Collagen content, but not the ratios of collagen type III/I mRNAs, differs among hypertensive, alcoholic, and idiopathic dilated cardiomyopathy

Non-invasive in vivo imaging of changes in Collagen III turnover in myocardial fibrosis

Heart failure (HF) affects 64 million people globally with enormous societal and healthcare costs. Myocardial fibrosis, characterised by changes in collagen content drives HF. Despite evidence that collagen type III (COL3) content changes during myocardial fibrosis, in vivo imaging of COL3 has not been achieved. Here, we discovered the first imaging probe that binds to COL3 with high affinity and specificity, by screening candidate peptide-based probes. Characterisation of the probe showed favourable magnetic and biodistribution properties. The probe's potential for in vivo molecular cardiac magnetic resonance imaging was evaluated in a murine model of myocardial infarction. Using the new probe, we were able to map and quantify, previously undetectable, spatiotemporal changes in COL3 after myocardial infarction and monitor response to treatment. This innovative probe provides a promising tool to non-invasively study the unexplored roles of COL3 in cardiac fibrosis and other cardiovascular conditions marked by changes in COL3.

Interleukin-10 deficiency induces thoracic perivascular adipose tissue whitening and vascular remodeling

Perivascular adipose tissue (PVAT) is an adipose layer, surrounding blood vessels, with a local modulatory role. Interleukin-10 (IL-10) has been shown to modulate vascular tissue. This study aimed to characterize the endogenous role of IL-10 in vascular remodeling, and PVAT phenotyping. Thoracic aortic segments from control (C57BL/6J) and IL-10 knockout (IL-10-/-) male mice were used. Analyzes of aorta/PVAT morphometry, and elastin, collagen and reticulin deposition were performed. Tissue uncoupling protein 1 (UCP1) was accessed by Western blotting. Endogenous absence of IL-10 reduced total PVAT area (p = 0.0310), and wall/lumen ratio (p = 0.0024), whereas increased vascular area and thickness (p < 0.0001). Total collagen deposition was augmented in IL-10-/-, but under polarized light, the reduction of collagen-I (p = 0.0075) and the increase of collagen-III (p = 0.0055) was found, simultaneously with reduced elastic fibers deposition (p = 0.0282) and increased deposition of reticular fibers (p < 0.0001). Adipocyte area was augmented in the IL-10 absence (p = 0.0225), and UCP1 expression was reduced (p = 0.0420). Moreover, relative frequency of white adipose cells and connective tissue was augmented in IL-10-/- (p < 0.0001), added to a reduction in brown adipose cells (p < 0.0001). Altogether, these data characterize aorta PVAT from IL-10-/- as a white-like adipocyte phenotype. Endogenous IL-10 prevents vascular remodeling and favors a brown-like adipocyte phenotype, suggesting a modulatory role for IL-10 in PVAT plasticity.

Galectin-3 (Gal-3) and the tissue inhibitor of matrix metalloproteinase (TIMP-2) as potential biomarkers for the clinical evolution of chronic Chagas cardiomyopathy

BACKGROUND

Chronic Chagas cardiomyopathy (CCC) is responsible for the highest morbidity and worst prognosis in Chagas disease patients. However, predicting factors that correlate with disease progression, morbidity, and mortality is challenging. It is necessary to have simple, quantitative, and economical risk biomarkers that add value to conventional methods and assist in the diagnosis and prognosis of patients with CCC or in evolution.

OBJECTIVES

We evaluated molecules related to cardiac remodeling and fibrosis, such as MMP-2, MMP-9, TIMP-2, TIMP-1, PICP, CTXI, and Gal-3, and correlated these biomarkers with echocardiographic variables (LVDD, LVEF, and E/e' ratio).

METHODS

Blood samples from Chagasic patients without apparent cardiopathy (WAC), CCC patients, and healthy individuals were used to perform plasma molecule dosages using Luminex or ELISA.

RESULTS

MMP-2 and TIMP-2 presented higher levels in CCC; in these patients, the inhibitory role of TIMP-2 over MMP-2 was reinforced. The ratio of MMP-2/TIMP-2 in WAC patients showed a bias in favor of the gelatinase pathway. MMP-9 and TIMP-1 showed higher levels in Chagas patients compared to healthy subjects. PICP and CTXI are not associated with cardiac deterioration in Chagas disease. Increased levels of Gal-3 are associated with worse cardiac function in CCC. Receiver operating characteristic (ROC) curve analysis identified Gal-3 and TIMP-2 as putative biomarkers to discriminate WAC from cardiac patients.

CONCLUSIONS

Among the molecules evaluated, Gal-3 and TIMP-2 have the potential to be used as biomarkers of cardiac remodeling and progressive myocardial fibrosis in Chagas disease.

Distinct Transcriptomic and Proteomic Profile Specifies Patients Who Have Heart Failure With Potential of Myocardial Recovery on Mechanical Unloading and Circulatory Support

BACKGROUND

Extensive evidence from single-center studies indicates that a subset of patients with chronic advanced heart failure (HF) undergoing left ventricular assist device (LVAD) support show significantly improved heart function and reverse structural remodeling (ie, termed "responders"). Furthermore, we recently published a multicenter prospective study, RESTAGE-HF (Remission from Stage D Heart Failure), demonstrating that LVAD support combined with standard HF medications induced remarkable cardiac structural and functional improvement, leading to high rates of LVAD weaning and excellent long-term outcomes. This intriguing phenomenon provides great translational and clinical promise, although the underlying molecular mechanisms driving this recovery are largely unknown.

METHODS

To identify changes in signaling pathways operative in the normal and failing human heart and to molecularly characterize patients who respond favorably to LVAD unloading, we performed global RNA sequencing and phosphopeptide profiling of left ventricular tissue from 93 patients with HF undergoing LVAD implantation (25 responders and 68 nonresponders) and 12 nonfailing donor hearts. Patients were prospectively monitored through echocardiography to characterize their myocardial structure and function and identify responders and nonresponders.

RESULTS

These analyses identified 1341 transcripts and 288 phosphopeptides that are differentially regulated in cardiac tissue from nonfailing control samples and patients with HF. In addition, these unbiased molecular profiles identified a unique signature of 29 transcripts and 93 phosphopeptides in patients with HF that distinguished responders after LVAD unloading. Further analyses of these macromolecules highlighted differential regulation in 2 key pathways: cell cycle regulation and extracellular matrix/focal adhesions.

CONCLUSIONS

This is the first study to characterize changes in the nonfailing and failing human heart by integrating multiple -omics platforms to identify molecular indices defining patients capable of myocardial recovery. These findings may guide patient selection for advanced HF therapies and identify new HF therapeutic targets.

Global PIEZO1 Gain-of-Function Mutation Causes Cardiac Hypertrophy and Fibrosis in Mice

PIEZO1 is a subunit of mechanically-activated, nonselective cation channels. Gain-of-function PIEZO1 mutations are associated with dehydrated hereditary stomatocytosis (DHS), a type of anaemia, due to abnormal red blood cell function. Here, we hypothesised additional effects on the heart. Consistent with this hypothesis, mice engineered to contain the M2241R mutation in PIEZO1 to mimic a DHS mutation had increased cardiac mass and interventricular septum thickness at 8–12 weeks of age, without altered cardiac contractility. Myocyte size was greater and there was increased expression of genes associated with cardiac hypertrophy (Anp, Acta1 and β-MHC). There was also cardiac fibrosis, increased expression of Col3a1 (a gene associated with fibrosis) and increased responses of isolated cardiac fibroblasts to PIEZO1 agonism. The data suggest detrimental effects of excess PIEZO1 activity on the heart, mediated in part by amplified PIEZO1 function in cardiac fibroblasts.

Bone-Marrow Stem Cells and Acellular Human Amniotic Membrane in a Rat Model of Heart Failure

Myocardial infarction (MI) remains the leading cause of cardiovascular death worldwide and a major cause of heart failure. Recent studies have suggested that cell-based therapies with bone marrow stem cells (BMSC) and human amniotic membrane (hAM) would recover the ventricular function after MI; however, the mechanisms underlying these effects are still controversial. Herein, we aimed to compare the effects of BMSC and hAM in a rat model of heart failure. MI was induced through coronary occlusion, and animals with an ejection fraction (EF) < 50% were included and randomized into three groups: control, BMSC, and hAM. The BMSC and hAM groups were implanted on the anterior ventricular wall seven days after MI, and a new echocardiographic analysis was performed on the 30th day, followed by euthanasia. The echocardiographic results after 30 days showed significant improvements on EF and left-ventricular end-sistolic and end-diastolic volumes in both BMSC and hAM groups, without significant benefits in the control group. New blood vessels, desmine-positive cells and connexin-43 expression were also elevated in both BMSC and hAM groups. These results suggest a recovery of global cardiac function with the therapeutic use of both BMSC and hAM, associated with angiogenesis and cardiomyocyte regeneration after 30 days.

Tissue engineering techniques for iPSC derived three-dimensional cardiac constructs

Recent developments in applied developmental physiology have provided well-defined methodologies for producing human stem cell derived cardiomyocytes. Cardiomyocytes produced in this way have become commonplace as cardiac physiology research models. This accessibility has also allowed for the development of tissue engineered human heart constructs for drug screening, surgical intervention, and investigating cardiac pathogenesis. However, cardiac tissue engineering is an interdisciplinary field that involves complex engineering and physiological concepts, which limits its accessibility. This review provides a readable, broad reaching, and thorough discussion of major factors to consider for the development of cardiovascular tissues from stem cell derived cardiomyocytes. This review will examine important considerations in undertaking a cardiovascular tissue engineering project, and will present, interpret, and summarize some of the recent advancements in this field. This includes reviewing different forms of tissue engineered constructs, a discussion on cardiomyocyte sources, and an in-depth discussion of the fabrication and maturation procedures for tissue engineered heart constructs.

Extracellular Matrix Protein Ratios in the Human Heart and Vessels: How to Distinguish Pathological From Physiological Changes?

Cardiovascular pathology is often accompanied by changes in relative content and/or ratios of structural extracellular matrix (ECM) proteins within the heart and elastic vessels. Three of these proteins, collagen-I, collagen-III, and elastin, make up the bulk of the ECM proteins in these tissues, forming a microenvironment that strongly dictates the tissue biomechanical properties and effectiveness of cardiac and vascular function. In this review, we aim to elucidate how the ratios of collagen-I to collagen-III and elastin to collagen are altered in cardiovascular diseases and the aged individuum. We elaborate on these major cardiovascular ECM proteins in terms of structure, tissue localization, turnover, and physiological function and address how their ratios change in aging, dilated cardiomyopathy, coronary artery disease with myocardial infarction, atrial fibrillation, aortic aneurysms, atherosclerosis, and hypertension. To the end of guiding in vitro modeling approaches, we focus our review on the human heart and aorta, discuss limitations in ECM protein quantification methodology, examine comparability between studies, and highlight potential in vitro applications. In summary, we found collagen-I relative concentration to increase or stay the same in cardiovascular disease, resulting in a tendency for increased collagen-I/collagen-III and decreased elastin/collagen ratios. These ratios were found to fall on a continuous scale with ranges defining distinct pathological states as well as a significant difference between the human heart and aortic ECM protein ratios.

Second harmonic generation light quantifies the ratio of type III to total (I + III) collagen in a bundle of collagen fiber

The ratio of type III to type I collagen is important for properly maintaining functions of organs and cells. We propose a method to quantify the ratio of type III to total (type I + III) collagen (λ_III) in a given collagen fiber bundle using second harmonic generation (SHG) light. First, the relationship between SHG light intensity and the λ_III of collagen gels was examined, and the slope (k₁) and SHG light intensity at 0% type III collagen (k₂) were determined. Second, the SHG light intensity of a 100% type I collagen fiber bundle and its diameter (D) were measured, and the slope (k₃) of the relationship was determined. The λ_III in a collagen fiber bundle was estimated from these constants (k_1-3) and SHG light intensity. We applied this method to collagen fiber bundles isolated from the media and adventitia of porcine thoracic aortas, and obtained λ_III = 84.7% ± 13.8% and λ_III = 17.5% ± 15.2%, respectively. These values concurred with those obtained with a typical quantification method using sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The findings demonstrated that the method proposed is useful to quantify the ratio of type III to total collagen in a collagen fiber bundle.

Cardiac Toxicity From Ethanol Exposure in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Alcohol use prior to and during pregnancy remains a significant societal problem and can lead to developmental fetal abnormalities including compromised myocardia function and increased risk for heart disease later in life. Alcohol-induced cardiac toxicity has traditionally been studied in animal-based models. These models have limitations due to physiological differences from human cardiomyocytes (CMs) and are also not suitable for high-throughput screening. We hypothesized that human-induced pluripotent stem cell-derived CMs (hiPSC-CMs) could serve as a useful tool to study alcohol-induced cardiac defects and/or toxicity. In this study, hiPSC-CMs were treated with ethanol at doses corresponding to the clinically relevant levels of alcohol intoxication. hiPSC-CMs exposed to ethanol showed a dose-dependent increase in cellular damage and decrease in cell viability, corresponding to increased production of reactive oxygen species. Furthermore, ethanol exposure also generated dose-dependent increased irregular Ca2+ transients and contractility in hiPSC-CMs. RNA-seq analysis showed significant alteration in genes belonging to the potassium voltage-gated channel family or solute carrier family, partially explaining the irregular Ca2+ transients and contractility in ethanol-treated hiPSC-CMs. RNA-seq also showed significant upregulation in the expression of genes associated with collagen and extracellular matrix modeling, and downregulation of genes involved in cardiovascular system development and actin filament-based process. These results suggest that hiPSC-CMs can be a novel and physiologically relevant system for the study of alcohol-induced cardiac toxicity.

Histopathological and Morphometric Study of Fibrosis and Nuclear Pleomorphism in Dilated Cardiomyopathy

Histopathological changes associated with dilated cardiomyopathy (CMD) are frequently nonspecific and often only present in the terminal stage of the disease. The study followed the histopathological and morphometric quantification of fibrosis and nuclear pleomorphism in CMD. We analyzed left ventricle myocardial fragments harvested during autopsy, from 35 cases with clinical diagnosis of CMD and 5 cases of normal myocardium. Fibrosis was present in all CMD cases, with higher values compared with control cases. Nuclear pleomorphism was identified in 18 cases (45%), two of the analyzed parameters, respectively the ratio of nuclear diameters and roundness of nucleus, revealing significant differences in CMD compared to the control cases. Myocardial fibrosis present in all cases of CMD represents a major feature of the disease. The nuclear pleomorphism due to the nuclei change in diameters and size was more pronounced in the vicinity of fibrosis areas, possibly related to this alteration.

Histopathologic features of alcoholic cardiomyopathy compared with idiopathic dilated cardiomyopathy

BACKGROUND

The histologic difference between alcoholic cardiomyopathy (ACM) and idiopathic dilated cardiomyopathy (IDCM) is unclear. The present study aimed to identify the quantitative pathologic features of ACM compared with IDCM.

METHODS

Specimens from 6 regions (anterior left ventricle [LV], lateral LV, inferior LV, interventricular septum [IVS], anterior right ventricle [RV], and inferior RV) were sampled from each explanted heart. Specimens from 4 healthy donor hearts were obtained as normal control. Tissues were sectioned and Masson trichrome stained. Histomorphometry was performed to evaluate the amount of myocyte, fibrosis, fatty tissue, and interstitium by Image-Pro Plus 6.0 (Media Cybernetics).

RESULTS

A total of 408 specimens were obtained from 34 ACMs and 34 IDCMs; 8 specimens were obtained from 4 healthy donor hearts. Compared to healthy donor hearts, we observed an increase in fibrosis which replaces myocytes in myocardium of end-stage cardiomyopathy. The overall myocyte ratio in myocardium was 69.5 ± 8.7% in ACM vs 71.9 ± 7.4% in IDCM (P < .05). The percentage of interstitium was 10.8 ± 4.8% in ACM vs 9.2 ± 6.2% in IDCM (P < .05). A significant difference of fibrosis, fatty tissue was not discovered. Moreover, the myocyte area was 65.37 ± 11.8% in ACM LV vs 70.03 ± 9.0% in IDCM LV (P < .001).

CONCLUSION

We described histologic characteristics in ACM and IDCM. There might be a quantitative difference of myocyte, interstitium in myocardium between ACM and IDCM, especially in LV. No difference was found in the percentage of fibrosis between the 2 groups.

Pharmacological Inhibition of Soluble Epoxide Hydrolase Ameliorates Chronic Ethanol-Induced Cardiac Fibrosis by Restoring Autophagic Flux

BACKGROUND

Chronic drinking leads to myocardial contractile dysfunction and dilated cardiomyopathy, and cardiac fibrosis is a consequence of these alcoholic injuries. Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) to less bioactive diols, and EETs have cardioprotective properties. However, the effects of sEH inhibition in ethanol (EtOH)-induced cardiac fibrosis are unknown.

METHODS

This study was designed to investigate the role and underlying mechanisms of sEH inhibition in chronic EtOH feeding-induced cardiac fibrosis. C57BL/6J mice were fed a 4% Lieber-DeCarli EtOH diet for 8 weeks, and the sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) was administered throughout the experimental period.

RESULTS

The results showed that chronic EtOH intake led to cardiac dilatation, collagen deposition, and autophagosome accumulation, while TPPU administration ameliorated these effects. In vitro, treating primary cardiac fibroblasts (CFs) with EtOH resulted in CF activation, including alpha smooth muscle actin overexpression, collagen synthesis, and cell migration. Moreover, EtOH disturbed CF autophagic flux, as evidenced by the increased LC3 II/I ratio and SQSTM1 expression, and by the enhanced autophagosome accumulation. TPPU treatment prevented the activation of CF induced by EtOH and restored the impaired autophagic flux by suppressing mTOR activation.

CONCLUSIONS

Taken together, these findings suggest that sEH pharmacological inhibition may be a unique therapeutic strategy for treating EtOH-induced cardiac fibrosis.

A three-dimensional in vitro dynamic micro-tissue model of cardiac scar formation

In vitro cardiac models able to mimic the fibrotic process are paramount to develop an effective anti-fibrosis therapy that can regulate fibroblast behaviour upon myocardial injury. In previously developed in vitro models, typical fibrosis features were induced by using scar-like stiffness substrates and/or potent morphogen supplementation in monolayer cultures. In our model, we aimed to mimic in vitro a fibrosis-like environment by applying cyclic stretching of cardiac fibroblasts embedded in three-dimensional fibrin-hydrogels alone. Using a microfluidic device capable of delivering controlled cyclic mechanical stretching (10% strain at 1 Hz), some of the main fibrosis hallmarks were successfully reproduced in 7 days. Cyclic strain indeed increased cell proliferation, extracellular matrix (ECM) deposition (e.g. type-I-collagen, fibronectin) and its stiffness, forming a scar-like tissue with superior quality compared to the supplementation of TGFβ1 alone. Taken together, the observed findings resemble some of the key steps in the formation of a scar: (i) early fibroblast proliferation, (ii) later phenotype switch into myofibroblasts, (iii) ECM deposition and (iv) stiffening. This in vitro scar-on-a-chip model represents a big step forward to investigate the early mechanisms possibly leading later to fibrosis without any possible confounding supplementation of exogenous potent morphogens.

Cardiomyocytes Sense Matrix Rigidity through a Combination of Muscle and Non-muscle Myosin Contractions

Mechanical properties are cues for many biological processes in health or disease. In the heart, changes to the extracellular matrix composition and cross-linking result in stiffening of the cellular microenvironment during development. Moreover, myocardial infarction and cardiomyopathies lead to fibrosis and a stiffer environment, affecting cardiomyocyte behavior. Here, we identify that single cardiomyocyte adhesions sense simultaneous (fast oscillating) cardiac and (slow) non-muscle myosin contractions. Together, these lead to oscillating tension on the mechanosensitive adaptor protein talin on substrates with a stiffness of healthy adult heart tissue, compared with no tension on embryonic heart stiffness and continuous stretching on fibrotic stiffness. Moreover, we show that activation of PKC leads to the induction of cardiomyocyte hypertrophy in a stiffness-dependent way, through activation of non-muscle myosin. Finally, PKC and non-muscle myosin are upregulated at the costameres in heart disease, indicating aberrant mechanosensing as a contributing factor to long-term remodeling and heart failure.

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Talin in cardiomyocytes is unstretched, cyclically stretched, or continuously stretched

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Talin stretching depends on stiffness, myofibrillar tension, and non-myofibrillar tension

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Non-myofibrillar contractility requires PKC, Src, FHOD1, and non-muscle myosin

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PKC and non-muscle myosin activity are enhanced in cardiac disease

Guanxin Danshen Formulation Protects against Myocardial Ischemia Reperfusion Injury-Induced Left Ventricular Remodeling by Upregulating Estrogen Receptor β

Background: Guanxin Danshen formulation (GXDSF) is a traditional Chinese herbal recipe recorded in the Chinese Pharmacopeia since 1995 edition, which consists of Salviae miltiorrhizae Radix et Rhizoma, Notoginseng Radix et Rhizoma and Dalbergiae odoriferae Lignum. Our previous research suggested GXDSF had positive effect on cardiovascular disease. Therefore, the aim of this study was to elucidate the effects of GXDSF on myocardial ischemia reperfusion injury-induced left ventricular remodelling (MIRI-LVR). Methods: The effects of GXDSF on cardiac function were detected by haemodynamics and echocardiograms. The effects of GXDSF on biochemical parameters (AST, LDH and CK-MB) were analyzed. Histopathologic examinations were performed to evaluate the effect of GXDSF on cardiac structure. In addition, the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to predict the main target of GXDSF. Target validation was conducted by using western blots and immunofluorescent double staining assays. Results: We found that +dp/dt and LVSP were significantly elevated in the GXDSF-treated groups compared with the MIRI-LVR model group. Left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were increased in the GXDSF-treated groups compared with the model group. All biochemical parameters (AST, LDH and CK-MB) were considerably decreased in the GXDSF-treated groups compared with the model group. Fibrosis parameters (collagen I and III, α-SMA, and left ventricular fibrosis percentage) were decreased to different degrees in the GXDSF-treated groups compared with the model group, and the collagen III/I ratio was elevated by the same treatments. TCMSP database prediction and western blot results indicated that estrogen receptor β (ERβ) could be the main target of GXDSF. PHTPP, a selective antagonist of ERβ, could inhibit the expression of ERβ and the phosphorylation of PI3K and Akt in myocardial tissue induced by GXDSF, and partly normalize the improving effects of GXDSF on +dp/dt, LVEF, LVFS, LDH, CK-MB, α-SMA and myocardial fibrosis. Conclusion: Collectively, GXDSF showed therapeutic potential for use in the prevention and treatment of myocardial ischemia reperfusion injury-induced ventricular remodeling by upregulating ERβ via PI3K/Akt signaling. Moreover, these findings may be valuable in understand the mechanism of disease and provide a potential therapy of MIRI-IVR.

Dose-related ethanol intake, Cx43 and Nav1.5 remodeling: Exploring insights of altered ventricular conduction and QRS fragmentation in excessive alcohol users

BACKGROUND

Chronic, excessive ethanol intake has been linked with various electrical instabilities, conduction disturbances, and even sudden cardiac death, but the underlying cause for the latter is insufficiently delineated.

METHODS

We studied surface electrocardiography (ECG) in a community-dwelling cohort with moderate-to-heavy daily alcohol intake (grouped as >90g/day, ≤90g/day, and nonintake).

RESULTS

Compared with nonintake, heavier alcohol users showed markedly widened QRS duration and higher prevalence of QRS fragmentation (64.3%, 50.9%, and 33.7%, respectively, χ² 12.0, both p<0.05) on surface ECG across the 3 groups. These findings were successfully recapitulated in 14-week-old C57BL/6 mice that were chronically given a 4% or 6% alcohol diet and showed dose-related slower action potential upstroke, reduced resting membrane potential, and disorganized or decreased intraventricular conduction (all p<0.05). Immunodetection further revealed increased ventricular collagen I depots with Cx43 downregulation and remodeling, together with clustered and diminished membrane Nav1.5 distribution. Administration of Cx43 blocker (heptanol) and Nav1.5 inhibitor (tetrodotoxin) in the mice each attenuated the suppression ventricular conduction compared with nonintake mice (p<0.05).

CONCLUSIONS

Chronic excessive alcohol ingestion is associated with dose-related phenotypic intraventricular conduction disturbances and QRS fragmentation that can be recapitulated in mice. The mechanisms may involve suppressed gap junction and sodium channel functions, together with enhanced cardiac fibrosis that may contribute to arrhythmogenesis.

Early changes in right ventricular longitudinal function in chronic asymptomatic alcoholics revealed by two-dimensional speckle tracking echocardiography

BACKGROUND

Heart ventricular dysfunction has been characterized as reduced longitudinal function of the right ventricle (RV), and is associated with chronic alcohol abuse. This study investigated the use of two-dimensional speckle tracking echocardiography (2DSTE) to assess the longitudinal systolic and diastolic RV function of patients with alcoholic myocardial damage.

METHODS

We stratified 92 asymptomatic alcoholic men into three groups of increasing alcohol intake, Groups A-C. Thirty age-matched normal adult men served as the control group. Conventional echocardiography and tricuspid annulus peak systolic excursion (TAPSE) parameters were obtained. 2DSTE parameters were recorded from an apical 4-chamber view of the RV free wall. LV peak global longitudinal systolic strain was calculated from segmental averaging of the three apical long-axis views.

RESULTS

In Group C, the RV end diastolic diameter (RVEDD) was dramatically higher than that of Groups A, B and the control, while TAPSE was significantly lower in Group C compared with the other experimental groups. In Group B, the longitudinal early diastolic strain rate (SRe) and late diastolic strain rate (SRa) of the RV free wall, and LV longitudinal strain were significantly lower than that of Group A or the control. In Group C, all the 2DSTE parameters were significantly lower than that of the other groups. A significant negative linear correlation was noted between global RV systolic parameters systolic strain peak (S), peak systolic strain rate (SRs) and TAPSE (r1=-0.84, r2=-0.72, respectively, P <0.05).

CONCLUSIONS

Two-dimensional STE provided an effective and non-invasive method to assess the RV longitudinal function of patients with alcoholic myocardial damage. This methodology may be useful for diagnosing, directing treatment, and judging prognosis of alcoholic cardiac damage.

Effect of vitamin C on collagen structure of cardinal and uterosacral ligaments during pregnancy

OBJECTIVE

This study aimed to investigate changes in collagen structure in the cardinal and uterosacral ligaments of rats that were administered vitamin C during pregnancy.

STUDY DESIGN

Eighteen female rats were divided into three groups: six pregnant rats administered 1.25mg/ml/day of vitamin C during pregnancy (Group A); six non-pregnant rats that were not administered vitamin C (Group B); and six pregnant rats that were not administered vitamin C during pregnancy (Group C). Fifteen days after delivery, the uteruses of all rats were removed. The intensity of staining (mild, moderate or severe) and the extent of positive staining areas (%) of type I and type III collagen H scores for types I and III collagen, and intensity of elastin fibres in the cardinal and uterosacral ligaments were investigated immunohistochemically. Differences between groups were analysed using Kruskal-Wallis and independent samples tests.

RESULTS

The intensity and extent of type I and type III collagen, the H scores for type I and type III collagen, and the ratio of type III collagen H score: type I collagen H score differed significantly between groups. Pregnant rats administered vitamin C (Group A) had significantly higher values compared with non-pregnant rats (Group B): intensity of type I collagen (p=0.001), extent of type I collagen (p≤0.001), H score for type I collagen (p≤0.001), intensity for type III collagen (p=0.002), extent of type IV collagen (p=0.007), H score for type III collagen (p=0.017), type III collagen H score: type I collagen H score (p=0.039) and intensity of elastin fibres (p=0.097). A significant difference in the ratio of type III collagen H score: type I collagen H score was found between pregnant rats administered vitamin C (Group A) and pregnant rats not administered vitamin C (Group C) (p=0.002).

CONCLUSIONS

The administration of vitamin C to rats during pregnancy had a favourable impact on collagen structure in the cardinal and uterosacral ligaments, suggesting that vitamin C supplementation during pregnancy may help to prevent pelvic organ prolapse and stress urinary incontinence.

Application of UVA-riboflavin crosslinking to enhance the mechanical properties of extracellular matrix derived hydrogels

Hydrogels derived from extracellular matrix (ECM) have become increasing popular in recent years, particularly for use in tissue engineering. One limitation with ECM hydrogels is that they tend to have poor mechanical properties compared to native tissues they are trying to replicate. To address this problem, a UVA (ultraviolet-A) riboflavin crosslinking technique was applied to ECM hydrogels to determine if it could be used to improve their elastic modulus. Hydrogels fabricated from corneal, cardiac and liver ECM were used in this study. The mechanical properties of the hydrogels were characterized using a spherical indentation technique. The microstructure of the hydrogels and the cytotoxic effect of crosslinking on cell seeded hydrogels were also evaluated. The combination of UVA light and riboflavin solution led to a significant increase in elastic modulus from 6.8kPa to 24.7kPa, 1.4kPa to 6.9kPa and 0.9kPa to 1.6kPa for corneal, cardiac and liver ECM hydrogels respectively. The extent of this increase was dependent on a number of factors including the UVA exposure time and the initial hydrogel concentration. There were also a high percentage of viable cells within the cell seeded hydrogels with 94% of cells remaining viable after 90min exposure to UVA light. These results suggest that UVA-riboflavin crosslinking is an effective approach for improving the mechanical properties of ECM hydrogels without resulting in a significant reduction of cell viability.

Imaging Fibrosis and Separating Collagens using Second Harmonic Generation and Phasor Approach to Fluorescence Lifetime Imaging

In this paper we have used second harmonic generation (SHG) and phasor approach to auto fluorescence lifetime imaging (FLIM) to obtain fingerprints of different collagens and then used these fingerprints to observe bone marrow fibrosis in the mouse femur. This is a label free approach towards fast automatable detection of fibrosis in tissue samples. FLIM has previously been used as a method of contrast in different tissues and in this paper phasor approach to FLIM is used to separate collagen I from collagen III, the markers of fibrosis, the largest groups of disorders that are often without any effective therapy. Often characterized by an increase in collagen content of the corresponding tissue, the samples are usually visualized by histochemical staining, which is pathologist dependent and cannot be automated.

Alcohol modulation of cardiac matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs favors collagen accumulation

BACKGROUND

Chronic alcohol consumption has been shown in human and animal studies to result in collagen accumulation, myocardial fibrosis, and heart failure. Cardiac fibroblasts produce collagen and regulate extracellular matrix (ECM) homeostasis through the synthesis and activity of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs), with the balance of MMPs/TIMPs determining the rate of collagen turnover. Dynamic changes of MMP and TIMP expression were reported in alcohol-induced hepatic fibrosis; however, the effect of alcohol on MMP/TIMP balance in the heart and cardiac fibroblasts is unknown. We hypothesized that alcohol exposure alters cardiac fibroblast MMP and TIMP expression to promote collagen accumulation in the heart.

METHODS

Cardiac fibroblasts isolated from adult rats were cultured in the presence of alcohol (12.5 to 200 mM) for 48 hours. MMP, TIMP, and collagen type I and III expression were assayed by Western blot analysis. Hydroxyproline (HPro) was used as a marker of collagen production. The in vivo cardiac effects of ethanol (EtOH) were determined using rats exposed to EtOH vapor for 2 weeks, resulting in blood alcohol levels of 150 to 200 mg/dl. Cardiac collagen volume fraction (CVF), as well as MMP, TIMP, and collagen expression, was assessed.

RESULTS

EtOH-exposed rats exhibited up-regulation of TIMP-1, TIMP-3 and TIMP-4 in the heart, with no significant increases in MMPs. Cardiac fibroblasts exhibited transformation to a profibrotic phenotype following exposure to alcohol. These changes were reflected by increased α-smooth muscle actin and collagen I and III expression, as well as increased collagen secretion. In vivo EtOH exposure also produced fibrosis, indicated by increased CVF and expression of collagens.

CONCLUSIONS

Alcohol exposure modulates cardiac fibroblast MMP/TIMP expression favoring a profile associated with collagen accumulation. Our data suggest that this disrupted MMP/TIMP profile may contribute to the development of myocardial fibrosis and cardiac dysfunction resulting from chronic alcohol abuse.

Connexin 43, angiotensin II, endothelin 1, and type III collagen alterations in heart of rats having undergone fatal electrocution

Death due to accidental electrocution occurs frequently. The aim of this study was to investigate alterations in cardiac connexin 43 (Cx43), angiotensin II (Ang II), endothelin 1 (ET-1), and type III collagen associated with fatal electrocution.Twenty-four Sprague-Dawley rats were divided into control, fatal electrocution (220 V, 50 Hz, 60 seconds), and electrical injury (220 V, 50 Hz, 60 seconds) groups. Animals were deeply anesthetized with sodium pentobarbital before each treatment, with the anode connected to the left foreleg and the cathode to the right hindleg, followed by cervical dislocation. Control animals received cervical dislocation alone. Immunohistochemical analysis was performed to evaluate the cardiac protein expression of Cx43, Ang II, ET-1, and type III collagen. Sections were analyzed by digital image analysis.The expression of Cx43 was significantly reduced after fatal electrocution, with the integrated optical density also lower when compared with control (P < 0.05). Expression of both Ang II and ET-1 was significantly increased after fatal electrocution, supported by integrated optical density when compared with control (P < 0.05). But no significant difference was found in type III collagen expression between the fatal electrocution group and the control group.In summary, cardiac protein expression of Cx43, Ang II, and ET-1 was found to be significantly altered with fatal electrocution, suggesting that these 3 proteins may be important underlying mechanisms of death during fatal electrocution. The current findings indicate that such alterations would be reflected in abnormal cardiac function and a possible cause of sudden death.

Angiotensin-(1-7) ameliorates myocardial remodeling and interstitial fibrosis in spontaneous hypertension: role of MMPs/TIMPs

Angiotensin-(1-7) displays antihypertensive and antiproliferative properties although its effect on cardiac remodeling and hypertrophy in hypertension has not been fully elucidated. The present study was designed to examine the effect of chronic angiotensin-(1-7) treatment on myocardial remodeling, cardiac hypertrophy and underlying mechanisms in spontaneous hypertension. Adult male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were treated with or without angiotensin-(1-7) or the angiotensin-(1-7) antagonist A-779 for 24 weeks. Mean arterial pressure, left ventricular geometry, expression of the hypertrophic markers ANP and β-MHC, collagen contents (type I and III), collagenase (MMP-1), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of MMPs-1 (TIMP-1) were evaluated in WKY and SHR rats with or without treatment. Our data revealed that chronic angiotensin-(1-7) treatment significantly suppressed hypertension, left ventricular hypertrophy, expression of ANP and β-MHC as well as myocardial fibrosis in SHR rats, the effects of which were nullified by the angiotensin-(1-7) receptor antagonist A-779. In addition, angiotensin-(1-7) treatment significantly counteracted hypertension-induced changes in the mRNA expression of MMP-2 and TIMP-1 and collagenase activity, the effects of which were blunted by A-779. In vitro study revealed that angiotensin-(1-7) directly increased the activity of MMP-2 and MMP-9 while decreasing the content of TIMP-1 and TIMP-2. Taken together, our results revealed a protective effect of angiotensin-(1-7) against cardiac hypertrophy and collagen deposition, which may be related to concerted changes in MMPs and TIMPs levels. These data indicated the therapeutic potential of angiotensin-(1-7) in spontaneous hypertension-induced cardiac remodeling.

Differences in antiapoptotic, proliferative activities and morphometry in dilated and ischemic cardiomyopathy: study of hearts explanted from transplant recipients

BACKGROUND

Antiapoptotic as well as replacement and proliferative mechanisms take place in the myocardium in dilated cardiomyopathy (DCM) and ischemic heart disease (IHD). We sought to estimate antiapoptotic, proliferative and replacement activities in cardiomyopathies.

MATERIALS

The study groups included seven hearts with DCM and eight with IHD, which had been explanted at the time of transplantation. The comparator group consisted of cases of myocardial hypertrophy and the control group, donor fragments.

METHODS

Antiapoptotic and proliferative responses were determined immunohistochemically as Bcl-2 and Ki67 expression by semiquantitative assessment of the intensity of staining. We also measured and statistically analyzed the integrative morphometric measurements of the fraction of fibrosis area, the nucleosarcoplasmic ratio, and cardiocyte diameter.

RESULTS

No Bcl-2 expression was observed in the controls. The strongest reaction was seen in the DCM group, then in the IHD, and in the comparator group of myocardial hypertrophy. Proliferative activity was seen only in endocardial and interstitial fibroblasts in DCM and IHD cases. The cardiocyte diameter showed no statistical association between myocardial hypertrophy and IHD, or IHD and DCM, whereas the nucleosarcoplasmic ratios were significantly different from control groups for all comparisons. Myocardial fibrosis showed the highest values in DCM and IHD. Discriminant analysis showed the value of interstitial fibrosis and cardiocyte diameter to categorize the analyzed groups.

CONCLUSIONS

Antiapoptotic Bcl-2 activity seemed to play an important role in cardiocyte preservation, while proliferative activity was resticted to interstitial connective tissue cells as a replacement process. Myocardial Bcl-2 expression, the extent of myocardial fibrosis, and cardiocyte diameter may serve as additional diagnostic tools to differentiate cardiomyopathies.