Effects of edoxaban and warfarin on vascular remodeling: Atherosclerotic plaque progression and collateral artery growth.

BACKGROUND AND PURPOSE: Oral anticoagulation prevents thromboembolism in atrial fibrillation. Factor Xa inhibitors, like edoxaban, are known to reduce inflammation and proliferation of smooth muscle cells, while vitamin K antagonism can cause vascular calcific damage. The influence of edoxaban compared to warfarin on vascular remodeling, atherosclerosis and arteriogenesis is unknown. EXPERIMENTAL APPROACH: Apolipoprotein E knockout (ApoE -/-) mice were fed cholesterol-rich diet alone (control, co), with warfarin+vitamin K1 (warf) or with edoxaban (Edo) for 8 weeks. After 6 weeks, femoral artery ligation was performed. KEY RESULTS: There was no difference in hind-limb perfusion restoration between the three groups after 14 days (Co 0.36 ± 0.05 vs. Warf 0.39 ± 0.09 (p = .39), Co vs. Edo 0.51 ± 0.06 (p = .089), Warf vs. Edo (p = .83)) after ligation. Immuno-histologically, there was no difference in smooth muscle cell count in both hindlimbs between the three groups or in the amount of perivascular macrophages in collateral-bearing hindlimb tissue. Edoxaban showed the lowest amount of plaque tissue in the aortic sinus tissue (Co 74 ± 11% vs. Edo 62 ± 12% (p = .024), Co vs. Warf 69 ± 14% (p = .30), Edo vs. Warf (p = .14)) as well as the least amount of fibrosis (Co 3.1 ± 0.9% vs. Edo 1.7 ± 0.6% (p = .027), Co vs. Warf 4.1 ± 0.7% (p = .081), Edo vs. Warf (p < .001)). No difference in mRNA content of inflammatory cytokines in muscle tissue or spleen was detected between the three groups. CONCLUSION AND IMPLICATIONS: These data suggest that treatment with edoxaban unlike warfarin prevents vascular maladaptive remodeling, which may be clinically important.

Echocardiographic criteria to detect unicuspid aortic valve morphology.

Aims: Unicuspid aortic valve (UAV) is a rare congenital malformation associated with severe aortic stenosis or regurgitation. This study aimed to systematically determine echocardiographic criteria to identify UAV. Methods and results: All patients underwent a preoperative baseline examination, including echocardiography. A total of 69 patients with intraoperatively confirmed UAV underwent an aortic valve repair procedure between August 2001 and May 2011. To compare the findings of UAV cases with those of other valve morphologies, we examined 99 consecutive patients with a bicuspid aortic valve (BAV) and 103 consecutive patients with a tricuspid aortic valve (TAV) undergoing isolated aortic valve surgery before May 2016. The mean age of the 271 patients was 44.2 ± 12.8 years; 85% were male, with a mean body mass index of 26.2 ± 4.0 kg/m2. Patients with UAV were younger and had fewer co-morbidities than patients with BAV or TAV, respectively. The major criteria for the echocardiographic diagnosis of UAV were defined based on our preoperative examination as follows: (i) single commissural attachment zone, (ii) rounded, leaflet-free edge on the opposite side of the commissural attachment zone, (iii) eccentric valvular orifice during systole, and (iv) patient age <20 years and mean transvalvular gradient >15 mmHg. The minor criteria were defined as an associated thoracic aortopathy and age <40 years. Three out of the four major criteria or two out of the four major criteria and one minor criterion were met in all patients with UAV and in none of the patients with BAV or TAV. Associated 95% confidence intervals were calculated for each estimate of sensitivity (94.7-100%) and specificity (98.1-100%), indicating that an adequate number of patients were included in each of the three groups. Conclusion: The proposed echocardiographic score appears to be a specific and sensitive method to distinguish UAV from BAV and TAV.

Long-Term Hemodynamic Improvement after Transcatheter Mitral Valve Repair.

BACKGROUND: Correction of mitral regurgitation (MR) alters the load on the left ventricle. There are few data on the long-term hemodynamic adaptations of the cardiovascular system after transcatheter mitral valve repair (TMVR). The aim of this study was to determine a comprehensive hemodynamic status using noninvasive pressure-volume analysis. METHODS: Pressure-volume parameters were calculated from echocardiography with simultaneous arm-cuff blood pressure measurements at baseline before TMVR and 12 months after TMVR. Eighty-eight consecutive patients undergoing edge-to-edge mitral clip implantation because of grade 3+ or 4+, symptomatic (79.5% in New York Heart Association functional class ≥III) MR were prospectively enrolled. The mean left ventricular (LV) ejection fraction was 42 ± 14%. Sixty-seven percent of the patients had secondary MR. RESULTS: Twelve months after TMVR, 17.7% of patients had died, and 19.0% were rehospitalized because of decompensated heart failure. MR grade was ≤2+ in 90% of surviving patients, and 77% were in New York Heart Association functional class ≤II. LV end-diastolic volume index decreased from 87 ± 38 to 77 ± 40 mL/m2 (P < .0001), end-systolic volume index changed from 54 ± 34 to 50 ± 36 mL/m2 (P = .018), hence total stroke volume index was reduced (from 34 ± 11 to 28 ± 7 ml/m2, P < .0001). Ejection fraction and global longitudinal peak systolic strain remained unchanged. Increased forward ejection fraction (30 ± 14% vs 41 ± 20%, P < .0001), cardiac index (from 1.7 ± 0.4 to 1.9 ± 0.5 mL/min/m2, P = .003), and peak power index (214 ± 114 vs 280 ± 149 mm Hg/sec, P = .0001) as well as similar end-systolic elastance at reduced LV volumes indicated improved LV performance. Cardiac efficiency, measured as cardiac index relative to myocardial energy, was improved (0.012 ± 0.008 vs 0.019 ± 0.010 mm Hg-1, P = .002). Logistic regression analysis revealed baseline values of total ejection fraction and diastolic pulmonary pressure gradient as predictors of clinical improvement (odds ratios, 1.076 [P = .009] and 0.812 [P = .015], respectively) after TMVR. CONCLUSIONS: One year after TMVR, patients showed reverse remodeling and improved LV performance that was associated with improved symptom status. This hemodynamic improvement supports TMVR as long-term effective therapy for patients with symptomatic MR.

Red Wine Prevents the Acute Negative Vascular Effects of Smoking.

BACKGROUND: Moderate consumption of red wine is associated with fewer cardiovascular events. We investigated whether red wine consumption counteracts the adverse vascular effects of cigarette smoking. METHODS: Participants smoked 3 cigarettes alone or after drinking a titrated volume of red wine. Clinical chemistry, blood counts, plasma cytokine enzyme-linked immunosorbent assays, immunomagnetic separation of CD14+ monocytes for gene expression analysis, fluorescence-activated cell sorting for microparticles, and isolation of circulating mononuclear cells to measure telomerase activity were performed, and urine cotinine levels were quantified. RESULTS: Compared with baseline, leukocytosis (P = .019), neutrophilia (P <.001), lymphopenia (P <.001), and eosinopenia (P = .008) were observed after only smoking. Endothelial and platelet-, monocyte-, and leukocyte-derived microparticles (P <.001 each) were elevated. In monocytes, messenger RNA expression of interleukin (IL)-6 (2.6- ± 0.57-fold), tumor necrosis factor alpha (2.2- ± 0.62-fold), and IL-1b (2.3- ± 0.44-fold) were upregulated, as was IL-6 (1.2 ± 0.12-fold) protein concentration in plasma. Smoking acutely inhibited mononuclear cell telomerase activity. Markers of endothelial damage, inflammation, and cellular aging were completely attenuated by red wine consumption. CONCLUSION: Cigarette smoke results in acute endothelial damage, vascular and systemic inflammation, and indicators of the cellular aging processes in otherwise healthy nonsmokers. Pretreatment with red wine was preventive. The findings underscore the magnitude of acute damage exerted by cigarette smoking in "occasional lifestyle smokers" and demonstrate the potential of red wine as a protective strategy to avert markers of vascular injury.

WITHDRAWN: Corrigendum to "Red wine prevents the acute negative vascular effects of smoking".

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Early Hemodynamic Improvement after Percutaneous Mitral Valve Repair Evaluated by Noninvasive Pressure-Volume Analysis.

BACKGROUND: Mitral regurgitation represents a volume load on the left ventricle leading to congestion and symptoms of heart failure. The aim of this study was to characterize early hemodynamic adaptions after percutaneous mitral valve (MV) repair. METHODS: Forty-six consecutive patients with symptomatic high-grade MV insufficiency (mean age, 72 years; 54% men) were prospectively included in the study and examined before and after successful catheter-based clip implantation. Seventy percent of patients had secondary mitral regurgitation. Noninvasive pressure-volume loops were reconstructed from echocardiography with simultaneous blood pressure measurements. RESULTS: MV repair reduced left ventricular end-diastolic volume index from 87 ± 41 to 80 ± 40 mL/m(2) (P < .0001). End-systolic volume index was 55 ± 37 mL/m(2) before versus 54 ± 37 mL/m(2) after repair (P = .52). Hence, total stroke volume decreased from 60 ± 23 to 49 ± 16 mL (P < .0001), as did total ejection fraction (from 41 ± 14% to 37 ± 13%, P = .002) and global longitudinal strain (from -11 ± 4.9% to -9.1 ± 4.4%, P = .0001). Forward stroke volume, forward ejection fraction, and forward cardiac output remained constant (43 ± 12 mL vs 42 ± 11 mL, 33 ± 17% vs 35 ± 18%, and 3.2 ± 0.9 L/min vs 3.4 ± 0.8 L/min, respectively). Parameters of left ventricular contractility (end-systolic elastance and peak power index) and measurements of afterload (arterial elastance, end-systolic wall stress, and total peripheral resistance) were similar before and after MV repair. Forward ejection fraction correlated more strongly with end-systolic elastance (r = 0.61, P < .0001) than did total ejection fraction (r = 0.35, P = .0007) or global longitudinal strain (r = -0.38, P = .0002). Total mechanical energy (pressure-volume area) decreased from 10,903 ± 4,410 to 9,124 ± 2,968 mm Hg × mL (P = .0007) because of reduced stroke work (5,546 ± 2,241 mm Hg × mL vs 4,414 ± 1,412 mm Hg × mL, P < .0001). At 3 months, symptom status had improved (76% of patients in New York Heart Association classes I and II), and 97% of patients had mitral regurgitation grade ≤2+. CONCLUSIONS: Left ventricular contractility and forward cardiac output remained unchanged after percutaneous MV repair despite decreases in total ejection fraction and global longitudinal strain. The left ventricle was unloaded through reduced end-diastolic volume. Thus, MV repair is associated with an improved hemodynamic state in noninvasive pressure-volume analysis.

Exercise promotes collateral artery growth mediated by monocytic nitric oxide.

OBJECTIVE: Collateral artery growth (arteriogenesis) is an important adaptive response to hampered arterial perfusion. It is unknown whether preventive physical exercise before limb ischemia can improve arteriogenesis and modulate mononuclear cell function. This study aimed at investigating the effects of endurance exercise before arterial occlusion on MNC function and collateral artery growth. APPROACH AND RESULTS: After 3 weeks of voluntary treadmill exercise, ligation of the right femoral artery was performed in mice. Hindlimb perfusion immediately after surgery did not differ from sedentary mice. However, previous exercise improved perfusion restoration ≤7 days after femoral artery ligation, also when exercise was stopped at ligation. This was accompanied by an accumulation of peri-collateral macrophages and increased expression of endothelial nitric oxide synthase and inducible nitric oxide synthase (iNOS) in hindlimb collateral and in MNC of blood and spleen. Systemic monocyte and macrophage depletion by liposomal clodronate but not splenectomy attenuated exercise-induced perfusion restoration, collateral artery growth, peri-collateral macrophage accumulation, and upregulation of iNOS. iNOS-deficient mice did not show exercise-induced perfusion restoration. Transplantation of bone marrow-derived MNC from iNOS-deficient mice into wild-type animals inhibited exercise-induced collateral artery growth. In contrast to sedentary controls, thrice weekly aerobic exercise training for 6 months in humans increased peripheral blood MNC iNOS expression. CONCLUSIONS: Circulating mononuclear cell-derived inducible nitric oxide is an important mediator of exercise-induced collateral artery growth.

Therapeutic approaches in the stimulation of the coronary collateral circulation.

Arteriogenesis as a way to restore blood flow after arterial occlusion has been under investigation for the treatment of coronary artery disease (CAD) for decades. Therapeutic approaches so far have included delivery of cytokines and growth factors as well as mechanical stimulation such as external counterpulsation. As knowledge on the mechanisms of arteriogenesis expanded, new therapeutic approaches have emerged. This review summarizes recent attempts to stimulate the growth of the coronary vasculature and discusses their potential in clinical application. This article also delivers an overview of current studies and trials on coronary arteriogenesis.

Differential effects on inhibition of cholesterol absorption by plant stanol and plant sterol esters in apoE-/- mice.

AIMS: 'Functional foods' supplemented with plant sterol esters (PSE) and plant stanol esters (PSA) are therapeutic options for the management of hypercholesterolaemia. However, their effects on blood monocytes, endothelial function, atherogenesis, and sterol tissue concentrations are poorly understood. METHODS AND RESULTS: Male apoE-/- mice (n= 30) were randomized to three different diets for 6 weeks (n= 10 per group): high-cholesterol (1.25%) western-type diet (WTD), WTD + 2% PSE, and WTD + 2% PSA. Both supplements reduced serum cholesterol. WTD + PSE resulted in increased plant sterol serum concentrations and increased inflammatory Ly-6C(high) monocyte numbers. WTD + PSA increased plant stanol serum concentrations and Ly-6C-monocyte numbers, but decreased vascular superoxide release, lipid hydroperoxides, and inflammatory cytokines in aortic tissue, in plasma, and in circulating monocytes. Despite reduced serum cholesterol concentrations, both supplements impaired endothelial vasodilation compared with WTD. WTD + PSA reduced the development of atherosclerotic lesions compared with WTD alone (12.7 ± 3.7 vs. 28.3 ± 3.5%), and WTD + PSE was less effective (17.5 ± 3.7%). WTD + PSE and WTD + PSA reduced the cholesterol content in the liver, but not in the brain. However, WTD + PSE and WTD + PSA increased plant sterol and plant stanol concentrations in the liver as well as in the brain. CONCLUSION: PSE and PSA supplementation reduced serum cholesterol, but increased plant sterol and plant stanol concentrations. Elevated levels of PSE and PSA were associated with endothelial dysfunction and increased central nervous system depositions. Atherosclerotic lesion retardation was more pronounced in WTD + PSA, coinciding with higher regenerative monocyte numbers, decreased oxidative stress, and decreased inflammatory cytokines compared with WTD + PSE.

Leptin augments cerebral hemodynamic reserve after three-vessel occlusion: distinct effects on cerebrovascular tone and proliferation in a nonlethal model of hypoperfused rat brain.

The adipocytokine leptin has distinct functions regulating vascular tone, inflammation, and collateral artery growth. Arteriogenesis is an inflammatory process and provides a mechanism to overcome the effects of vascular obstruction. We, therefore, tested the effects of leptin in hypoperfused rat brain (three-vessel occlusion). Systemic leptin administration for 1 week after occlusion surgery increased cerebral hemodynamic reserve similar to granulocyte-macrophage colony-stimulating factor (GM-CSF), as indicated by improved CO(2) reactivity (vehicle 0.53%±0.26% versus leptin 1.05%±0.6% per mm Hg arterial pCO(2), P<0.05). Infusion of microspheres under maximal vasodilation failed to show a positive effect of leptin on cerebral perfusion (vehicle 64.9%±4.5% versus leptin 66.3%±7.0%, occluded/nonoccluded hemisphere). Acute treatment with GM-CSF led to a significant increased CO(2) reactivity and cerebral perfusion (79.2%±8.1% versus 64.9%±4.5%, P<0.05). Vasoconstrictive response of isolated rat carotid artery rings, after phenylephrine was attenuated at 24 hours following preincubation with leptin, was unaffected by removal of endothelium but abrogated by coculture with N-(omega)-nitro-L-arginine methylester, pointing toward an inducible nitric oxide synthase-mediated mechanism. In chronic cerebral hypoperfusion, acute leptin treatment restored the hemodynamic reserve of the cerebral vasculature through its effects on vascular tone, while leaving vascular outward remodeling unaffected. Our results, for the first time, reveal a protective role of leptin on vascular function in hemodynamically compromised brain tissue.

Blocking interferon {beta} stimulates vascular smooth muscle cell proliferation and arteriogenesis.

Increased interferon (IFN)-ß signaling in patients with insufficient coronary collateralization and an inhibitory effect of IFNß on collateral artery growth in mice have been reported. The mechanisms of IFNß-induced inhibition of arteriogenesis are unknown. In stimulated monocytes from patients with chronic total coronary artery occlusion and decreased arteriogenic response, whole genome expression analysis showed increased expression of IFNß-regulated genes. Immunohistochemically, the IFNß receptor was localized in the vascular media of murine collateral arteries. Treatment of vascular smooth muscle cells (VSMC) with IFNß resulted in an attenuated proliferation, cell-cycle arrest, and increased expression of cyclin-dependent kinase inhibitor-1A (p21). The growth inhibitory effect of IFNß was attenuated by inhibition of p21 by RNA interference. IFNß-treated THP1 monocytes showed enhanced apoptosis. Subsequently, we tested if collateral artery growth can be stimulated by inhibition of IFNß-signaling. RNA interference of the IFNß receptor-1 (IFNAR1) increased VSMC proliferation, cell cycle progression, and reduced p21 gene expression. IFNß signaling and FAS and TRAIL expression were attenuated in monocytes from IFNAR1(-/-) mice, indicating reduced monocyte apoptosis. Hindlimb perfusion restoration 1 week after femoral artery ligation was improved in IFNAR1(-/-) mice compared with wild-type mice as assessed by infusion of fluorescent microspheres. These results demonstrate that IFNß inhibits collateral artery growth and VSMC proliferation through p21-dependent cell cycle arrest and induction of monocyte apoptosis. Inhibition of IFNß stimulates VSMC proliferation and collateral artery growth.

Interferon-beta signaling is enhanced in patients with insufficient coronary collateral artery development and inhibits arteriogenesis in mice.

Stimulation of collateral artery growth in patients has been hitherto unsuccessful, despite promising experimental approaches. Circulating monocytes are involved in the growth of collateral arteries, a process also referred to as arteriogenesis. Patients show a large heterogeneity in their natural arteriogenic response on arterial obstruction. We hypothesized that circulating cell transcriptomes would provide mechanistic insights and new therapeutic strategies to stimulate arteriogenesis. Collateral flow index was measured in 45 patients with single-vessel coronary artery disease, separating collateral responders (collateral flow index, >0.21) and nonresponders (collateral flow index, < or 1). Isolated monocytes were stimulated with lipopolysaccharide or taken into macrophage culture for 20 hours to mimic their phenotype during arteriogenesis. Genome-wide mRNA expression analysis revealed 244 differentially expressed genes (adjusted P, <0.05) in stimulated monocytes. Interferon (IFN)-beta and several IFN-related genes showed increased mRNA levels in 3 of 4 cellular phenotypes from nonresponders. Macrophage gene expression correlated with stimulated monocytes, whereas resting monocytes and progenitor cells did not display differential gene regulation. In vitro, IFN-beta dose-dependently inhibited smooth muscle cell proliferation. In a murine hindlimb model, perfusion measured 7 days after femoral artery ligation showed attenuated arteriogenesis in IFN-beta-treated mice compared with controls (treatment versus control: 31.5+/-1.2% versus 41.9+/-1.9% perfusion restoration, P<0.01). In conclusion, patients with differing arteriogenic response as measured with collateral flow index display differential transcriptomes of stimulated monocytes. Nonresponders show increased expression of IFN-beta and its downstream targets, and IFN-beta attenuates proliferation of smooth muscle cells in vitro and hampers arteriogenesis in mice. Inhibition of IFN-beta signaling may serve as a novel approach for the stimulation of collateral artery growth.

START Trial: a pilot study on STimulation of ARTeriogenesis using subcutaneous application of granulocyte-macrophage colony-stimulating factor as a new treatment for peripheral vascular disease.

BACKGROUND: Granulocyte-macrophage colony-stimulating factor (GM-CSF) was recently shown to increase collateral flow index in patients with coronary artery disease. Experimental models showed beneficial effects of GM-CSF on collateral artery growth in the peripheral circulation. Thus, in the present study, we evaluated the effects of GM-CSF in patients with peripheral artery disease. METHODS AND RESULTS: A double-blinded, randomized, placebo-controlled study was performed in 40 patients with moderate or severe intermittent claudication. Patients were treated with placebo or subcutaneously applied GM-CSF (10 microg/kg) for a period of 14 days (total of 7 injections). GM-CSF treatment led to a strong increase in total white blood cell count and C-reactive protein. Monocyte fraction initially increased but thereafter decreased significantly as compared with baseline. Both the placebo group and the treatment group showed a significant increase in walking distance at day 14 (placebo: 127+/-67 versus 184+/-87 meters, P=0.03, GM-CSF: 126+/-66 versus 189+/-141 meters, P=0.04) and at day 90. Change in walking time, the primary end point of the study, was not different between groups. No change in ankle-brachial index was found on GM-CSF treatment at day 14 or at day 90. Laser Doppler flowmetry measurements showed a significant decrease in microcirculatory flow reserve in the control group (P=0.03) and no change in the GM-CSF group. CONCLUSIONS: The present study does not support the use of GM-CSF for treatment of patients with moderate or severe intermittent claudication. Issues that need to be addressed are dosing, the selection of patients, and potential differences between GM-CSF effects in the coronary and the peripheral circulation.

Leukocyte subpopulations and arteriogenesis: specific role of monocytes, lymphocytes and granulocytes.

OBJECTIVE: Circulating leukocytes play a crucial role during arteriogenesis. However, known pro-arteriogenic compounds (MCP-1, GM-CSF) acting via monocytic pathways also exert positive effects on granulocytes and lymphocytes. The role of these two cell types in arteriogenesis remains yet to be clarified, which was the aim of the current study. METHODS: Ninety New Zealand White Rabbits received either phosphate buffered saline (PBS), monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), neutrophil activating protein-2 (NAP-2) or lymphotactin (Ltn) via osmotic minipumps after unilateral femoral artery ligation. In vitro stimulation and in vivo assessment of chemoattraction confirmed cell-specific action of the compounds in rabbits. Arteriogenesis was evaluated by angiography and collateral conductance measurements using fluorescent microspheres. Quantitative immunohistology was used to quantify transmigrated leukocyte subtypes after infusion of the factors. RESULTS: MCP-1 infusion attracts monocytes and granulocytes, whereas IL-8 attracts all three cell types albeit monocytes to a significantly lower degree than MCP-1. NAP-2 and lymphotactin selectively attract granulocytes, respectively, lymphocytes. Of the tested cytokines, only MCP-1 stimulates arteriogenesis, as assessed by collateral conductance measurements ((ml/(min 100 mmHg)): PBS, 50.70+/-5.15; MCP-1, 216.30+/-12.30; IL-8, 58.91+/-5.56; NAP-2, 66.83+/-8.72; Ltn, 52.80+/-5.37) and angiographic findings. CONCLUSION: This study for the first time provides evidence that not granulocytes or T-lymphocytes but monocytes are the key mediators of arteriogenesis.

Anti-tumor necrosis factor-{alpha} therapies attenuate adaptive arteriogenesis in the rabbit.

The specific antagonists of tumor necrosis factor-alpha (TNF-alpha), infliximab and etanercept, are established therapeutic agents for inflammatory diseases such as rheumatoid arthritis and Crohn's disease. Although the importance of TNF-alpha in chronic inflammatory diseases is well established, little is known about its implications in the cardiovascular system. Because proliferation of arteriolar connections toward functional collateral arteries (arteriogenesis) is an inflammatory-like process, we tested in vivo the hypothesis that infliximab and etanercept have antiarteriogenic actions. Sixty-three New Zealand White rabbits underwent femoral artery occlusion and received infliximab, etanercept, or vehicle according to clinical dosage regimes. After 1 wk, collateral conductance, assessed with fluorescent microspheres, revealed significant inhibition of arteriogenesis (collateral conductance): 52.4 (SD 8.1), 35.2 (SD 7.7), and 33.3 (SD 10.1) ml x min(-1) x 100 mmHg(-1) with PBS, infliximab, and etanercept, respectively (P < 0.001). High-resolution angiography showed no significant differences in number of collateral arteries, but immunohistochemical analysis demonstrated a decrease in mean collateral diameter, proliferation of vascular smooth muscle cells, and reduction of leukocyte accumulation around collateral arteries in treated groups. Infliximab and etanercept bound to infiltrating leukocytes, which are important mediators of arteriogenesis. Infliximab induced monocyte apoptosis, and neither substance affected monocyte expression of the adhesion molecule Mac-1. We demonstrated that TNF-alpha serves as a pivotal modulator of arteriogenesis, which is attenuated by treatment with TNF-alpha inhibitors. Reduction of collateral conductance is most likely due to inhibition of perivascular leukocyte infiltration and subsequent lower vascular smooth muscle cell proliferation. This is the first report showing a negative influence of TNF-alpha inhibitors on collateral artery growth.

Stimulation of collateral artery growth: a potential treatment for peripheral artery disease.

In the course of peripheral artery occlusive disease, blood flow to peripheral tissue progressively decreases in a substantial portion of patients, leading to insufficient oxygenation and to the occurrence of claudication or critical limb ischemia. Arteriogenesis (collateral artery growth) is a powerful natural mechanism by which large conductance vessels develop that circumvent sites of obstruction. Promising experimental data on both hypoxia-driven angiogenesis as well as monocyte-orchestrated arteriogenesis have raised high hopes for clinical application. Both endothelial growth factors to stimulate angiogenesis (i.e., capillary growth) and monocyte-attracting or -activating substances to stimulate arteriogenesis, have been proposed as potential new therapeutic agents. However, transferring the promising experimental results into clinical practice has been more cumbersome than initially anticipated. Some recent clinical studies are now focusing more specifically on the stimulation of arteriogenesis. This review will critically evaluate the results of preclinical and clinical investigations on the stimulation of vascular growth, focusing specifically on the peripheral circulation.

Design of the START-trial: STimulation of ARTeriogenesis using subcutaneous application of GM-CSF as a new treatment for peripheral vascular disease. A randomized, double-blind, placebo-controlled trial.

Peripheral arterial disease (PAD) affects a large percentage of the elderly population. Standard invasive treatment, apart from risk factor modulation, consists of bypass surgery or percutaneous transluminal angioplasty. However, symptomatic recurrence rates are high for both procedures and a substantial part of the patient population with PAD is not a candidate for invasive revascularization due to complexity of the lesion and/or co-morbidity. Therapeutic arteriogenesis has been proposed as an alternative treatment option. The present paper describes the design of the START-trial. This trial aims to determine the potential of the pro-arteriogenic substance granulocyte/macrophage colony stimulating factor (GM-CSF) to increase maximal walking distance in patients with intermittent claudication. A double-blinded, randomized, placebo-controlled study will be performed in 40 patients with peripheral obstructive arterial disease Rutherford grade I, category 2 or 3, that are candidates for bypass surgery or percutaneous transluminal angioplasty. Based on pharmacokinetic and toxicologic studies, a dose of 10 microg/kg will be used. Patients will be treated for a period of 14 days on each consecutive day, with the last injection applied on day 12. The primary endpoint will be the change in walking distance from day 0 to day 14 as assessed by an exercise treadmill test. Secondary endpoints will be the ankle-brachial index at rest and after exercise, the pain-free walking distance and cutaneous microcirculatory alterations as assessed by laser Doppler fluxmetry. Iliac flow reserve and conductance will be measured by magnetic resonance imaging.