[Mild therapeutic hypothermia: Improved survival after resuscitation]. / Milde therapeutische Hypothermie: Verbesserung des Überlebens nach Reanimation.

BACKGROUND: The favorable effect of mild therapeutic hypothermia (MTH) on neurologic status as well as on overall survival was shown in several trials; however, MTH is not readily implemented in daily routine. OBJECTIVE: We examined the effect of the implementation of MTH on neurologic outcome and overall survival in an emergency care hospital. STUDY DESIGN AND METHODS: The data of 68 patients between 09/2010 and 11/2011 who received MTH for 24 h at 33 °C after cardiopulmonary resuscitation (CPR) were compared with prospectively collected data from 180 patients before introduction of MTH (2001-2006). Survival and neurological status at discharge were determined using the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). RESULTS: MTH raised the percentage of patients with a CPC score of 1 or 2 from 70 % to 85 %. Furthermore, survival increased from 47/180 (26 %) between 01/2000 and 01/2006 to 27/68 (40 %) between 09/2010 and 11/2011. DISCUSSION: Implementation of MTH leads to improved neurological status and overall survival after CPR.

Intra-individual head-to-head comparison of Sirolimus®- and Paclitaxel®-eluting stents for coronary revascularization. A randomized, multi-center trial.

BACKGROUND: Despite the known effects of drug-eluting stents (DES), other cofactors attributed to patient characteristics affect their success. Interest focused on designing a study minimizing these factors to answer continuing concerns on the heterogeneity of response to different DESs. The study's aim was to investigate the feasibility and impact of an intra-individual comparison design in patients (pts) with two coronary artery stenosis treated with a Sirolimus- (SES) and a Paclitaxel- (PES) eluting stent. METHODS AND RESULTS: The study was conducted as a prospective, randomized, multi-center trial in 112 pts who consented to treatment with a SES and a PES. Pts were eligible if they suffered from the presence of two single primary target lesions in two different native coronary arteries. Lesions were randomized to either SES or PES treatment. The primary endpoint was in-stent luminal late loss (LLL), as determined by quantitative angiography at 8 months; clinical follow up was obtained at 1, 8, and 12 months additionally. The LLL (0.13 ± 0.28 mm SES vs. 0.26 ± 0.35 mm PES, p=0.011) showed less neointima in SES. With a predefined cut-off criterion of 0.2mm difference in LLL, 53/87 pts SES and PES were similar effective. 34/87 pts had a divergent result, 26 pts had greater benefit from SES while 8 pts had greater benefit from PES. Overall, MACE (MI, TLR, and death) occurred in 19 (17%) pts. Based on lesion analysis of 108 lesions treated with SES and 110 lesions treated with PES, 5 (4.6%) lesions with SES and 3 (2.7%) lesions with PES required repeated TLR. CONCLUSION: An intra-individual comparison design to assess differences in efficacy of different DESs is feasible, safe and achieves similar results to inter-individual studies. This study is among the first to show that failure of one DES does not necessarily implicate failure of another DES and vice versa.

[Anticoagulant therapy for chronic cardiac diseases. Atrial fibrillation, valvular heart disease, congestive heart failure]. / Antikoagulation bei chronischen Herzerkrankungen. Vorhofflimmern, Herzklappenerkrankungen, Herzinsuffizienz.

In cardiology, anticoagulant therapy is absolutely indicated after mechanical valve replacement, but is much more often necessary as a prophylactic measure in atrial fibrillation for prevention of embolic stroke. For more than 50 years, there has been no alternative to the oral application of vitamin K antagonists (VKA), which are known to have a very narrow therapeutic window. Despite being highly effective in preventing embolic stroke, many patients are not adequately treated with VKA, and up to 45% of the time the values lie outside the therapeutic range. The reasons for this might be difficult adjustment of VKA dosage, interactions with drugs and food, the necessity of constant monitoring of the blood coagulation, and the fear of severe bleeding complications. More recently, different anticoagulants binding directly to thrombin or factor Xa have been developed, which allows anticoagulant therapy without the need for numerous coagulation checks, representing a major breakthrough in anticoagulant therapy. In this review, the new guidelines for the use of antithrombotic therapy in atrial fibrillation are presented, followed by a discussion of study results with the new thrombin inhibitors and factor Xa inhibitors for prevention of thromboembolic stroke. Moreover, principles of anticoagulant therapy in valvular heart disease and chronic heart failure are described.

[Angina pectoris and ST-elevation after chemotherapy with 5-fluorouracil]. / Angina Pectoris und ST-Hebungen nach Chemotherapie mit 5-FU.

We report on the case of a 64 year old male who received chemotherapy for a metastatic squamous cell carcinoma of the oropharynx. The chemotherapeutic regimen consisted of 5-fluorouracil (5-FU) and cisplatin. Six hours after completion of the first 24 h continuous infusion of 5-FU, the patient developed severe chest pain accompanied by vegetative symptoms and a pronounced ST-elevation of the precordial leads. Under the suspicion of an acute anterior myocardial infarction an immediate coronary angiogram was performed, demonstrating a total occlusion of the left anterior descending (LAD) coronary artery close to the left main stem. The other coronary arteries appeared smooth. After the intracoronary administration of nitroglycerine, the LAD reopened spontaneously without any residual stenosis, paralleled by complete relief of all symptoms. Therefore, 5-FU induced coronary spasm was diagnosed. After initial therapy with intravenous nitrate followed by oral calcium channel blocker, the patient remained free of symptoms and no rise in cardiac enzymes were noted. The chemotherapeutic regimen was changed to cisplatin plus docetaxel. No new attacks of chest pain occurred and the antivasospastic therapy could be stopped without further events.

[Chest pain, reduced physical activity, and polyserositis in a 35-year old patient with anticonvulsive medication]. / Leistungsknick, Thoraxschmerz und Polyserositis bei einem 35-jährigen Patienten mit antikonvulsiver Therapie.

We report on a rare case of a late-onset drug-induced lupus erythematosus. A 35 year old male patient complained about dyspnea, chest pain and reduced physical activity for three months. His medical history consisted of epilepsy treated with carbamazepine for 20 years. After diagnosis of a large pericardial effusion and percardiocentesis (1200 ml) the diagnosis of viral perimyocarditis was suspected. Under antiphlogistic treatment the symptoms vanished initially. Four weeks later the pericardial effusion recurred and a livedo reticularis became evident. A structural or infectious heart disease, in particular viral myocarditis, was ruled out invasively. Serologic testing revealed antinuclear antibodies and antibodies against histones without presence of antibody against ds-DNA, thereby confirming the diagnosis of carbamazepine-induced lupus erythematodes. After discontinuation of carbamazepine and immunosuppressive medication the patient recovered completely.

[52-year old patient with recurrent syncope and temporary right precordial EKG-changes with fever]. / 52-jähriger Patient mit rezidivierenden Synkopen und temporären rechtspräkordialen EKG-Veränderungen bei Fieber.

This case report highlights the importance of considering the differential diagnosis of a primary electrical cardiac disease in a patient with unexplained syncope. In the absence of positive findings in his cardiac and neurological work-up, the presented patient had been diagnosed with "cryptogenic" epilepsy. During a febrile episode, however, his 12-lead ECG showed ST-segment elevations in leads V(1) and V(2), typical for the Brugada-Syndrome. Hence, his antiepileptic medication was discontinued and the patient received an implantable defibrillator. Pathophysiology, diagnosis, risk stratification, as well as the treatment options for this disease of the cardiac sodium channel are reviewed.

[18-year old patient with anti-epileptic therapy and sudden cardiac death]. / 18-jährige Patientin mit antiepileptischer Therapie und KammerflimmernKasuistik eines hochmalignen LQT2-Syndroms.

An 18-year old female taking anti-epileptic medication was found unconscious in her bed early in the morning. After documented ventricular fibrillation and successful resuscitation, the patient was admitted to our emergency care unit. According to ECG criteria a long-QT syndrome of the subtype 2 was suspected. A few days later, however, the patient died because of hypoxic brain death. From previous hospital reports it turned out that the patient had repeatedly experienced syncopes in the past, which were interpreted as epileptic seizures. Her 17-year old sister and the female twin of her mother had both recently died from sudden cardiac death of unknown cause. An ECG screening in the family revealed six members with LQTS. A genetic analysis revealed in all of them a previously not described rearrangement mutation (888 delG insAA) in the LQT2 gene ( HERG) that was predicted to cause a protein truncation (360X) in the amino acid chain of the I(Kr)-channel subunit. This casuistic contribution exemplifies some classical aspects of LQTS (typical adrenergic trigger mechanism, classical false diagnosis "epilepsy") and demonstrates the possibility of a genotypic classification guided by phenotypic ECG characteristics. It represents an unusual case of a LQTS with a high degree of malignancy, which requires aggressive therapeutic interventions for the family survivors.

[Surgical angioplasty of the left main coronary artery. Evaluation and postoperative follow-up with intravascular ultrasound]. / Ostiumplastik des linken Hauptstammes Indikationsstellung und postoperative Qualitätskontrolle durch Intravaskulären Ultraschall.

We report the case of a 45 year old man presenting to our emergency ward with acute onset of typical chest pain. The ECG showed ST-segment depression in the postero-lateral leads without elevation of any cardiac enzymes. The coronary angiogram showed a three-vessel disease with a subtotal, short stenosis of the right coronary artery and a severe ostial stenosis of the left main coronary artery. An operative revascularization with a venous graft to the right coronary artery and a angioplasty with an autologous vein patch of the left main coronary artery were performed. No peri- or postoperative complications occurred. Because of the importance of the left main coronary artery, the patient underwent an early post-operative coronary angiogram with intravascular ultrasound (IVUS) to confirm the patency of the patch angioplasty. We discuss the historical development, the indications and the main advantages of the patch angioplasty in comparison to conventional CABG procedures. The main issue of the presentation is the special value of IVUS in the pre- and postoperative assessment of the left main coronary artery. Within the last few years, IVUS has emerged from a pure research tool to the gold standard of coronary imaging. It is playing a more and more important role in the assessment of angiographically unclear lesions, mainly in the left main stem and its bifurcation. In addition, IVUS has a large influence in clinical decision making, e.g., reverral to CABG or PCI. It is also a powerful tool for optimizing the operative setting and provides the best possible postoperative control.

Regulation of smooth muscle cell migration and integrin expression by the Gax transcription factor.

Homeobox transcription factors specify body plan by regulating differentiation, proliferation, and migration at a cellular level. The homeobox transcription factor Gax is expressed in quiescent vascular smooth muscle cells (VSMCs), and its expression is downregulated by vascular injury or other conditions that lead to VSMC proliferation. Previous investigations demonstrate that Gax may regulate VSMC proliferation by upregulating the cyclin-dependent kinase (cdk) inhibitor p21. Here we examined whether Gax influences VSMC migration, a key feature in the development of stenotic lesions after balloon injury. Transduction of a Gax cDNA inhibited the migratory response of VSMCs toward PDGF-BB, basic fibroblast growth factor, or hepatocyte growth factor/scatter factor. Gax expression also inhibited migration of NIH.3T3 fibroblasts and embryonic fibroblasts lacking p53. Gax was unable to inhibit the migration of fibroblasts lacking p21, but this effect could be restored in these cells by providing exogenous p21 or by overexpressing another cdk inhibitor, p16. Flow cytometric analysis implicated a Gax-mediated downregulation of alpha(v)beta(3) and alpha(v)beta(5) integrin expression in VSMCs as a potential cause for reduced cell motility. Gax specifically downregulated beta(3) and beta(5) in VSMCs in culture and after acute vascular injury in vivo. Repression of integrin expression was also found in NIH 3T3 cells and p53 knockout fibroblasts, but not in p21-knockout fibroblasts, unless these cells express exogenous p21 or p16. These data suggest that cycle progression, integrin expression, and cell migration can be regulated in VSMCs by the homeobox gene product Gax.

Antibody blockade of thrombospondin accelerates reendothelialization and reduces neointima formation in balloon-injured rat carotid artery.

BACKGROUND: Remodeling of the extracellular matrix plays an important role during the pathogenesis of atherosclerosis and restenosis. The matrix glycoprotein thrombospondin-1 (TSP1) inhibits endothelial cell proliferation and migration in vitro. In contrast, TSP1 facilitates the growth and migration of cultured vascular smooth muscle cells. Accordingly, we investigated the hypothesis that administration of anti-TSP1 antibody could facilitate reendothelialization and inhibit neointimal thickening in balloon-injured rat carotid artery. METHODS AND RESULTS: Sprague-Dawley rats were subjected to left common carotid artery denudation, after which arteries were treated with C6.7 anti-TSP1 or control antibody. Evans blue dye staining 2 weeks after injury disclosed significantly increased reendothelialization in arteries treated with C6.7 antibody compared with the control group, and this effect was associated with increased number of proliferating cell nuclear antigen-positive endothelial cells. In contrast, treatment with C6.7 antibody decreased the number of proliferating cell nuclear antigen-positive vascular smooth muscle cells in the injured arterial wall. Neointimal thickening was correspondingly attenuated to a statistically significant degree in arteries receiving C6.7 antibody versus the control group at both the 2-week and 4-week time points. CONCLUSIONS: Intra-arterial delivery of antibody against TSP1 facilitated reendothelialization and reduced neointimal lesion formation after balloon denudation.

Impaired collateral vessel development associated with reduced expression of vascular endothelial growth factor in ApoE-/- mice.

BACKGROUND: The impact of disordered lipid metabolism on collateral vessel development was studied in apolipoprotein (apo)E-/- mice with unilateral hindlimb ischemia. METHODS AND RESULTS: Hindlimb blood flow and capillary density were markedly reduced in apoE-/- mice versus C57 controls. This was associated with reduced expression of vascular endothelial growth factor (VEGF) in the ischemic limbs of apoE-/- mice. Cell-specific immunostaining localized VEGF protein expression to skeletal myocytes and infiltrating T cells in the ischemic limbs of C57 mice; in contrast, T-cell infiltrates in ischemic limbs of apoE-/- mice were severely reduced. The critical contribution of T cells to VEGF expression and collateral vessel growth was reinforced by the finding of accelerated limb necrosis in athymic nude mice with operatively induced hindlimb ischemia. Adenoviral VEGF gene transfer to apoE-/- mice resulted in marked augmentation of hindlimb blood flow and capillary density. CONCLUSIONS: These findings thus underscore the extent to which hyperlipidemia adversely affects native collateral development but does not preclude augmented collateral vessel growth in response to exogenous cytokines. Moreover, results obtained in the apoE-/- and athymic nude mice imply a critical role for infiltrating T cells as a source of VEGF in neovascularization of ischemic tissues.

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.

Disturbance of myocardial energy metabolism in experimental virus myocarditis by antibodies against the adenine nucleotide translocator.

OBJECTIVE: The adenine nucleotide translocator (ANT) of the inner mitochondrial membrane is an autoantigen in myocarditis and in dilated cardiomyopathy. Clinical and experimental studies showed that specific autoantibodies inhibit the transmembrane nucleotide transport. In isolated hearts of guinea pigs immunized with the ANT, energy metabolism is disturbed. This metabolic disorder is related to functionally active specific antibodies and to a reduced heart function. This study tests whether similar immunological, metabolical and functional responses also occur in experimental virus myocarditis. METHODS AND RESULTS: Experimental virus myocarditis was induced in A.SW/SnJ-mice by Coxsackie B3 virus infection. Specific antibodies against the ANT were detected by Western Blot in 14 out of 19 infected animals. In the isolated perfused hearts of five of these 14 mice cytosolic and mitochondrial ATP/ADP-ratios, determined by nonaqueous fractionation, were significantly altered, signalling a reduced ANT function [cytosolic ATP/ADP: 59 +/- 18 vs. 136 +/- 20 (controls), mitochondrial ATP/ADP: 4.2 +/- 1.0 vs. 1.1 +/- 0.3], all P < 0.05. Also, left ventricular pressure [43 +/- 9 vs. 78 +/- 6 mmHg (noninfected controls)], rate-pressure product (15.8 +/- 3.2 vs. 30.5 +/- 3.0 mmHg/min/1000), dp/dt (2410 +/- 222 vs. 3250 +/- 118 mmHg/s), and oxygen consumption (4.7 +/- 0.9 vs. 7.3 +/- 0.7 mumol/g/min), all P < 0.05, were lowered. CONCLUSION: The data support the hypothesis that a virus infection alters cardiac energy metabolism and function by an antibody-mediated modulation of the function of the ANT.

Vascular endothelial growth factor-C (VEGF-C/VEGF-2) promotes angiogenesis in the setting of tissue ischemia.

Recently, vascular endothelial growth factor-C (VEGF-C or VEGF-2) was described as a specific ligand for the endothelial receptor tyrosine kinases VEGFR-2 and VEGFR-3. In vivo data, limited to constitutive overexpression in transgenic mice, have been interpreted as evidence that the growth-promoting effects of VEGF-C are restricted to development of the lymphatic vasculature. The current studies were designed to test the hypothesis that constitutive expression of VEGF-C in adult animals promotes angiogenesis. In vitro, VEGF-C exhibited a dose-dependent mitogenic and chemotactic effect on endothelial cells, particularly for microvascular endothelial cells (72% and 95% potency, respectively, compared with VEGF-A/VEGF-1). VEGF-C stimulated release of nitric oxide from endothelial cells and increased vascular permeability in the Miles assay; the latter effect was attenuated by pretreatment with the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester. Both VEGFR-2 and VEGFR-3 receptors were shown to be expressed in human saphenous vein and internal mammary artery. The potential for VEGF-C to promote angiogenesis in vivo was then tested in a rabbit ischemic hindlimb model. Ten days after ligation of the external iliac artery, VEGF-C was administered as naked plasmid DNA (pcVEGF-C; 500 microg) from the polymer coating of an angioplasty balloon (n = 8 each) or as recombinant human protein (rhVEGF-C; 500 microg) by direct intra-arterial infusion. Physiological and anatomical assessments of angiogenesis 30 days later showed evidence of therapeutic angiogenesis for both pcVEGF-C and rhVEGF-C. Hindlimb blood pressure ratio (ischemic/normal) after pcVEGF-C increased to 0.83 +/- 0.03 after pcVEGF-C versus 0.59 +/- 0.04 (P < 0.005) in pGSVLacZ controls and to 0.76 +/- 0.04 after rhVEGF-C versus 0.58 +/- 0.03 (P < 0.01) in control rabbits receiving rabbit serum albumin. Doppler-derived iliac flow reserve was 2.7 +/- 0.1 versus 2.0 +/- 0.2 (P < 0.05) for pcVEGF-C versus LacZ controls and 2.9 +/- 0.3 versus 2.1 +/- 0.2 (P < 0.05) for rhVEGF-C versus albumin controls. Neovascularity was documented by angiography in vivo (angiographic scores: 0.85 +/- 0.05 versus 0.51 +/- 0.02 (P < 0.001) for plasmid DNA and 0.74 +/- 0.08 versus 0.53 +/- 0.03 (P < 0.05) for protein), and capillary density (per mm2) was measured at necropsy (252 +/- 12 versus 183 +/- 10 (P < 0.005) for plasmid DNA and 229 +/- 20 versus 164 +/- 20 (P < 0.05) for protein). In contrast to the results of gene targeting experiments, constitutive expression of VEGF-C in adult animals promotes angiogenesis in the setting of limb ischemia. VEGF-C and its receptors thus constitute an apparently redundant pathway for postnatal angiogenesis and may represent an alternative to VEGF-A for strategies of therapeutic angiogenesis in patients with limb and/or myocardial ischemia.

Chemotactic properties of angiopoietin-1 and -2, ligands for the endothelial-specific receptor tyrosine kinase Tie2.

Angiopoietin-1 and its putative natural antagonist, angiopoietin-2, were recently isolated, and the critical role of angiopoietin-1 in embryogenic angiogenesis was demonstrated by targeted gene disruption. Specific biological effects of angiopoietin-1, however, have yet to be defined. In this study we demonstrate that angiopoietin-1, but not angiopoietin-2, is chemotactic for endothelial cells. In contrast, angiopoietin-1 as well as angiopoietin-2 exhibit no proliferative effect on endothelial cells. Excess soluble Tie2, but not Tie1 receptor, abolish the chemotactic response of endothelial cells toward angiopoietin-1. Angiopoietin-2 dose-dependently blocks directed migration toward angiopoietin-1, consistent with the role of angiopoietin-2 as a naturally occurring inhibitor of angiopoietin-1. Fibroblasts stably transfected with Tie2 receptor exhibit chemotactic responses for both angiopoietin-1 and angiopoietin-2. Fibroblasts stably expressing a transfected chimeric receptor consisting of the ectodomain of TrkC fused to the cytoplasmic domain of Tie2 also exhibit a chemotactic response to neurotrophin 3 (NT-3), a specific ligand for TrkC. Endothelial cells are shown to express angiopoietin-2 mRNA and protein, indicating the potential for autocrine activation of angiopoietin/Tie2. Finally, the demonstration that Tie2 as well as angiopoietin-1 are expressed in normal human arteries and veins suggests that the role of angiopoietin/Tie2 may extend beyond embryonic angiogenesis to maintaining integrity of the adult vasculature.

Mouse model of angiogenesis.

Neovascularization of ischemic muscle may be sufficient to preserve tissue integrity and/or function and may thus be considered to be therapeutic. The regulatory role of vascular endothelial growth factor (VEGF) in therapeutic angiogenesis was suggested by experiments in which exogenously administered VEGF was shown to augment collateral blood flow in animals and patients with experimentally induced hindlimb or myocardial ischemia. To address the possible contribution of postnatal endogenous VEGF expression to collateral vessel development in ischemia tissues, we developed a mouse model of hindlimb ischemia. The femoral artery of one hindlimb was ligated and excised. Laser Doppler perfusion imaging (LDPI) was employed to document the consequent reduction in hindlimb blood flow, which typically persisted for up to 7 days. Serial in vivo examinations by LDPI disclosed that hindlimb blood flow was progressively augmented over the course of 14 days, ultimately reaching a plateau between 21 and 28 days. Morphometric analysis of capillary density performed at the same time points selected for in vivo analysis of blood flow by LDPI confirmed that the histological sequence of neovascularization corresponded temporally to blood flow recovery detected in vivo. Endothelial cell proliferation was documented by immunostaining for bromodeoxyuridine injected 24 hours before each of these time points, providing additional evidence that angiogenesis constitutes the basis for improved collateral-dependent flow in this animal model. Neovascularization was shown to develop in association with augmented expression of VEGF mRNA and protein from skeletal myocytes as well as endothelial cells in the ischemic hindlimb; that such reparative angiogenesis is indeed dependent upon VEGF up-regulation was confirmed by impaired neovascularization after administration of a neutralizing VEGF antibody. Sequential characterization of the in vivo, histological, and molecular findings in this novel animal model thus document the role of VEGF as endogenous regulator of angiogenesis in the setting of tissue ischemia. Moreover, this murine model represents a potential means for studying the effects of gene targeting on nutrient angiogenesis in vivo.

Potentiated angiogenic effect of scatter factor/hepatocyte growth factor via induction of vascular endothelial growth factor: the case for paracrine amplification of angiogenesis.

BACKGROUND: Scatter factor/hepatocyte growth factor (SF/HGF) is a pleiotropic growth factor that stimulates proliferation and migration of endothelial cells (ECs) via the c-Met receptor, present on ECs as well as other cell types, including smooth muscle cells (SMCs). We studied the effects of recombinant human (rh) SF/HGF in vitro and in vivo in a rabbit model of hindlimb ischemia. We further compared these effects with those of recombinant human vascular endothelial growth factor (rhVEGF165), an EC-specific mitogen. METHODS AND RESULTS: In vitro, rhSF/HGF and rhVEGF165 exhibited similar effects on proliferation and migration of ECs. When both cytokines were administered together, the result was an additive effect on EC proliferation and a synergistic effect on EC migration. Application of rhSF/HGF to cultures of human SMCs resulted in the induction of VEGF mRNA and protein. In vivo, administration of rhSF/HGF (500 microg x 3) was associated with significant improvements in collateral formation (P<.001) and regional blood flow (P<.0005) and with a significant reduction in muscle atrophy (P<.0001). These effects were significantly more pronounced than those of rhVEGF165 administered according to the same protocol (P<.05). Neither remote angiogenesis nor other pathological sequelae were observed with either rhSF/HGF or rhVEGF165. CONCLUSIONS: The pleiotropic effects of certain growth factors may potentiate angiogenesis via a combination of direct effects on EC proliferation and migration and indirect effects that result in the generation of other potent EC mitogens from non-EC populations. The synergistic effects demonstrated when SF/HGF and VEGF are administered together in vitro may be reproduced in vivo by SF/HGF-induced upregulation of VEGF in vascular SMCs.

Reciprocal relation between VEGF and NO in the regulation of endothelial integrity.

Balloon angioplasty disrupts the protective endothelial lining of the arterial wall, rendering arteries susceptible to thrombosis and intimal thickening. We show here that vascular endothelial growth factor (VEGF), an endothelial cell mitogen, is upregulated in medial smooth muscle cells of the arterial wall in response to balloon injury. Both protein kinase C (PKC) and tyrosine kinase pp60src mediate augmented VEGF expression. In contrast, nitric oxide (NO) donors inhibit PKC-induced VEGF upregulation by interfering with binding of the transcription factor activator protein-1 (AP-1) to the VEGF promoter. Inhibition of VEGF promoter activation suggests that NO secreted by a restored endothelium functions as the negative feedback mechanism that downregulates VEGF expression to basal levels. Administration of a neutralizing VEGF antibody impaired reendothelialization following balloon injury performed in vivo. These findings establish a reciprocal relation between VEGF and NO in the endogenous regulation of endothelial integrity following arterial injury.