Esmolol is antiarrhythmic in doxorubicin-induced arrhythmia in cultured cardiomyocytes - determination by novel rapid cardiomyocyte assay

Doxorubicin-induced apoptosis enhances monocyte infiltration and adverse cardiac remodeling in diabetic animals

Diabetic cancer patients were treated with doxorubicin (DOX), a potent chemotherapeutic drug that induces cardiac toxicity; however, molecular mechanisms of cardiac toxicity in this specific disease progression in patients and animal models are completely unknown. Therefore, we designed a study to understand the effects of DOX-induced cardiac toxicity in diabetic animals and the involved pathophysiological mechanisms. C57BL/6 J mice were divided into four DOX- and diabetic (streptozotocin; STZ) - treated groups; control, STZ, DOX, and DOX+STZ. At day 14, animals were sacrificed, echocardiography was used to examine heart function, and heart and blood samples were collected to investigate apoptotic mechanisms (caspase 3, BAX, B-Cell leukemia/lymphoma 2 (Bcl2)), inflammation, and cardiac remodeling. Our data shows a significant (p < 0.05) increase in glucose levels, apoptotic markers, and monocyte infiltration at the site of apoptosis and triggered inflammatory immune response (tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6)), in DOX+STZ animals compared with control and experimental groups. We also observed significant (p < 0.05) increase in myofibrillar area, fibrosis, and significantly decreased (p < 0.05) cardiac function in DOX-treated diabetic animals compared with controls. In conclusion, our data suggest that DOX induces significantly increased apoptosis, fibrosis, and structural alterations in diabetic hearts compared with non-diabetic animals.

Anticancer Therapy-Induced Atrial Fibrillation: Electrophysiology and Related Mechanisms

Some well-established immunotherapy, radiotherapy, postoperation, anticancer drugs such as anthracyclines, antimetabolites, human epidermal growth factor receptor 2 blockers, tyrosine kinase inhibitors, alkylating agents, checkpoint inhibitors, and angiogenesis inhibitors, are significantly linked to cardiotoxicity. Cardiotoxicity is a common complication of several cancer treatments. Some studies observed complications of cardiac arrhythmia associated with the treatment of cancer, including atrial fibrillation (AF), supraventricular arrhythmias, and cardiac repolarization abnormalities. AF increases the risk of cardiovascular morbidity and mortality; it is associated with an almost doubled risk of mortality and a nearly 5-fold increase in the risk of stroke. The occurrence of AF is also usually researched in patients with advanced cancer and those undergoing active cancer treatments. During cancer treatments, the incidence rate of AF affects the prognosis of tumor treatment and challenges the treatment strategy. The present article is mainly focused on the cardiotoxicity of cancer treatments. In our review, we discuss these anticancer therapies and how they induce AF and consequently provide information on the precaution of AF during cancer treatment.

Phenolic constituents from the root bark of Morus alba L. and their cardioprotective activity in vitro

A flavanone C-glycoside, steppogenin-5'-C-β-D-glucopyranoside, six prenylated 2-arylbenzofuran derivatives, moracin O-3″-O-β-D-glucopyranoside, moracin O-3'-O-β-D-xylopyranoside, moracin P-2″-O-β-D-glucopyranoside, moracin P-3'-O-β-D-glucopyranoside, moracin P-3'-O-α-L-arabinopyranoside and moracin P-3'-O-[β-D-glucopyranosyl-(1 → 2)]-α-L-arabinopyranoside, two phenolic acids, 2,4-dihydroxy-5-(4-hydroxybenzyl) benzoic acid and 2,4-dihydroxy-5-(3,4-dihydroxybenzyl) benzoic acid, as well as three known compounds, moracinoside C, moracin O, and moracin P were isolated from the root bark of Morus alba L. Their structures were ascertained on the basis of spectroscopic evidence. The protective effects of the compounds against doxorubicin-induced cardiomyopathy in H9c2 cells was investigated in vitro. Of all of the isolated compounds, moracin P-3'-O-β-D-glucopyranoside, moracin O and moracin P had a strong protective influence against doxorubicin-induced cell death with EC₅₀ values of 9.5 ± 2.6, 4.5 ± 1.3, and 8.8 ± 2.4 μM, respectively.

Burden of Cardiac Arrhythmias in Patients With Anthracycline-Related Cardiomyopathy

OBJECTIVES

The objective of this study was to determine the incidence of arrhythmias and device (internal cardiac defibrillator/cardiac resynchronization therapy defibrillator) therapies in patients with a diagnosis of cardiomyopathy and anthracycline exposure.

BACKGROUND

The burden of arrhythmias in adult cancer survivors with anthracycline-related cardiomyopathy has not been studied, but might have important implications for clinical management and outcomes.

METHODS

Retrospective cohort study of all patients with left ventricular dysfunction (LVD) who underwent internal cardiac defibrillator/cardiac resynchronization therapy defibrillator implantation at the Mayo Clinic from 1990 to 2012. Ninety-five patients were cancer survivors (on average, 5 years), 23 of which had anthracycline-related cardiomyopathy (CA-ACM) and 72 of which had non-anthracycline-related cardiomyopathy (CA-NACM). A second control group of 68 noncancer patients with ischemic heart disease-related LVD or dilated cardiomyopathy (ischemic heart disease [IHD]/DCM) was age- and gender-matched to patients with CA-ACM. All patients were followed for arrhythmias and appropriate ICD therapies, total mortality, heart transplantation, and left ventricular ejection fraction.

RESULTS

More than 5.5 ± 3.0 years after device implantation, nonsustained ventricular tachycardia was the most common arrhythmia in patients with CA-ACM followed by atrial fibrillation and sustained ventricular tachycardia or fibrillation (73.9%, 56.6%, and 30.4%, respectively), which was not significantly different from CA-NACM and IHD/DCM. The 5-year rate of ICD therapies was 19.9% in the CA-ACM group versus 22.1% in the CA-NACM group and 32.6% in the IHD/DCM group (p = NS for both). Device therapy-free, heart transplantation-free, and/or overall survival as well as cardiac function dynamics over time were not different in patients with CA-ACM than in patients with CA-NACM and IHD/DCM.

CONCLUSIONS

This study indicates that the burden of arrhythmia in patients with anthracycline-related cardiomyopathy is not different from cancer and non-cancer patients with IHD-related LVD or DCM.

Pathophysiology of cancer therapy-provoked atrial fibrillation

Atrial fibrillation (AF) occurs with increased frequency in cancer patients, especially in patients who undergo surgery or chemotherapy. AF disturbs the prognosis of cancer patients and challenges therapeutic outcomes of cancer treatment. Elucidating the mechanisms of cancer-induced AF would help identify specific strategies for preventing AF occurrence. In addition to concurrent risk factors of cancer and AF, cancer surgery, side effects of anticancer agents, and cancer-associated immune responses play critical roles in the genesis of AF. In this review, we provide succinct potential mechanisms of AF genesis in cancer patients.

Robinin modulates doxorubicin-induced cardiac apoptosis by TGF-β1 signaling pathway in Sprague Dawley rats

The study focussed on the cardioprotective effect of robinin on doxorubicin-induced cardio-toxicity in Sprague Dawley rats. After the experimental period, animals were sacrificed and the various parameters such as cardiac markers, toxicity parameters, antioxidant status, ROS generation, lipid peroxidation status and inflammatory parameters were assessed. Gene expression study by RT-PCR analysis and proteins expression study by western blotting were done. Doxorubicin causes significant increase in the levels of cardiac marker enzymes, namely lactate dehydrogenase (LDH), creatine phospokinase (CPK), toxicity parameters like serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT). Antioxidant enzyme levels were decreased; lipid peroxidation products in heart tissue and inflammatory markers, namely cyclooxygenase (COX2) and lipooxygenase (LOX15) were significantly increased. Gene expression study by RT-PCR analysis of transforming growth factor-β1 (TGF-β1), Smad2, murine double minute (Mdm2), Smad3, cyclin-dependent kinase inhibitor 2A (CDKN2A), Smad4 and Smad7 were significantly altered. The western blotting study of p53, Bcl-2 and Bax also showed altered expression. The supplementation of the Robinin along with DOX caused normalised level of all the above parameters and cardio-toxicity. This study revealed the cardioprotective nature of Robinin on doxorubicin-induced cardiac toxicity by modulating TGF-β1 signaling pathway in Sprague Dawley rats.

Non-invasive imaging of stem cells by scanning ion conductance microscopy: future perspective

The most valuable property of stem cells (SCs) is their potential to differentiate into many or all cell types of the body. So far, monitoring SC differentiation has only been possible after cells were fixed or destroyed during sample preparation. It is, however, important to develop nondestructive methods of monitoring SCs. Scanning ion conductance microscopy (SICM) is a unique imaging technique that uses similar principles to the atomic force microscope, but with a pipette for the probe. This allows scanning of the surface of living cells noninvasively and enables measurement of cellular activities under more physiological conditions than is possible with other high-resolution microscopy techniques. We report here the novel use of the SICM for studying SCs to assess and monitor the status of SCs and various cell types differentiated from SCs.

Potential biomedical applications of the scanned nanopipette

One grand challenge in current biology is to understand how individual cellular molecules interact together to form a functioning living cell. This requires new methods to image a live cell on the nanoscale. The scanned nanopipette can be used to obtain high resolution noncontact images of the surface of live cells under physiological conditions and has been used to develop a family of related methods that allow mapping of cell function on the nanoscale, and hence allow the relationship between cell structure and function to be probed. This is a powerful method to bridge the current gap between high resolution structures of individual molecular complexes and low resolution imaging of live cell structure and function.

Functional characterization of embryonic stem cell-derived cardiomyocytes using scanning ion conductance microscopy

We report here the novel use of scanning ion conductance microscopy (SICM) to produce surface images of embryonic stem cell-derived cardiomyocytes (ESCM) to identify individual contracting cardiomyocytes among different cell types. By measuring amplitude and rhythm we can quantitate contraction of ESCM. This method gives, within the same experiment, an assessment of the number and position of ESCM within the layer of mixed cell types, as well as an accurate measure of the response of individual ESCM. Using different modulators of contraction as examples we showed how SICM could be used for recording their responses. We subsequently demonstrated that this model can be used to investigate the protective effect of antiarrhythmogenic drugs.