Statins, nitric oxide and neovascularization

Pravastatin suppresses inflammatory cytokines and endothelial activation in patients at risk of developing preeclampsia: INOVASIA study

INTRODUCTION

The Indonesian INOVASIA study is an ongoing multicentre randomized, open controlled trial of pravastatin for the prevention of preeclampsia in patients deemed to be high risk. Here we evaluate the effects of pravastatin on circulating inflammatory and endothelial markers, i.e. Vascular Endothelial Growth Factor (VEGF), Interleukin-6 (IL-6), Endothelin-1 (ET-1), and Nitric Oxide (NO).

METHODS

Pregnant women deemed to be at a high risk of developing preeclampsia women were recruited based on the Fetal Medicine Foundation preeclampsia screening test or a history of preterm preeclampsia, or clinical risk factors in combination with an abnormal uterine artery Doppler flow pattern at 11-20 week's gestation. This is a nested cohort study within the larger trial (INOVASIA); 38 patients were consecutively recruited and assigned to the pravastatin group and the control group. Participants in the pravastatin group received pravastatin (2 × 20 mg p.o) in addition to a standard regimen of aspirin (80 mg p.o) and calcium (1 g p.o), from 14 to 20 weeks until delivery. Blood samples to measure the various biomarkers were obtained in consecutive patients before starting the research medication and just before delivery (pre and post-test examination).

RESULT

The number of samples on the 2 time points for the various biomarkers was: VEGF: 38, IL-6: 30, ET-1: 38, and NO: 35. IL-6 levels decreased significantly in the pravastatin group (mean ± SD): (191.87 ± 82.99 vs. 151.85 + 48.46, p = .013), while levels in the control group did not change significantly (median (interquartile range)) (144.17 (53.91) vs. 140.82 (16.18), p = .177). ET-1 levels decreased significantly in the pravastatin group (3.64 ± 0.85 vs. 3.01 ± 0.74, p = .006) while the control group had more or less stable levels (3.57 ± 1.12 vs. 3.78 ± 0.73 p = .594). NO was the only serum marker that showed significant changes in both groups. NO levels increased in pravastatin group (11.30 (17.43) vs. 41.90 (53.18), p = .044) and decreased in control group (38.70 (34.80) vs. 10.03 (26.96), p = .002). VEGF levels appeared to follow opposite trends in the 2 groups (NS) (Pravastatin: 3.22 (0.62) vs. 3.28 (0.75), p = .402. Control: 3.38 (0.83) vs. 3.06 (0.74), p = .287).

CONCLUSION

Administration of 40 mg pravastatin resulted in an improvement in NO levels, and a decrease in IL-6 and endothelin (ET-1) levels. The direction of the effect of pravastatin on these biomarkers appears to underpin the potential for a beneficial effect of pravastatin in the prevention of preeclampsia.

Atorvastatin increases oxidative stress and inhibits cell migration of oral squamous cell carcinoma in vitro

OBJECTIVE

This study aimed to evaluate the effect of atorvastatin treatment on reactive oxygen species (ROS) production and tumor angiogenesis in oral squamous cell carcinomas.

MATERIAL AND METHODS

An HN13 cell line was treated with 1 µM, 5 µM, and 10 µM of atorvastatin. VEGF-A gene expression was evaluated by quantitative real time PCR. VEGF-A protein expression was quantified from total protein and conditioned media by ELISA. Cellular oxidative stress was measured using 2',7'-dichlorfluorescein-diacetate (DCFH-DA). Angiogenesis assay was performed using human umbilical vein endothelial cells (HUVEC). The effect of atorvastatin on cell migration was evaluated by wound healing assay.

RESULTS

5 µM and 10 µM of atorvastatin significantly increased VEGF-A gene expression in the HN13 cell line. Intracellular expression of the VEGF-A protein was higher in the cells treated with 5 µM and 10 µM than in the control cells. VEGF-A protein expression was also higher in the conditioned media from the atorvastatin-treated cells than in the media from the DMSO-treated cells. 5 µM and 10 µM of atorvastatin increased oxidative stress. Regarding angiogenesis assay, 5 µM of atorvastatin resulted in higher numbers of branch points, compared to the solvent. 10 µM of atorvastatin treatment resulted in significantly reduced cell migration.

CONCLUSIONS

This study showed that atorvastatin increases the oxidative stress and angiogenesis in oral squamous cell carcinomas. The decrease of cell migration indicates atorvastatin's inhibitory effect in oral tumors. These results suggest that atorvastatin could increase the intracellular oxidative stress in these cells, leading to a toxic microenvironment and inhibiting their metastasis.

Role of lipids and intraplaque hypoxia in the formation of neovascularization in atherosclerosis

According to the current paradigm, chronic vascular inflammation plays a central role in the pathogenesis of atherosclerosis. The plaque progression is typically completed with rupture and subsequent acute cardiovascular complications. Previously, the role of adventitial vasa vasorum in atherogenesis was underestimated. However, investigators then revealed that vasa vasorum neovascularization can be observed when no clinical manifestation of atherosclerosis is present. Vasa vasorum is involved in various proatherogenic processes such as intimal accumulation of inflammatory leukocytes, intimal thickening, necrotic core formation, intraplaque haemorrhage, lesion rupture and atherothrombosis. Due to the destabilizing action of the intraplaque microenvironment, lesional vasa vasorum neovessels experience serious defects and abnormalities during development that leads to their immaturity, fragility and leakage. Indeed, intraplaque neovessels are a main cause of intraplaque haemorrhage. Visualization techniques showed that presence of neovascularization/haemorrhage can serve as a good indicator of lesion instability and higher risk of rupture. Vasa vasorum density is a strong predictor of acute cardiovascular events such as sudden death, myocardial infarction and stroke. At present, arterial vasa vasorum neovascularization is under intensive investigation along with development of therapeutic tools focused on the control of formation of vasa vasorum neovessels in order to prevent plaque haemorrhage/rupture and thromboembolism. KEY MESSAGE Neovascularization plays an important role in atherosclerosis, being involved in unstable plaque formation. Presence of neovascularization and haemorrhage indicates plaque instability and risk of rupture. Various imaging techniques are available to study neovascularization.

Paracrine effect of CXCR4-overexpressing mesenchymal stem cells on ischemic heart injury

It has been reported that CXCR4-overexpressing mesenchymal stem cells (MSC^CX4 ) can repair heart tissue post myocardial infarction. This study aims to investigate the MSCCX4-derived paracrine cardio-protective signaling in the presence of myocardial infarction. Mesenchymal stem cells (MSCs) were divided into 3 groups: MSC only, MSC^CX4 , and CXCR4 gene-specific siRNA-transduced MSC. Mesenchymal stem cells were exposed to hypoxia, and then MSCs-conditioned culture medium was incubated with neonatal and adult cardiomyocytes, respectively. Cell proliferation-regulating genes were assessed by real-time polymerase chain reaction (RT-PCR). In vitro: The number of cardiomyocytes undergoing DNA synthesis, cytokinesis, and mitosis was increased to a greater extent in MSC^CX4 medium-treated group than control group, while this proproliferative effect was reduced in CXCR4 gene-specific siRNA-transduced MSC-treated cells. Accordingly, the maximal enhancement of vascular endothelial growth factor, cyclin 2, and transforming growth factor-β2 was observed in hypoxia-exposed MSC^CX4 . In vivo: MSCs were labeled with enhanced green fluorescent protein (EGFP) and engrafted into injured myocardium in rats. The number of EGFP and CD31 positive cells in the MSC^CX4 group was significantly increased than other 2 groups, associated with the reduced left ventricular (LV) fibrosis, the increased LV free wall thickness, the enhanced angiogenesis, and the improved contractile function. CXCR4 overexpression can mobilize MSCs into ischemic area, whereby these cells can promoted angiogenesis and alleviate LV remodeling via paracrine signaling mechanism.

The effects of pravastatin on the normal human placenta: Lessons from ex-vivo models

Introduction

Research in animal models and preliminary clinical studies in humans support the use of pravastatin for the prevention of preeclampsia. However, its use during pregnancy is still controversial due to limited data about its effect on the human placenta and fetus.

Methods

In the present study, human placental cotyledons were perfused in the absence or presence of pravastatin in the maternal reservoir (PraM). In addition, placental explants were treated with pravastatin for 5, 24 and 72 h under normoxia and hypoxia. We monitored the secretion of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), endothelial nitric oxide synthase (eNOS) expression and activation and the fetal vasoconstriction response to angiotensin-II.

Results

The concentrations of PlGF, sFlt-1 and sEng were not significantly altered by pravastatin in PraM cotyledons and in placental explants compared to control. Under hypoxic conditions, pravastatin decreased sFlt-1 concentrations. eNOS expression was significantly increased in PraM cotyledons but not in pravastatin-treated placental explants cultured under normoxia or hypoxia. eNOS phosphorylation was not significantly affected by pravastatin. The feto-placental vascular tone and the fetal vasoconstriction response to angiotensin-II, did not change following exposure of the maternal circulation to pravastatin.

Conclusion

We found that pravastatin does not alter the essential physiological functions of the placenta investigated in the study. The relevance of the study lays in the fact that it expands the current knowledge obtained thus far regarding the effect of the drug on the normal human placenta. This data is reassuring and important for clinicians that consider the treatment of high-risk patients with pravastatin, a treatment that exposes some normal pregnancies to the drug.

Herbal Formula Danggui-Shaoyao-San Promotes Neurogenesis and Angiogenesis in Rat Following Middle Cerebral Artery Occlusion

Current studies demonstrated that traditional Chinese herbal formula Danggui-Shaoyao-San (DSS) is not only used for the treatment of menstrual disorder, but has also found its use in neurological diseases. However, the neuroprotective role of DSS on ischemia-induced brain injury is still unclear. The aim of the present study is to explore the effect of DSS in ischemic brain injury. Total 30 adult female Sprague-Dawley rats underwent 90 min transient middle cerebral artery occlusion (MCAO). DSS (600 mg/kg) was administered through the intragastric route at the time of reperfusion and then performed every day thereafter until sacrifice. Results showed that DSS treatment significantly improved neurobehavioral outcomes (N=10 per group, P<0.05). Immunohistochemical staining showed that microvessel density in the perifocal region of DSS-treated rats was significantly increased compared to the saline-treated group (N=4 per group, P<0.01). Similarly, the numbers of BrdU(+)/DCX(+) cells in the subventricular zone were increased in DSS-treated rats compared to the saline-treated group (P<0.05). Furthermore, we demonstrated that DSS treatment activated vascular endothelial growth factor (N=4 per group, P<0.05) and promoted eNOS phosphorylation (N=4 per group, P<0.05). Thus, we concluded that DSS promoted focal angiogenesis and neurogenesis, and attenuated ischemia-induced brain injury in rats after MCAO, suggesting that DSS is a potential drug for ischemic stroke therapy.

Atorvastatin increases oxidative stress and modulates angiogenesis in Ossabaw swine with the metabolic syndrome

OBJECTIVE

The purpose of the present study was to evaluate the effect of atorvastatin on oxidative stress and angiogenesis in ischemic myocardium in a clinically relevant porcine model of the metabolic syndrome.

METHODS

Sixteen Ossabaw pigs were fed either a high-fat diet alone or a high-fat diet supplemented with atorvastatin (1.5 mg/kg daily) for 14 weeks. Chronic myocardial ischemia was induced by ameroid constrictor placement around the circumflex artery. After 6 months of the diet, myocardial perfusion was measured at rest and with demand pacing. The heart was harvested for analysis of perfusion, microvessel relaxation, protein expression, and oxidative stress.

RESULTS

Both groups had similar endothelium-dependent microvessel relaxation to adenosine diphosphate and endothelium-independent relaxation to sodium nitroprusside. Myocardial perfusion in the ischemic territory was also not significantly different either at rest or with demand pacing. Atorvastatin treatment increased total myocardial protein oxidation and serum lipid peroxidation. However, the expression of markers of oxidative stress, including NOX2, RAC1, myeloperoxidase, and superoxide dismutase 1, 2, and 3, were not statistically different. The expression of proangiogenic proteins endothelial nitric oxide synthase, phosphorylated endothelial nitric oxide synthase (Ser 1177), phosphorylated adenosine monophosphate kinase (Thr 172), phosphorylated extracellular signal-regulated kinase (T202, Y204), and vascular endothelial growth factor were all upregulated in the atorvastatin group.

CONCLUSIONS

Atorvastatin increased the capillary and arteriolar density and upregulated the proangiogenic proteins endothelial nitric oxide synthase and phosphorylated endothelial nitric oxide synthase, phosphorylated adenosine monophosphate kinase, phosphorylated extracellular signal-regulated kinase, and vascular endothelial growth factor in a swine model of the metabolic syndrome. However, it failed to increase myocardial perfusion. Atorvastatin treatment was associated with increased myocardial and serum oxidative stress, which might contribute to the lack of collateral-dependent perfusion in the setting of angiogenesis.

Progenitor cell mobilizing treatments prevent experimental transplant arteriosclerosis

OBJECTIVE

Vascular rejection after organ transplantation is characterized by an arterial occlusive lesion, resulting from intimal proliferation occurring in response to arterial wall immune aggression. Our hypothesis is that an early endothelial repair may prevent vascular graft rejection. The aim of the current study was to compare different pharmacologic progenitor cell mobilizing treatments for their protective effects against vascular rejection.

METHODS AND RESULTS

Aortic transplants were made from balb/c donor to C57Bl/6 recipient mice. Three different mobilizing pharmacologic agents were used: low molecular weight fucoidan (LMWF), simvastatin, and AMD3100. The circulating levels of progenitor cells were found to be increased by all three treatments, as determined by flow cytometry. For each treatment, the design was: treated allografts, nontreated allografts, treated isografts, and nontreated isografts. After 21 d, morphometric and immunohistochemical analyses were performed. We found that the three treatments significantly reduced intimal proliferation, compared with nontreated allografts. This was associated with intimal re-endothelialization of the grafts. Further, in chimeric mice that had previously received GFP-transgenic bone marrow transplantation, GFP-positive cells were found in the vascular allograft intima, indicating that re-endothelialization was, at least partly, due to the recruitment of bone marrow-derived, presumably endothelial progenitor circulating cells.

CONCLUSIONS

In this aortic allograft model, three different mobilizing treatments were found to partially prevent vascular transplant rejection. Bone marrow-derived progenitor cells mobilized by the three treatments may play a direct role in the endothelial repair process and in the suppression of intimal proliferation.

Ablation of cholesterol biosynthesis in neural stem cells increases their VEGF expression and angiogenesis but causes neuron apoptosis

Although sufficient cholesterol supply is known to be crucial for neurons in the developing mammalian brain, the cholesterol requirement of neural stem and progenitor cells in the embryonic central nervous system has not been addressed. Here we have conditionally ablated the activity of squalene synthase (SQS), a key enzyme for endogenous cholesterol production, in the neural stem and progenitor cells of the ventricular zone (VZ) of the embryonic mouse brain. Mutant embryos exhibited a reduced brain size due to the atrophy of the neuronal layers, and died at birth. Analyses of the E11.5-E15.5 dorsal telencephalon and diencephalon revealed that this atrophy was due to massive apoptosis of newborn neurons, implying that this progeny of the SQS-ablated neural stem and progenitor cells was dependent on endogenous cholesterol biosynthesis for survival. Interestingly, the neural stem and progenitor cells of the VZ, the primary target of SQS inactivation, did not undergo significant apoptosis. Instead, vascular endothelial growth factor (VEGF) expression in these cells was strongly upregulated via a hypoxia-inducible factor-1-independent pathway, and angiogenesis in the VZ was increased. Consistent with an increased supply of lipoproteins to these cells, the level of lipid droplets containing triacylglycerides with unsaturated fatty acyl chains was found to be elevated. Our study establishes a direct link between intracellular cholesterol levels, VEGF expression, and angiogenesis. Moreover, our data reveal a hitherto unknown compensatory process by which the neural stem and progenitor cells of the developing mammalian brain evade the detrimental consequences of impaired endogenous cholesterol biosynthesis.

Beneficial effects of statin treatment after myocardial infarction: Is progenitor cell mobilization the missing link?

It is widely accepted that statin treatment improves survival in patients with myocardial infarction. Evidence also suggests that aggressive statin treatment is superior than standard dose during the post-infarction period. However, the exact mechanisms are still not well understood. Endothelial progenitor cells (EPC) play a key role in vascular homeostasis, since they contribute to the repair of damaged endothelium post-myocardial infarction, while they induce neoangiogenesis. Recent evidence suggests that statins may exert their beneficial effect in patients with recent myocardial infarction, by inducing EPC mobilization, and this may be a key mechanism by which statins improve survival in these patients. However, large scale clinical trials remain to prove that aggressive statin treatment is superior than standard dose in these patients, by inducing a more effective EPC mobilization.

Benidipine, a dihydropyridine-Ca2+ channel blocker, increases the endothelial differentiation of endothelial progenitor cells in vitro

Benidipine is a dihydropyridine-Ca2+ channel blocker used in the treatment of hypertension and angina pectoris. In the present study, we examined the effects of benidipine on the endothelial differentiation of circulating endothelial progenitor cells (EPCs) using an in vitro culture method. Peripheral blood derived mononuclear cells (PBMCs) containing EPCs were isolated from C57BL/6 mice, and then the cells were cultured on vitronectin/gelatin-coated slide glasses. After 7 days of culture, endothelial cells differentiated from EPCs were identified as adherent cells with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine-labeled acetylated low density lipoprotein (Dil-Ac-LDL) uptake and lectin binding under a fluorescent microscope. Incubation of PBMCs for 7 days with benidipine (0.01-1 micromol/l) significantly increased the number of Dil-Ac-LDL+/fluorescein isothiocyanate-lectin (FITC-Lectin)+ cells. Wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor, selectively attenuated the effect of benidipine on the endothelial differentiation. In addition, benidipine treatment augmented the phosphorylation of Akt, indicating that the PI3K/Akt pathway contributed, at least in part, to the endothelial differentiation induced by benidipine. These results suggest that the treatment with benidipine may increase the endothelial differentiation of circulating EPCs and contribute to endothelial protection, prevention of cardiovascular disease, and/or an improvement of the prognosis after ischemic damage.