Myocardial Tissue Research Articles

Fucoxanthin Attenuates Myocardial Ischemia/Reperfusion-Induced Injury via AMPK/GSK-3β/Nrf2 Axis.

Fucoxanthin (Fx), a xanthophyll carotenoid abundant in brown algae, possesses several biological functions, such as antioxidant, anti-inflammatory, and cardiac-protective activities. However, the role of Fx in myocardial ischemia/reperfusion (MI/R) is still unclear. Thus, the aim of this study was to investigate the effect of Fx on MI/R-induced injury and explore the underlying mechanisms. Our results showed that invitro, Fx treatment significantly suppressed inflammatory response, oxidative stress, and apoptosis in rat cardiomyocytes exposed to hypoxia/reoxygenation (H/R). In addition, Fx led to increased phosphorylation of AMPK, AKT, and GSK-3β, and enhanced activation of Nrf2 in cardiomyocytes under H/R conditions. Notably, pretreatment with Compound C (AMPK inhibitor), partially reduced the beneficial effects of Fx in cardiomyocytes exposed to H/R. Invivo, Fx ameliorated myocardial damage, inhibited inflammatory response, oxidative stress, and apoptosis, and activated the AMPK/GSK-3β/Nrf2 signaling in myocardial tissues in MI/R rat model. Taken together, these findings indicated that Fx attenuates MI/R-induced injury by inhibiting oxidative stress, inflammatory response, and apoptosis. The AMPK/GSK-3β/Nrf2 pathway is involved in the cardioprotective effect of Fx in MI/R injury. Thus, Fx may be a promising drug for the treatment of MI/R.

Revealing the unrevealed: echocardiography for non-ischemic scar tissue detection.

The detection of myocardial scar tissue profoundly influences athletes care and prognostic categorization. Athletes appear to be at risk of developing fatal arrhythmias when harboring a quiescent cardiac disorder. Early identification of disease in asymptomatic individuals through preparticipation screening is means to prevent these events. We presented a male marathon runner master athlete who came at our Department of Sports Medicine for a preparticipation screening. Baseline 12-lead standard electrocardiogram was normal. A maximal cycle ergometer exercise test revealed exercise-induced premature ventricular contractions (PVCs) with uncommon morphology. Echocardiography revealed an hyperechogenic zone at mid-basal posterior segments of the left ventricle. Twenty-four-hours ECG Holter monitoring, with training session, showed some isolated polymorphic PVCs even during training session. Cardiac magnetic resonance (CMR) confirmed the presence of a non-ischemic left ventricular scar (subepicardial) into the mid-basal segment of the posterior wall. Echocardiography is a first-line, economic, and accessible diagnostic test for athletes and it can be useful, when abnormalities are detected, to indicate further investigations, such as CMR. Although non-ischemic left ventricular scarring is difficult to detect on echocardiography, this event is sometimes possible and require further investigation when observed.

Monitoring of myocardial injury by serial measurements of QRS area and T area: The MaastrICCht cohort.

Manually derived electrocardiographic (ECG) parameters were not associated with mortality in mechanically ventilated COVID-19 patients in earlier studies, while increased high-sensitivity cardiac troponin-T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were. To provide evidence for vectorcardiography (VCG) measures as potential cardiac monitoring tool, we investigated VCG trajectories during critical illness. All mechanically ventilated COVID-19 patients were included in the Maastricht Intensive Care Covid Cohort between March 2020 and October 2021. Serum hs-cTnT and NT-proBNP concentrations were measured daily. Conversion of daily 12-lead ECGs to VCGs by a MATLAB-based script provided QRS area, T area, maximal QRS amplitude, and QRS duration. Linear mixed-effect models investigated trajectories in serum and VCG markers over time between non-survivors and survivors, adjusted for confounders. In 322 patients, 5461 hs-cTnT, 5435 NT-proBNP concentrations and 3280 ECGs and VCGs were analyzed. Non-survivors had higher hs-cTnT concentrations at intubation and both hs-cTnT and NT-proBNP significantly increased compared with survivors. In non-survivors, the following VCG parameters decreased more when compared to survivors: QRS area (-0.27 (95% CI) (-0.37 to -0.16, p < .01) μVs per day), T area (-0.39 (-0.62 to -0.16, p < .01) μVs per day), and maximal QRS amplitude (-0.01 (-0.01 to -0.01, p < .01) mV per day). QRS duration did not differ. VCG-derived QRS area and T area decreased in non-survivors compared with survivors, suggesting that an increase in myocardial damage and tissue loss play a role in the course of critical illness and may drive mortality. These VCG markers may be used to monitor critically ill patients.

Immuno-Nanocomplexes Target Heterogenous Network of Inflammation and Immunity in Myocardial Infarction.

Despite the proceeds in the management of acute myocardial infarction (AMI), the current therapeutic landscape still suffers from limited success in the clinic. Exaggerated inflammatory immune response and excessive oxidative stress are key pathological features aggravating myocardium damage. Herein, catalytic immunomodulatory nanocomplexes as anti-AMI therapeutics to resolve reactive oxygen species (ROS)-proinflammatory neutrophils-specific-inflammation is engineered. The nanocomplexes contain lyophilic S100A8/9 inhibitor ABR2575 in the core of nanoemulsions, which effectively disrupts the neutrophils-S100A8/A9-inflammation signaling pathway in the AMI microenvironment. Additionally, ROS scavenger ultrasmall CuxO nanoparticles are incorporated into the nanoemulsions via coordinating with SH groups of poly(ethylene glycol) (PEG)-conjugated lipids, which mimic multiple enzymes, dramatically alleviating the oxidative stress damage to myocardial tissue. This combination strategy significantly suppresses the infiltration of pro-inflammatory monocytes, macrophages, and neutrophils, as well as the secretion of inflammatory cytokines. Additionally, it potentially triggers cardiac Tert activation, which promotes myocardial function and decreases infarction size in preclinical murine AMI models. This approach offers a new nanomedicine for treating AMI, resulting in a dramatically enhanced therapeutic outcome.

Characterisation and distribution of human coronary artery innervation.

A detailed understanding of the sympathetic innervation of coronary arteries is relevant to facilitate the development of novel treatment approaches. This study aimed to quantitatively examine periarterial innervation in human epicardial coronary arteries. Coronary arteries with adjacent epicardial adipose tissue were excised along the left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) from 28 body donors and examined histologically. Immunofluorescence staining was performed to characterise sympathetic nerve fibres. A total of 42,573 nerve fibres surrounding 100 coronary arteries (LMCA: n=21, LAD: n=27, LCx: n=26, RCA: n=26) were analysed. The nerve fibre diameter decreased along the vessel course (median [interquartile range]): (proximal 46 μm [31-73], middle 38 μm [26-58], distal 31 μm [22-46]; p<0.001), with the largest nerve fibre diameter along the LMCA (50 μm [31-81]), followed by the LAD (42 μm [27-72]; p<0.001). The total nerve fibre density was highest along the RCA (123 nerves/cm² [82-194]). Circumferentially, nerve density was higher in the myocardial tissue area of the coronary arteries (132 nerves/cm² [76-225]) than in the epicardial tissue area (101 nerves/cm² [61-173]; p<0.001). The median lumen-nerve distance was smallest around the LMCA (2.2 mm [1.2-4.1]), followed by the LAD (2.5 mm [1.1-4.5]; p=0.005). Human coronary arteries are highly innervated with sympathetic nerve fibres, with significant variation in the distribution and density. Understanding these patterns informs pathophysiological understanding and, potentially, the development of catheter-based approaches for cardiac autonomic modulation.

Ozone Administration Reduces Myocardial Ischemia Reperfusion Injury in Streptozotocin Induced Diabetes Mellitus Rat Model.

This study aimed to demonstrate whether ozone has cardioprotective effects on the myocardial ischemia-reperfusion injury (IRI) in rats with streptozotocin(STZ)-induced diabetes. A total of 38 male Wistar Albino rats were divided into five groups as follows: control group (group C,n=6), diabetic group (group D,n=6), diabetic ozone group (group DO,n=6), diabetic-ischemia/reperfusion (group DIR,n=6), diabetic-ischemia/reperfusion-ozone (group DIRO,n=6). Six rats died during this period and two died because of surgical complications. A myocardial ischemia-reperfusion model was created using a thoracotomy incision from 4th intercostal space. The LAD was ligated using an 8-0 prolene suture for 30min. Ozone was administered intraperitoneally(1mg/kg) 5min before reperfusion. The reperfusion time was 120min. At the end of the reperfusion procedure, myocardial tissue histopathological examinations, and serum biochemical analyses were performed. The percentage of TUNEL(+) cardiomyocytes/HPF was significantly higher in the DIR group than in the C, D, and DO groups. Conversely, TUNEL positivity was significantly lower in the DIRO group than in the DIR group. The IRI score was significantly higher in the DIR and DIRO groups than that in the C, D, and DO groups. In contrast, the IRI damage score in the DIRO group was significantly lower than that in the DIR group. Serum MDA levels were significantly higher in the DIR group than in the C, D, and DO groups. Similarly, MDA levels were significantly higher in the DIRO group than in the C and D groups. CAT activity was significantly higher in the DIR group than in the C and D groups. SOD activity was significantly higher in the DIR group than in the C and DO groups. Our study showed that ozone exerts cardioprotective effects in STZ-induced diabetic rats through its antioxidant role against oxidative stress. Both biochemical and histological analyses clearly revealed that ozone has beneficial effects against IRI in the diabetic rat myocardium.

Angelica sinensis Polysaccharide Suppresses Pyroptosis in Myocardial Ischemia/Reperfusion Injury via the FN1/NF-κB/NLRP3 Pathway

Background Pyroptosis, a form of inflammatory programmed cell death, has recently emerged as a pivotal factor in the pathogenesis of myocardial ischemia/reperfusion (MI/R) injury. Despite its significance, effective therapeutic strategies targeting MI/R-induced pyroptosis remain elusive in current clinical practice. Previous studies have demonstrated the promising anti-inflammatory effects of Angelica sinensis polysaccharide (ASP) in the context of certain inflammatory disorders. Objectives We aimed to investigate the effects of ASP on pyroptosis in MI/R injury and elucidate the potential molecular mechanisms by combining transcriptomic analysis with complementary in vivo and in vitro experiments. Materials and methods H9c2 cells were used to establish a hypoxia/reoxygenation (H/R) model, and MI/R injury was induced in rats by ligating and releasing the left anterior coronary artery. Myocardial tissue samples were harvested for transcriptomic sequencing and bioinformatic analyses. Cardioprotective effects were evaluated through electrocardiography, echocardiography, and histological examination. Enzyme-linked immunosorbent assay (ELISA) was employed to quantify levels of inflammatory mediators. Biochemical assays were conducted to assess myocardial injury biomarkers and Caspase-1 activity. Western blotting was performed to analyze the protein expression levels of Fibronectin 1 (FN1), Nuclear factor kappa B (NF-κB) p65, phosphorylated NF-κB p65 (p-NF-κB p65), Nod-like receptor protein 3 (NLRP3), and Gasdermin-D (GSDMD). Results Pretreatment with ASP conferred potent cardioprotective effects in a rat model of MI/R injury, as evidenced by significant attenuation of infarct size, myocardial enzyme levels, and ST-segment elevation on electrocardiography, alongside notable improvements in cardiac function. Transcriptomic profiling unveiled that differentially expressed genes modulated by ASP treatment were predominantly implicated in the pyroptosis-elicited inflammatory response. Concordantly, both in vivo and in vitro experiments substantiated that ASP treatment effectively attenuated MI/R-induced pyroptosis, as manifested by diminished levels of pyroptosis-related indicators, encompassing the proportion of TUNEL-positive cells, Caspase-1 activation, GSDMD cleavage, and the liberation of pro-inflammatory cytokines. Further mechanistic investigations revealed ASP inhibition of the FN1/NF-κB/NLRP3 signaling pathway. Conclusions Our investigation, leveraging system-level transcriptomic profiling, demonstrates that ASP confers cardioprotective effects against MI/R injury through the suppression of cardiomyocyte pyroptosis, culminating from downregulation of the FN1/NF-κB/NLRP3 pathway.

ST-Segment Alterations in the Electrocardiogram of Acute Pulmonary Thromboembolism: A Rabbit Model

In this study, we investigated the mechanism underlying electrocardiogram (ECG) alterations in a rabbit model of acute pulmonary thromboembolism (PTE). Twelve healthy adult New Zealand white rabbits were used, with eight in the experimental group (PTE group) and four in the control group. After developing the rabbit model of acute PTE, ECG and coronary angiography were performed. HE staining was conducted on the right and left ventricular tissues, and polymerase chain reaction (PCR) was used to determine brain natriuretic peptide (BNP), tumor necrosis factor-alpha (TNF-α), and Troponin I (TNI) mRNA expression in the myocardium. There were considerable changes in the ST segment of the ECG in the PTE group. Coronary angiography revealed the absence of spasm, stenosis, and occlusion. In the plasma of the PTE group, the levels of D-dimer, BNP, TNF-α, and TNI were significantly elevated, and these changes were statistically significant (P&lt;0.05). PCR analysis of ventricular myocardial tissue indicated significantly higher levels of BNP, TNF-α, and TNI mRNA in the PTE group than in the control group. These differences were statistically significant (P&lt;0.05). The ST-T variations on the ECG of rabbits with acute PTE correlate strongly with the temporary changes in right heart volume caused by acute PTE.

Cardiovascular imaging in cardio-oncology.

Advances in cancer treatment have improved in patient survival rate. On the other hand, management of cardiovascular complications has been increasingly required in cancer patients. Thus, cardio-oncology has attracted the attention by both oncologists and cardiologists. Cardiovascular imaging has played a key role for non-invasive assessment of cardiovascular alterations complimentary to biomarkers and clinical assessment. Suitable imaging selection and interpretation may allow early diagnosis of cardiovascular injury with potential implications for therapeutic management and improved outcomes after cancer therapy. Echocardiography has been commonly used to evaluate cardiac dysfunction in cardio-oncology area. Cardiac CT is valuable for assessing structural abnormalities of the myocardium, coronary arteries, and aorta. Molecular imaging has an important role in the assessment of the pathophysiology and future treatment strategy of cardiovascular dysfunction. Cardiac MRI is valuable for characterization of myocardial tissue. PET and SPECT molecular imaging has potential roles for quantitative assessment of cardiovascular disorders. Particularly, FDG-PET is considered as an elegant approach for simultaneous assessment of tumor response to cancer therapy and early detection of possible cardiovascular involvement as well. This review describes the promising potential of these non-invasive cardiovascular imaging modalities in cardio-oncology.

Pathophysiological insights into HFpEF from studies of human cardiac tissue.

Heart failure with preserved ejection fraction (HFpEF) is a major, worldwide health-care problem. Few therapies for HFpEF exist because the pathophysiology of this condition is poorly defined and, increasingly, postulated to be diverse. Although perturbations in other organs contribute to the clinical profile in HFpEF, altered cardiac structure, function or both are the primary causes of this heart failure syndrome. Therefore, studying myocardial tissue is fundamental to improve pathophysiological insights and therapeutic discovery in HFpEF. Most studies of myocardial changes in HFpEF have relied on cardiac tissue from animal models without (or with limited) confirmatory studies in human cardiac tissue. Animal models of HFpEF have evolved based on theoretical HFpEF aetiologies, but these models might not reflect the complex pathophysiology of human HFpEF. The focus of this Review is the pathophysiological insights gained from studies of human HFpEF myocardium. We outline the rationale for these studies, the challenges and opportunities in obtaining myocardial tissue from patients with HFpEF and relevant comparator groups, the analytical approaches, the pathophysiological insights gained to date and the remaining knowledge gaps. Our objective is to provide a roadmap for future studies of cardiac tissue from diverse cohorts of patients with HFpEF, coupling discovery biology with measures to account for pathophysiological diversity.

Aerobic Exercise Activates AMPK/PGC-1α Pathway, Inhibits Cardiomyocyte Apoptosis Improves Mitochondrial and Infarcted Heart Function.

Aerobic exercise (AE) has attracted considerable research attention as a non-invasive therapeutic tool in recent years. Accumulating evidence has revealed its protective role against a wide range of diseases. In this study, we aimed to establish whether AE could inhibit apoptosis in infarcted cardiomyocytes and protect the heart. AE in post-myocardial infarction (post-MI) mice improved their cardiac and physical functions. Transmission electron microscopy of myocardial tissue and adenosine 5'-triphosphate (ATP) assay findings revealed an increased mitochondrial number but decreased ATP content in the post-MI mice. Notably, this change was significantly reversed by AE. Immunofluorescence/ TUNEL staining assay results showed that AE inhibited cardiomyocyte apoptosis. Using immunoblotting of myocardial tissues, we found that AE increased the level of the anti-apoptotic protein Bcl-2/Bax, significantly decreased the expression of the pro-apoptotic protein caspase-3, and activated the AMPK/PGC-1α signaling pathway. Our findings provide evidence that AE activates the AMPK/PGC-1α signaling pathway, improves mitochondrial energy supply capacity, and effectively inhibits apoptosis in cardiomyocytes. Therefore, AE can be considered a promising post-infarction therapeutic intervention.

Propofol pretreatment inhibits ferroptosis and alleviates myocardial ischemia-reperfusion injury through the SLC16A13-AMPK-GPX4 pathway

This study investigates the protective effects of propofol on the myocardium by inhibiting the expression of SLC16A13 through in vivo animal experiments, while also exploring its mechanism in ferroptosis to provide new strategies for preventing perioperative myocardial ischemia-reperfusion injury. We randomly divided 30 rats into three groups (n=10 each): sham surgery group, ischemia-reperfusion (I/R) group, and propofol pretreatment group. The results showed that compared with the sham surgery group, the I/R group had a significant decrease in cardiac function and an increase in infarct size. Propofol pretreatment effectively alleviated the damage caused by ischemia-reperfusion (I/R). In the next phase of the study, we administered the PPARα agonist GW7647 to artificially increase the expression of SLC16A13. Fifty rats were randomly divided into five groups (n=10 each), with the GW7647 pretreatment group and propofol+GW7647 pretreatment group added based on the previous three groups. Afterwards, we validated the in vivo results using H9C2 and further explored the mechanism by which propofol inhibits ferroptosis. The study found that L-lactic acid in myocardial tissue of the GW7647 group was further increased compared to the I/R group, and the degree of ferroptosis was aggravated. In addition, upregulation of SLC16A13 significantly inhibited the phosphorylation of AMPK, weakened the protective mechanism of AMPK, and exacerbated cardiac damage. However, propofol pretreatment can effectively inhibit the expression of SLC16A13, maintain normal myocardial cell morphology, and protect cardiac function. These results indicate that propofol inhibits the expression of SLC16A13, alleviates myocardial cell ferroptosis via the AMPK/GPX4 pathway, and reverses damage caused by myocardial ischemia-reperfusion.

An injectable multicomponent integrated microgel promotes cardiomyocyte regeneration and heart function after ischemia reperfusion injury

Myocardial ischemia reperfusion (I/R) injury frequently impacts the outcome of patients with coronary heart disease and lacks effective therapeutic strategies. We have summarized the challenges in treating IR injury into three aspects, namely inflammatory reaction, fibrosis, and impaired proliferation ability of myocardial tissue. To address these issues, we have developed an injectable composite microgel called DMP@mgel by integrating three types of biomaterials: placental-derived mesenchymal stem cells loaded microgel, PEDOT:PSS loaded microgel, and siRNA-loaded carrier DP7-C. Upon injection into the injured area, DMP@mgel could regulate the inflammatory microenvironment, promote angiogenesis by the function of stem cells paracrine. Additionally, it enhances coupling between myocardial cells due to its high electrical conductivity. Moreover, DP7-C/siRNA complex can efficiently transfect into myocardial cells to inhibit Hippo pathway activity and promote cell proliferation. The electrostatic interaction enables DP7-C to combine all components into a stable delivery system. In vitro and in vivo experiments confirmed that each ingredient of DMP@mgel exhibits their respective functions such as neovascularization promotion, Hippo pathway inhibition, and antioxidation capability. Finally, administration of DMP@mgel in I/R injured rats significantly improved heart function while reducing fibrosis as evidenced by echocardiography results along with Evans blue staining and histological examination.

Cardiac magnetic resonance for ventricular arrhythmias: a systematic review and meta-analysis

BackgroundCardiac magnetic resonance (CMR) allows comprehensive myocardial tissue characterisation, revealing areas of myocardial inflammation or fibrosis that may predispose to ventricular arrhythmias (VAs). With this study, we aimed to estimate...

A comprehensive experimental analysis of the local passive response across the healthy porcine left ventricle

This work provides a comprehensive characterization of porcine myocardial tissue, combining true biaxial (TBx), simple triaxial shear (STS) and confined compression (CC) tests to analyze its elastic behavior under cyclic loads. We expanded this study to different zones of the ventricular free wall, providing insights into the local behavior along the longitudinal and radial coordinates. The aging impact was also assessed by comparing two age groups (4 and 8 months). Resulting data showed that the myocardium exhibits a highly nonlinear hyperelastic and incompressible behavior. We observed an anisotropy ratio of 2-2.4 between averaged peak stresses in TBx tests and 1-0.59-0.40 orthotropy ratios for normalised fiber-sheet-normal peak stresses in STS tests. We obtained a highly incompressible response, reaching volumetric pressures of 2-7 MPa for perfused tissue in CC tests, with notable differences when fluid drainage was allowed, suggesting a high permeability. Regional analysis showed reduced stiffness and anisotropy (20-25%) at the apical region compared to the medial, which we attributed to differences in the fiber field dispersion. Compressibility also increased towards the epicardium and apical regions. Regarding age-related variations, 8-month animals showed stiffer response (at least 25% increase), particularly in directions where the mechanical stress is absorbed by collagenous fibers (more than 90%), as supported by a histological analysis. Although compressibility of perfused tissue remained unchanged, permeability significantly reduced in 8-month-old animals. Our findings offer new insights into myocardial properties, emphasizing on local variations, which can help to get a more realistic understanding of cardiac mechanics in this common animal model. Statement of significanceIn this work, we conducted a comprehensive analysis of the passive mechanical behavior of porcine myocardial tissue through biaxial, triaxial shear, and confined compression tests. Unlike previous research, we investigated the variation in mechanical response across the left ventricular free wall, conventionally assumed homogeneous, revealing differences in terms of stiffness and compressibility. Additionally, we evaluated age-related effects on mechanical properties by comparing two age groups, observing significant variations in stiffness and permeability. To date, there has been no such in-depth exploration of myocardial elastic response and compressibility considering regional variations along the wall and may contribute to a better understanding of the cardiac tissue’s passive mechanical response.

Real-Time Wireless Sensing of Cardiomyocyte Contractility by Integrating Magnetic Microbeam and Oriented Nanofibers.

In vitro cardiomyocyte mechano-sensing platform is crucial for evaluating the mechanical performance of cardiac tissues and will be an indispensable tool for application in drug discovery and disease mechanism study. Magnetic sensing offers significant advantages in real-time, in situ wireless monitoring and resistance to ion interference. However, due to the mismatch between the stiffness of traditional rigid magnetic material and myocardial tissue, sensitivity is insufficient and it is difficult to achieve cell structure induction and three-dimensional cultivation. Herein, a magnetic sensing platform that integrates a neodymium-iron-boron/polydimethylsiloxane (NdFeB/PDMS) flexible microbeam with suspended and ordered polycaprolactone (PCL) nanofiber membranes was developed, providing a three-dimensional anisotropic culture environment for cardiomyocyte growth and simultaneously realizing in situ wireless contractility monitoring. The as-prepared sensor presented an ultrahigh sensitivity of 442.2 μV/μm and a deflection resolution of 2 μm. By continuously monitoring the cardiomyocyte growth status and drug stimulation feedback, we verified the capability of the platform to capture dynamic changes in cardiomyocyte contractility. This platform provides a perspective tool for evaluating cardiomyocyte maturity and drug performance.

Heart Transplant Rejection: From the Endomyocardial Biopsy to Gene Expression Profiling.

Heart transplant prolongs life for patients with end-stage heart failure but rejection remains a complication that reduces long-term survival. The aim is to provide a comprehensive overview of the current status in HT rejection. EMB is an invasive diagnostic tool, consisting in the sampling of a fragment of myocardial tissue from the right ventricular septum using fluoroscopic guidance. This tissue can later be subjected to histopathological, immunohistochemical or molecular analysis, providing valuable information for cardiac allograft rejection, but this procedure is not without complications. To increase the accuracy of the rejection diagnosis, EMB requires a systematic evaluation of endocardium, myocardium, interstitium and intramural vessels. There are three types of rejection: hyperacute, acute or chronic, diagnosed by the histopathological evaluation of EMB as well as by new diagnostic methods such as DSA, ddcfDNA and gene expression profiling, the last having a high negative predictive value. More than 50 years after the introduction of EMB in medical practice, it still remains the "gold standard" in monitoring rejection in HT recipients but other new, less invasive diagnostic methods reduce the number of EMBs required.

In Silico and In Vivo Studies of β-Sitosterol Nanoparticles as a Potential Therapy for Isoprenaline-Induced Cognitive Impairment in Myocardial Infarction, Targeting Myeloperoxidase.

This study aimed to compare the effects of β-sitosterol nanoparticles (BETNs) and β-sitosterol (BET) on cognitive impairment, oxidative stress, and inflammation in a myocardial infarction (MI) rat model using in silico and in vivo methods. β-Sitosterol (BET) and myeloperoxidase (MPO) ligand-receptor binding affinities were evaluated using Autodock Vina for docking and Gromacs for dynamics simulations. BET nanoparticles, prepared via solvent evaporation, had their size confirmed by a nanoparticle analyzer. ISO-induced cognitive impairment in rats was assessed through Morris water maze and Cook's pole climbing tests. Oxidative stress, inflammation, and cardiac injury were evaluated by measuring GSH, SOD, MDA, MPO, CkMB, LDH, lipid profiles, and ECGs. Histopathology of the CA1 hippocampus and myocardial tissue was performed using H&E staining. In silico analyses revealed strong binding affinities between BET and MPO, suggesting BET's potential anti-inflammatory effect. BETN (119.6 ± 42.6 nm; PDI: 0.809) significantly improved MI-induced cognitive dysfunction in rats (p < 0.001 ***), increased hippocampal GSH (p < 0.01 **) and SOD (p < 0.01 **) levels, and decreased hippocampal MDA (p < 0.05 *) and MPO levels (p < 0.01 **). BETNs also elevated cardiac GSH (p < 0.01 **) and SOD (p < 0.01 **) levels and reduced cardiac MPO (p < 0.01 **), CkMB (p < 0.001 **) and LDH (p < 0.001 **) levels. It restored lipid profiles, normalized ECG patterns, and improved histology in the hippocampal CA1 region and myocardium. Compared with BET treatment, BETNs were more effective in improving cognitive impairment, oxidative damage, and inflammation in MI rats, suggesting its potential in treating cognitive dysfunction and associated pathological changes in MI.

Myocardial Recovery versus Myocardial Regeneration: Mechanisms and Therapeutic Modulation.

Myocardial recovery is characterized by a return toward normal structure and function of the heart after an injury. Mechanisms of myocardial recovery include restoration and/or adaptation of myocyte structure and function, mitochondrial activity and number, metabolic homeostasis, electrophysiological stability, extracellular matrix remodeling, and myocardial perfusion. Myocardial regeneration is an element of myocardial recovery that involves the generation of new myocardial tissue, a process which is limited in adult humans but may be therapeutically augmented. Understanding the mechanisms of myocardial recovery and myocardial regeneration will lead to novel therapies for heart failure.

Clinical Applications of Cardiac Magnetic Resonance Parametric Mapping.

Cardiovascular magnetic resonance (CMR) imaging is widely regarded as the gold-standard technique for myocardial tissue characterization, allowing for the detection of structural abnormalities such as myocardial fatty replacement, myocardial edema, myocardial necrosis, and/or fibrosis. Historically, the identification of abnormal myocardial regions relied on variations in tissue signal intensity, often necessitating the use of exogenous contrast agents. However, over the past two decades, innovative parametric mapping techniques have emerged, enabling the direct quantitative assessment of tissue magnetic resonance (MR) properties on a voxel-by-voxel basis. These mapping techniques offer significant advantages by providing comprehensive and precise information that can be translated into color-coded maps, facilitating the identification of subtle or diffuse myocardial abnormalities. As unlikely conventional methods, these techniques do not require a substantial amount of structurally altered tissue to be visually identifiable as an area of abnormal signal intensity, eliminating the reliance on contrast agents. Moreover, these parametric mapping techniques, such as T1, T2, and T2* mapping, have transitioned from being primarily research tools to becoming valuable assets in the clinical diagnosis and risk stratification of various cardiac disorders. In this review, we aim to elucidate the underlying physical principles of CMR parametric mapping, explore its current clinical applications, address potential pitfalls, and outline future directions for research and development in this field.