Total Panax notoginseng saponin inhibits balloon injury-induced neointimal hyperplasia in rat carotid artery models by suppressing pERK/p38 MAPK pathways

Total Panax notoginseng saponin (TPNS) is the main bioactivity compound derived from the roots and rhizomes of Panax notoginseng (Burk.) F.H. Chen. The aim of this study was to investigate the effectiveness of TPNS in treating vascular neointimal hyperplasia in rats and its mechanisms. Male Sprague-Dawley rats were randomly divided into five groups, sham (control), injury, and low, medium, and high dose TPNS (5, 10, and 20 mg/kg). An in vivo 2F Fogarty balloon-induced carotid artery injury model was established in rats. TPNS significantly and dose-dependently reduced balloon injury-induced neointimal area (NIA) (P<0.001, for all doses) and NIA/media area (MA) (P<0.030, for all doses) in the carotid artery of rats, and PCNA expression (P<0.001, all). The mRNA expression of smooth muscle (SM) α-actin was significantly increased in all TPNS groups (P<0.005, for all doses) and the protein expression was significantly increased in the medium (P=0.006) and high dose TPNS (P=0.002) groups compared to the injury group. All the TPNS doses significantly decreased the mRNA expression of c-fos (P<0.001). The medium and high dose TPNS groups significantly suppressed the upregulation of pERK1/2 protein in the NIA (P<0.025) and MA (P<0.004). TPNS dose-dependently inhibited balloon injury-induced activation of pERK/p38MAPK signaling in the carotid artery. TPNS could be a promising agent in inhibiting cell proliferation following vascular injuries.

In-stent restenosis assessed with frequency domain optical coherence tomography shows smooth coronary arterial healing process in second-generation drug-eluting stents

INTRODUCTION@#The pathophysiology and mechanism of in-stent restenosis (ISR) after implantation of second-generation drug-eluting stents (DESs) are not fully clear. We compared the morphological characteristics of ISR between first- and second-generation DESs using frequency domain optical coherence tomography (OCT).@*METHODS@#Patients who underwent follow-up coronary angiography (CAG) after first-generation (CYPHER™ and TAXUS™) and second-generation (Nobori®, PROMUS Element™, Resolute Integrity and XIENCE) DES implantations were examined. ISR was defined as lesions of over 50% diameter stenosis at follow-up CAG. Frequency domain OCT was performed at the time of revascularisation of ISR. Tissue morphology was assessed at minimum lumen area. OCT images of DESs at both early (≤ 1 year) and late (> 1 year) phase follow-up were compared.@*RESULTS@#On qualitative OCT assessment, the ratios of homogeneous, layered, heterogeneous without-attenuation and heterogeneous with-attenuation morphologies were 57.1%, 17.1%, 20.0% and 5.7%, respectively, for second-generation DES ISR (n = 35), and 16.7%, 25.0%, 25.0% and 33.3%, respectively, for first-generation DES ISR (n = 36). At late phase follow-up, homogeneous morphology was significantly more common for second-generation DES ISR compared to first-generation DES ISR (first-generation: 8.0% vs. second-generation: 50.0%; p < 0.01) while heterogeneous with-attenuation morphology was significantly more common for first-generation DES ISR (first-generation: 44.0% vs. second-generation: 5.6%; p < 0.01).@*CONCLUSION@#Homogeneous tissue morphology was more frequently found for second-generation than first-generation DES ISR, especially in the late phase. This suggested that neointimal hyperplasia was the main mechanism in second-generation DES ISR, and that the neointima was stabilised, much like in bare metal stent implantation.

Anti-malarial Drugs Reduce Vascular Smooth Muscle Cell Proliferation via Activation of AMPK and Inhibition of Smad3 Signaling

OBJECTIVE: The aim of this study was to investigate the effects of 2 anti-malarial drugs, chloroquine (CQ) and hydroxychloroquine (HCQ), on inhibition of vascular smooth muscle cell (VSMC) proliferation both in vivo and in vitro via Adenosine monophosphate-activated protein kinase (AMPK) activation. METHODS: Protein and mRNA levels were determined by western blot analysis and real-time reverse transcription-polymerase chain reaction in primary rat VSMCs treated with CQ and HCQ, respectively. Cell proliferation was measured by flow cytometry and cell counting. Mice carotid arteries were ligated and treated with CQ or HCQ every other day for 3 weeks. Pathological changes of carotid arteries were visualized by both microscopy and fluorescence microscopy. RESULTS: CQ and HCQ increase AMPK phosphorylation in VSMCs. Both CQ and HCQ decrease platelet-derived growth factor-induced VSMC proliferation and cell cycle progression in an AMPK-dependent manner. In addition, CQ and HCQ inhibit Smad3 phosphorylation and VSMC proliferation induced by transforming growth factor-β1. Moreover, CQ and HCQ diminished neointimal proliferation in a mouse model of carotid artery ligation-induced neointima formation. CONCLUSION: The results demonstrated that CQ and HCQ inhibit cell proliferation and cell cycle progression in VSMCs via the AMPK-dependent signaling pathway. Carotid artery ligation-induced intima thickness was reduced in mouse arteries treated with CQ or HCQ, suggesting a role for antimalarial drugs in treating atherosclerosis and restenosis.

Randomized Comparison of Strut Coverage between Ticagrelor and Clopidogrel in Acute Myocardial Infarction at 3-Month Optical Coherence Tomography

PURPOSE: This study aimed to compare the effects of ticagrelor and clopidogrel on early neointimal healing assessed with optical coherence tomography (OCT) after drug-eluting stent (DES) implantation in patients with acute myocardial infarction (AMI). MATERIALS AND METHODS: AMI patients were randomly assigned to either the ticagrelor or clopidogrel arm. After DES implantation, OCT was performed to assess the percentages of uncovered struts immediately after procedure and 3 months later. RESULTS: Due to early termination, 83 patients out of 106 initially enrolled patients (24% of planned participants) underwent 3-month OCT. Differences in vascular healing patterns between the two groups, including percentage of uncovered struts on 3-month OCT (9.6% vs. 11.7% in ticagrelor vs. clopidogrel, respectively; p=0.867), neointimal thickness, percentage of malapposed struts, and healing scores did not reach statistical significance. The predictors of uncovered strut on 3-month OCT included greater reference vessel diameter [odds ratio (OR)=1.96, p < 0.001] and more malapposed struts (OR=1.12, p=0.003). CONCLUSION: The current study did not explore favorable effect of ticagrelor on 3-month vascular healing after DES implantation. Our findings should only be considered for generating hypothesis, due to insufficient power.

A Novel Urotensin II Receptor Antagonist, KR-36996 Inhibits Smooth Muscle Proliferation through ERK/ROS Pathway

Urotensin II (UII) is a mitogenic and hypertrophic agent that can induce the proliferation of vascular cells. UII inhibition has been considered as beneficial strategy for atherosclerosis and restenosis. However, currently there is no therapeutics clinically available for atherosclerosis or restenosis. In this study, we evaluated the effects of a newly synthesized UII receptor (UT) antagonist, KR-36996, on the proliferation of SMCs in vitro and neointima formation in vivo in comparison with GSK-1440115, a known potent UT antagonist. In primary human aortic SMCs (HASMCs), UII (50 nM) induced proliferation was significantly inhibited by KR-36996 at 1, 10, and 100 nM which showed greater potency (IC₅₀: 3.5 nM) than GSK-1440115 (IC₅₀: 82.3 nM). UII-induced proliferation of HASMC cells was inhibited by U0126, an ERK1/2 inhibitor, but not by SP600125 (inhibitor of JNK) or SB202190 (inhibitor of p38 MAPK). UII increased the phosphorylation level of ERK1/2. Such increase was significantly inhibited by KR-36996. UII-induced proliferation was also inhibited by trolox, a scavenger for reactive oxygen species (ROS). UII-induced ROS generation was also decreased by KR-36996 treatment. In a carotid artery ligation mouse model, intimal thickening was dramatically suppressed by oral treatment with KR-36996 (30 mg/kg) which showed better efficacy than GSK-1440115. These results suggest that KR-36996 is a better candidate than GSK-1440115 in preventing vascular proliferation in the pathogenesis of atherosclerosis and restenosis.

Inhibitory effect of sustained perivascular delivery of paclitaxel on neointimal hyperplasia in the jugular vein after open cutdown central venous catheter placement in rats

PURPOSE: Inhibitory effect of paclitaxel on neointimal hyperplasia after open cutdown has not been elucidated. METHODS: For the control group (n = 16), silicone 2.7-Fr catheters were placed via the right external jugular vein with the cutdown method. For the treatment group (n = 16), a mixture of 0.65 mg of paclitaxel and 1 mL of fibrin glue was infiltrated around the exposed vein after cutdown. After scheduled intervals (1, 2, 4, and 8 weeks), the vein segment was harvested and morphometric analysis was performed on cross-sections. RESULTS: Proliferation of smooth muscle cell (SMC) was strongly suppressed in the treatment group, and the ratio of neointima to vein wall was significantly reduced in the treatment group (8 weeks; 0.63 ± 0.08 vs. 0.2 ± 0.08, P < 0.05). Luminal patency was significantly more preserved in the treatment group, and the luminal area was significantly wider in the paclitaxel-treated group compared to the control group (8 weeks; 1.91 ± 0.43 mm² vs. 5.1 ± 0.43 mm², P < 0.05). Mean SMC counts measured at 1 and 2 weeks after cutdown were significantly lower in the treatment group (2 weeks; 115 ± 22 vs. 62 ± 22). Paclitaxel was undetectable in systemic circulation (<10 ng/mL). CONCLUSION: Sustained perivascular delivery of paclitaxel with fibrin glue was effective in inhibiting neointimal hyperplasia in rat jugular vein after open cutdown.

Formation and Transformation of Neointima after Drug-eluting Stent Implantation: Insights from Optical Coherence Tomographic Studies

After coronary stent implantation, neointima formation resembles the wound healing process as it involves the sequential processes of inflammation, granulation, and remodeling. Because antiproliferative drugs and polymers of drug-eluting stents (DESs) delay vascular healing compared with bare metal stents, fibrin deposition can remain long after stent implantation, or inflammation can be excessive. Delayed vascular healing can be associated with adverse clinical outcomes including DES thrombosis or restenosis, and poor endothelization of DES neointima can accelerate neoatherosclerotic change inside the neointima, further contributing to luminal restenosis or neointimal instability. Despite the lack of correlation between pathologic and optical coherence tomography (OCT) findings, OCT assessments of neointima under various circumstances can reveal vascular responses to stent therapy. Homogeneous, heterogeneous, and layered neointima patterns can be recognized by OCT and can change with time. Homogeneous neointima might be associated with better clinical outcomes after DES implantation, whereas non-homogeneous neointima or neoatherosclerotic change can be associated with poorer clinical outcomes. However, limited data are currently available, and further studies are required to comprehensively address these questions.

Effect of Stents Coated with Artemisinin or Dihydroartemisinin in a Porcine Coronary Restenosis Model

BACKGROUND AND OBJECTIVES: Artemisinin and dihydroartemisinin are drugs used to treat malaria. These drugs suppress inflammatory reactions. The aim of this study was to examine the anti-intima hyperplasia effect of a novel drug-eluting stent with artemisinin or dihydroartemisinin in a porcine coronary restenosis model. MATERIALS AND METHODS: Pigs were randomized into four groups; in the first, the coronary arteries (20 pigs, a total of 40 coronary arteries, with 10 coronary arteries in each group) was implanted with bare metal stents (BMS, n=10); the second group was given polymer-coated stents (PCS, n=10); the third group was treated with artemisinin-eluting stents (AES, n=10); and the fourth group was given dihydroartemisinin-eluting stents (DAES, n=10). Histopathologic analysis was performed 28 days after stenting. RESULTS: The injury and fibrin scores among the four groups were not significantly different. However, the internal elastic lamina, lumen area, and neointima area were significantly different. Moreover, the percent area of stenosis (46.2±18.66% in BMS vs. 89.4±10.92% in PCS vs. 83.3±17.07% in AES vs. 36.7±11.20% in DAES, p<0.0001) and inflammation score (1.0 [range: 1.0-1.0] vs. 3.0 [range: 2.25-3.0] vs. 3.0 [range: 1.0-3.0] vs. 2.0 [range: 1.75-3.0] in BMS, PCS, AES, and DAES, respectively; p<0.001) were markedly decreased in the DAES group compared to the PCS group. CONCLUSION: DES, which uses a natural substance, dihydroartemisinin, showed a neointima and inflammatory suppressive effect in a porcine coronary restenosis model.

Related factors of optical coherence tomography detected in-stent heterogonous neointima / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the related factors of optical coherence tomography (OCT) detected in-stent heterogeneous neointimal in coronary stents.</p><p><b>METHODS</b>A total of 143 cases of coronary heart disease patients with OCT detected in-stent neointimal hyperplasia in Fuwai hospital from September 2009 to April 2012 were included in this study and patients data were retrospectively analyzed. Patients were divided into heterogeneous intima group(26 cases) and homogeneous intima group(117 cases)according to neointimal characteristics. Clinical features and OCT characteristics of the 2 groups were compared and binary logistic regression analysis was performed to analyze the risk factors of in-stent heterogonous neointimal hyperplasia.</p><p><b>RESULTS</b>Compared to homogeneous intima group, patients in heterogeneous intima group had significantly higher cholesterol level ((5.31±1.11)mmol/L vs.(4.70±0.94)mmol/L, P=0.005), low-density lipoprotein cholesterol level ((2.57±0.87)mmol/L vs.(2.29±0.46)mmol/L, P=0.021) and triglyceride level (2.12(1.82-2.87)mmol/L vs. 1.90(1.73-2.11)mmol/L, P=0.015). Moreover, the percent of percutaneous coronary intervention (PCI) because of acute coronary syndrome (23.1%(6/26) vs. 6.8%(8/117), P=0.022) and the thin cap neoatheroma (5.8%(28/481)vs. 3.9%(89/2 276), P=0.043) were also significantly higher in heterogeneous intima group than in homogeneous intima group. Binary logistic regression analysis showed that low-density lipoprotein cholesterol (OR=2.74, 95%CI 1.04-7.24, P=0.042), triglyceride (OR=2.88, 95%CI 1.05-7.89, P=0.040), PCI for acute coronary syndrome (OR=12.74, 95%CI 2.69-60.49, P=0.001), and cerebrovascular disease (OR=13.09, 95%CI 2.16-79.53, P=0.005) were risk factors for in-stent heterogenous intima. Time post stent implantation was protective factor for in-stent heterogenous intima (OR=0.63, 95%CI 0.42-0.96, P=0.033).</p><p><b>CONCLUSION</b>OCT detected heterogeneous intima is correlated with level of blood lipid, PCI for acute coronary syndrome and history of cerebrovascular disease, and it may lead to unstable intima.</p>

Blockade of Urotensin II Receptor Prevents Vascular Dysfunction

Urotensin II (UII) is a potent vasoactive peptide and mitogenic agent to induce proliferation of various cells including vascular smooth muscle cells (VSMCs). In this study, we examined the effects of a novel UII receptor (UT) antagonist, KR-36676, on vasoconstriction of aorta and proliferation of aortic SMCs. In rat aorta, UII-induced vasoconstriction was significantly inhibited by KR-36676 in a concentration-dependent manner. In primary human aortic SMCs (hAoSMCs), UII-induced cell proliferation was significantly inhibited by KR-36676 in a concentration-dependent manner. In addition, KR-36676 decreased UII-induced phosphorylation of ERK, and UII-induced cell proliferation was also significantly inhibited by a known ERK inhibitor U0126. In mouse carotid ligation model, intimal thickening of carotid artery was dramatically suppressed by oral treatment with KR-36676 (30 mg/ kg/day) for 4 weeks compared to vehicle-treated group. From these results, it is indicated that KR-36676 suppress UII-induced proliferation of VSMCs at least partially through inhibition of ERK activation, and that it also attenuates UII-induced vasoconstriction and vascular neointima formation. Our study suggest that KR-36676 may be an attractive candidate for the pharmacological management of vascular dysfunction.

Effect of cilostazol on neointimal hyperplasia in iliac arteries of pigs after transluminal angioplasty / Efeito do cilostazol na hiperplasia neointimal em artérias ilíacas de suínos submetidas à angioplastia transluminal

OBJECTIVE: To evaluate whether systemic administration of cilostazol reduces neointimal hyperplasia in iliac arteries of pigs submitted to balloon catheter angioplasty. METHODS:Twenty pigs underwent angioplasty with a 6x40 mm balloon catheter in the right common iliac artery, guided by Doppler ultrasound. The animals were randomized into two groups: group 1 (n=10), which received 50mg cilostazol twice a day, and group 2 (n=10), control. After 30 days, the animals were killed and the iliac arteries prepared for histological analysis. The histological sections were digitized and analyzed by digital morphometry. Statistical analysis was performed using the Student t and Mann-Whitney tests. RESULTS:When comparing the iliac arteries submitted to angioplasty with those not subjected to angioplasty, there was significant neointimal hyperplasia (0.228 versus 0.119 mm2; p=0.0001). In arteries undergoing angioplasty, there was no difference between group 1 (cilostazol) and group 2 (control) as for the lumen area (2.277 versus 2.575 mm2; p=0.08), the tunica intima (0.219 versus 0.237 mm2; p=0.64), the tunica media (2.262 vs. 2.393 mm2; p=0.53) and the neointimal occlusion percentage (8.857 vs. 9.257 %; p=0.82). CONCLUSION:The use of cilostazol 50mg administered in two daily doses did not reduce neointimal hyperplasia in iliac arteries of pigs submitted to balloon angioplasty catheter.

OBJETIVO: Avaliar se a administração sistêmica de cilostazol reduz a hiperplasia neointimal nas artérias ilíacas de suínos submetidas à angioplastia com cateter balão. MÉTODOS:Vinte suínos foram submetidos à angioplastia com cateter balão 6x40 mm na artéria ilíaca comum direita, guiada por ultrassonografia com Doppler. Os animais foram randomizados em dois grupos: grupo 1 (n=10), no qual foi administrado cilostazol 50mg em duas doses diárias, e grupo 2 (n=10), considerado controle. Após 30 dias, os animais foram mortos, e as artérias ilíacas preparadas para análise histológica. Os cortes histológicos foram digitalizados e analisados por morfometria digital. A análise estatística foi realizada com o teste t de Student e o de Mann-Whitney. RESULTADOS: Comparando as artérias ilíacas submetidas à angioplastia com as artérias não submetidas à angioplastia, houve hiperplasia neointimal significativa (0,228 versus 0,119 mm2; p=0,0001). Nas artérias submetidas à angioplastia, não houve diferença entre o grupo 1 (cilostazol) e o grupo 2 (controle) na área do lúmen (2,277 versus 2,575 mm2; p=0,08), área da íntima (0,219 versus 0,237 mm2; p=0,64), área da média (2,262 versus 2,393 mm2; p=0,53) e no percentual de obstrução neointimal (8,857 versus 9,257 %; p=0,82).CONCLUSÃO: O uso de cilostazol 50mg administrado em duas doses diárias durante 30 dias não reduziu a hiperplasia neointimal em artérias ilíacas de suínos submetidas à angioplastia com cateter balão.

Clinical Characteristics and Prognosis of Peri-strut Low-intensity Area Detected by Optical Coherence Tomography / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Peri-strut low-intensity area (PLIA) is a typical image pattern of neointima detected by optical coherence tomography (OCT) after stent implantation. However, few studies evaluated the predictors and prognosis of the PLIA; therefore, we aimed to explore the genesis and prognosis of PLIA detected by OCT in this study.</p><p><b>METHODS</b>Patients presenting neointimal hyperplasia documented by OCT reexamination after percutaneous coronary intervention were prospectively included from 2009 to 2011. Peri-strut intensity was analyzed and classified into two patterns: Low-intensity and high-intensity. Clinical characteristics were analyzed to assess their contribution to peri-strut intensity patterns. Follow-up were performed in patients who did not receive revascularization during OCT reexamination, and the prognosis of the patients was evaluated.</p><p><b>RESULTS</b>There were 128 patients underwent OCT reexamination after stent implantation included in the study. PLIA was detected in 22 (17.2%) patients. The incidence of PLIA was positively correlated with serum triglyceride (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.14-3.90, P = 0.017), low-density lipoprotein (OR: 2.61, 95% CI: 1.22-5.66, P = 0.015), history of cerebrovascular disease (OR: 101.11, 95% CI: 6.54-1562.13, P < 0.001), and initial clinical presentation of acute coronary syndrome (ACS, OR: 18.77, 95% CI: 2.73-128.83, P = 0.003) while negatively correlated with stent implantation time (OR: 0.57, 95% CI: 0.33-0.98, P = 0.043). The median follow-up was longer than 3.8 years. Major adverse cardiovascular events (MACEs) occurred in 7 (7.3%) patients while showed no correlation with PLIA. A total of 17 (17.7%) patients experienced unstable angina (UA) and showed significant correlation with PLIA (hazard ratio: 6.16, 95% CI: 1.25-30.33, P = 0.025).</p><p><b>CONCLUSIONS</b>PLIA detected by OCT was positively correlated with higher serum lipid level, history of cerebrovascular disease and initial presentation of ACS, and negatively correlated with stent implantation time. Patients with PLIA were more likely to have UA than those with high-intensity while no significant difference was found in MACEs.</p>

A Preliminary Study of the Therapeutic Role of Human Early Fetal Aorta-derived Endothelial Progenitor Cells in Inhibiting Carotid Artery Neointimal Hyperplasia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Endothelial cell damage is an important pathophysiological step of restenosis after angioplasty and stenting. Cell transplantation has great therapeutic potential for endothelial recovery. We investigated the effect of transplanting endothelial progenitor cells (EPCs) derived from human early fetal aortas in rat injured arteries.</p><p><b>METHODS</b>The carotid arterial endothelium of Sprague-Dawley rats was damaged by dilatation with a 1.5 F balloon catheter, and then EPCs derived from human early fetal aortas (<14 weeks) were injected into the lumen of the injured artery in transplanted rats, with an equal volume of normal saline injected into control rats. Rats were sacrificed at 2 and 4 weeks after treatment and transplanted cells were identified by immunohistochemical staining with anti-human CD31 and anti-human mitochondria antibodies. Arterial cross-sections were analyzed by pathology, immunohistochemistry, and morphometry.</p><p><b>RESULTS</b>Green fluorescence-labeled EPCs could be seen in the endovascular surface of balloon-injured vessels after transplantation. The intimal area and intimal/medial area ratio were significantly smaller in the transplanted group than in the control (P < 0.05) and the residual lumen area was larger (P < 0.05). After EPC transplantation, a complete vascular endothelial layer was formed, which was positive for human von Willebrand factor after immunohistochemical staining, and immunohistochemical staining revealed many CD31- and mitochondria-positive cells in the re-endothelialized endothelium with EPC transplantation but not control treatment.</p><p><b>CONCLUSION</b>EPCs derived from human early fetal aorta were successfully transplanted into injured vessels and might inhibit neointimal hyperplasia after vascular injury.</p>

Effect of Pretreatment of Ezetimibe/Simvastatin on Arterial Healing and Endothelialization after Drug-Eluting Stent Implantation in a Porcine Coronary Restenosis Model

BACKGROUND AND OBJECTIVES: We sought to evaluate the effect of the early use of ezetimibe/simvastatin (Vytorin(R)) on arterial healing and endothelialization after the implantation of a drug-eluting stent (DES) in a porcine model of coronary restenosis. MATERIALS AND METHODS: A total of 20 pigs (40 coronary arteries) were randomly allocated to a pretreatment or no treatment group. The pretreatment group (n=20) received oral ezetimibe/simvastatin (10/20 mg) daily for 7 days before stenting and the no pretreatment group (n=20) did not. All pigs were treated with ezetimibe/simvastatin (10/20 mg) daily after stenting for 4 weeks. Stenting was performed using a bare-metal stent (BMS, n=10) and three types of DES: biolimus A9-eluting stent (BES, n=10), zotarolimus-eluting stent (ZES, n=10), and everolimus-eluting stents (EES, n=10). Four weeks later, pigs underwent a follow-up coronary angiography and were sacrificed for histopathologic analysis. RESULTS: There were no significant differences between the pretreatment and no pretreatment groups in the internal elastic lamina area, lumen area, neointima area, stenotic area, injury score, fibrin score, and inflammation score. In both groups, the fibrin score was higher in pigs with DES than in BMS, particularly in ZES and EES. The inflammatory score was not different between DES and BMS. CONCLUSION: In a porcine model of coronary restenosis, pretreatment with ezetimibe/simvastatin before DES implantation failed to improve arterial healing and endothelialization compared to treatment after stenting.

Effect of imatinib mesylate and rapamycin on the preformed intimal hyperplasia in rat carotid injury model

PURPOSE: Intimal hyperplasia (IH) is the main cause of restenosis or occlusion after vascular procedures. Imatinib mesylate and rapamycin are known to prevent IH. The purpose of this study was to evaluate the effect of these drugs on the regression of preformed IH in rat carotid injury model. METHODS: IH was established in rat carotid arteries using a balloon catheter. The drug effects were assessed in vitro on proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) in the neointima. And in vivo studies were carried out in 4 groups: imatinib, rapamycin, combined, and no medication. After 2-week oral medication, morphometric analysis evaluated the number and density of neointimal cells, intima-to-media (I/M) ratio and cross-sectional area. Cell proliferation, apoptosis, and collagen changes were also investigated by immunohistochemical staining (IHCS). RESULTS: Imatinib and rapamycin significantly inhibited VSMC proliferation and migration, and promoted apoptosis in vitro. In morphometric analysis, the number and density of neointimal cells decreased significantly in all medication groups compared with control group (P < 0.01). However, there was no significant difference in neointimal cross-sectional area and I/M ratio among groups. In IHCS, imatinib and rapamycin inhibited neointimal cell proliferation significantly. However, there was no significant change in cell apoptosis and collagen composition. CONCLUSION: Combined treatment of with imatinib and rapamycin induced reduction of cell mass in preformed intimal hyperplasia, but failed to induce regression of intimal mass in this short-term medication study. Further studies will be needed with additional strategies of inducing lysis of the extracellular matrix.

The Contribution of Resident Vascular Stem Cells to Arterial Pathology

Intimal accumulation of smooth muscle cells contributes to the development and progression of atherosclerotic lesions and restenosis following endovascular procedures. Arterial smooth muscle cells display heterogeneous phenotypes in both physiological and pathological conditions. In response to injury, dedifferentiated or synthetic smooth muscle cells proliferate and migrate from the tunica media into the intima. As a consequence, smooth muscle cells in vascular lesions show a prevalent dedifferentiated phenotype compared to the contractile appearance of normal media smooth muscle cells. The discovery of abundant stem antigen-expressing cells in vascular lesions also rarely detected in the tunica media of normal adult vessels stimulated a great scientific debate concerning the possibility that proliferating vascular wall-resident stem cells accumulate into the neointima and contribute to the progression of lesions. Although several experimental studies support this hypothesis, others researchers suggest a positive effect of stem cells on plaque stabilization. So, the real contribute of vascular wall-resident stem cells to pathological vascular remodelling needs further investigation. This review will examine the evidence and the contribution of vascular wall-resident stem cells to arterial pathobiology, in order to address future investigations as potential therapeutic target to prevent the progression of vascular diseases.

Different Responses of Neointimal Cells to Imatinib Mesylate and Rapamycin Compared with Normal Vascular Smooth Muscle Cells

PURPOSE: This study was designed to investigate whether vascular smooth muscle cells (VSMC) from the neointima showed any different response to antiproliferative agents, such as rapamycin or imatinib mesylate, compared to VSMCs from normal artery. MATERIALS AND METHODS: Intimal hyperplasia was made by carotid balloon in jury in male rats. Neointimal cells at 4 weeks after injury and normal VSMCs were extracted by enzymatic isolation method and cultured. Cell viability and proliferation were tested in VSMCs from injured left carotid artery and uninjured right carotid artery. Tests were repeated with rapamycin, imatinib mesylate or both in various concentrations. RESULTS: Rapamycin decreased cell viability only at a high concentration of 10(-5) M in uninjured VSMCs. Combined drugs decreased cell viability at a lower concentration of 10(-7) M in uninjured VSMCs, and at a higher concentration of 10(-5) M in neointimal cells. Overall, rapamycin showed cytocidal effects at a high concentration of 10(-5) M, whereas imatinib did not. Cell proliferation of neointima was significantly decreased along with the drug concentration. Cell proliferation of uninjured VSMCs was significantly decreased at higher drug concentrations. Combined drug therapy showed synergistic effects. Overall, neointimal cells are more susceptible to the antiproliferative effects of the drugs. CONCLUSION: Neointimal cells from the injured carotid artery are more susceptible to the antiproliferative effect of imatinib and rapamycin. Both drugs can be a used for the prevention of intimal hyperplasia, which could be investigated through further in vivo studies.

Optical Coherence Tomographic Observation of Morphological Features of Neointimal Tissue after Drug-Eluting Stent Implantation

PURPOSE: The impacts of different time courses and the degree of neointimal growth on neointimal morphology have not yet been sufficiently investigated. Therefore, we evaluated the morphological features of neointimal tissue after drug-eluting stent (DES) implantation using optical coherence tomography (OCT). MATERIALS AND METHODS: The morphological features of neointimal tissue in stented segments with a maximal percentage of cross-sectional area (CSA) stenosis of neointima were evaluated in 507 DES-treated lesions with >100 microm mean neointimal thickness on follow-up OCT. Neointimal tissue was categorized as homogeneous, heterogeneous, layered, or neoatherosclerotic. RESULTS: In lesions with or =50% of neointimal CSA stenosis, layered neointima was most frequently observed (68.3%), followed by neoatherosclerotic neointima (25.2%). In subgroup analysis of lesions with > or =50% of neointimal CSA stenosis, 89.5% of the lesions with a stent age or =30 months were neoatherosclerotic neointima. CONCLUSION: This study suggests that the OCT-detected morphology of DES neointimal tissue was different according to the follow-up time course and degree of neointimal hyperplasia.

Dissulfeto isomerase proteica como via integrativa entre estresse oxidativo e resposta a proteínas mal-enoveladas na reparação à lesão vascular / Protein disulfide isomerase as an integrative way between oxidative stress and unfolded protein response during vascular repair to injury

O remodelamento vascular é um determinante fundamental do lúmen em doenças vasculares, porém os mecanismos envolvidos não estão completamente elucidados. Nós investigamos o papel da chaperona redox residente do retículo endoplasmático Dissulfeto Isomerase Proteica (PDI) e sua fração localizada na superfície celular (peri/epicelular=pecPDI) no calibre e arquitetura vascular durante reparação à lesão. Em artérias ilíacas de coelho submetidas à lesão in vivo, houve importante aumento do mRNA e expressão proteica (~25x aumento 14 dias pós-lesão vs. controle) da PDI. O silenciamento da PDI por siRNA (cultura de órgãos) acentuou o estresse do retículo e apoptose, diferentemente da inibição da pecPDI com anticorpo neutralizante (PDI Ab). Bloqueio in vivo da pecPDI por aplicação de gel perivascular contendo PDI Ab no 12° dia após lesão, com análise após 48 h, promoveu ca.25% redução no calibre vascular analisado por arteriografia e diminuição similar na área total do vaso detectada por tomografia de coerência óptica. Neste processo, não ocorreu alteração no tamanho da neoíntima, indicando assim, que PDI Ab acentuou remodelamento constrictivo. Neutralização da pecPDI promoveu importantes alterações na arquitetura da matriz de colágeno e citoesqueleto, resultando em fibras com orientação invertida e desorganizadas. Diminuição na produção de espécies reativas de oxigênio e óxidos de nitrogênio também ocorreu. Análise de propriedades viscoelásticas nas artérias indicou redução na ductilidade vascular, evidenciada pela menor distância para ruptura. As alterações subcelulares no citoesqueleto observadas in vivo após PDI Ab foram recapituladas em um modelo de estiramento cíclico em células musculares lisas vasculares, com importante redução na formação das fibras de estresse. Em modelo de migração randômica de células musculares lisas, a exposição a PDI Ab reduziu a resiliência de regulação da polaridade. Embora a neutralização da pecPDI não tenha afetado a atividade...

Whole-vessel remodeling is a critical lumen caliber determinant in vascular disease, but underlying mechanisms are poorly understood. We investigated the role of endoplasmic reticulum chaperone Protein Disulfide Isomerase(PDI) and cell-surface PDI(peri/epicellular=pecPDI) pool in vascular caliber and architecture during vascular repair after injury(AI). After rabbit iliac artery balloon injury, there was marked increase in PDI mRNA and protein (25-fold vs. basal at day 14AI), with increase in both intracellular and pecPDI. Silencing PDI by siRNA (organ culture) induced ER stress augmentation and apoptosis, contrarily to pecPDI neutralization with PDI-antibody(PDI Ab). PecPDI neutralization in vivo with PDIAb-containing perivascular gel from days 12-14AI promoted ca.25% decrease in vascular caliber at arteriography and similar decreases in total vessel circumference at optical coherence tomography, without changing neointima, indicating increased constrictive remodeling. PecPDI neutralization promoted marked changes in collagen and cytoskeleton architecture, with inverted fiber orientation and disorganization. Decreased ROS and nitrogen oxide production also occurred. Viscoelastic artery properties assessment showed decreased ductility, evidenced by decreased distance to rupture. Subcellular cytoskeletal disruption by PDI Ab was recapitulated in vascular smooth muscle cell stretch model, with marked decrease in stress fiber buildup. Also, PDI Ab incubation promoted decreased regulation resilience of vascular smooth muscle migration properties. While pecPDI neutralization did not affect global RhoA activity, there was altered RhoA redistribution to the cell surface and association with caveolin-containing clusters, which mislocalized after stretch. In human coronary atheromas, PDI expression inversely correlated with constrictive remodeling. Thus, strongly-expressed PDI after injury reshapes matrix and cytoskeleton architecture to support an...