A Rat Carotid Balloon Injury Model to Test Anti-vascular Remodeling Therapeutics.

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is also a valuable model system to test, and to evaluate therapeutics and drugs that negate maladaptive remodeling in the vessel. The injury, or barotrauma, in the vessel lumen caused by an inflated balloon via an inserted catheter induces subsequent neointimal growth, often leading to hyperplasia or thickening of the vessel wall that narrows, or obstructs the lumen.

Vessel ultrasound sonographic assessment of soluble receptor for advanced glycation end products efficacy in a rat balloon injury model.

Objective: We aimed to assess the therapeutic efficacy of differentially modified soluble receptor for advanced glycation end products (sRAGE) in vivo using vessel ultrasound sonography and to compare the sonography data with those from postmortem histomorphologic analyses to have a practical reference for future clinical applications.

Methods: Vessel ultrasound sonography was performed in a sRAGE-treated rat carotid artery balloon injury model at different time points after the surgery, and therapeutic efficacy of different doses of sRAGE produced in Chinese hamster ovary cells and with different N-glycoform modifications were assessed.

Results: Vessel ultrasound sonography found that sRAGE produced in Chinese hamster ovary cells with complex N-glycoform modifications is highly effective, and is consistent with our recent findings in the same model assessed with histology.

The N-glycoform of sRAGE is the key determinant for its therapeutic efficacy to attenuate injury-elicited arterial inflammation and neointimal growth.

Unlabelled: Signaling of the receptor for advanced glycation end products (RAGE) has been implicated in the development of injury-elicited vascular complications. Soluble RAGE (sRAGE) acts as a decoy of RAGE and has been used to treat pathological vascular conditions in animal models. However, previous studies used a high dose of sRAGE produced in insect Sf9 cells (sRAGE(Sf9))and multiple injections to achieve the therapeutic outcome.

Chronic administration of small nonerythropoietic peptide sequence of erythropoietin effectively ameliorates the progression of postmyocardial infarction-dilated cardiomyopathy.

The cardioprotective properties of erythropoietin (EPO) in preclinical studies are well documented, but erythropoietic and prothrombotic properties of EPO preclude its use in chronic heart failure (CHF). We tested the effect of long-term treatment with a small peptide sequence within the EPO molecule, helix B surface peptide (HBSP), that possesses tissue-protective, but not erythropoietic properties of EPO, on mortality and cardiac remodeling in postmyocardial infarction-dilated cardiomyopathy in rats. Starting 2 weeks after permanent left coronary artery ligation, rats received i.

Myocardial infarction: cardioprotection by erythropoietin.

Extensive research during the last decade demonstrated that a single systemic administration of -erythropoietin (EPO) lead to significant attenuation of myocardial infarction (MI) induced in animals, mostly small rodents, either by a myocardial ischemia followed by reperfusion or by a permanent ligation of a coronary artery. Both methods are critically reviewed with the aim of helping the reader in appreciating key issues in the translation of experimental results to the clinic. Results of several clinical trials in patients with acute MI completed to date failed to demonstrate beneficial effects of EPO, and thus put into question the validity of results obtained in animal models.

Acute hemodynamic effects of erythropoietin do not mediate its cardioprotective properties.

Activation of nitric oxide (NO) signaling is considered, at list partially, a mechanistic basis for EPO-induced cardioprotection. Surprisingly, hemodynamic response subsequent to NO activation after EPO administration has never been reported. The objectives of this study were to evaluate the acute hemodynamic and cardiovascular responses to EPO administration, to confirm their NO genesis, and to test the hypothesis that EPO-induced cardioprotection is mediated through cardiovascular changes related to NO activation.

Chronic treatment with a broad-spectrum metalloproteinase inhibitor, doxycycline, prevents the development of spontaneous aortic lesions in a mouse model of vascular Ehlers-Danlos syndrome.

There is no proven therapy or prevention for vascular Ehlers-Danlos syndrome (vEDS), a genetic disorder associated with the mutation of procollagen type III and characterized by increased fragility of vascular and hollow organ walls. Heterozygous COL3A1-deficient (HT) mice recapitulate a mild presentation of one of the variants of vEDS: haploinsufficiency for collagen III. Adult HT mice are characterized by increased metalloproteinase (MMP) activity, reduced collagen content in the arterial walls, and spontaneous development of various severity lesions in aorta.

Did clinical trials in which erythropoietin failed to reduce acute myocardial infarct size miss a narrow therapeutic window?

Background: To test a hypothesis that in negative clinical trials of erythropoietin in patients with acute myocardial infarction (MI) the erythropoietin (rhEPO) could be administered outside narrow therapeutic window. Despite overwhelming evidence of cardioprotective properties of rhEPO in animal studies, the outcomes of recently concluded phase II clinical trials have failed to demonstrate the efficacy of rhEPO in patients with acute MI. However, the time between symptoms onset and rhEPO administration in negative clinical trials was much longer that in successful animal experiments.

SRT1720 improves survival and healthspan of obese mice.

Sirt1 is an NAD(+)-dependent deacetylase that extends lifespan in lower organisms and improves metabolism and delays the onset of age-related diseases in mammals. Here we show that SRT1720, a synthetic compound that was identified for its ability to activate Sirt1 in vitro, extends both mean and maximum lifespan of adult mice fed a high-fat diet. This lifespan extension is accompanied by health benefits including reduced liver steatosis, increased insulin sensitivity, enhanced locomotor activity and normalization of gene expression profiles and markers of inflammation and apoptosis, all in the absence of any observable toxicity.

Fenoterol enantiomers do not possess beneficial therapeutic properties of their racemic mixture in the rat model of post myocardial infarction dilated cardiomyopathy.

Purpose: A salutary effect of β(2) adrenergic receptor (AR) agonist, fenoterol has been demonstrated in a rat model of post-myocardial infarction (MI) dilated cardiomyopathy (DCM). Recent reports on single cardiomyocyte experiments suggested that out of two enantiomers, RR and SS, that constitute a racemic mixture of fenoterol, only RR-enantiomer is an active component that might be a promising new drug for treatment of chronic heart failure. The objective of this study was to compare the efficacy of the RR enantiomer of fenoterol with efficacy of racemic fenoterol, and SS, an inactive enantiomer, in whole animal experimental models of DCM.

Allele-specific siRNA knockdown as a personalized treatment strategy for vascular Ehlers-Danlos syndrome in human fibroblasts.

The vascular type of the Ehlers-Danlos syndrome (vEDS) is caused by dominant-negative mutations in the procollagen type III (COL3A1) gene. Patients with this autosomal dominant disorder have a shortened life expectancy due to complications from ruptured vessels or hollow organs. We tested the effectiveness of allele-specific RNA interference (RNAi) to reduce the mutated phenotype in fibroblasts.

Effects of calorie restriction on cardioprotection and cardiovascular health.

Multiple health benefits of calorie restriction (CR) and alternate day fasting (ADF) regimens are widely recognized. Experimental data concerning the effects of calorie restriction on cardiac health are more controversial, ranging from evidence that ADF protects heart from ischemic damage but results in developing of diastolic dysfunction, to reports that CR ameliorates the age-associated diastolic dysfunction. Here we investigated the effects of chronic CR on morphology and function of the cardiovascular system of aged rats and cardioprotective effect of CR against ischemic damage in the experimental rat model of MI.

Doxycycline ameliorates the susceptibility to aortic lesions in a mouse model for the vascular type of Ehlers-Danlos syndrome.

The vascular form of Ehlers-Danlos syndrome (vEDS), a rare disease with grave complications resulting from rupture of major arteries, is caused by mutations of collagen type III [α1 chain of collagen type III (COL3A1)]. The only, recently proven, preventive strategy consists of the reduction of arterial wall stress by β-adrenergic blockers. The heterozygous (HT) Col3a1 knockout mouse has reduced expression of collagen III and recapitulates features of a mild presentation of the disease.

A small nonerythropoietic helix B surface peptide based upon erythropoietin structure is cardioprotective against ischemic myocardial damage.

Strong cardioprotective properties of erythropoietin (EPO) reported over the last 10 years have been difficult to translate to clinical applications for ischemic cardioprotection owing to undesirable parallel activation of erythropoiesis and thrombogenesis. A pyroglutamate helix B surface peptide (pHBP), recently engineered to include only a part of the EPO molecule that does not bind to EPO receptor and thus, is not erythropoietic, retains tissue protective properties of EPO. Here we compared the ability of pHBP and EPO to protect cardiac myocytes from oxidative stress in vitro and cardiac tissue from ischemic damage in vivo.

Chronic alternate-day fasting results in reduced diastolic compliance and diminished systolic reserve in rats.

Background: Based on animal experiments and limited data from the few human trials, alternate-day fasting (ADF) resulted in weight loss, prolonged life, reduced metabolic risk factors for diabetes and cardiovascular diseases, and reduced prevalence of age-related diseases. The present study is the first comprehensive examination of the long-term effects of ADF on general cardiovascular fitness in rats.

Methods And Results: Four-month-old male Sprague-Dawley rats were started on ADF or continued on ad libitum diets and followed for 6 months with serial echocardiography.

β₂ AR agonists in treatment of chronic heart failure: long path to translation.

The main clinical manifestations of advanced chronic heart failure (CHF), e.g. in dilated cardiomyopathy (DCM), are reduced systolic and diastolic functions, increased arterial elastance and arterio-ventricular uncoupling, accompanied and exacerbated by an excessive sympathetic activation and extensive abnormalities in the βAR signaling.

Therapeutic efficacy of a combination of a beta1-adrenoreceptor (AR) blocker and beta2-AR agonist in a rat model of postmyocardial infarction dilated heart failure exceeds that of a beta1-AR blocker plus angiotensin-converting enzyme inhibitor.

We had proposed previously a novel combination of beta2-adrenoreceptor (AR) agonist and beta1-AR blocker that in the rat model of postmyocardial infarction (MI) dilated cardiomyopathy exceeds the therapeutic effectiveness of either monotherapy. In the present study, we compared that treatment with a combination of beta1-AR blocker and angiotensin-converting enzyme inhibitor (ACEi), a current standard chronic heart failure (CHF) therapy. Two weeks after coronary artery ligation, rats were divided into groups of similar average MI size, measured by echocardiography, and the following 12-month treatments were initiated: fenoterol (250 microg/kg/day), a beta2-AR agonist, plus metoprolol (100 mg/kg/day), a beta1-AR blocker (beta1-beta2+); metoprolol plus enalapril (20 mg/kg/day), an ACEi (beta1-ACEi); and a combination of all three drugs (beta1-beta2+ACEi).

Cardioprotective and survival benefits of long-term combined therapy with beta2 adrenoreceptor (AR) agonist and beta1 AR blocker in dilated cardiomyopathy postmyocardial infarction.

We have reported therapeutic effectiveness of pharmacological stimulation of beta2 adrenoreceptors (ARs) to attenuate the cardiac remodeling and myocardial infarction (MI) expansion in a rat model of dilated cardiomyopathy (DCM) post-MI. Furthermore, the combination of beta2 AR stimulation with beta1 AR blockade exceeded the therapeutic effectiveness of beta1 AR blockade. However, these studies were relatively short (6 weeks).

Intrahippocampal microinjection of an exquisitely low dose of ouabain mimics NaCl loading and stimulates a bufadienolide Na/K-ATPase inhibitor.

Background: Brain endogenous ouabain (EOU) raises blood pressure (BP) via an angiotensin II (ATII)-sensitive pathway in NaCl-loaded Dahl salt-sensitive rats (DSS). Brain EOU activates central and adrenocortical renin-angiotensin systems, and stimulates marinobufagenin, a vasoconstrictor and natriuretic inhibitor of sodium pump.

Methods: We studied effects of acute NaCl loading (17 mmol/kg NaCl, intraperitoneally) on levels of EOU and marinobufagenin in several brain areas in DSS.

Therapeutic effectiveness of a single vs multiple doses of erythropoietin after experimental myocardial infarction in rats.

Background: Systemic application of recombinant human erythropoietin (rhEPO) greatly limits cardiac tissue damage and attenuates left ventricular (LV) remodeling after experimentally induced myocardial infarction (MI). However, multiple injections of rhEPO stimulate red blood cell production and elevate the hematocrit (Htc), which might negatively affect the outcome of acute MI. We compared the outcome of experimental MI in rats treated with a single or multiple doses of rhEPO.

Pharmacological stimulation of beta2-adrenergic receptors (beta2AR) enhances therapeutic effectiveness of beta1AR blockade in rodent dilated ischemic cardiomyopathy.

Background: We have reported that beta2 adrenoreceptor (beta2AR) stimulation is anti-apoptotic, and has strong beneficial effect on cardiac remodeling in an experimental model of post myocardial infarction chronic heart failure (CHF) in rats. Here we investigate whether the addition of chronic pharmacological beta2AR stimulation enhances the therapeutic effects of beta1AR blockade on cardiac remodeling in the same model.

Methods And Results: Metoprolol, a beta1AR blocker, given alone (beta1) or in combination with beta2AR agonist, fenoterol (beta1beta2) were administered to rats via drinking water for 6 weeks, beginning 2 weeks following permanent coronary ligation.

Erythropoietin, modified to not stimulate red blood cell production, retains its cardioprotective properties.

Erythropoietin (EPO), a hematopoietic cytokine, possesses strong antiapoptotic, tissue-protective properties. For clinical applications, it is desirable to separate the hematopoietic and tissue-protective properties. Recently introduced carbamylated erythropoietin (CEPO) does not stimulate the erythropoiesis but retains the antiapoptotic and neuroprotective effects.

Cardioprotection by recombinant human erythropoietin following acute experimental myocardial infarction: dose response and therapeutic window.

Background: Recombinant human erythropoietin (rhEPO) protects tissue from ischemic damage, but translation of this finding into useful guidelines with respect to human trials for myocardial infarction (MI) requires a determination of the minimum effective rhEPO dose and the therapeutic window following MI.

Method And Results: Serial echocardiography revealed that during four weeks following MI, induced by a permanent coronary ligation in rats, the LV end-diastolic and end-systolic volumes in untreated rats expanded from 0.35 +/- 0.

Brain ouabain stimulates peripheral marinobufagenin via angiotensin II signalling in NaCl-loaded Dahl-S rats.

Objective: In NaCl-loaded Dahl salt-sensitive (DS) rats the transient stimulation of brain endogenous ouabain (EO) precedes the increase in renal excretion of marinobufagenin (MBG), a vasoconstrictor and natriuretic. In hypertensive DS rats, EO raises blood pressure (BP) via an ATII-sensitive pathway. We hypothesized that an NaCl-induced increase in MBG is linked to the EO-stimulated ATII pathway.

Beneficial effects of chronic pharmacological manipulation of beta-adrenoreceptor subtype signaling in rodent dilated ischemic cardiomyopathy.

Background: Studies in isolated cardiac myocytes have demonstrated that signaling via specific beta1-adrenergic receptor subtypes (beta1ARs) promotes but that signaling via beta2ARs protects from cell death. We hypothesized that prolonged beta(2)AR stimulation or beta1AR blockade would each protect myocytes from death and thereby ameliorate cardiac remodeling in chronic heart failure.

Methods And Results: A large myocardial infarction (MI) induced in rats by coronary artery ligation resulted in a dilated cardiomyopathy (DCM) characterized by infarct expansion and a progressive increase in left ventricular (LV) end-diastolic volume, accompanied by a reduction in ejection fraction (EF), as assessed by repeated echocardiography.