Anti-monocyte chemoattractant protein-1/monocyte chemotactic and activating factor antibody inhibits neointimal hyperplasia in injured rat carotid arteries

Monocyte chemoattractant protein-1 (MCP-1)/monocyte chemotactic and activating factor (MCAF) has been suggested to promote atherogenesis. The effects of in vivo neutralization of MCP-1 in a rat model were examined in an effort to clarify the role of MCP-1 in the development of neointimal hyperplasia. Competitive polymerase chain reaction analysis revealed maximum MCP-1 mRNA expression at 4 hours after carotid arterial injury. Increased immunoreactivities of MCP-1 were also detected at 2 and 8 hours after injury. Either anti-MCP-1 antibody or nonimmunized goat IgG (10 mg/kg) was then administered every 12 hours to rats that had undergone carotid arterial injury. Treatment with 3 consecutive doses of anti-MCP-1 antibody within 24 hours (experiment 1) and every 12 hours for 5 days (experiment 2) significantly inhibited neointimal hyperplasia at day 14, resulting in a 27.8% reduction of the mean intima/media ratio (P<0.05) in experiment 1 and a 43.6% reduction (P<0.01) in experiment 2. This effect was still apparent at day 56 (55.6% inhibition; P<0.05). The number of vascular smooth muscle cells in the neointima at day 4 was significantly reduced by anti-MCP-1 treatment, demonstrating the important role of MCP-1 in early neointimal lesion formation. However, recombinant MCP-1 did not stimulate chemotaxis of vascular smooth muscle cells in an in vitro migration assay. These results suggest that MCP-1 promotes neointimal hyperplasia in early neointimal lesion formation and that neutralization of MCP-1 before, and immediately after, arterial injury may be effective in preventing restenosis after angioplasty. Further studies are needed to clarify the mechanism underlying the promotion of neointimal hyperplasia by MCP-1.     

Prostacyclin synthase gene transfer inhibits neointimal formation in rat balloon-injured arteries without bleeding complications.

OBJECTIVE: This study was designed to compare the effects of prostacyclin synthase (PCS) gene transfer with those of a systemic infusion of beraprost sodium (BPS), a prostacyclin analogue, on vascular smooth muscle cell (VSMC) proliferation and neointimal formation after arterial injury. METHODS: PCS gene (3 or 30 micrograms) was transfected into rat balloon-injured carotid arteries by a non-viral lipotransfection method. BPS (100 or 300 micrograms/kg/day) was subcutaneously infused with osmotic pumps after the injury. LacZ gene (30 micrograms) was used as a control. VSMC proliferation was estimated by the bromodeoxyuridine (BrdU) index (BrdU-positive nuclei/total nuclei) at day 7. Neointimal formation was evaluated at day 14. Each treatment group had six rats. RESULTS: PCS gene transfer prevented the increase in intimal/medial area ratio (3 micrograms: 46.6%, 30 micrograms: 61.1% reduction; P < 0.05, P < 0.01, respectively), as did BPS 300 micrograms/kg/day (49.8% reduction; P < 0.05). BPS 100 micrograms/kg/day, however, had no effects on the ratio. PCS gene transfer and BPS 300 micrograms/kg/day significantly suppressed the BrdU index. BPS 300 micrograms/kg/day group had more frequent hematoma and longer bleeding time. There were no significant differences in blood pressure, heart rate, or urinary volume among all groups. CONCLUSION: Both PCS gene transfer and BPS 300 micrograms/kg/day reduced neointimal formation after arterial injury by inhibiting VSMC proliferation. PCS gene transfer may be a safer therapeutic modality against neointimal formation than a systemic infusion of BPS because the former method resulted in fewer bleeding complications.     

Erythropoietin-mobilized endothelial progenitors enhance reendothelialization via Akt-endothelial nitric oxide synthase activation and prevent neointimal hyperplasia

We investigated whether the mobilization of endothelial progenitor cells (EPCs) by exogenous erythropoietin (Epo) promotes the repair of injured endothelium. Recombinant human Epo was injected (1000 IU/kg for the initial 3 days) after wire injury of the femoral artery of mice. Neointimal formation was inhibited by Epo to 48% of the control (P<0.05) in an NO-dependent manner. Epo induced a 1.4-fold increase in reendothelialized area of day 14 denuded vessels, 55% of which was derived from bone marrow (BM) cells. Epo increased the circulating Sca-1(+)/Flk-1(+) EPCs (2.0-fold, P<0.05) with endothelial properties NO dependently. BM replacement by GFP- or beta-galactosidase-overexpressing cells showed that Epo stimulated both differentiation of BM-derived EPCs and proliferation of resident ECs. BM-derived ECs increased 2.2- to 2.7-fold (P<0.05) in the Epo-induced neoendothelium, where the expression of Epo receptor was upregulated. Epo induced Akt/eNOS phosphorylation and NO synthesis on EPCs and exerted an antiapoptotic action on wire-injured arteries. In conclusion, Epo treatment inhibits the neointimal hyperplasia after arterial injury in an NO-dependent manner by acting on the injured vessels and mobilizing EPCs to the neo-endothelium.     

甲氨蝶呤抑制兔颈动脉球囊损伤后新生内膜形成

目的　探讨不同剂量甲氨蝶呤 (MTX)对血管损伤后新生内膜形成的影响。方法　制备兔颈动脉球囊损伤模型 ,动物随机分为对照组、MTX 0 5mg/kg、MTX 1 5mg/kg及MTX 5mg/kg组 ,每组 5～ 8只 ,采用肌肉注射方式给药 ,于术后 2周和 4周取材 ,分别进行伊文思染色观察内皮覆盖情况、增殖细胞核抗原 (PCNA)免疫组化染色和定量组织形态学分析。结果　MTX治疗组血管内膜面积、内膜 /中膜面积比值均显著低于对照组 ,内膜面积抑制率达 4 6 %～ 5 6 %,不同剂量MTX之间差异无显著性。内膜及中膜PCNA阳性细胞数目较对照组减少。伊文思蓝染色显示各组间内皮修复程度差异无显著性。结论　MTX能够有效地抑制球囊损伤后血管平滑肌细胞的增殖和新生内膜形成 ,在一定剂量范围内 ,MTX的作用无明显差异。     

Lowering of dietary advanced glycation endproducts (AGE) reduces neointimal formation after arterial injury in genetically hypercholesterolemic mice

Restenosis remains a major cause of morbidity and mortality after coronary angioplasty. Injury-induced inflammation, thrombosis, smooth muscle cell (SMC) proliferation, and neointimal formation contribute to restenosis. These events are linked to circulating glucose-derived advanced gycation endproducts (AGE), known to promote cell proliferation, lipid glycoxidation and oxidant stress. This study evaluates the association between dietary AGE content and neointimal formation after arterial injury in genetically hypercholesterolemic mice. Male, 12-week-old, apolipoprotein E-deficient (apoE(-/-)) mice were randomly assigned to receive either a high AGE diet (HAD; AGE=15000 U/mg), or a similar diet with ten-fold lower AGE (LAD; AGE=1500 U/mg). These mice underwent femoral artery injury 1 week later, and were maintained on their diets for an additional 4 weeks. At 4 weeks after injury, significant decrease in neointimal formation was noted in LAD-fed mice. Neointimal area, intima/media ratio, and stenotic luminal area (LA) were less pronounced in the LAD group than the HAD group (P<0.05). These quantitative differences were associated with a marked reduction ( approximately 56%) of macrophages in the neointimal lesions, as well as an obvious reduction of SMC content of LAD-fed mice. The reduction of neointimal formation in the LAD mice correlated with a approximately 40% decrease in circulating AGE levels (P<0.0005). Immunohistochemistry also showed a reduced ( approximately 1.5-fold) deposition of AGE in the endothelia, SMC, and macrophages in neointimal lesions of LAD-fed mice. These results represent the first evidence in vivo for a causal relationship between dietary AGE and the vessel wall response to acute injury, suggesting a significant potential for dietary AGE restriction in the prevention of restenosis after angioplasty.     

The calcium inhibitor SR33805 reduces intimal formation following injury of the porcine carotid artery

We studied the effect of SR33805, a calcium channel blocker, in vitro on the proliferation of vascular smooth muscle cells (SMC) stimulated by foetal calf serum, basic fibroblast growth factor and platelet derived growth factor, and in vivo with regard to SMC migration and proliferation which occurred following injury of the porcine carotid artery. The intimal lesion was induced by a silasten collar surgically positioned around the carotid artery and by a stenosis reducing blood flow by 50% for 30 days. Animals received SR33805 (5 mg/kg/day) 8 days before the induction of the lesion and up to 30 days after. In vitro, SR33805 inhibited in a dose-dependent manner growth factor-induced proliferation of SMC (0.20相似文献   

Anti-human von willebrand factor monoclonal antibody AJvW-2 prevents thrombus deposition and neointima formation after balloon injury in guinea pigs

Immediately after angioplasty, platelet adhesion to the injured arterial wall and subsequent release of various mitogens may contribute to neointima formation. The purpose of this study was to evaluate the inhibitory effect of AJvW-2, a monoclonal antibody against human von Willebrand factor (vWF), on neointima formation in a guinea pig model. The carotid artery was injured with a balloon catheter, and AJvW-2 was administered by a single bolus injection. AJvW-2 dose-dependently prevented neointima formation 14 days after injury. Significant inhibition was observed at 1.8 mg/kg, at which dose significant inhibition of platelet aggregation was achieved for 2 days. By elastic-Masson staining, organized thrombi were observed in the neointimal lesion on day 14. The thrombus area was significantly correlated with neointimal thickness. Furthermore, thrombus deposition, immunostained for vWF and fibrin(ogen), was observed on the media immediately after balloon injury. AJvW-2 significantly reduced the deposition of both adhesive proteins and reduced the incidence of organized thrombus formation, which might affect subsequent neointima formation. However, the proliferation of cultured smooth muscle cells was not affected by AJvW-2. These results suggest that AJvW-2 prevents neointima formation by inhibition of initial platelet-mediated thrombus formation rather than by direct inhibition of smooth muscle cell proliferation.     

Monoclonal antibody against vascular cell adhesion molecule-1 inhibits neointimal formation after periadventitial carotid artery injury in genetically hypercholesterolemic mice

Vascular cell adhesion molecule (VCAM)-1 is induced in smooth muscle cells after arterial injury, in which it has been implicated in the recruitment of inflammatory cells to the site of injury. To investigate the effect of hypercholesterolemia on VCAM-1 induction after injury and the role of VCAM-1 in neointimal response to injury, we injured the carotid artery of wild-type and apolipoprotein E null (KO) mice fed normal and high cholesterol chow. We demonstrate a graded response of VCAM-1 induction as well as monocyte/macrophage infiltration by immunohistochemistry 3 days after injury that correlated with increasing circulating cholesterol levels. Three weeks after injury, KO mice fed high cholesterol chow (KO HC group) had a significantly greater neointimal formation compared with wild-type and KO mice fed normal chow (P<0.05). Inhibition of VCAM-1 function in the KO HC group by monoclonal antibody treatment significantly reduced monocyte/macrophage infiltration and neointimal formation. There was reduced alpha-actin expression in KO HC mice 7 days after injury that was partially inhibited by VCAM-1 antibody treatment. Cell migration in an in vitro injury model was partially inhibited by monoclonal VCAM-1 antibody treatment. We propose an additional role for VCAM-1 in smooth muscle cell activation and neointimal formation after injury.     

Effects of oral prednisone after stenting in a rabbit model of established atherosclerosis.

OBJECTIVES: The aim of this study was to compare the effects of systemic prednisone in combination with a bare-metal stent (BMS) or a paclitaxel-eluting stent (Taxus, Boston Scientific Corp., Natick, Massachusetts) on neointimal inhibition and vessel healing in an atherosclerotic rabbit model. BACKGROUND: Inflammation plays a critical role in neointimal formation after coronary artery stenting. The efficacy of immunosuppressive doses of oral prednisone to inhibit in-stent neointimal proliferation was compared with BMS and with a commercially available paclitaxel-eluting stent (Taxus) in a rabbit model of established atherosclerosis. METHODS: Bilateral iliac artery injury in atherosclerotic New Zealand White rabbits fed an atherogenic diet was followed by stent implantation. Animals randomly received Taxus stents, BMS (Express, Boston Scientific Corp.) and placebo, or BMS and oral prednisone (2.1 mg/kg/day for the first 7 days, followed by 1.4 mg/kg/day for 14 days and 0.7 mg/kg/day for 21 days). Stented arterial segments were harvested at 42 days and processed for light microscopy, immunohistochemistry, and organoid culture. RESULTS: Compared with control subjects, prednisone-treated animals showed a 30% reduction in percent stenosis (p = 0.009), a 35% decrease in neointimal area (p < 0.003), and a 66% decrement in neointimal thickness (p < 0.001). Taxus stents also reduced all 3 parameters significantly (-34%, -39%, and -83%, respectively), but showed significantly more inflammatory cells and fibrin deposition and less endothelialization compared with the other 2 groups. Plaque burden was equal among groups, as shown by the identical stent and vessel area, and no remodeling was observed. CONCLUSIONS: Systemic prednisone treatment and Taxus stents reduce neointimal formation compared with BMS. The extent of neointimal reduction is similar between prednisone- and Taxus stent-treated animals; however, Taxus stents resulted in a significantly greater delay in healing. Targeting of inflammatory pathways after percutaneous coronary intervention may be an efficacious way to prevent restenosis without the long-term risk of late thrombosis.     

Inhibition of Thrombin Attenuates Stenosis After Arterial Injury in Minipigs

Objectives. We sought to determine whether brief, profound inhibition of thrombin or prothrombin activation by factor Xa limits neointimal formation and stenosis after arterial injury.

Background. Thrombin has been implicated as a mediator of neointimal formation, but adjunctive administration of anticoagulant agents has not proven effective to decrease restenosis in patients undergoing coronary angioplasty.

Methods. We infused recombinant desulfatohirudin (r-hirudin, bolus of 2 mg/kg body weight followed by 2 mg/kg per h, n = 9), heparin (100 U/kg per h, n = 6) or recombinant tick anticoagulant peptide (rTAP, 1-mg/kg bolus followed by 3 mg/kg per h, n = 5), a specific inhibitor of factor Xa, intravenously, beginning 15 min before and for up to 3 h after repetitive balloon hyperinflations sufficient to disrupt the internal elastic lamina in a carotid artery of minipigs with hypercholesterolemia induced by feeding them an atherogenic diet.

Results. Partial thromboplastin time was increased six- to sevenfold over baseline levels at the end of the infusions of the anticoagulant agents. Lumen stenosis measured histologically 4 weeks after balloon-induced carotid injury was 29 ± 16% (mean ± SEM) in r-hirudin–treated, 52 ± 19% in rTAP-treated and 76 ± 18% in heparin-treated pigs (p < 0.02 for r-hirudin vs. heparin treatment).

Conclusions. The marked reduction of stenosis in r-hirudin–treated animals indicates that thrombin plays a major role in neointimal formation after balloon-induced arterial injury. A relatively brief interval of profound, direct inhibition of thrombin may be particularly effective to attenuate restenosis after balloon angioplasty.

(J Am Coll Cardiol 1996;28:1849–55)     

Sulindac inhibits neointimal formation after arterial injury in wild-type and apolipoprotein E-deficient mice

Neointimal hyperplasia is a critical component of restenosis, a major complication of angioplasty and related therapeutic procedures. We studied the effects of hyperlipidemia and the nonsteroidal anti-inflammatory drugs, aspirin (acetyl-salicylic acid; ASA), and sulindac, on neointimal formation in a mouse femoral arterial injury model. At 2 months of age, normolipidemic, wild-type (WT), and hyperlipidemic, apolipoprotein E-deficient (apoE-/-) mice were divided into three treatment groups: Western-type diet (WD), WD + ASA (200 mg/kg food), and WD + sulindac (300 mg/kg food). After 1 week, mice underwent arterial injury and treatments were maintained for 4 weeks. Histomorphometry of the injured arteries showed striking effects of plasma cholesterol levels and drug treatment on neointimal hyperplasia. In the WD or WD + ASA groups, apoE-/- mice had twice the neointimal area than WT mice ( approximately 30,000 vs. 13,000 microm(2) per section; P < 0.0001). Compared with ASA or WD alone, sulindac treatment resulted in approximately 70% (P = 0.0001) and 50% (P = 0.01) reductions in the neointimal area in apoE-/- and WT mice, respectively. ASA, at a dose sufficient to inhibit platelet aggregation, did not affect neointimal formation in mice of either genotype. Evidence of macrophages was noted in the lesions of apoE-/- mice in the WD and WD + ASA groups, but remarkably, none was detectable with sulindac treatment, despite hyperlipidemia, suggesting early steps in the response to injury were abrogated. These results demonstrate sulindac reduces neointimal formation in both normolipidemic and hyperlipidemic settings and raise the possibility that similar benefits may be obtained in patients undergoing angioplasty and related procedures.     

白藜芦醇抑制大鼠颈动脉球囊损伤后平滑肌增殖

目的研究白藜芦醇对大鼠颈动脉内膜球囊损伤后血管平滑肌细胞增殖的影响。方法 72只雄性Wistar大鼠随机分为假手术组、损伤组和干预组,每组各24只。干预组于手术前1周及术后给予白藜芦醇50 mg/kg灌胃,余两组用等量生理盐水灌胃。术后1、7和14天观察大鼠颈总动脉形态学变化并进行图像分析;免疫组织化学检测增殖细胞核抗原(PCNA)的表达,RT-PCR检测血管平滑肌中妊娠相关血浆蛋白A(PAPP-A)的表达。结果与假手术组比较,损伤组和干预组7、14天管腔面积明显减小。与损伤组比较,干预组7、14天管腔面积明显扩大(P<0.01),内膜面积/中膜面积明显减小(P<0.01);干预组7、14天PCNA,PAPP-A表达较损伤组明显降低(P<0.01)。结论白藜芦醇可能是通过抑制血管内膜平滑肌细胞PAPP-A的表达,减轻大鼠颈动脉球囊损伤后血管内膜平滑肌的增殖,为临床白藜芦醇抗血管平滑肌增殖的治疗提供理论依据。     

瘦素通过其受体刺激小鼠血管平滑肌细胞增殖而促进动脉内膜增生

目的 探讨瘦素是否影响动脉内膜的增生及其发生机制.方法 利用野生型(Wt)、瘦素基因缺陷(Lep-/-)、瘦素受体基冈缺陷(LepR-/-)小鼠,通过股动脉内膜损伤及瘦素疗法,结合组织学特性,分析瘦素影响动脉内膜增生情况及其机制.结果 动脉内膜损伤后4周,Lep-/-和LepR-/-小鼠的内膜面积与中层面积比值(I/M)均小于Wt小鼠,差异均有统计学意义(Lep-/-小鼠比Wt小鼠为0.80±0.14比1.50±0.22,P<0.01;LepR-/-小鼠比Wt小鼠为0.55±0.20比1.50 ±0.22,P<0.05).Lep-/-和LepR-/-小鼠经动脉内膜损伤并同时给予瘦素治疗后,前者的I/M显著增加,而后者的I/M无明显变化.α-肌动蛋白和5-溴-2-脱氧尿嘧啶染色显示,二者在各组动脉增生内膜的阳性率分布趋势与内膜增厚程度一致.结论 瘦素缺乏或瘦素受体缺乏防止动脉内膜增生,外源性瘦素恢复Lep-/-小鼠动脉内膜增生,但对LepR-/-小鼠内膜无影响.本研究从动物模型上证明,高瘦素血症是动脉内膜增生的高危因素,并说明瘦素通过瘦素受体刺激血管平滑肌细胞增殖而促进动脉内膜增生.     

Effect of platelet-derived growth factor receptor-alpha and -beta blockade on flow-induced neointimal formation in endothelialized baboon vascular grafts

The growth of neointima and neointimal smooth muscle cells in baboon polytetrafluoroethylene grafts is regulated by blood flow. Because neointimal smooth muscle cells express both platelet-derived growth factor receptor-alpha and -beta (PDGFR-alpha and -beta), we designed this study to test the hypothesis that inhibiting either PDGFR-alpha or PDGFR-beta with a specific mouse/human chimeric antibody will modulate flow-induced neointimal formation. Bilateral aortoiliac grafts and distal femoral arteriovenous fistulae were placed in 17 baboons. After 8 weeks, 1 arteriovenous fistulae was ligated, normalizing flow through the ipsilateral graft while maintaining high flow in the contralateral graft. The experimental groups received a blocking antibody to PDGFR-alpha (Ab-PDGFR-alpha; 10 mg/kg; n=5) or PDGFR-beta (Ab-PDGFR-beta; 10 mg/kg; n=6) by pulsed intravenous administration 30 minutes before ligation and at 4, 8, 15, and 22 days after ligation. Controls received carrier medium alone (n=8). Serum antibody concentrations were followed. Grafts were harvested after 28 days and analyzed by videomorphometry. Serum Ab-PDGFR-alpha concentrations fell rapidly after day 7 to 0, whereas serum Ab-PDGFR-beta concentrations were maintained at the target levels (>50 microg/mL). Compared with controls (3.7+/-0.3), the ratio of the intimal areas (normalized flow/high flow) was significantly reduced in Ab-PDGFR-beta (1.2+/-0.2, P<0.01) but not in Ab-PDGFR-alpha (2.2+/-0.4). Ab-PDGFR-alpha decreased significantly the overall smooth muscle cell nuclear density of the neointima (P<0.01) compared with either the control or Ab-PDGFR-beta treated groups. PDGFR-beta is necessary for flow-induced neointimal formation in prosthetic grafts. Targeting PDGFR-beta may be an effective pharmacological strategy for suppressing graft neointimal development.     

L-arginine supplementation does not inhibit neointimal formation after coronary stenting in human beings: an intravascular ultrasound study

Background

In-stent restenosis results from neointimal tissue proliferation. L-arginine supplementation improves endothelial function and reduces neointimal formation after arterial injury in animals. The aim of the study was to assess the influence of L-arginine administration on neointimal proliferation after coronary stenting in human beings.

Methods

We performed a prospective, randomized, double-blinded, placebo-controlled study in 60 men without diabetes. L-arginine/placebo was administered intravenously 12 hours before percutaneous coronary intervention (200 mg/kg for 240 minutes), during the procedure (200 mg/kg for 240 minutes), and intracoronarily immediately before stent implantation (500 mg for 10 minutes), and it was followed by oral treatment for next 2 weeks (6.0 g/d). By quantitative coronary angiography, late lumen loss, and intravascular ultrasound, neointimal volume and percent neointimal volume were calculated after 7 months of follow-up to assess neointimal formation.

Results

There were no differences in baseline clinical or angiographic characteristics between the two groups. Intravenous infusion of L-arginine increased plasma L-arginine concentrations 6-fold compared with placebo (661 ± 264 vs 107 ± 71 mmol/L, P < .001). During the 2-week period of oral treatment with L-arginine there was a sustained, significant increase of plasma L-arginine level (150 ± 50 vs 100 ± 17, P < .001, 135 ± 42 vs 89 ± 27, P < .001, respectively, on days 7 and 14 in the L-arginine group vs placebo). However, at 7-month follow-up, there was no difference in neointimal formation measured both by quantitative coronary angiography and intravascular ultrasound between the study groups.

Conclusions

Chronic systemic L-arginine administration has no effect on neointimal formation after coronary stenting in human beings.     

Short-term rapamycin for inhibition of neointima formation after balloon-mediated aortic injury in rats: is there a window of opportunity for systemic prophylaxis of restenosis?

PURPOSE: To evaluate the efficacy of limited short-term systemic administration of rapamycin to prevent neointimal intimal hyperplasia (NIH) in a double-injury rat model of restenosis. METHODS: Aortic lesions were induced by perivascular placement of silicone cuffs around the aorta of 36 Lewis rats. After 3 weeks, the cuffs were removed, and the vessels were subjected to secondary balloon injury. Rapamycin (sirolimus) was intravenously administered for 5 days in dosages of 0.5 or 2 mg/kg/d beginning at various time points relative to the balloon injury: (1) days -2 to +2, (2) days 1 to 5, or (3) days 7 to 11. For each treatment period, 6 rats received the 5-day course of the lower or higher dose of rapamycin. Eight rats served as controls undergoing 2-stage injury without rapamycin treatment. Morphometry and immunohistochemistry were performed at 21 days after angioplasty. RESULTS: NIH and intimal alpha-actin expression were inhibited by both dosages when treatment started 2 days before or 1 day after angioplasty. Results were statistically significant for the lower dose when started 1 day after angioplasty (p < 0.01) and for the higher dose when initiated 2 days before the intervention (p < 0.05). Treatment commencing at 7 days did not reduce NIH in either dosage group. CONCLUSIONS: In a double-injury rat model, NIH can be inhibited by short-term systemic rapamycin, but suppression of early cell migration and proliferation is pivotal. A limited peri-interventional antiproliferative therapy may be of value as an adjunct to control restenosis after balloon angioplasty and/or stenting.     

Effects of pentoxifylline on the vascular response to injury after angioplasty in rabbit iliac arteries

Pentoxifylline (PTX) inhibits the effects of several cytokines and reduces injury-related collagen accumulation. The aim of the present study was to investigate the effect of PTX on the vascular response to injury. We treated rabbits with PTX (100 mg/kg/day) or placebo (saline) subcutaneously from 2 days before angioplasty of an iliac artery until euthanasia 7 or 28 days later. At 7 days after injury, PTX treatment was associated with a more differentiated (less proliferation, more smoothelin-positive) intimal smooth muscle cell phenotype. Furthermore, PTX reduced myofibroblast accumulation in adventitia. At 28 days after injury, PTX-treated rabbits had a 48.5% larger lumen area (P = 0.03) and a 28.1% larger area within the external elastic lamina (P = 0.04). There were no significant differences between PTX-treated rabbits and the placebo group with regard to neointima and media area. Angioplasty induced marked neoadventitial hyperplasia, which was reduced by 20.5% (P = 0.01) in the PTX-treated group. Finally, PTX reduced collagen density in all three arterial layers. We conclude that PTX treatment induces less proliferation within the vessel wall early after angioplasty and increases late lumen size after angioplasty by a positive effect on vascular remodeling. Martin Busk and Michael Maeng contributed equally to this paper. Returned for 1. Revision: 6 September 2007 1. Revision received: 4 October 2007 Returned for 2. Revision: 24 October 2007 2. Revision received: 31 October 2007     

Inhibitory effect on arterial injury-induced neointimal formation by adoptive B-cell transfer in Rag-1 knockout mice

We investigated the effect of B-cell reconstitution in immune-deficient Rag-1 knockout (KO) mice subjected to arterial injury. After 21 days, injury induced a 4- to 5-fold increase in neointimal formation in Rag-1 KO mice fed normal chow compared with wild-type (WT) mice (0.020+/-0.0160 [n=8] versus 0.0049+/-0.0022 [n=8] mm(2), respectively; P<0.05) and in western-type diet-fed Rag-1 KO mice compared with WT mice (0.0312+/-0.0174 [n=7] versus 0.0050+/-0.0028 [n=6] mm(2), respectively; P<0.05). To investigate the role of B cells in response to injury, Rag-1 KO mice were reconstituted with B cells derived from the spleens of WT mice, with donors and recipients on the same diet. Reconstitution of Rag-1 KO mice with B cells from WT mice (both fed normal chow) reduced neointimal formation compared with the effect in unreconstituted Rag-1 KO mice (0.0076+/-0.0039 [n=9] versus 0.020+/-0.0160 [n=8] mm(2), respectively; P<0.05). Reconstitution of Rag-1 KO mice with B cells from WT mice (both fed a western diet) reduced neointimal formation compared the effect in Rag-1 KO mice (0.0087+/-0.0037 [n=8] versus 0.0312+/-0.0174 [n=7] mm(2), respectively; P<0.05). Injured carotid arteries from reconstituted Rag-1 KO mice had detectable IgM and IgG, indicating viable transfer of B cells. The results suggest that B cells modulate the response to arterial injury.     

Triptolide attenuates pulmonary arterial hypertension and neointimal formation in rats

This paper reports the effect of triptolide (a diterpenoid triepoxide) on the development of monocrotaline (MCT)-induced pulmonary hypertension in pneumonectomized rats. Male Sprague- Dawley rats were injected with MCT (60 mg/kg) on Day 7 after left pneumonectomy. Rats received therapy from Day 5 to 35 with triptolide (0.25 mg/kg intraperitoneally, every other day, n = 10), or vehicle (0.1 ml of ethanol/cremophor intraperitoneally, every other day, n = 10). By Day 35, triptolide-treated rats demonstrated lower mean pulmonary arterial pressure (mPAP) than vehicle-treated rats (mPAP 21 +/- 3 versus 42 +/- 5 mm Hg, p < 0.001). Triptolide-treated rats also had significantly less right ventricular hypertrophy (RVH) and pulmonary arterial neointimal formation. In a rescue experiment, rats initiated therapy on Day 21. At Day 35, vehicle-treated rats (n = 4) had higher mPAP (40 +/- 9 mm Hg), greater RVH, and more severe pulmonary arterial neointimal formation than rats that received triptolide (0.25 mg/kg every other day, n = 7, mPAP 30 +/- 4 mm Hg) and rats that received triptolide (0.2 mg/kg daily, n = 7, mPAP 25 +/- 5 mm Hg, p < 0.01). In pneumonectomized rats that receive MCT, triptolide attenuates the development of pulmonary hypertension and RVH, and promotes regression of pulmonary arterial neointimal formation.     

The eNOS enhancer AVE 9488: a novel cardioprotectant against ischemia reperfusion injury

Nitric oxide (NO) is an important regulator of vascular and myocardial function. Cardiac ischemia/reperfusion injury is reduced in mice overexpressing endothelial NO synthase (eNOS) suggesting cardioprotection by eNOS. Novel pharmacological substances, so called eNOS enhancers, upregulate eNOS expression and thereby increase NO production. We tested the effects of the eNOS enhancer AVE 9488 on cardiac ischemia/reperfusion injury in vivo in mice. After treatment with the eNOS enhancer AVE 9488 (30 mg/kg/day) or placebo for one week mice underwent 30 min of coronary artery ligation and 24 h of reperfusion in vivo. Ischemia-reperfusion damage was significantly reduced in mice treated with the eNOS enhancer when compared to placebo treated mice (infarct/area at risk 65.4 ± 4.1 vs. 36.9 ± 4.0%, placebo vs. eNOS enhancer, P = 0.0002). The protective effect was blunted in eNOS knockout mice treated with the eNOS enhancer (infarct/area at risk 64.1 ± 6.2%, eNOS knockout + eNOS enhancer vs. WT + eNOS enhancer, P = ns). Reactive oxygen species were significantly reduced in mice treated with the eNOS enhancer as indicated by significantly lower malondialdehyde–thiobarbituric acid levels (placebo vs. eNOS enhancer, 3.2 ± 0.5 vs. 0.8 ± 0.07 μmol/l, P = 0.0003). Thus pharmacological interventions addressed to increase eNOS-derived NO production constitute a promising therapeutic approach to prevent myocardial ischemia/reperfusion injury.