, during treatment of the arteries with Ox-LDL or lysoPC attenuated the augmentative effects of Ox-LDL and lysoPC on endothelial ICAM-1 expression, endothelial adhesiveness to PMNs, and PMN-induced EDR impairment. Treatment of the arteries with phorbol 12-myristate 13-acetate, a potent stimulator of PKC, induced ICAM-1 expression and enhanced the endothelial adhesiveness to PMNs and PMN-induced EDR impairment, mimicking the effects of Ox-LDL. These results suggest that lysoPC in Ox-LDL induces endothelial ICAM-1 expression, which facilitates PMN adherence to endothelium and the subsequent augmentation of PMN-induced EDR impairment. PKC activation in endothelial cells by lysoPC in Ox-LDL may at least in part be involved in these effects of Ox-LDL. LysoPC in Ox-LDL increases endothelial susceptibility to PMN-induced endothelial dysfunction.

Animals↗

PubMed1995

cGMP and nitric oxide modulate thrombin-induced endothelial permeability. Regulation via different pathways in human aortic and umbilical vein endothelial cells.

Previous studies have demonstrated that cGMP and cAMP reduce the endothelial permeability for fluids and macromolecules when the endothelial permeability is increased by thrombin. In this study, we have investigated the mechanism by which cGMP improves the endothelial barrier function and examined whether nitric oxide (NO) can serve as an endogenous modulator of endothelial barrier function. Thrombin increased the passage of macromolecules through human umbilical vein and human aortic endothelial cell monolayers and concomitantly increased [Ca]2+ in vitro. Inhibition of these increases by the intracellular Ca2+ chelator BAPTA indicated that cytoplasmic Ca2+ elevation contributes to the thrombin-induced increase in endothelial permeability. The cGMP-dependent protein kinase activators 8-bromo-cGMP (8-Br-cGMP) and 8-(4-chlorophenylthio)cGMP (8-PCPT-cGMP) decreased the thrombin-induced passage of macromolecules. Two pathways accounted for this observation. Activation of cGMP-dependent protein kinase by 8-PCPT-cGMP decreased the accumulation of cytoplasmic Ca2+ in aortic endothelial cells and hence reduced the thrombin-induced increase in permeability. On the other hand, in umbilical vein endothelial cells, cGMP-inhibited phosphodiesterase (PDE III) activity was mainly responsible for the cGMP-dependent reduction of endothelial permeability. The PDE III inhibitors Indolidan (LY195115) and SKF94120 decreased the thrombin-induced increase in permeability by 50% in these cells. Thrombin treatment increased cGMP formation in the majority of, but not all, cell cultures. Inhibition of NO production by NG-nitro-L-arginine methyl ester (L-NAME) enhanced the thrombin-induced increase in permeability, which was restricted to those cell cultures that displayed an increased cGMP formation after addition of thrombin. Simultaneous elevation of the endothelial cGMP concentration by atrial natriuretic factor, sodium nitroprusside, or 8-Br-cGMP prevented the additional increase in permeability induced by L-NAME. These data indicate that cGMP reduces thrombin-induced endothelial permeability by inhibition of the thrombin-induced Ca2+ accumulation and/or by inhibition of cAMP degradation by PDE III. The relative contribution of these mechanisms differs in aortic and umbilical vein endothelial cells. NO can act in vitro as an endogenous permeability-counteracting agent by raising cGMP in endothelial cells of large vessels.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1985

Influence of anti-endothelial cell antibodies on the interactions of leukocytes with vascular endothelial cells in vitro.

The role of mononuclear cells in antibody-mediated endothelial cell damage and vascular diseases is not well understood when compared to our understanding of the role of neutrophil-mediated endothelial injury in vascular diseases. Thus we initiated these in-vitro studies to investigate the interactions of leukocytes (neutrophils and mononuclear cells) with vascular endothelial cells in the presence and absence of antiendothelial cell antibodies (anti-red blood cell antiserum-anti-RBC). Cultured endothelial cells were isolated from bovine pulmonary artery. The effects of unfractionated and fractionated human leukocytes (neutrophils, mononuclear cells, or lymphocytes) on endothelial cell viability was examined both quantitatively (51Cr release) and qualitatively (electron microscopy). Results from these studies indicated that the interactions of mononuclear cells and lymphocytes with antibody-coated endothelial cells resulted in a significant endothelial cell lysis within 1 to 6 hours of reactions. Neutrophils, on the other hand, failed to induce significant endothelial cell damage compared to mononuclear cells and lymphocytes when tested under similar conditions. In the absence of anti-RBC antibodies, all cell types (neutrophils, mononuclear cells, or lymphocytes) did not produce detectable endothelial damage. Additionally, the effectiveness of mononuclear cells to injure antibody-labeled endothelial cells was confirmed by ultrastructural examination. Similar studies, utilizing leukocytes obtained from patients with atherosclerosis disease, were also undertaken. In these studies we found that, again, only mononuclear cells and lymphocytes wer capable of inducing damage to endothelial cells precoated with antibodies. In summary, our results demonstrate the ability of mononuclear cells and lymphocytes to induce significant damage to antibody-coated endothelial cells. This finding suggests a major role of mononuclear leukocytes in vascular endothelial destruction in diseases that are characterized by the presence of circulating autoantibodies in serum and the adhesion of mononuclear cells to the vascular wall. Such diseases include vasculitis, allograft rejection, serum sickness, and perhaps atherosclerosis particularly in patients with autoimmune diseases.

Animals↗

PubMed2006

A new ATP-sensitive potassium channel opener protects endothelial function in cultured aortic endothelial cells.

OBJECTIVE: Endothelial dysfunction is an early risk factor for cardiovascular disease and hypertension. Mechanisms that participate in endothelial dysfunction include reduced nitric oxide (NO) generation and increased endothelin-1 (ET-1) generation. Endothelial ATP-sensitive potassium (K(ATP)) channels are responsible for maintaining the resting potential of endothelial cells and modulating the release of vasoactive compounds. We hypothesized that activation of endothelial K(ATP) channels might result in the protection against endothelial dysfunction. METHODS: Using cultured bovine or rat aortic endothelial cells, we examined the effects of a new K(ATP) channels opener, iptakalim, on the secretion of vasoactive substances. We also investigated its effects on the expression of adhesion molecules in metabolically disturbed cultured endothelial cells. RESULTS: In cultured aortic endothelial cells, iptakalim caused a concentration-dependent inhibition of ET-1 release and synthesis that correlated with reduced levels of mRNA for ET-1 and endothelin-converting enzyme. These effects of iptakalim were significantly inhibited by pretreatment with glibenclamide (a K(ATP) channel blocker) for 1 h. Similarly, iptakalim enhanced the release of NO in a concentration-dependent manner and increased basal levels of free intracellular calcium. Iptakalim at the concentrations of 100 and 1000 microM increased the activities of NO synthase (NOS) significantly. After the activity of NOS was blocked by L-N(omega)-nitro-arginine methyl ester (L-NAME), the inhibition of iptakalim on ET-1 release was abolished. In endothelial cell models of metabolic disturbance induced by low-density lipoprotein, homocysteine, or hyperglycemia, treatment with iptakalim could inhibit the overexpression of monocyte chemoattractant protein-1 (MCP-1), Intercellular adhesive molecule-1 (ICAM-1), and vascular cell adhesive molecule-1 (VCAM-1) mRNA. CONCLUSION: Iptakalim is a promising drug that could protect against endothelial dysfunction through activating K(ATP) channels in endothelial cells.

ATP-Binding Cassette Transporters↗

PubMed2005

Stability of vision, topography, and endothelial cell density from 1 year to 2 years after deep lamellar endothelial keratoplasty surgery.

PURPOSE: To evaluate whether the visual, topographic, and endothelial cell count results observed 1 year after deep lamellar endothelial keratoplasty (DLEK) surgery remain stable up to 2 years after surgery. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Twenty eyes of 20 patients with corneal edema from Fuchs' endothelial dystrophy. METHODS: Deep lamellar endothelial keratoplasty endothelial replacement surgery, with a 9.0-mm or 9.5-mm scleral access incision and a specialized intrastromal trephine, was performed. Snellen visual acuities, corneal topography, and endothelial cell counts were prospectively measured preoperatively and 1 year and 2 years after DLEK. MAIN OUTCOME MEASURES: Uncorrected and best spectacle-corrected visual acuity (BSCVA), refractive and topographic astigmatism, mean corneal curvature, topographic regularity and symmetry, and endothelial cell density. RESULTS: At 1 year postoperatively, BSCVA averaged 20/50 (range, 20/25-20/200), spherical equivalents (SE) averaged -0.194+/-1.521 diopters (D), manifest refraction (MR) astigmatism averaged 2.04+/-1.05 D (range, 0.0-4.0 D), topographic astigmatism averaged 2.3+/-1.1 D, mean corneal curvature was 43.2+/-1.8 D, the surface regularity index (SRI) averaged 1.16+/-0.41, and the surface asymmetry index (SAI) averaged 1.05+/-1.09. At 2 years postoperatively, BSCVA averaged 20/48 (range, 20/25-20/200), SE averaged -0.369+/-1.267 D, MR astigmatism averaged 1.76+/-0.66 D (range, 0.75-3.0 D), topographic astigmatism averaged 2.4+/-1.1 D, mean corneal curvature was 43.6+/-1.8 D, the SRI averaged 1.13+/-0.44, and the SAI averaged 0.76+/-0.59. There was no significant change in visual or topographic parameters between 1 year and 2 years postoperatively (P>0.05). Endothelial cell counts averaged 2335+/-468 cells/mm(2) at 1 year and 2151+/-457 cells/mm(2) at 2 years postoperatively (P = 0.041). CONCLUSIONS: Deep lamellar endothelial keratoplasty provides stable refractions, corneal topography, and endothelial cell densities as long as 2 years after surgery. The absence of corneal sutures in this technique seems to prevent the sutures in/sutures out changes in SE refractions and corneal topography sometimes seen after penetrating keratoplasty (PK). Deep lamellar endothelial keratoplasty is, therefore, an excellent alternative to PK for patients with endothelial dystrophies.

Aged↗

PubMed2002

[Chronic endothelial cell loss of the graft after penetrating keratoplasty: influence of endothelial cell migration from graft to host].

BACKGROUND: Chronic endothelial cell loss of the graft is common after penetrating keratoplasty. Some kind of subclinical immunological reaction that is not visible at the slitlamp has been suspected as main cause for this phenomenon. Furthermore, migration of graft endothelial cells towards the host cornea has been discussed to add to this loss in special cases. In this study, 3 homogenous patient groups with similar risk of immunological reactions were examined. Main difference between these groups was the potential of graft endothelial cells to migrate towards the host cornea. PATIENTS AND METHODS: Patients with keratoconus without cataract surgery (group I with little migration potential, n = 273), patients with Fuchs endothelial dystrophy without/with cataract surgery (groups IIa/IIb with moderate migration potential, n = 89/n = 165) and patients with bullous keratopathy after cataract surgery (group III with potentially large migration tendency, n = 188) were included in the study. All patients had a first keratoplasty. Patients with glaucoma or further intraocular procedures after keratoplasty were excluded from the study. Clear graft survival and ratio of grafts without immune reactions were estimated according to Kaplan and Meier. Endothelial analysis concerned only patients without immune reactions and with at least 3 postoperative endothelial cell density values of the graft center (76 patients in I, 18 patients in IIa, 41 patients in IIb and 23 patients in III). RESULTS: Mean relative loss of endothelial cells per year was 14.0 +/- 19.0 % in group I, 17.0 +/- 19.1 % in group IIa, 20.8 +/- 18.2 % in group IIb and 29.4 +/- 17.6 % in group III (ANOVA, p < 0.01). Five years postoperatively in group I 99 %, in group IIa 98 %, in group IIb 93 % and in group III 69 % of the grafts were centrally clear (log rank test, p < 0.001). In the same period in group I 88 %, in group IIa 86 %, in group IIb 83 % and in group III 81 % of the grafts were free of immune reactions (log rank test, p < 0.05). Reasons for irreversible graft failure were immune reactions (0 in group I; 0 in group IIa; 1 in group IIb; 9 in group III, ), surface disorders (1 in group I; 0 in IIa; 1 in group IIb; 3 in group III) and endothelial failure (0 in group I; 1 in group IIa; 5 in group IIb; 6 in group III) (chi square test, p < 0.01). CONCLUSIONS: In patients with bullous keratopathy endothelial cell loss via migration seems to add significantly to the general chronic loss which is suspected to be immunological. Peripheral migration of endothelial cells, therefore, most probably contributes to limited prognosis of patients with bullous keratopathy in terms of clear graft survival. In consequence, corneal grafts for bullous keratopathy should be as large as immunologically tolerable, and endothelial cell density should be as high as possible in order to counteract this special endothelial loss factor.

Adult↗

PubMed2004

Induction of endothelial nitric oxide synthase expression by melanoma sensitizes endothelial cells to tumor necrosis factor-driven cytotoxicity.

PURPOSE: The cascade of molecular events leading to tumor necrosis factor (TNF)-mediated tumor regression is still incompletely elucidated. We investigated the role of endothelial nitric oxide synthase in determining the tumor-selective activity of TNF. EXPERIMENTAL DESIGN: Using quantitative real-time PCR, endothelial nitric oxide synthase gene levels were measured in melanoma metastases of the skin and normal skin biopsies obtained from 12 patients before undergoing TNF-based therapy. In vitro, the ability of melanoma cells supernatant to affect endothelial nitric oxide synthase transcription by endothelial cells and the influence of nitric oxide synthase inhibition on TNF cytotoxicity toward endothelial cells was evaluated. RESULTS: Endothelial nitric oxide synthase transcript abundance resulted significantly greater in tumor samples rather than in normal skin samples and in patients showing complete response to TNF-based treatment rather than in those showing partial/minimal response. In vitro, melanoma cells' supernatant induced endothelial nitric oxide synthase gene expression by endothelial cells. Nitric oxide synthase inhibition slowed endothelial cells proliferation and, if induced before TNF administration, decreased the cytokine-mediated cytotoxicity on endothelial cells. CONCLUSIONS: Taken together, these findings support the hypothesis that high expression of endothelial nitric oxide synthase in the tumor microenvironment might increase or be a marker for endothelial cells sensitivity to TNF. These observations may have important prognostic and/or therapeutic implications in the clinical setting.

Biopsy↗

PubMed2006

Vascular endothelial growth factor upregulates expression of ADAMTS1 in endothelial cells through protein kinase C signaling.

PURPOSE: ADAMTS1 (a disintegrin and metalloproteinase with thrombospondin motifs) has been demonstrated to inhibit angiogenesis in vivo and to suppress endothelial cell proliferation in vitro. The purpose of this study was to investigate the expression of ADAMTS1 in endothelial cells and in a mouse model of ischemia-induced retinal neovascularization and to study the regulation of ADAMTS1 expression in endothelial cells by vascular endothelial growth factor (VEGF). In addition, the potential function of endothelial cell-derived ADAMTS1 on cell proliferation was investigated. METHODS: Expression of ADAMTS1 in human retinal endothelial cells (HRECs), human umbilical vein endothelial cells (HUVECs), and the mouse model of ischemia-induced retinal neovascularization was assayed by real-time PCR and Western blot analysis. The effect of ADAMTS1 on endothelial cell proliferation was evaluated using siRNA knockdown and [3H] thymidine incorporation. RESULTS: ADAMTS1 mRNA and protein levels were increased in a mouse model of ischemia-induced retinal neovascularization, and VEGF induced time- and dose-dependent increases in ADAMTS1 mRNA and protein expression in endothelial cells. This upregulation was inhibited by the VEGF receptor (VEGFR)2 inhibitor SU1498, anti-VEGFR2 neutralizing antibody, and the phospholipase C (PLC)-gamma inhibitor U73122. VEGF upregulation of ADAMTS1 expression was completely abolished by the inhibition of protein kinase C by calphostin C and largely blocked by the specific inhibition of PKCbeta. Knockdown of endogenous ADAMTS1 resulted in increased proliferation of endothelial cells. CONCLUSIONS: These results indicate that VEGF significantly induces ADAMTS1 expression in endothelial cells in a PKC-dependent fashion. ADAMTS1 expression is also increased, along with VEGF expression, in vivo in ischemia-induced retinal neovascularization. In addition, ADAMTS1 appears to be an endogenous regulator of endothelial cell proliferation. Therefore, VEGF upregulation of ADAMTS1, a potent angiogenesis inhibitor, may represent a mechanism for feedback inhibition of angiogenesis and retinal neovascularization.

ADAM Proteins↗

PubMed1999

Induction of endothelial cell chemotaxis by sphingosine 1-phosphate and stabilization of endothelial monolayer barrier function by lysophosphatidic acid, potential mediators of hematopoietic angiogenesis.

Angiogenesis, the formation of new blood vessels, is an important component of restoration of hematopoiesis after BMT, but the mediators involved in hematopoietic angiogenesis have not been identified. We examined the influence of the lipid growth factors, phosphatidic acid (PA), lysophosphatidic acid (LPA), and sphingosine 1-phosphate (S1P), on several angiogenic properties of endothelial cells, including migration and stabilization of vascular barrier integrity. In a previous study, PA was found to disrupt the permeability of established endothelial monolayers, an early event in the angiogenic response that liberates cells for subsequent mobilization. In the present study, both PA and LPA weakly induced the chemotactic migration of endothelial cells from an established monolayer. The chemotactic response induced by PA and LPA was similar in intensity to that observed with optimal levels of the known protein endothelial cell chemoattractants, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). A markedly greater chemotactic response was effected by nanomolar concentrations of S1P, indicating that this platelet-derived factor plays an important role in a key aspect of angiogenesis, chemotactic migration of endothelial cells. The chemotactic response to S1P was completely inhibited by preincubation of endothelial cells with antisense oligonucleotides to the high-affinity S1P receptor, Edg-1. In addition, chemotaxis of endothelial cells to S1P was inhibited by preincubation of cells with specific inhibitors of tyrosine kinases, but inhibitors of phosphatidylinositol 3' kinase had little effect. Finally, LPA effectively stabilized endothelial monolayer barrier function, a late event in angiogenesis. Thus, the phospholipid growth factors, PA, S1P, and LPA, display divergent and potent effects on angiogenic properties of endothelial cells and angiogenic differentiation of endothelial cells potentially act in tandem to effectively induce neovascularization. These mediators may thus exert important roles in restoration of hematopoiesis, as they facilitate blood vessel formation at sites of transplanted stem cells, allowing the progeny of engrafted progenitors to move from marrow sinusoids to the peripheral vasculature.

Animals↗