Emilio Di Lorenzo

Inhibition of cellular ras prevents smooth muscle cell proliferation after vascular injury in vivo

Proliferation of smooth muscle cells of the arterial wall in response to local injury is an important aetiologic factor of vascular proliferative disorders such as atherosclerosis and restenosis after angioplasty. Ras proteins are key transducers of mitogenic signals from membrane to nucleus in many cell types. We investigated the role of ras proteins in the vascular response to arterial injury by inactivating cellular ras of rats in which the common carotid artery was subjected to balloon injury. DNA vectors expressing ras transdominant negative mutants, which interfere with ras function, reduced neointimal formation after injury. Our results indicate a key role for ras in smooth muscle cell proliferation and show that the local delivery of transdominant negative mutants of ras in vivo might prevent some of the acute vascular injury caused by balloon injury.

Smooth Muscle Cell Proliferation Is Proportional to the Degree of Balloon Injury in a Rat Model of Angioplasty

BACKGROUND A variable degree of smooth muscle cell (SMC) proliferation after balloon injury has been reported in previous rat studies. It is unknown whether balloon injury induces c-fos expression and whether it is related to the degree of vascular injury in vivo. Therefore, we tested the hypothesis that proportional increases in neointimal formation and c-fos expression might be present after different degrees of balloon dilation. METHODS AND RESULTS Angioplasty of the carotid artery was performed with a balloon catheter. Vascular injury was evaluated at 0, 0.5, 1.0, 1.5, and 2 atm (n = 6 for all). In 40 additional rats, total RNA dot blots were performed to assess the effect of various degrees of balloon injury on c-fos expression. SMC proliferation proportional to the increases of inflation pressure was found between 0 and 2 atm with neointimal areas of 0.002 +/- 0.002, 0.069 +/- 0.014, 0.128 +/- 0.043, 0.190 +/- 0.010, and 0.255 +/- 0.041 mm2, respectively. When the degree of SMC proliferation (neointima and neointima/media ratio) was plotted against balloon inflation pressure, a linear relation was observed (r = .733, P < .001 and r = .755, P < .001, respectively). An increase in c-fos expression proportional to the degree of injury was found 30 minutes after injury. CONCLUSIONS Neointimal proliferation produced by balloon injury is related to balloon inflation pressure, supporting the concept of an SMC proliferative response proportional to the degree of injury. The increase in SMC proliferation is associated with a proportional increase in the early expression of the c-fos nuclear proto-oncogene.

Effects of hydroxymethylglutaryl coenzyme A reductase inhibitor simvastatin on smooth muscle cell proliferation in vitro and neointimal formation in vivo after vascular injury

OBJECTIVES We sought to evaluate the effects of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on vascular smooth muscle cell (VSMC) proliferation in vitro and neointimal formation in vivo after vascular injury. BACKGROUND Neointimal hyperplasia after vascular injury is responsible for restenosis after arterial stenting, whereas arterial remodeling and neointimal formation are the causes of restenosis after percutaneous transluminal coronary angioplasty. METHODS We assessed the effect of simvastatin on in vitro VSMC proliferation. To study the effects of simvastatin in vivo, balloon injury and stent deployment were performed in the common carotid artery of rats. Neointimal area was measured two weeks later in the balloon injury model and three weeks after stent deployment. RESULTS Simvastatin markedly inhibits VSMC proliferation in vitro. In vivo, simvastatin reduced, in a dose-dependent manner, the neointimal area and the neointima-media ratio after balloon injury from 0.266 +/- 0.015 mm2 to 0.080 +/- 0.026 mm2 and from 1.271 +/- 0.074 to 0.436 +/- 0.158 (p < 0.001 vs. control rats) at the highest dose. Simvastatin also significantly reduced the neointimal formation and the neointima-media ratio after stenting from 0.508 +/- 0.035 mm2 to 0.362 +/- 0.047 mm2 (p < 0.05 vs. control rats) and from 2.000 +/- 0.136 to 1.374 +/- 0.180 (p < 0.05 vs. control rats). The vessel thrombosis rate after stent deployment was 30% in the control group and 11.1% in the treated group (p = NS). Moreover, the systemic administration of simvastatin did not affect hepatic and renal functions, blood pressure or heart rate. CONCLUSIONS Simvastatin potently inhibits VSMC proliferation in vitro and reduces neointimal formation in a rat model of vascular injury.

Hydroxymethylglutaryl Coenzyme A Reductase Inhibitor Simvastatin Prevents Cardiac Hypertrophy Induced by Pressure Overload and Inhibits p21ras Activation

Background—Patients with cardiac hypertrophy are at increased cardiovascular risk. It has been hypothesized that hydroxymethylglutaryl coenzyme A reductase inhibitors may exert beneficial effects other than their cholesterol-lowering actions. The aims of the study were to assess the in vivo effects of simvastatin (SIM) on cardiac hypertrophy and on Ras signaling in rats with ascending aorta banding. Methods and Results—Wistar rats were randomized to receive either treatment with SIM or placebo, and then short-term (group I) and long-term (group II) left ventricular pressure overload was performed by placing a tantalum clip on ascending aorta. At the end of treatment period, left and right ventricular weight, body weight, and tibial length were measured and echocardiographic evaluations were performed. Ras signaling was investigated by analyzing Ras membrane localization and activation, ERK2 phosphorylation, and p27kip1 and cdk4 levels. In SIM-treated rats, a significant reduction of left ventricular weight/body weight, echocardiographic left ventricular mass, and left ventricular end-diastolic diameter and end-diastolic pressure was found. In rats with pressure overload, SIM treatment significantly reduced Ras membrane targeting, Ras in vivo activation, ERK2 phosphorylation, and the ratio cdk4/p27kip1. Conclusions—HMG CoA inhibitor SIM inhibits in vivo Ras signaling and prevents left ventricular hypertrophy development in aortic-banded animals.

Efficacy and safety of drug-eluting stents in ST-segment elevation myocardial infarction: a meta-analysis of randomized trials

BACKGROUND Recent concerns have emerged on the potential higher risk of stent thrombosis after DES implantation, that might be even more pronounced among STEMI patients. Thus, the aim of the current study was to perform a meta-analysis to evaluate the benefits and safety of DES as compared to BMS in patients undergoing primary angioplasty for STEMI. METHODS The literature was scanned by formal searches of electronic databases (MEDLINE and CENTRAL). We examined all completed randomized trials of DES for STEMI. The following key words were used for study selection: randomized trial, myocardial infarction, reperfusion, primary angioplasty, stenting, DES, sirolimus-eluting stent (SES), Cypher, paclitaxel-eluting stent (PES), Taxus. Information on study design, type of stent, inclusion and exclusion criteria, primary endpoint, number of patients, angiographic and clinical outcome, were extracted by two investigators. Disagreements were resolved by consensus. RESULTS A total of 11 trials were included in the meta-analysis, involving 3605 patients (1888 or 52.3% randomized to DES and 1719 or 47.7% randomized to BMS). At 12 months follow-up, no significant difference was observed in mortality (4.1% vs 4.4%, OR [95% CI]=0.91 [0.66-1.27], p=0.59, reinfarction (3.1% vs 3.4%, OR [95% CI]=0.85 [0.58, 1.23], p=0.38 or stent thrombosis (1.6% vs 2.2%, OR [95% CI]=0.76 [0.47, 1.23], p=0.22), whereas DES were associated with a significant reduction in TVR (5.0% vs 12.6%, OR [95% CI]=0.36 [0.28, 0.47], p<0.0001). Safety and efficacy of DES were confirmed at 18 to 24 months follow-up (data available from 4 trials including 1178 patients). CONCLUSIONS This meta-analysis shows that among selected STEMI patients undergoing primary angioplasty, SES and PES, as compared to BMS, are safe and associated with a significant reduction in TVR at 1 and 2 years follow-up.

Effects of Balloon Injury on Neointimal Hyperplasia in Streptozotocin-Induced Diabetes and in Hyperinsulinemic Nondiabetic Pancreatic Islet–Transplanted Rats

Background—The mechanisms of increased neointimal hyperplasia after coronary interventions in diabetic patients are still unknown. Methods and Results—Glucose and insulin effects on in vitro vascular smooth muscle cell (VSMC) proliferation and migration were assessed. The effect of balloon injury on neointimal hyperplasia was studied in streptozotocin-induced diabetic rats with or without adjunct insulin therapy. To study the effect of balloon injury in nondiabetic rats with hyperinsulinemia, pancreatic islets were transplanted under the kidney capsule in normal rats. Glucose did not increase VSMC proliferation and migration in vitro. In contrast, insulin induced a significant increase in VSMC proliferation and migration in cell cultures. Furthermore, in VSMC culture, insulin increased MAPK activation. A reduction in neointimal hyperplasia was consistently documented after vascular injury in hyperglycemic streptozotocin-induced diabetic rats. Insulin therapy significantly increased neointimal hyperplasia in these rats. This effect of hyperinsulinemia was totally abolished by transfection on the arterial wall of the N17H-ras–negative mutant gene. Finally, after experimental balloon angioplasty in hyperinsulinemic nondiabetic islet-transplanted rats, a significant increase in neointimal hyperplasia was observed. Conclusions—In rats with streptozotocin-induced diabetes, balloon injury was not associated with an increase in neointimal formation. Exogenous insulin administration in diabetic rats and islet transplantation in nondiabetic rats increased both blood insulin levels and neointimal hyperplasia after balloon injury. Hyperinsulinemia through activation of the ras/MAPK pathway, rather than hyperglycemia per se, seems to be of crucial importance in determining the exaggerated neointimal hyperplasia after balloon angioplasty in diabetic animals.

The PASEO (PaclitAxel or Sirolimus-Eluting Stent Versus Bare Metal Stent in Primary Angioplasty) Randomized Trial

OBJECTIVES The aim of this study was to evaluate the benefits of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) as compared with bare-metal stents (BMS) in patients undergoing primary angioplasty. BACKGROUND Recent concerns have emerged on the potential higher risk of stent thrombosis after drug-eluting stent implantation, especially among ST-segment elevation myocardial infarction (STEMI) patients. METHODS We randomly assigned STEMI patients admitted within 12 h of symptom onset undergoing primary angioplasty and stent implantation to BMS, PES, or SES. The primary study end point was target lesion revascularization at 1-year follow-up. All patients were reviewed at our outpatient clinic or by telephone interview at 6, 12, and 24 months. RESULTS From October 2003 to December 2005, 270 STEMI patients undergoing primary angioplasty were randomized to BMS (n = 90), PES (n = 90), or SES (n = 90). No patient was lost to follow-up. As compared with BMS (14.4%), both PES (4.4%, p = 0.023) and SES (3.3%, p = 0.016) were associated with a significant reduction in target lesion revascularization at 1-year follow-up. At 2-year follow-up no difference was observed in terms of death, reinfarction, and combined death and/or reinfarction, but as compared with BMS, both PES and SES were associated with significant benefits in major adverse cardiac events (PES: 16.7%, p = 0.015; SES: 15.6%, p = 0.009, respectively). CONCLUSIONS This study shows that among STEMI patients undergoing primary angioplasty, both SES and PES are safe and associated with significant benefits in terms of target lesion revascularization up to the 2-year follow-up. Thus, until the results of further large randomized trials with long-term follow-up become available, drug-eluting stents may be considered for STEMI patients undergoing primary angioplasty. (PaclitAxel or Sirolimus-Eluting Stent versus Bare Metal Stent in Primary Angioplasty [PASEO] Randomized Trial; NCT00759850).

Impact of Diabetes on Long-Term Outcome After Primary Angioplasty Insights from the DESERT cooperation

OBJECTIVE Diabetes has been shown to be associated with worse survival and repeat target vessel revascularization (TVR) after primary angioplasty. The aim of the current study was to evaluate the impact of diabetes on long-term outcome in patients undergoing primary angioplasty treated with bare metal stents (BMS) and drug-eluting stents (DES). RESEARCH DESIGN AND METHODS Our population is represented by 6,298 ST-segment elevation myocardial infarction (STEMI) patients undergoing primary angioplasty included in the DESERT database from 11 randomized trials comparing DES with BMS. RESULTS Diabetes was observed in 972 patients (15.4%) who were older (P < 0.001), more likely to be female (P < 0.001), with higher prevalence of hypertension (P < 0.001), hypercholesterolemia (P < 0.001), and longer ischemia time (P < 0.001), and without any difference in angiographic and procedural characteristics. At long-term follow-up (1,201 ± 441 days), diabetes was associated with higher rates of death (19.1% vs. 7.4%; P < 0.0001), reinfarction (10.4% vs. 7.5%; P < 0.001), stent thrombosis (7.6% vs. 4.8%; P = 0.002) with similar temporal distribution—acute, subacute, late, and very late—between diabetic and control patients, and TVR (18.6% vs. 15.1%; P = 0.006). These results were confirmed in patients receiving BMS or DES, except for TVR, there being no difference observed between diabetic and nondiabetic patients treated with DES. The impact of diabetes on outcome was confirmed after correction for baseline confounding factors (mortality, P < 0.001; repeat myocardial infarction, P = 0.006; stent thrombosis, P = 0.007; TVR, P = 0.027). CONCLUSIONS This study shows that among STEMI patients undergoing primary angioplasty, diabetes is associated with worse long-term mortality, reinfarction, and stent thrombosis in patients receiving DES and BMS. DES implantation, however, does mitigate the known deleterious effect of diabetes on TVR after BMS.

Long-Term outcome of drug-eluting stents compared with bare metal stents in ST-segment elevation myocardial infarction: results of the paclitaxel- or sirolimus-eluting stent versus bare metal stent in Primary Angioplasty (PASEO) Randomized Trial.

BACKGROUND Drug-eluting stents may offer benefits in terms of repeat revascularization that may be counterbalanced by a potential higher risk of stent thrombosis, especially among ST-segment elevation myocardial infarction (STEMI) patients. No data have been reported so far on the long-term benefits and safety of drug-eluting stents in STEMI. Thus, the aim of the present study was to evaluate the short- and long-term benefits of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) compared with bare metal stents (BMS) in patients undergoing primary angioplasty. METHODS AND RESULTS Consecutive STEMI patients admitted within 12 hours of symptom onset and undergoing primary angioplasty and stent implantation at a tertiary center with 24-hour primary percutaneous coronary intervention capability were randomly assigned to BMS, PES, or SES. All patients received upstream glycoprotein IIb/IIIa inhibitors. The primary end point was target lesion revascularization at the 1-year follow-up. Secondary end points were death and/or reinfarction, in-stent thrombosis, and major adverse cardiac events (combined death and/or reinfarction and/or target lesion revascularization) at long-term follow-up (up to 4 to 6 years). Cumulative incidence of end points was investigated. No patient was lost to follow-up. From October 1, 2003, to December 31, 2005, 270 patients with STEMI were randomized to BMS (n=90), PES (n=90), or SES (n=90). Procedural success was obtained in 93% to 95% of patients. Follow-up data were available for all patients. Compared with BMS (14.4%), both PES (4.4%; hazard ratio, 0.29; 95% confidence interval, 0.095 to 0.89; P=0.023) and SES (3.3%; hazard ratio, 0.21; 95% confidence interval, 0.06 to 0.75; P=0.016) were associated with a significant reduction in target lesion revascularization at the 1-year follow-up (primary study end point). At the long-term follow-up (4.3 years; 25th to 75th percentile, 3.7 to 5 years), no difference was observed in terms of death, reinfarction, and combined death and/or reinfarction, but compared with BMS (22.2%), both PES (6.7%; hazard ratio, 0.27; 95% confidence interval, 0.11 to 0.68; P=0.005) and SES (5.6%; hazard ratio, 0.22; 95% confidence interval, 0.083 to 0.59; P=0.003) were associated with a significant reduction in target lesion revascularization. CONCLUSIONS This study shows that among STEMI patients undergoing primary angioplasty, both SES and PES are associated with significant benefits in terms of target lesion revascularization at the long-term follow-up compared with BMS with no excess risk of thrombotic complications. Thus, until the results of further large randomized trials with long-term follow-up become available, drug-eluting stents may be considered among STEMI patients undergoing primary angioplasty.

A new rat model of small vessel stenting.

AbstractObjectives: Restenosis is the major complication of coronary angioplasty and stenting. In addition, the small vessel diameter represents a major limitation to the wide use of the technology. The aim of this study was to assess the feasibility and the vascular response of stent deployment in rat small vessels. Methods: In 40 Wistar rats (500–550 g) a Nir stent crimped on a 1.5 mm Comet angioplasty balloon catheter was deployed at high pressure in the common carotid artery. Neointimal area, neointima/media ratio and the arterial dimension were assessed immediately and at 7, 14, 21, and 28 days after stenting. Results: After stent deployment, the neointimal area and the neointima/media ratio increased progressively and peaked at 14 days (p < 0.05 vs 0 and 7 days). Alpha-actin-positive cells were found circumferentially organized on the lumen surface. At 21 and 28 days after stenting, the neointima and the neointima/media ratio were not statistically different compared with the results obtained fourteen days after stent deployment. No significant differences in the area of external elastic lamina were observed during the study period. In contrast, the internal lumen area was reduced significantly at 14, 21, and 28 days after the stent deployment. Subacute thrombosis rate after stent implantation was 26.5%. Conclusions: The results of this study demonstrated that the balloon expandable stents can be safely placed into rat arteries and the reduction of the internal arterial lumen observed after stent deployment was only due to the neointima formation whereas remodeling did not occur.