Establishment of a rat model of myocardial infarction with a high survival rate: A suitable model for evaluation of efficacy of stem cell therapy

In vivo characterization of a luffa-based composite scaffold for subcutaneous implantation in rats

Recent advancements in tissue engineering have witnessed luffa-derived scaffolds, exhibiting their exceptional potential in cellular proliferation, biocompatibility, appropriate interconnectivity, and biomechanical strength. In vivo studies involved implanting fabricated scaffolds subcutaneously in Wistar rats to evaluate their impact on the heart, liver, and kidneys. This approach provided a safe and minimally invasive means to evaluate scaffold compatibility with surrounding tissues. Male Wistar rats were categorized into four distinct groups, Group A, B, C, and D are referred to as 3% LC implanted scaffolds, 5% LC implanted scaffolds, control (without luffa scaffolds), and Sham (without any scaffold implantation), respectively. Histological analysis in all the groups indicated that the animal models did not exhibit any signs of inflammation or toxicity, suggesting favorable tissue response to the implanted scaffolds. Initial observations revealed elevated levels of enzymes and biomarkers in the experimental groups after a 24 h interval, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, creatine kinase-MB (CK-MB), and serum creatinine. However, these parameters normalized 3 weeks post-implantation, with no significant increase compared to the control groups, suggesting that the implanted luffa-based scaffolds did not induce adverse effects on the heart, liver, and kidneys. Furthermore, the scaffold's significant pore size and porosity enable it to release drugs, including antibacterial medications. This study demonstrates promising results, indicating excellent scaffold porosity, sustained drug release, affirming the in vivo biocompatibility, absence of inflammatory responses, and overall tissue compatibility highlighting the immense potential of these luffa-based scaffolds in various tissue engineering and regenerative medicine applications.

Cardioprotective role of royal jelly in the prevention of celecoxib-mediated cardiotoxicity in adult male albino rats

BACKGROUND

Celecoxib, a cyclooxygenase-2 selective inhibitor non-steroidal anti-inflammatory drugs, is used for the management of short- and long-term pain as well as in other inflammatory conditions. Unfortunately, its chronic use is highly associated with serious abnormal cardiovascular events. The current study was designed to explore the effect of long-term administration of celecoxib on the cardiac tissues of male albino rats. The study also examined the alleged cardioprotective effect of royal jelly.

METHODS

Thirty, male albino rats were randomly divided into 3 equal groups; 10 each: (1) rats served as the control group and received no drug; (2) rats received celecoxib (50 mg/kg/day, orally), for 30 consecutive days; (3) rats received celecoxib (50 mg/kg/day, orally) plus royal jelly (300 mg/kg/day, orally) for 30 consecutive days. Sera were collected to assay cardiac enzymes and oxidant/antioxidant status. Rats were euthanatized and cardiac tissues were dissected for quantitative estimation of apoptotic genes (Bax) and anti-apoptotic gene (Bcl-2).

RESULTS

Long-term celecoxib administration caused cardiotoxicity in male albino rats as manifested by significant elevation of serum levels of creatine phosphokinase (CPK), creatine kinase-MB (CK-MB), and lactate dehydrogenase (LDH), with ameliorative effects of royal jelly against celecoxib-induced cardiotoxicity as manifested by significantly decrease in serum CPK, CK-MB, and LDH levels. It also showed a significant decrease in the oxidative stress indicator malondialdehyde (MDA) levels and the bax gene. Additionally, it demonstrated significant increases in the bcl-2 gene and superoxide dismutase (SOD) levels, which contribute to its therapeutic effects against celecoxib-induced cardiotoxicity.

CONCLUSION

Long-term celecoxib administration caused cardiotoxicity in male albino rats with protective effect of royal jelly being given together. It could be concluded that royal jelly may prove a useful adjunct in patients being prescribed celecoxib.

TRIAL REGISTRATION

Not applicable.

Considerations for choosing an optimal animal model of cardiovascular disease

The decision to use the optimal animal model to mimic the various types of cardiovascular disease is a critical one for a basic scientist. Clinical cardiovascular disease can be complex and presents itself as atherosclerosis, hypertension, ischemia/reperfusion injury, myocardial infarcts, and cardiomyopathies, amongst others. This may be further complicated by the simultaneous presence of two or more cardiovascular lesions (for example, atherosclerosis and hypertension) and co-morbidities (i.e., diabetes, infectious disease, obesity, etc). This variety and merging of disease states creates an unusually difficult situation for the researcher who needs to identify the optimal animal model that is available to best represent all of the characteristics of the clinical cardiovascular disease. The present manuscript reviews the characteristics of the various animal models of cardiovascular disease available today, their advantages and disadvantages, with the goal to allow the reader access to the most recent data available for optimal choices prior to the initiation of the study. The animal species that can be chosen, the methods of generating these models of cardiovascular disease, as well as the specific cardiovascular lesions involved in each of these models are reviewed. A particular focus on the JCR:LA-cp rat as a model of cardiovascular disease is discussed.

The In Vitro, In Vivo, and PBPK Evaluation of a Novel Lung-Targeted Cardiac-Safe Hydroxychloroquine Inhalation Aerogel

Hydroxychloroquine (HCQ) was repurposed for COVID-19 treatment. Subtherapeutic HCQ lung levels and cardiac toxicity of oral HCQ were overcome by intratracheal (IT) administration of lower HCQ doses. The crosslinker-free supercritical fluid technology (SFT) produces aerogels and impregnates them with drugs in their amorphous form with efficient controlled release. Mechanistic physiologically based pharmacokinetic (PBPK) modeling can predict the lung's epithelial lining fluid (ELF) drug levels. This study aimed to develop a novel HCQ SFT formulation for IT administration to achieve maximal ELF levels and minimal cardiac toxicity. HCQ SFT formulation was prepared and evaluated for physicochemical, in vitro release, pharmacokinetics, and cardiac toxicity. Finally, the rat HCQ ELF concentrations were predicted using PBPK modeling. HCQ was amorphous after loading into the chitosan-alginate nanoporous microparticles (22.7±7.6 μm). The formulation showed a zero-order release, with only 40% released over 30 min compared to 94% for raw HCQ. The formulation had a tapped density of 0.28 g/cm3 and a loading efficiency of 35.3±1.3%. The IT administration of SFT HCQ at 1 mg/kg resulted in 23.7-fold higher bioavailability, fourfold longer MRT, and eightfold faster absorption but lower CK-MB and LDH levels than oral raw HCQ at 4 mg/kg. The PBPK model predicted 6 h of therapeutic ELF levels for IT SFT HCQ and a 100-fold higher ELF-to-heart concentration ratio than oral HCQ. Our findings support the feasibility of lung-targeted and more effective SFT HCQ IT administration for COVID-19 compared to oral HCQ with less cardiac toxicity. Graphical abstract.

Vericiguat preserved cardiac function and mitochondrial quality in a rat model of mitral regurgitation

AIMS

New drugs for heart failure (HF) that target restoring the impaired NO-sGC-cGMP pathway are being developed. We aimed to investigate the effects of vericiguat, an sGC stimulator, on cardiac function, blood pressure (BP), cardiac mitochondrial quality, and cardiac fibrosis in rat models of chronic mitral regurgitation (MR).

MATERIALS AND METHODS

We surgically induced MR in 20 Sprague-Dawley rats and performed sham procedures on 10 rats (negative control). Four weeks post-surgery, we randomly divided the MR rats into two groups: MR group and MR + vericiguat group. Vericiguat (0.5 mg/kg, PO) was administered once a day via oral gavage for 8 weeks, while the sham and MR groups received equivalent volumes of drinking water instead. We took echocardiography and BP measurements at baseline (4 weeks post-surgery) and at the end of study (8 weeks after treatment). At the study end, all rats were euthanized and their hearts were immediately collected, weighed, and used for histopathology and mitochondrial quality assessments.

KEY FINDINGS

Vericiguat preserved cardiac functions and structural remodeling in the MR rats, with significantly lower systolic BPs than baseline values (P < 0.05). Additionally, vericiguat significantly improved the mitochondrial quality by attenuating ROS production, depolarization and swelling when comparing the values in both groups (P < 0.05). The fibrosis area also significantly decreased in the MR + vericiguat group (P < 0.05).

SIGNIFICANCE

Vericiguat demonstrated cardioprotective effects on cardiac function, BP, and fibrosis by preserving mitochondrial quality in rats with HF due to MR.

Effect of trehalose on heart functions in rats model after myocardial infarction: assessment of novel intraventricular pressure and heart rate variability

Background

Myocardial infarctions remain a leading cause of global deaths. Developing novel drugs to target cardiac remodeling after myocardial injury is challenging. There is an increasing interest in exploring natural cardioprotective agents and non-invasive tools like intraventricular pressure gradients (IVPG) and heart rate variability (HRV) analysis in myocardial infarctions. Trehalose (TRE), a natural disaccharide, shows promise in treating atherosclerosis, myocardial infarction, and neurodegenerative disorders.

Objectives

The objective of this study was to investigate the effectiveness of TRE in improving cardiac functions measured by IVPG and HRV and reducing myocardial remodeling following myocardial infarction in rat model.

Methods

Rats were divided into three groups: sham, myocardial infarction (MI), and trehalose-treated MI (TRE) groups. The animals in the MI and TRE groups underwent permanent ligation of the left anterior descending artery. The TRE group received 2% trehalose in their drinking water for four weeks after the surgery. At the end of the experiment, heart function was assessed using conventional echocardiography, novel color M-mode echocardiography for IVPG evaluation, and HRV analysis. After euthanasia, gross image scoring, histopathology, immunohistochemistry, and quantitative real-time PCR were performed to evaluate inflammatory reactions, oxidative stress, and apoptosis.

Results

The MI group exhibited significantly lower values in multiple IVPG parameters. In contrast, TRE administration showed an ameliorative effect on IVPG changes, with results comparable to the sham group. Additionally, TRE improved HRV parameters, mitigated morphological changes induced by myocardial infarction, reduced histological alterations in wall mass, and suppressed inflammatory reactions within the infarcted heart tissues. Furthermore, TRE demonstrated antioxidant, anti-apoptotic and anti-fibrotic properties.

Conclusion

The investigation into the effect of trehalose on a myocardial infarction rat model has yielded promising outcomes, as evidenced by improvements observed through conventional echocardiography, histological analysis, and immunohistochemical analysis. While minor trends were noticed in IVPG and HRV measurements. However, our findings offer valuable insights and demonstrate a correlation between IVPG, HRV, and other traditional markers of echo assessment in the myocardial infarction vs. sham groups. This alignment suggests the potential of IVPG and HRV as additional indicators for future research in this field.

A review on experimental surgical models and anesthetic protocols of heart failure in rats

Heart failure (HF) is a serious health and economic burden worldwide, and its prevalence is continuously increasing. Current medications effectively moderate the progression of symptoms, and there is a need for novel preventative and reparative treatments. The development of novel HF treatments requires the testing of potential therapeutic procedures in appropriate animal models of HF. During the past decades, murine models have been extensively used in fundamental and translational research studies to better understand the pathophysiological mechanisms of HF and develop more effective methods to prevent and control congestive HF. Proper surgical approaches and anesthetic protocols are the first steps in creating these models, and each successful approach requires a proper anesthetic protocol that maintains good recovery and high survival rates after surgery. However, each protocol may have shortcomings that limit the study's outcomes. In addition, the ethical regulations of animal welfare in certain countries prohibit the use of specific anesthetic agents, which are widely used to establish animal models. This review summarizes the most common and recent surgical models of HF and the anesthetic protocols used in rat models. We will highlight the surgical approach of each model, the use of anesthesia, and the limitations of the model in the study of the pathophysiology and therapeutic basis of common cardiovascular diseases.

Novel protocol to establish the myocardial infarction model in rats using a combination of medetomidine-midazolam-butorphanol (MMB) and atipamezole

Background

Myocardial infarction (MI) is one of the most common cardiac problems causing deaths in humans. Previously validated anesthetic agents used in MI model establishment are currently controversial with severe restrictions because of ethical concerns. The combination between medetomidine, midazolam, and butorphanol (MMB) is commonly used in different animal models. The possibility of MMB combination to establish the MI model in rats did not study yet which is difficult because of severe respiratory depression and delayed recovery post-surgery, resulting in significant deaths. Atipamezole is used to counter the cardiopulmonary suppressive effect of MMB.

Objectives

The aim of the present study is to establish MI model in rats using a novel anesthetic combination between MMB and Atipamezole.

Materials and methods

Twenty-five Sprague Dawley (SD) rats were included. Rats were prepared for induction of the Myocardial infarction (MI) model through thoracotomy. Anesthesia was initially induced with a mixture of MMB (0.3/5.0/5.0 mg/kg/SC), respectively. After endotracheal intubation, rats were maintained with isoflurane 1% which gradually reduced after chest closing. MI was induced through the left anterior descending (LAD) artery ligation technique. Atipamezole was administered after finishing all surgical procedures at a dose rate of 1.0 mg/kg/SC. Cardiac function parameters were evaluated using ECG (before and after atipamezole administration) and transthoracic echocardiography (before and 1 month after MI induction) to confirm the successful model. The induction time, operation time, and recovery time were calculated. The success rate of the MI model was also calculated.

Results

MI was successfully established with the mentioned anesthetic protocol through the LAD ligation technique and confirmed through changes in ECG and echocardiographic parameters after MI. ECG data was improved after atipamezole administration through a significant increase in heart rate (HR), PR Interval, QRS Interval, and QT correction (QTc) and a significant reduction in RR Interval. Atipamezole enables rats to recover voluntary respiratory movement (VRM), wakefulness, movement, and posture within a very short time after administration. Echocardiographic ally, MI rats showed a significant decrease in the left ventricular wall thickness, EF, FS, and increased left ventricular diastolic and systolic internal diameter. In addition, induction time (3.440 ± 1.044), operation time (29.40 ± 3.663), partial recovery time (10.84 ± 3.313), and complete recovery time (12.36 ± 4.847) were relatively short. Moreover, the success rate of the anesthetic protocol was 100%, and all rats were maintained for 1 month after surgery with a survival rate of 88%.

Conclusion

Our protocol produced a more easy anesthetic effect and time-saving procedures with a highly successful rate in MI rats. Subcutaneous injection of Atipamezole efficiently counters the cardiopulmonary side effect of MMB which is necessary for rapid recovery and subsequently enhancing the survival rate during the creation of the MI model in rats.

Myocardial perfusion recovery induced by an α-calcitonin gene-related peptide analogue

BACKGROUND

Endogenous calcitonin gene-related peptide (CGRP) induces cardioprotective effects through coronary vasodilation. However, the systemic administration of CGRP induces peripheral vasodilation and positive chronotropic and inotropic effects. This study aims to examine the net effect on coronary perfusion of the systemically administered α-calcitonin gene-related peptide analogue, SAX, in rats during myocardial infarction.

METHODS

Forty Sprague-Dawley rats underwent myocardial infarction. Following left anterior descending artery occlusion, [99mTc]Tc-sestamibi was administered to determine the myocardial perfusion before treatment. Twenty minutes, 24 and 48 h after [99mTc]Tc-sestamibi injection, the rats were treated with either SAX or placebo. Final infarct size was determined three weeks later by [99mTc]Tc-sestamibi SPECT/CT scan.

RESULTS

Thirty-one rats survived the surgery and 20 completed the follow-up SPECT/CT scan (SAX n = 12; Placebo n = 8). At baseline, there was no difference in size of perfusion defect between the groups (P = .88), but at follow-up the SAX group had improved myocardial recovery compared to the placebo group (P = .04), corresponding to a relative perfusion recovery of 55% in SAX-treated rats.

CONCLUSION

The CGRP analogue, SAX, has a cardioprotective effect in this rat model of myocardial infarction, improving myocardial perfusion recovery after chronic occlusion of the coronary artery.

Myocardial infarction from a tissue engineering and regenerative medicine point of view: A comprehensive review on models and treatments

In the modern world, myocardial infarction is one of the most common cardiovascular diseases, which are responsible for around 18 million deaths every year or almost 32% of all deaths. Due to the detrimental effects of COVID-19 on the cardiovascular system, this rate is expected to increase in the coming years. Although there has been some progress in myocardial infarction treatment, translating pre-clinical findings to the clinic remains a major challenge. One reason for this is the lack of reliable and human representative healthy and fibrotic cardiac tissue models that can be used to understand the fundamentals of ischemic/reperfusion injury caused by myocardial infarction and to test new drugs and therapeutic strategies. In this review, we first present an overview of the anatomy of the heart and the pathophysiology of myocardial infarction, and then discuss the recent developments on pre-clinical infarct models, focusing mainly on the engineered three-dimensional cardiac ischemic/reperfusion injury and fibrosis models developed using different engineering methods such as organoids, microfluidic devices, and bioprinted constructs. We also present the benefits and limitations of emerging and promising regenerative therapy treatments for myocardial infarction such as cell therapies, extracellular vesicles, and cardiac patches. This review aims to overview recent advances in three-dimensional engineered infarct models and current regenerative therapeutic options, which can be used as a guide for developing new models and treatment strategies.

Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In order to explore the pathophysiological changes after myocardial infarction and design future treatments, research models of MI are required. Permanent ligation of the left coronary artery (LCA) in mice is a popular model to investigate cardiac function and ventricular remodeling post MI. Here we describe a less invasive, reliable, and reproducible surgical murine MI model by permanent ligation of the LCA. Our surgical model comprises of an easily reversible general anesthesia, endotracheal intubation that does not require a tracheotomy, and a thoracotomy. Electrocardiography and troponin measurement should be performed to ensure MI. Echocardiography at day 28 after MI will discern heart function and heart failure parameters. The degree of cardiac fibrosis can be evaluated by Masson's trichrome staining and cardiac MRI. This MI model is useful for studying the pathophysiological and immunological alterations after MI.

Animal Models to Study Cardiac Arrhythmias

Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.

3D Biofabrication of a Cardiac Tissue Construct for Sustained Longevity and Function

In this study, we developed three-dimensional (3D) printed annular ring-like scaffolds of hydrogel (gelatin-alginate) constructs encapsulated with a mixture of human cardiac AC16 cardiomyocytes (CMs), fibroblasts (CFs), and microvascular endothelial cells (ECs) as cardiac organoid models in preparation for investigating the role of microgravity in cardiovascular disease initiation and development. We studied the mechanical properties of the acellular scaffolds and confirmed their cell compatibility as well as heterocellular coupling for cardiac tissue engineering. Rheological analysis performed on the acellular scaffolds showed the scaffolds to be elastogenic with elastic modulus within the range of a native in vivo heart tissue. The microstructural and physicochemical properties of the scaffolds analyzed through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total reflectance (ATR-FTIR) confirmed the mechanical and functional stability of the scaffolds for long-term use in in vitro cell culture studies. HL-1 cardiomyocytes bioprinted in these hydrogel scaffolds exhibited contractile functions over a sustained period of culture. Cell mixtures containing CMs, CFs, and ECs encapsulated within the 3D printed hydrogel scaffolds exhibited a significant increase in viability and proliferation over 21 days, as shown by flow cytometry analysis. Moreover, via the expression of specific cardiac biomarkers, cardiac-specific cell functionality was confirmed. Our study depicted the heterocellular cardiac cell interactions, which is extremely important for the maintenance of normal physiology of the cardiac wall in vivo and significantly increased over a period of 21 days in in vitro. This 3D bioprinted "cardiac organoid" model can be adopted to simulate cardiac environments in which cellular crosstalk in diseased pathologies like cardiac atrophy can be studied in vitro and can further be used for drug cytotoxicity screening or underlying disease mechanisms.

Chlorogenic acid prevents acute myocardial infarction in rats by reducing inflammatory damage and oxidative stress

Recent studies have suggested that the prevention of myocardial infarction (MI) through diet is very important and that the intake of polyphenol-rich foods can improve cardiovascular health. In this study, adult male SD rats were randomly divided into 2 groups. The chlorogenic acid (CGA) group (n = 18) was administered 100 mg/kg/day CGA by gavage, and the control (CON) group (n = 18) was given the equivalent volume of water for 4 weeks. A model of MI was established by ligating the left anterior descending (LAD) coronary artery, which was monitored by an electrocardiogram (ECG). Blood samples were analyzed by enzyme-linked immunosorbent assays and biochemical experiments 24 h after the operation. In addition, histopathological analysis was performed to assess the size and severity of the infarct area. The administration of CGA before MI minimized weight gain and was associated with decreased postoperative mortality. CGA moderated the coronary artery ligation-induced changes observed by ECG and decreased the plasma levels of the myocardial markers. In the histopathological analysis, CGA notably reduced infarct size and decreased myocardial injury and fibrosis. Furthermore, CGA significantly reduced the levels of pro-inflammatory factors, and this reduction was accompanied by an upregulation of anti-inflammatory cytokines and an increase in antioxidant enzyme activities. This study indicated that CGA improved the survival rate after MI and demonstrated that CGA had a protective effect on MI by reducing the inflammatory response and exerting antioxidant activity.

Ginsenoside Re Preserves Cardiac Function and Ameliorates Left Ventricular Remodeling in a Rat Model of Myocardial Infarction

Ginsenoside Re, an herbal ingredient from ginseng, has been demonstrated to protect the heart from various cardiovascular diseases. In this study, we investigated the protective effects and mechanisms of ginsenoside Re (Gin-Re) on cardiac function and left ventricular remodeling in a rat model of myocardial infarction (MI). After ligating the left anterior descending coronary artery, Wistar rats were treated with Gin-Re (135 mg/kg) by gavage everyday for 4 weeks. Serological detection showed that Gin-Re significantly inhibited myocardial injury and attenuated oxidative stress in MI rats. Echocardiographic observation showed that Gin-Re significantly improved cardiac function and prevented left ventricular dilatation induced by MI. Pathological observation found that Gin-Re significantly decreased interstitial fibrosis in the left ventricle of MI rats. Compared with the MI group, Gin-Re treatment promoted AMPKα phosphorylation, decreased TGF-β1 expression, and attenuated Smad2/3 activation. After Gin-Re treatment, the phosphorylation of FAK, PI3K p110α, and Akt was enhanced in MI rats, while PI3K p110β showed no difference compared with the MI group. These results indicate that Gin-Re may improve MI-induced cardiac dysfunction and mitigate ventricular remodeling through regulation of the AMPK/TGF-β1/Smad2/3 and FAK/PI3K p110α/Akt signaling pathways.

Cardioprotective effects of garcinol following myocardial infarction in rats with isoproterenol-induced heart failure

Myocardial infarction is a clinical form of necrosis in the myocardium caused by an imbalance between the coronary blood supply and myocardial demand. Garcinol is a polyisoprenylated benzophenone found in the fruit of Garcinia indica, which is abundant in tropical regions. This fruit contains high levels of garcinol, isoxanthochymol, isogarcinol, hydroxycitric acid and xanthochymol. Garcinol and hydroxycitric acid have been shown to have antioxidant effects. In this study, rats were assigned to sham, control, low-dose, high-dose and positive control groups. Hemodynamic and apoptotic markers were evaluated, and histopathological analysis was conducted. The mRNA and protein levels of caspase-3, Bax, Bcl-2 and cleaved caspase-3 were quantified. Garcinol treatment increased the heart rate and improved the maximum rate of increase in left-ventricle (LV) pressure (+dp/dt_max), maximum rate of decrease in LV pressure (–dp/dt_max), LV ejection fraction and LV systolic pressure in rats with induced heart failure. Garcinol treatment reversed body, liver and heart weight changes, resulting in returns to near-normal levels. In the garcinol treatment group, the number of broken fibers, extent of inflammatory cell infiltration and rate of apoptosis remained within normal ranges. Garcinol reduced the cross-sectional areas of cardiomyocytes, and reduced interstitial fibrosis to a normal level. The mRNA and protein levels of cleaved caspase-3, caspase-3 and Bax were reduced, whereas those of Bcl-2 were increased, following high-dose (100 mg/kg) garcinol treatment. These findings suggest that garcinol effectively prevents apoptosis in rats with isoproterenol-induced heart failure and in cardiac H9C2 cells.

Selective infarct zone imaging with intravenous acoustically activated droplets

Background

Microbubbles (MB) can be compressed to nanometer-sized droplets and reactivated with diagnostic ultrasound; these reactivated MB possess unique imaging characteristics.

Objective

We hypothesized that droplets formed from compressing Definity MB may be used for infarct-enhancement imaging.

Methods

Fourteen rats underwent ligation of their left anterior descending (LAD) artery, and five pigs underwent 90 minute balloon occlusions of their mid LAD. At 48 hours in rats, transthoracic ultrasound was performed at two and four minutes following 200 μL intravenous injections (IVI) of Definity droplets (DD), at which point the MI was increased from 0.5 to 1.5 to assess for a transient contrast enhancement zone (TEZ) within akinetic segments. In pigs, 1.0 mL injections of DD were administered and low frame rate (triggered end systolic or 10 Hz) imaging 2–4 minutes post iVI to selectively activate and image the infarct zone (IZ). Infarct size was defined by delayed enhancement magnetic resonance imaging (DE-MRI) and post-mortem staining (TTC).

Results

Increasing MI to 1.5 (at two or four minutes after IVI) resulted in a TEZ in rats, which correlated with infarct size (r = 0.94, p<0.001). A TEZ was not seen at 2–4 minutes in any rat (n = 8) following Definity MB injections. Fluorescent staining confirmed DD presence within the infarct zone 10 minutes after intravenous injection. In pigs, selective enhancement within the IZ was achieved by using a low frame rate single pulse harmonic mode; IZ size matched the location seen with DE-MRI and correlated with TTC defect size (r = 0.90, p<0.05).

Conclusion

DD formulated from commercially available MB can be acoustically activated for selective infarct enhancement imaging.

Echocardiographic evaluation of cardiac function in ischemic rats: value of m-mode echocardiography

Background:

Echocardiography is a well-established diagnostic tool for a safe, reproducible and accurate evaluation of cardiac anatomy, hemodynamics and function in clinical practice.

Objectives:

We sought to demonstrate the efficacy and feasibility of M-mode echocardiography to evaluate cardiac structure and function in normal and MI-induced adult rats.

Materials and Methods:

All animal procedures were approved by the ethics committee of Tehran University of Medical Sciences and the investigation conformed to the “Guide for the Care and Use of Laboratory Animals” published by the United States National Institutes of Health. Forty-eight male Wistar rats weighing 280-300 grams were obtained from a single breeding colony. The statistical analyses were performed using SPSS 20.0.

Results:

Echocardiographic measurements were possible in all rats before and after the operation. In our survey, we studied echocardiographic alterations in rats after MI induction. Changes can be seen in all echocardiographic mean values after myocardial infarction (MI), but significant decrease (P < 0.01) of Fractional shortening and Ejection Fraction as well as significant increase (P < 0.05) of end systolic diameter and systolic volume after left anterior descending coronary artery (LAD) ligation can be good signs of MI induction.

Conclusions:

In light of our results, it can be concluded that we succeeded in establishing a precise echocardiographic method to confidently assess the success of LAD ligation surgery in rats. It is feasible to thoroughly monitor the functional efficiency of regional therapeutic interventions such as intra-myocardial stem cell injection.