Myocardial Matrix Research Articles

Cardiac Matrix-Derived Granular Hydrogel Enhances Cell Function in 3D Culture.

Hydrogels derived from decellularized porcine myocardial matrix have demonstrated significant potential as therapeutic delivery platforms for promoting cardiac repair after injury. Our previous study developed a fibrin-enriched cardiac matrix hydrogel to enhance its angiogenic capacities. However, the bulk hydrogel structure may limit their full potential in cell delivery. Recently, granular hydrogels have emerged as a promising class of biomaterials, offering unique features such as a highly interconnected porous structure that facilitates nutrient diffusion and enhances cell viability. Several techniques have been developed for fabricating various types of granular hydrogels, among which extrusion fragmentation is particularly appealing due to its adaptability to many types of hydrogels, low cost, and high scalability. In this study, we first confirmed the effects of the bulk cardiac matrix hydrogel on the viability of encapsulated human umbilical vein endothelial cells and human mesenchymal stem cells. We then tested the feasibility of producing granular hydrogels from both cardiac matrix and fibrin-enriched cardiac matrix through cellular cross-linking of microgels fabricated by extrusion fragmentation. Afterward, we examined the roles of the produced granular hydrogels in the embedded cells and cell spheroids. Our in vitro data demonstrate that cardiac matrix-derived granular hydrogels support optimal viability of encapsulated cells and promote sprouting of human mesenchymal stem cell spheroids. Additionally, granular hydrogel derived from fibrin-enriched cardiac matrix accelerates angiogenic sprouting of embedded human mesenchymal stem cell spheroids. The results obtained from this study lay an important foundation for the future exploration of using cardiac matrix-derived granular hydrogels for cardiac cell therapy.

Myocardial Matrix Hydrogels Mitigate Negative Remodeling and Improve Function in Right Heart Failure Model

This study evaluates the effectiveness of myocardial matrix (MM) hydrogels in mitigating negative right ventricular (RV) remodeling in a rat model of RV heart failure. The goal was to assess whether a hydrogel derived from either the right or left ventricle could promote cardiac repair. Injured rat right ventricles were injected with either RV-or left ventricular-derived MM hydrogels. Both hydrogels improved RV function and morphology and reduced negative remodeling. This study supports the potential of injectable biomaterial therapies for treating RV heart failure.

Left Ventricular Mass, Myocardial Structure, and Function in Severe Aortic Stenosis: an Echocardiographic and Cardiac Magnetic Resonance Imaging Study

In severe aortic stenosis (AS), there are conflicting data on the prognostic implications of left ventricular (LV) hypertrophy (LVH). We aimed to characterize the LV geometry, myocardial matrix structural changes, and prognostic stratification using cardiac magnetic resonance imaging (CMR) and echocardiography in subjects with severe AS with and without LVH. Consecutive patients who had severe isolated AS and sufficient quality echocardiography and CMR within 6months of each other were evaluated for LVH, cardiac structure, morphology, and late gadolinium-enhancement imaging. Kaplan-Meier curves, linear models, and proportional hazards models were used for prognostic stratification. There were 93 patients enrolled (mean age 74 ± 11years, 48% female), of whom 38 (41%) had a normal LV mass index (LVMI), 41 (44%) had LVH defined at CMR by LVMI >2 SD higher than normal, and 14 (15% of the total) with >4 SD higher than the reference LVMI (severely elevated). The Society of Thoracic Surgeons scores were similar among the LVMI groups. Compared with those with normal LVMI, patients with LVH had higher LV end-diastolic and end-systolic volumes, increased late gadolinium-enhancement burden, and lower LV ejection fraction. Most notably, CMR feature-tracking global radial strain, 2-dimensional speckle-tracking echocardiography global longitudinal strain, and left atrial reservoir function were significantly worse. On the survival analyses, LVMI was not associated with a composite of all-cause mortality and/or heart failure hospitalization. In conclusion, compared with normal LVMI, elevated LVMI was not associated with a higher risk of adverse outcomes.

Proteomic Insights into Cardiac Fibrosis: From Pathophysiological Mechanisms to Therapeutic Opportunities.

Cardiac fibrosis is a common pathophysiologic process in nearly all forms of heart disease which refers to excessive deposition of extracellular matrix proteins by cardiac fibroblasts. Activated fibroblasts are the central cellular effectors in cardiac fibrosis, and fibrotic remodelling can cause several cardiac dysfunctions either by reducing the ejection fraction due to a stiffened myocardial matrix, or by impairing electric conductance. Recently, there is a rising focus on the proteomic studies of cardiac fibrosis for pathogenesis elucidation and potential biomarker mining. This paper summarizes the current knowledge of molecular mechanisms underlying cardiac fibrosis, discusses the potential of imaging and circulating biomarkers available to recognize different phenotypes of this lesion, reviews the currently available and potential future therapies that allow individualized management in reversing progressive fibrosis, as well as the recent progress on proteomic studies of cardiac fibrosis. Proteomic approaches using clinical specimens and animal models can provide the ability to track pathological changes and new insights into the mechanisms underlining cardiac fibrosis. Furthermore, spatial and cell-type resolved quantitative proteomic analysis may also serve as a minimally invasive method for diagnosing cardiac fibrosis and allowing for the initiation of prophylactic treatment.

Myocardial matrix hydrogel acts as a reactive oxygen species scavenger and supports a proliferative microenvironment for cardiomyocytes

As the native regenerative potential of adult cardiac tissue is limited post-injury, stimulating endogenous repair mechanisms in the mammalian myocardium is a potential goal of regenerative medicine therapeutics. Injection of myocardial matrix hydrogels into the heart post-myocardial infarction (MI) has demonstrated increased cardiac muscle and promotion of pathways associated with cardiac development, suggesting potential promotion of cardiomyocyte turnover. In this study, the myocardial matrix hydrogel was shown to have native capability as an effective reactive oxygen species scavenger and protect against oxidative stress induced cell cycle inhibition in vitro. Encapsulation of cardiomyocytes demonstrated an enhanced turnover in in vitro studies, and in vivo assessments of myocardial matrix hydrogel treatment post-MI showed increased thymidine analog uptake in cardiomyocyte nuclei compared to saline controls. Overall, this study provides evidence that properties of the myocardial matrix material provide a microenvironment mitigating oxidative damage and supportive of cardiomyocytes undergoing DNA synthesis, toward possible DNA repair or cell cycle activation. Statement of significanceLoss of adult mammalian cardiomyocyte turnover is influenced by shifts in oxidative damage, which represents a potential mechanism for improving restoration of cardiac muscle after myocardial infarction (MI). Injection of a myocardial matrix hydrogel into the heart post-MI previously demonstrated increased cardiac muscle and promotion of pathways associated with cardiac development, suggesting potential in promoting proliferation of cardiomyocytes. In this study, the myocardial matrix hydrogel was shown to protect cells from oxidative stress and increase proliferation in vitro. In a rat MI model, greater presence of tissue free thiol content spared from oxidative damage, lesser mitochondrial superoxide content, and increased thymidine analog uptake in cardiomyocytes was found in matrix injected animals compared to saline controls. Overall, this study provides evidence that properties of the myocardial matrix material provide a microenvironment supportive of cardiomyocytes undergoing DNA synthesis, toward possible DNA repair or cell cycle activation.

Detection of extracellular myocardial matrix with Dual Energy computed tomography: systematic review and meta-analysis

Background. The amount of extracellular myocardial matrix is a non-invasive tool for quantitative assessment of myocardial fibrosis. MRI with late gadolinium-enhancement is considered to be the “Gold standard” of non-invasive practice. Dual Energy computed tomography is a new non-invasive approach for detection of myocardial fibrosis and its prognostic value remains unclear. The purpose of this study was to summarize all available data and to study prognostic value of DECT for the detection of fibrotic changes in myocardium.Methods. We searched MEDLINE, EMBASE, Cochrane, SCOPUS and Web of Science for cohort studies up to October 2021 that reported myocardial extracellular volume fraction quantification using contrast enhanced dual energy CT or/and MRI with delayed enhancement.Results. Eleven studies met eligibility criteria. A systematic analysis demonstrated the difference in extracellular volume fraction in patients with fibrotic and inflammation changes of the myocardium, as well as good comparability between DECT and MRI. The value of extracellular volume fraction in myocardium with fibrotic or inflammatory changes was higher than in healthy tissue, which makes it possible to use the ECV as a non-invasive marker of myocardial fibrosis.

Characterization of decellularized left and right ventricular myocardial matrix hydrogels and their effects on cardiac progenitor cells

Congenital heart defects are the leading cause of right heart failure in pediatric patients. Implantation of c-kit+ cardiac-derived progenitor cells (CPCs) is being clinically evaluated to treat the failing right ventricle (RV), but faces limitations due to reduced transplant cell survival, low engraftment rates, and low retention. These limitations have been exacerbated due to the nature of cell delivery (narrow needles) and the non-optimal recipient microenvironment (reactive oxygen species (ROS)). Extracellular matrix (ECM) hydrogels derived from porcine left ventricular (LV) myocardium have emerged as a potential therapy to treat the ischemic LV and have shown promise as a vehicle to deliver cells to injured myocardium. However, no studies have evaluated the combination of an injectable biomaterial, such as an ECM hydrogel, in combination with cell therapy for treating RV failure. In this study we characterized LV and RV myocardial matrix (MM) hydrogels and performed in vitro evaluations of their potential to enhance CPC delivery, including resistance to forces experienced during injection and exposure to ROS, as well as their potential to enhance angiogenic paracrine signaling. While physical properties of the two hydrogels are similar, the decellularized LV and RV have distinct protein signatures. Both materials were equally effective in protecting CPCs against needle forces and ROS. CPCs encapsulated in either the LV MM or RV MM exhibited similar enhanced potential for angiogenic paracrine signaling when compared to CPCs in collagen. The RV MM without cells, however, likewise improved tube formation, suggesting it should also be evaluated as a potential standalone treatment.

Cardiac involvement in cystic fibrosis evaluated using cardiopulmonary magnetic resonance

Cystic fibrosis (CF) transmembrane conductance regulator is expressed in myocardium, but cardiac involvement in CF remains poorly understood. The recent development of a combined cardiopulmonary magnetic resonance imaging technology allows for a simultaneous interrogation of cardiac and pulmonary structure and function. The aim of this study was to investigate myocardial manifestations in adults with CF, both in a stable state and during an acute respiratory exacerbation, and to investigate the relationship between cardiac and pulmonary disease. Healthy adult volunteers (n = 12) and adults with CF (n = 10) were studied using a multiparametric cardiopulmonary magnetic resonance protocol. CF patients were scanned during an acute respiratory exacerbation and re-scanned when stable. Stable CF was associated with left ventricular dilatation and hypertrophy (LVH; left ventricular mass: CF 59 ± 9 g/m2 vs. control 50 ± 8 g/m2; p = 0.028). LVH was predominantly driven by extracellular myocardial matrix expansion (extracellular matrix mass: CF 27.5 ± 3.4 g vs. control 23.6 ± 5.2 g; p = 0.006; extracellular volume [ECV]: CF 27.6 [24.7–29.8]% vs. control 24.8 [22.9–26.0]%; p = 0.030). Acute CF was associated with an acute reduction in left ventricular function (ejection fraction: acute 57 ± 3% vs. stable 61 ± 5%; p = 0.025) and there was a suggestion of myocardial oedema. Myocardial oedema severity was strongly associated with the severity of airflow limitation (r = − 0.726, p = 0.017). Multiparametric cardiopulmonary magnetic resonance technology allows for a simultaneous interrogation of cardiac and pulmonary structure and function. Stable CF is associated with adverse myocardial remodelling, including left ventricular systolic dilatation and hypertrophy, driven by myocardial fibrosis. CF exacerbation is associated with acute myocardial contractile dysfunction. There is also a suggestion of myocardial oedema in the acute period which is related to pulmonary disease severity.

The Different Effect of Decellularized Myocardial Matrix Hydrogel and Decellularized Small Intestinal Submucosa Matrix Hydrogel on Cardiomyocytes and Ischemic Heart

Injectable decellularized matrix hydrogels derived from either myocardium or small intestinal submucosa (pDMYO-gel, pDSIS-gel) have been successfully used for myocardial injury repair. However, the relationship between tissue-specific biological functions and protein composition in these two materials is not clear yet. In this study, the protein composition, mechanical properties, and morphology of these two hydrogels and their effects on the behavior of neonatal rat cardiomyocytes (NRCMs) and human umbilical vein endothelial cells (HUVECs), are investigated. The results show that pDMYO-gel is more conducive to growth, adhesion, spreading, and maintenance of normal NRCM beating, due to its higher proportion of extracellular matrix (ECM) glycoproteins (49.55%) and some unique functional proteins such as annexin-6 (ANXA6), agrin (AGRN), cathepsin D (CTSD) and galectin-1 (LGALS1), whereas pDSIS-gel is more conducive to the proliferation of HUVECs. Animal study shows that pDMYO-gel has a better effect on improving cardiac function, inhibiting myocardial fibrosis and maintaining ventricular wall thickness in acute myocardial infarction models in vivo. Therefore, it is proposed that injectable pDMYO-gel hydrogel may be more suitable for functional recovery of myocardial injuries.

DYNAMIC BIOREACTOR MODEL TO MIMIC EARLY CARDIAC FIBROSIS IN DIABETES

In clinical diabetic cardiomyopathy, hyperglycemia and dyslipidemia induce tissue injury, activation of cardiac fibroblasts and interstitial and perivascular fibrosis. Myofibroblasts repair the injured tissue by increasing collagen deposition in the cardiac interstitium and suppressing the activity of matrix metalloproteinases. The goal of this study was to find an ideal model to mimic the effect of high glucose concentration on human cardiac fibroblast activation. The profibrotic role of the transforming growth factor-[Formula: see text] (TGF-[Formula: see text]) and the protective modulation of nitric oxide were examined in two-dimensional and three-dimensional cell culture models, as well as tissue engineering models, that involved the use of cardiac fibroblasts cultured within myocardial matrix scaffolds mounted in a bioreactor that delivered biochemical and mechanical stimuli. Results showed that high glucose levels were potent pro-fibrotic stimuli. In addition, high glucose levels in concert with TGF-[Formula: see text] constituted very strong signals that induced human cardiac fibroblast activation. Cardiac fibroblasts cultured within decellularized myocardial scaffolds and exposed to biochemical and mechanical stimuli represented an adequate model for this pathology. In conclusion, the bioreactor platform was instrumental in establishing an in vitro model of early fibrosis; this platform could be used to test the effects of various agents targeted to mitigate the fibrotic processes.

Preliminary assessment of an injectable extracellular matrix from decellularized bovine myocardial tissue.

The goal of this study was to develop an injectable form of decellularized bovine myocardial tissue matrix which could retain high levels of functional ECM molecules, and could gel at physiological temperature. Dissected ventricular tissue was processed by a detergent-based protocol, lyophilized, enzymatically-digested, and neutralized to form the injectable myocardial matrix (IMM). Histochemical analysis, DNA quantification, and agarose gel electrophoresis demonstrated the efficiency of the applied protocol. Chemical, thermal, morphological, and rheological characterization; protein and sulfated glycosaminoglycan (sGAG) content analysis were performed, in vitro biological properties were evaluated. An in vivo histocompatibility and biodegradability study was performed. Histochemistry revealed complete removal of myocardial cells. DNA content analysis revealed a significant decrease (87%) in the nuclear material, while protein and sGAG contents were highly preserved following decellularization. Soluble IMM was capable of turning into gel form at ∼37°C, indicating selfassembling property. In vitro findings showed the biomaterial was noncytotoxic, nonhemolytic, and supported the attachment and proliferation of mesenchymal stem cells. In vivo study demonstrated IMM was well-tolerated by rats receiving subcutaneous injection. This work demonstrates that the IMM from decellularized bovine myocardial tissue has the potential for use as a feasible regenerative biomaterial in prospective tissue engineering and regenerative medicine studies.

Injectable Myocardial Matrix Hydrogel Mitigates Negative Left Ventricular Remodeling in a Chronic Myocardial Infarction Model

A first-in-man clinical study on a myocardial-derived decellularized extracellular matrix hydrogel suggested the potential for efficacy in chronic myocardial infarction (MI) patients. However, little is understood about the mechanism of action in chronic MI. In this study, the authors investigated the efficacy and mechanism by which the myocardial matrix hydrogel can mitigate negative left ventricular (LV) remodeling in a rat chronic MI model. Assessment of cardiac function via magnetic resonance imaging demonstrated preservation of LV volumes and apical wall thickening. Differential gene expression analyses showed the matrix is able to prevent further negative LV remodeling in the chronic MI model through modulation of the immune response, down-regulation of pathways involved in heart failure progression and fibrosis, and up-regulation of genes important for cardiac muscle contraction.

Aldosterone-Related Myocardial Extracellular Matrix Expansion in Hypertension in Humans: A Proof-of-Concept Study by Cardiac Magnetic Resonance

ObjectivesThis study sought to assess the respective effects of aldosterone and blood pressure (BP) levels on myocardial fibrosis in humans. BackgroundExperimentally, aldosterone promotes left ventricular (LV) hypertrophy, and interstitial myocardial fibrosis in the presence of high salt intake. MethodsThe study included 20 patients with primary aldosteronism (PA) (high aldosterone and high BP), 20 patients with essential hypertension (HTN) (average aldosterone and high BP), 20 patients with secondary aldosteronism due to Bartter/Gitelman (BG) syndrome (high aldosterone and normal BP), and 20 healthy subjects (HS) (normal aldosterone and normal BP). Participants in each group were of similar age and sex distributions, and asymptomatic. Cardiac magnetic resonance including cine and T1 mapping was performed blind to the study group to quantify global LV mass index, as well as intracellular mass index and extracellular mass index considered as a measure of myocardial fibrosis in vivo. ResultsMedian plasma aldosterone concentration was as follows: PA = 709 pmol/l (interquartile range [IQR]: 430 to 918 pmol/l); HTN = 197 pmol/l (IQR: 121 to 345 pmol/l); BG = 297 pmol/l (IQR: 180 to 428 pmol/l); and HS = 105 pmol/l (IQR: 85 to 227 pmol/l). Systolic BP was as follows: PA = 147 ± 15 mm Hg; HTN = 133 ± 19 mm Hg; BG = 116 ± 9 mm Hg; and HS = 117 ± 12 mm Hg. LV end-diastolic volume showed underloading in BG and overloading in patients with PA (63 ± 13 ml/m2 vs. 82 ± 15 ml/m2; p < 0.0001). Intracellular mass index increased with BP across groups (BG: 36 [IQR: 29 to 41]; HS: 40 [IQR: 36 to 46]; HTN: 51 [IQR: 42 to 54]; PA: 50 [IQR: 46 to 67]; p < 0.0001). Extracellular mass index was similar in BG, HS, and HTN (16 [IQR: 12 to 20]; 15 [IQR: 11 to 18]; and 14 [IQR: 12 to 17], respectively) but 30% higher in PA (21 [IQR: 18 to 29]; p < 0.0001) remaining significant after adjustment for mean BP. ConclusionsOnly primary pathological aldosterone excess combined with high BP increased both extracellular myocardial matrix and intracellular mass. Secondary aldosterone excess with normal BP did not affect extracellular myocardial matrix. (Study of Myocardial Interstitial Fibrosis in Hyperaldosteronism; NCT02938910).

Characteristics of Fibrosis and Collagen Metabolism Disorders in the Myocardial Interstitial Matrix of Patients with Arterial Hypertension and the Potential Use of Sartan Drugs for Their Treatment

The chronic extension of heart and blood-vessel walls due to hypertension leads to metabolic disorders in their interstitial matrix. To assess involutive and hypertensive changes in the cardiac and vascular interstitial matrix and to assess the their potential correction with Valsartan and Veroshpiron, 30 normotensive elderly women and 30 patients of the same age with stage-II arterial hypertension (AH) have been examined. Echocardiography and Doppler cardiography were carried out, the volume fraction of interstitial collagen (VFIC) in the myocardium and cardiovascular conjugation (CVC) was measured, and the serum concentrations of systemic collagenogenesis markers were determined. In elderly patients with AH, a higher intensity of LV myocardial fibrosis was found with a statistically significant increase in VFIC as compared to the patients with normal tension. This was due to the increased activity of fibrosis markers. A decrease in their levels was observed after antihypertensive therapy, which proved the antifibrotic effect of the therapy.

MiR-1/133 attenuates cardiomyocyte apoptosis and electrical remodeling in mice with viral myocarditis.

The role of miR-1 and miR-133 in regulating the expression of potassium and calcium ion channels, and mediating cardiomyocyte apoptosis in mice with viral myocarditis (VMC) is investigated herein. Male Balb/c mice were randomly divided into groups: control group, VMC group, VMC + miR-1/133 mimics group, or VMC + miR-1/133 negative control (NC) group. VMC was induced with coxsackievirus B3 (CVB3). MiR-1/133 mimics ameliorated cardiac dysfunction in VMC mice and was compared to the VMC+NC group. Hematoxylin and eosin staining showed a well-arranged myocardium without inflammatory cell infiltration in the myocardial matrix of the control group. However, in the VMC and VMC+NC groups, the myocardium was disorganized and swollen with necrosis, and the myocardial matrix was infiltrated with inflammatory cells. These changes were alleviated by miR-1/133 mimics. TUNEL staining revealed decreased cardiomyocyte apoptosis in the VMC + miR-1/133 mimics group compared with the VMC group. In addition, miR-1/133 mimics up-regulated the expression of miR-1 and miR-133, the potassium channel genes Kcnd2 and Kcnj2, as well as Bcl-2, and down-regulated the expression of the potassium channel suppressor gene Irx5, L-type calcium channel subunit gene a1c (Cacna1c), Bax, and caspase-9 in the myocardium of VMC mice. MiR-1/133 also up-regulated the protein levels of Kv4.2 and Kir2.1, and down-regulated the expression of CaV1.2 in the myocardium of VMC mice. MiR-1 and miR-133 decreased cardiomyocyte apoptosis by mediating the expression of apoptosis-related genes in the hearts of VMC mice.

Optimizing Anisotropic Polyurethane Scaffolds to Mechanically Match with Native Myocardium.

Biodegradable cardiac patch is desirable to possess mechanical properties mimicking native myocardium for heart infarction treatment. We fabricated a series of anisotropic and biodegradable polyurethane porous scaffolds via thermally induced phase separation (TIPS) and tailored their mechanical properties by using various polyurethanes with different soft segments and varying polymer concentrations. The uniaxial mechanical properties, suture retention strength, ball-burst strength, and biaxial mechanical properties of the anisotropic porous scaffolds were optimized to mechanically match native myocardium. The optimal anisotropic scaffold had a ball burst strength (20.7 ± 1.5 N) comparable to that of native porcine myocardium (20.4 ± 6.0 N) and showed anisotropic behavior close to biaxial stretching behavior of the native porcine myocardium. Furthermore, the optimized porous scaffold was combined with a porcine myocardium-derived hydrogel to form a biohybrid scaffold. The biohybrid scaffold showed morphologies similar to the decellularized porcine myocardial matrix. This combination did not affect the mechanical properties of the synthetic scaffold alone. After in vivo rat subcutaneous implantation, the biohybrid scaffolds showed minimal immune response and exhibited higher cell penetration than the polyurethane scaffold alone. This biohybrid scaffold with biomimetic mechanics and good tissue compatibility would have great potential to be applied as a biodegradable acellular cardiac patch for myocardial infarction treatment.

Epidemiology and pathogenesis of heart failure with preserved ejection fraction.

Heart failure (HF) is a complex syndrome that affects approximately6.5 millionadults in the United States. About half of the 6.5 million adults with HF are estimated to be individuals with heart failure with preserved ejection fraction (HFpEF). It is a common cause for poor quality of life, increased health-care resource utilization, and early mortality. HF incidence has risen to epidemic proportions in the recent years. This review attempts to address the epidemiology and pathophysiology of HFpEF. The incidence of HFpEF increased from 48% to 57% from 2000 to 2007 with a slight decrease in 2010 to 52%. The temporal trends in heart failure show an overall stable incidence of HF over the last two decades with increasing incidence of HFpEF and decreasing HFrEF incidence. Many etiologies contribute to the development of HFpEF which makes the treatment very challenging. Pathophysiology of HFpEF is multifaceted stemming from several disease-specific aspects of inflammation and endothelial function, cardiomyocyte hypertrophy and fibrosis, ventricular-vascular uncoupling, pulmonary hypertension and chronotropic incompetence. Hence identifying the risk factors and etiologies is imperative to achieve optimal outcomes in this population. Newer insights into myocardial remodeling have led to an interesting finding of abnormal fibroblasts in HFpEF which are apoptosis resistant and initiate the development of an abnormal myocardial matrix resulting in initiation and progression of the disease. Upregulation of ROS has also been implicated in HFpEF. Further investigation could provide new avenues to target therapeutics specifically to stop initiation and progression of fibrosis.

P868 Dissecting myocardium

Abstract Introduction Incomplete rupture is a relatively uncommon type of free-wall rupture. It is found in 10% to 15% of total free-wall ruptures. Case report A 68-year-old male patient, heavy smoker, with medical history of diabetes mellitus and hypertension, had experienced an attack of acute retrosternal chest pain associated with dyspnea grade II-III one week before presentation. He presented to our facility complaining acute chest pain. Upon examination, the patient had stable vital signs and an unremarkable clinical examination except for distant heart sounds on auscultation. Electrocardiogram showed deep Q waves in V1 to V4 with residual ST segment elevation. Routine lab investigations were unremarkable including a negative troponin. A Chest X-ray showed an enlarged cardiac shadow. Echocardiography revealed a poor left ventricular systolic function due to an akinetic anterior wall and a dyskinetic apical cap containing a large highly mobile thread like mass which was suspected to be a thrombus. Coronary angiography revealed proximal 85% stenosis followed by mid segment total occlusion of the Left anterior descending (LAD) artery, proximal 75% stenosis of the left circumflex (LCX) artery and a tight lesion in the mid segment of the right coronary artery (RCA). The patient was diagnosed to have multi-vessel coronary artery disease and was maintained on medical treatment. Cardiac MRI was requested to detect myocardial viability before revascularization. Subsequently, cardiac magnetic resonance (CMR) revealed a dilated left ventricle with very poor systolic function, akinetic inferior wall, aneurysmally dilated apex and anterior wall with the same large highly mobile mass. Late gadolinium enhancement revealed scarred anterior, septal and inferior walls including all apical segments and surprisingly the mobile intra-ventricular mass also contained a scar tissue continuous with the anterior myocardial scar which means it is a part of the myocardium which was dissected or partially ruptured. Unfortunately, the patient suddenly experienced an attack of ventricular arrhythmia which was not resuscitated successfully. Conclusion Incomplete rupture is a rare type of free-wall rupture. It is thought that the infarcted myocardium wall is made weak in part by activation of metalloproteinases, which degrade the myocardial matrix. Structural weakness is associated with increased intra-cavitary pressure which predisposes the myocardial wall to rupture. Although Echocardiography is a good method of diagnosis but CMR is superior due to its high spatial resolution and good tissue characterization, plus the use of late gadolinium enhancement helps in identifying the location and the extent of prior infarctions guiding us to the next step in management. Abstract P868 Figure. Myocardial dissection with scarred flap

P1777 Circulating microRNAs are associated with myocardial damage in patients with coronary artery disease: implications for a role of microRNA in myocardial matrix remodeling

Abstract Background Recent studies have reported that circulating microRNA (miR) can target different metalloproteases involved in matrix remodelling and plaque vulnerability. Consequently, they might have a role in the diagnosis and prognosis of cardiovascular diseases. Aim. To quantify circulating miRs (miR126, miR146) which are suggested to have possible cardiovascular implications, as well as levels of MMP-1 and MMP-9, and to determine their association with left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), and arterial function, in patients with stable and unstable coronary artery disease (CAD). Methods 90 patients with CAD (61% men, 58+/-12 years), including 60 patients with ST elevation acute myocardial infarction (STEMI) and 30 patients with stable CAD were assessed within 24 hours of admission by serum microRNA quantification (TaqMan PCR analysis), and serum MMP-1 and MMP-9 analysis (ELISA kits). 2D and 3D echocardiography were used to assess LVEF; speckle tracking was used to asses GLS; echo tracking, CAVI, and peripheral Doppler were used to assess arterial function (Young"s elastic modulus - EP and β index, arterial stiffness, and ABI). Results Circulating levels of miR146, miR126, MMP1, and MMP9 were significantly increased in patients with STEMI vs. stable CAD (95% CI 1.92-8.43, p = 0.002). miR126 correlated with LVEF (r=-.41, p = 0.03) and arterial stiffness (r=.44, and r=.42, p = 0.02 for L-CAVI and R-CAVI respectively) in patients with STEMI, and with arterial stiffness (r=-.72, p = 0.04, r=-.72, p = 0.01 for L-CAVI and R-CAVI respectively) and ABI (r=-.62, p = 0.04, r=-.62, p = 0.03 for L-ABI and R-ABI respectively) in patients with stable CAD. miR146 did not have any significant correlations. Both MMP-1 and MMP-9 correlated with LV function, LVEF ( r=-.27, p = 0.04, r=-.40, p = 0.01) and GLS (r=-.27, p = 0.03, r=-.26, p = 0.04) in patients with STEMI, and with arterial stiffness (r=.40, p = 0.03, for L-CAVI and r = 0.42, p = 0.02 for R-CAVI) in patients with stable CAD. Conclusion miR126 and both MMP1 and MMP9 are potential biomarkers of LV function in STEMI patients. Meanwhile, they correlate with arterial function in patients with stable CAD. However, further studies are needed to establish whether these new biomarkers have diagnosis and prognosis significance. Abstract P1777 Figure.

Synergistic effects of adipose-derived stem cells combined with decellularized myocardial matrix on the treatment of myocardial infarction in rats

AimsThe aims of the study are to investigate whether the combination of adipose-derived stem cells (ADSCs) with decellularized extracellular matrix (dECM) of myocardium can exert synergistic therapeutic effects on acute MI and the underlying mechanism. Main methodsMyocardial dECM from fresh porcine myocardium was prepared in an injectable gel, ADSCs were seeded into the myocardial dECM gels, and then the mixture was injected into the myocardium of the infarct border zone after acute MI, which was induced by ligating the left anterior descending coronary artery in male SD rats, to assess the therapeutic potential. The degree of fibrosis was detected by Masson's trichrome. The evaluation of cardiac function was performed by Electrocardiography. Key findingsMyocardial dECM (2.0%) had a suitable aperture and arrangement for cell growth, and also exhibited suitable biomechanical properties. Four-weeks after treatment in vivo, the combination of ADSCs and myocardial dECM could obviously increase angiogenesis, reduce the degree of fibrosis, and decrease infarct size. Furthermore, the combination treatment exerted significant functional improvement. Compared with ADSCs or dECM group alone, the left ventricular ejection fraction (LVEF) in the combination group was 13.4% and 21.8% elevated, respectively. SignificanceThe combination of ADSCs and myocardial dECM has synergistic effects on cardiac repair in acute MI.