Search

We investigate cardiovascular (CV) developmental physiology and biomechanics in order to understand the dramatic acquisition of form and function during normal development and to identify the adaptive mechanisms that allow embryos to survive adverse genetic and epigenetic events. Cardiovascular patterning, morphogenesis, and growth occur via highly conserved genetic mechanisms. Structural and functional maturation of the embryonic heart is also conserved across a broad range of species with evidence for load dependence from onset of the heartbeat. The embryonic heart dynamically adapts to changes in biomechanical loading conditions and for reasons not yet clear, adapts better to increased than to decreased mechanical load. In mammals, maternal cardiovascular function dynamically impacts embryonic/fetal growth and hemodynamics and these interactions can now be studied longitudinally using high-resolution noninvasive techniques. Maternal exposure to hypoxia and to bioactive chemicals, such as caffeine, can rapidly impact embryonic/fetal cardiovascular function, growth, and outcome. Finally, tissue engineering approaches can be applied to investigate basic developmental aspects of the embryonic myocardium. We use isolated embryonic and fetal chick, mouse, or rat cardiac cells to generate 3D engineered early embryonic cardiac tissues (EEECT). EEECT retains the morphologic and proliferative features of embryonic myocardium, responds to increased mechanical load with myocyte hyperplasia, and may be an excellent future material for use in cardiac repair and regeneration. These insights into cardiovascular embryogenesis are relevant to identifying mechanisms for congenital cardiovascular malformations and for developing cell- and tissue-based strategies for myocardial repair. [ABSTRACT FROM AUTHOR]

The usefulness of B-type natriuretic peptide (BNP) levels to assess ventricular dysfunction in children and the congenital heart disease population remains largely unknown. We retrospectively analyzed 62 patients with or without known heart disease who had plasma BNP measured for the investigation of new or severity grading of known ventricular dysfunction. BNP levels were significantly higher in patients with ventricular dysfunction (mean 623 ± 146 pg/ml, range 5 to 5,000) than in patients without ventricular dysfunction (mean 22 ± 5 pg/ml, range 5 to 63; p <0.01). Using a cutoff of 40 pg/ml, BNP levels detected heart disease associated with ventricular dysfunction at a sensitivity of 85%, specificity of 81%, positive predictive value of 92%, and negative predictive value of 68%. The degree of BNP elevation was also associated with the severity of heart failure and high ventricular filling pressures. Plasma BNP elevation can be a reliable test in children and young adults with various kinds of congenital heart disease resulting in ventricular dysfunction. [Copyright &y& Elsevier]

Examines right and left ventricular wall deformation patterns in normal and left heart hypoplasia chick embryos. Developmental epicardial strain patterns; Ventricular dimensions and morphology; Atrioventricular inflow velocity.

Presents a study which investigated the ventricular deformation patterns during cardiac morphogenesis. Materials and methods; Results; Discussion.

Provides information on a study which investigated developmental changes in the in vivo end-systolic stress-strain relations of embryonic chick myocardium in white Leghorn chick embryos. Materials and methods of the study; Results; Discussion of the results.

Examines the maturation of end-systolic stress-strain relations in chick embryonic myocardium. End-systolic stress-strain relations; Multiple regression coeffcients for end-systolic stress-strain and stiffness-stress relations; Developmental changes in ventricular contractility.

Offers information on a study which evaluated the effects of acute alteration of loading condition to chick embryonic ventricular contractility using end-systolic myocardial stiffness based on the incremental elastic modulus concept. Account of similar studies; Materials and methods; Results and discussion.

Evaluates the effects of acute alteration of loading condition to chick embryonic ventricular contractility using end-systolic myocardial stiffness based on the incremental elastic modulus concept. Suggestion that normalized end-systolic myocardial stiffness is a load-independent index of ventricular contractility in developing embryonic chick ventricle.

Studies embryonic ventricular diastolic and systolic function during normal ejection and during acute ventricular outflow tract occlusion in the stage 21 chick embryo. Ventricular contractile reserve; Relationship between ventricular stroke volume and end-diastolic volume during alterations in preload and after acute conotruncal clamp.

Analyzes analog circuit models to characterize embryonic arterial impedance. Simultaneous dorsal aortic pressure and flow measurements; Improvements in the frequency resolution of the impedance spectrum; Fluctuation and phase-zero crossing; Elimination of overparameterization; Hemodynamic recordings and vascular impedance calculations.

Presents information pertaining to the ventricular-vascular uncoupling in the stage 21 chick embryo. Evaluation of embryonic ventricular diastolic and systolic function; Inclusion of experimental protocols; What ventricular-vascular coupling allows.

Presents a study on the characterization of embryonic aortic impedance with lumped parameter models. Construction and analysis of 18 analog circuit models; Measurement of simultaneous dorsal aortic pressure and flow; How the models were characterized; Results and discussion of the study.

Defines the relationship between simultaneous atrial and ventricular pressures in the stage 16-27 white Leghorn chick embryo. Measurement of atrial and ventricular blood pressures with servo-null micropressure systems; Discovery of a positive atrioventricular pressure gradient throughout ventricular filling.

Editorial. Describes impaired diastolic ventricular function measured by high-resolution ultrasound and evidence for atrial septal defect based in vivo ultrasound and postmortem magnetic resonance imaging. Use of the combined analysis of both cardiac function and structure in evaluating congenital cardiovascular (CV) phenotype; Mechanisms for CV malformations; Use of animal models with clinical syndromes.

Aim: To define the clinical characteristics, hemodynamics, and adverse events for pediatric patients with pulmonary arterial hypertension (PAH) undergoing right heart catheterization (RHC). Methods: The large referral single center data of 591 diagnostic RHC procedures performed between 2005 and 2020 on pediatric PAH patients was retrospectively collected and analyzed. Results: A total of 591 RHC procedures performed on 469 patients with congenital heart disease (CHD)-PAH (median age 8.8 years, 7.9% New York Heart Association (NYHA) class > II, 1.5% with syncope) and 122 patients with idiopathic PAH (median age of 9.0 years, 27.0% NYHA class > II, 27.0% with syncope) were included. Of those, 373 (63.1%) procedures were performed under general anesthesia. Eighteen patients (18/591, 3.0%) suffered adverse events (mainly pulmonary hypertensive crisis, PHC, n = 17) during the RHC procedure, including 14 idiopathic pulmonary arterial hypertension (IPAH) patients and 4 CHD-PAH patients, and one IPAH patient died in hospital 63 hours after RHC. The risk of developing PHC was significantly increased in patients with IPAH (OR = 14.02, 95%CI: 4.49–43.85, p < 0.001), atrial blood gas pH < 7.35 (OR = 12.504, 95%CI: 3.545–44.102, p < 0.001) and RAP > 14 mmHg (OR = 10.636, 95%CI: 3.668–30.847, p < 0.001). Conclusions: RHC is generally a low-risk procedure in pediatric patients with PAH. However, PHC occur in approximately 3% of patients. Therefore, RHC should be performed in a large, experienced referral pediatric cardiology center, especially in pediatric patients with IPAH requiring general anesthesia. [ABSTRACT FROM AUTHOR]

Pediatric patients with pulmonary arterial hypertension (PAH) are considered to be at risk for pulmonary hypertensive crisis (PHC) or even death during right heart catheterization (RHC). This retrospective study was designed to identify the risks and clinical characteristics associated with PHC in pediatric PAH patients. We included 163 consecutive procedures from 147 pediatric patients diagnosed with PAH who underwent diagnostic RHC in Beijing Anzhen Hospital between January 2007 and December 2020. The average patient age was 9.0 ±4.7 years and 84 (51.5%) were females. Before RHC, over 20% of patients were in New York Heart Association (NYHA) class III–IV. Sedation or general intravenous anesthesia was used in 103 procedures (63.2%), with spontaneous breathing in 93.2%. PHC occurred in 19 patients (11.7%), 5 (3.1%) required cardiac compression, and 1 died (0.6%). Compared to patients without PHC, those who experienced PHC were more likely to be in NYHA class III–IV (p=0.012) before RHC, require sedation (p=0.011), had echocardiographic indices of higher peak tricuspid regurgitation velocity (p=0.018), and right ventricle (RV) to left ventricle (LV) ratio (p< 0.001). Multivariate logistic regression for PHC identified the need for sedation and a higher RV/LV ratio as independent predictors. In conclusion, the risk of RHC remains significant in children with PAH, particularly in those with severe RV dilation who require sedation during cardiac catheterization. Comprehensive evaluation, close monitoring, and appropriate treatment before and during the procedure are essential for reducing mortality. [ABSTRACT FROM AUTHOR]

Aims: Hypoxia is known to influence cardiovascular (CV) function, in part, through adenosine receptor activation. We have shown in a mouse model that during primary cardiac morphogenesis, acute maternal hypoxia negatively affects fetal heart rate, and recurrent maternal caffeine exposure reduces fetal cardiac output (CO) and downregulates fetal adenosine A2A receptor gene expression. In the present study, we investigated whether maternal caffeine dosing exacerbates the fetal CV response to acute maternal hypoxia during the primary morphogenesis period. Material and Methods: Gestational-day-11.5 pregnant mice were exposed to hypoxia (45 s duration followed by 10 min of recovery and repeated 3 times) while simultaneously monitoring maternal and fetal CO using high-resolution echocardiography. Results: Following maternal hypoxia exposure, maternal CO transiently decreased and then returned to pre-hypoxia baseline values. In contrast to a uniform maternal cardiac response to each exposure to hypoxia, the fetal CO recovery time to the baseline decreased, and CO rebounded above baseline following the second and third episodes of maternal hypoxia. Maternal caffeine treatment inhibited the fetal CO recovery to maternal hypoxia by lengthening the time to CO recovery and eliminating the CO rebound post-recovery. Selective treatment with an adenosine A2A receptor antagonist, but not an adenosine A1 receptor antagonist, reproduced the altered fetal CO response to maternal hypoxia created by caffeine exposure. Conclusions: Results suggest an additive negative effect of maternal caffeine on the fetal CV response to acute maternal hypoxia, potentially mediated via adenosine A2A receptor inhibition during primary cardiovascular morphogenesis. [ABSTRACT FROM AUTHOR]

The Fontan operation is a palliative surgical procedure performed on children, born with congenital heart defects that have yielded only a single functioning ventricle. The total cavo-pulmonary connection (TCPC) is a common variant of the Fontan procedure, where the superior vena cava (SVC) and inferior vena cava (IVC) are routed directly into the pulmonary arteries (PA). Due to the limited pumping energy available, optimized hemodynamics, in turn, minimized power loss, inside the TCPC pathway is required for the best optimal surgical outcomes. To complement ongoing efforts to optimize the anatomical geometric design of the surgical Fontan templates, here, we focused on the characterization of power loss changes due to the temporal variations in between SVC and IVC flow waveforms. An experimentally validated pulsatile computational fluid dynamics solver is used to quantify the effect of phase-shift between SVC and !VC inflow waveforms and amplitudes on internal energy dissipation. The unsteady hemodynamics of two standard idealized TCPC geometries are presented, incorporating patient-specific real-time PC-MRJ flow waveforms of "functional" Fontan patients. The effects of respiration and pulsatility on the internal energy dissipation of the TCPC pathway are analyzed. Optimization of phase-shift between caval flows is shown to lead to lower energy dissipation up to 30% in these idealized models. For physiological patient-specific caval waveforms, the power loss is reduced significantly (up to 11%) by the optimization of all three major harmonics at the same mean pathway flow (3 L/min). Thus, the hemodynamic efficiency of single ventricle circuits is influenced strongly by the caval flow waveform quality, which is regulated through respiratory dependent physiological pathways. The proposed patient-specific waveform optimization protocol may potentially inspire new therapeutic applications to aid postoperative hemodynamics and improve the well being of the Fontan patients. [ABSTRACT FROM AUTHOR]

Altered blood pressure and flow impact cardiac function during morphogenesis. How the arterial system supports cardiac morphogenesis after circulatory disruptions is not well characterized. We manipulated arterial flow via left atrial ligation (LAL) or arterial load v/a right vitelline artery ligation (VAL) in Hamburger-Hamilton (HH) stage 21 chick embryos. Embryos were reincubated for 1 h (HH21), 14 h (HH24) or 30 h (HH27). At each stage we measured simultaneous dorsal aortic blood pressure and flow, and calculated arterial compliance, impedance and hydraulic power. LAL acutely reduced stroke volume (Vs), cardiac output (Q) and hydraulic power. Arterial pressure was preserved by a compensatory increase in characteristic impedance and decrease in compliance. Impedance parameters and compliance normalized by HH24 and all parameters normalized by HH27. VAL acutely increased arterial resistance. Embryos maintained arterial pressure by decreasing Vs and Q. These parameters remained altered through HH27. In summary, despite the intervention, compensatory alterations in Vs and arterial resistance maintained arterial pressure and fraction of oscillatory power within a narrow range. These results suggest that the maintenance of arterial pressure and circulatory energy efficiency, but not arterial flow, is critical to embryogenesis. [ABSTRACT FROM AUTHOR]

As revealed by a quality-of-life survey done in a small rural Kentucky cohort, adults who live in rural areas who have congenital heart disease have a relatively poor health-related quality of life and face unique challenges in gaining employment, maintaining health insurance, and overcoming the perceived childhood stigma of being “different.” [Copyright &y& Elsevier]

Rodent diabetic models have advanced our understanding of the pathophysiology of diabetic cardiomyopathy (DCM), however these models require long timelines to display DCM, and also display confounding influences inherent to in vivo models, but in vitro cardiomyocyte cultures could not reflect the structure-function relationship specific to the heart. Over the past 2 decades, engineered cardiac tissues (ECTs) have emerged as robust 3D in vitro models to investigate cardiac tissue maturation, structure-function relationships, cardiac injury response and repair. Advanced glycation end-products (AGEs), the proteins or lipids that become glycated in response to hyperglycemia, produce diabetes-associated tissue injury via receptor (RAGE) activating reactive oxygen or nitrogen species (ROS/RNS). Therefore, we developed a ECT model to investigate cardiac injury produced by AGEs. We used ECTs composed of neonatal murine cardiac cells and found: (1) AGEs at 150 µg/ml did not cause significant cytotoxicity (necrosis, detected by medium LDH or apoptosis, detected by c-caspase 3), but negatively impacted ECT function by 9-day treatment; (2) AGEs triggered fibrotic (Collagen I-α1, Collagen III-α1, FN1) and hypertrophic (ANP and β-MHC) responses on day 3 - 9 after treatment; (3) AGE also increased ECT's oxidative stress (3-NT, 4-HNE, HO-1, CAT, SOD2) and inflammation (PAI-1, TNF-α, NF-κB, ICAM); (4) All AGE-induced oxidative stress, inflammation, fibrotic response and hypertrophy and ECT dysfunction were prevented by the RAGE inhibitor FPS-ZM1 or by inhibiting ROS/RNS production via NAC. Thus, AGEs-treated neonatal murine ECTs recapitulate key cellular and molecular pathophysiological features of DCM and can serve as a robust ex vivo model to investigate cell-cell specific pathways relevant to DCM along with cardioprotective strategies. This model even has a great potential to directly investigate the effect of diabetes on human ECTs if human iPSC can be introduced. Disclosure: X. Wang: None. Y. Zheng: None. B.B. Keller: None. L. Cai: None. [ABSTRACT FROM AUTHOR]

Right ventricular (RV) dysfunction is the main determinant of mortality in patients with pulmonary arterial hypertension (PAH) and while inflammation is pathogenic in PAH, there is limited information on the role of RV inflammation in PAH. Sulforaphane (SFN), a potent Nrf2 activator, has significant anti-inflammatory effects and facilitates cardiac protection in preclinical diabetic models. Therefore, we hypothesized that SFN might play a comparable role in reducing RV and pulmonary inflammation and injury in a murine PAH model. We induced PAH using SU5416 and 10% hypoxia (SuHx) for 4 wk in male mice randomized to SFN at a daily dose of 0.5 mg/kg 5 days per week for 4 wk or to vehicle control. Transthoracic echocardiography was performed to characterize chamber-specific ventricular function during PAH induction. At 4 wk, we measured RV pressure and relevant measures of histology and protein and gene expression. SuHx induced progressive RV, but not LV, diastolic and systolic dysfunction, and RV and pulmonary remodeling, fibrosis, and inflammation. SFN prevented SuHx-induced RV dysfunction and remodeling, reduced RV inflammation and fibrosis, upregulated Nrf2 expression and its downstream gene NQO1, and reduced the inflammatory mediator leucine-rich repeat and pyrin domain-containing 3 (NLRP3). SFN also reduced SuHx-induced pulmonary vascular remodeling, inflammation, and fibrosis. SFN alone had no effect on the heart or lungs. Thus, SuHx-induced RV and pulmonary dysfunction, inflammation, and fibrosis can be attenuated or prevented by SFN, supporting the rationale for further studies to investigate SFN and the role of Nrf2 and NLRP3 pathways in preclinical and clinical PAH studies. [ABSTRACT FROM AUTHOR]

Nuclear factor erythroid 2-related factor 2 (Nrf2) is ubiquitously expressed in most eukaryotic cells and functions to induce a broad range of cellular defenses against exogenous and endogenous stresses, including oxidants, xenobiotics, and excessive nutrient/metabolite supply. Because the production and fate of stem cells are often modulated by cellular redox and metabolic homeostasis, important roles of Nrf2 have emerged in the regulation of stem cell quiescence, survival, self-renewal, proliferation, senescence, and differentiation. In a rapidly advancing field, this review summarizes Nrf2 signaling in the context of stem cell state and function and provides a rationale for Nrf2 as a therapeutic target in stem cell-based regenerative medicine. As a cellular metabolic and stress sensor, the transcription factor Nrf2 is a pivotal regulator of stem cell self-renewal, proliferation, and differentiation. Nrf2 displays cell type-specific and/or stage-dependent impact on stem cell biology in response to various environmental cues. Nrf2 modulates PSCs through the regulation of pluripotency factors, metabolism, redox homeostasis, and cellular stress responses. Nrf2 maintain ASCs self-renewal, quiescence, and regenerative capacity while protecting against ASC depletion in response to stress and aging. [ABSTRACT FROM AUTHOR]

We developed a protocol to investigate and optimize the application of contrast-enhanced ultrasound (CEUS) to non-invasive diagnosis of progressing fatty liver disease in mouse models. Eighteen 4-wk-old male C57 L/J mice were randomly assigned to one of the three groups and placed on a control diet, high-fat diet or non-alcoholic steatohepatitis diet for the next 10 wk. After 14 wk, B-mode imaging and CEUS imaging using a VisualSonics Vevo2100 system were performed. CEUS imaging and data analysis using three different parameters-peak enhancement, wash-in rate and wash-in perfusion index-revealed a significant decrease in representative blood flow in the high-fat diet group versus controls and a further significant decrease in the non-alcoholic steatohepatitis group (p < 0.001; n = 6/group). In conclusion, compared with B-mode imaging, non-targeted CEUS imaging was more sensitive in diagnosing early-stage fatty infiltration-mediated vascularity changes in liver parenchyma and provided a more accurate steatohepatitis diagnosis in mouse models. [ABSTRACT FROM AUTHOR]

The increasing prevalence of diabetic cardiomyopathy (DCM) is an important threat to health worldwide. While left ventricular (LV) dysfunction in DCM is well recognized, the accurate detection, diagnosis, and treatment of changes in right ventricular (RV) structure and function have not been well characterized. The pathophysiology of RV dysfunction in DCM may share features with LV diastolic and systolic dysfunction, including pathways related to insulin resistance and oxidant injury, although the RV has a unique cellular origin and composition and unique biomechanical properties and is coupled to the lower-impedance pulmonary vascular bed. In this review, we discuss potential mechanisms responsible for RV dysfunction in DCM and review the imaging approaches useful for early detection, protection, and intervention strategies. Additional data are required from animal models and clinical trials to better identify the onset and features of altered RV and pulmonary vascular structure and function during the onset and progression of DCM and to determine the efficacy of early detection and treatment of RV dysfunction on clinical symptoms and outcomes. [ABSTRACT FROM AUTHOR]

Embryonic aortic arches (AA) are initially bilaterally paired, transitional vessels and failures in remodeling based on hemodynamic and growth-related adaptations cause a spectrum of congenital heart disease (CHD) anatomies. Identifying regulatory mechanisms and cross-talk between the genetic elements of these vessels are critical to understand the ethiology of CHD and refine predictive computational models. This study aims to screen expression profiles of fundamental biological pathways in AA at early stages of chick embryo morphogenesis and correlate them with our current understanding of growth and mechanical loading. Reverse transcription-quantitative PCR (RT-qPCR) was followed by correlation and novel peak expression analyses to compare the behaviour and activation period of the genes. Available protein networks were also integrated to investigate the interactions between molecules and highlight major hierarchies. Only wall shear stress (WSS) and growth-correlated expression patterns were investigated. Effect of WSS was seen directly on angiogenesis as well on structural and apoptosis-related genes. Our time-resolved network suggested that WSS-correlated genes coordinate the activity of critical growth factors. Moreover, differential gene expression of left and right AA might be an indicator of subsequent asymmetric morphogenesis. These findings may further our understanding of the complex processes of cardiac morphogenesis and errors resulting in CHD. [ABSTRACT FROM AUTHOR]

Engineered cardiac tissues (ECTs) serve as robust in vitro models to study human cardiac diseases including cardiac toxicity assays due to rapid structural and functional maturation and the ability to vary ECT composition. Metallothionein (MT) has been shown to be cardioprotective for environmental toxicants including heavy metals. To date, studies on the role of cardiomyocyte (CM)-specific MT expression and function have occurred in dissociated single cell assays or expensive in vivo small animal models. Therefore, we generated 3D ECTs using neonatal mouse ventricular cells from wild-type (WT) and the CM-specific overexpressing MT-transgenic (MT-TG) to determine the effect of MT overexpression on ECT maturation and function. Because Cadmium (Cd) is an environmentally prevalent heavy metal toxicant with direct negative impact on cardiac structure and function, we then determined the effect of MT overexpression to reduce Cd mediated CM toxicity within ECTs. We found: (1) structural and functional maturation was similar in WT and MT-TG ECTs; (2) Cd exposure negatively impacted ECT cell survival, maturation, and function; and (3) MT-ECTs showed reduced Cd toxicity as defined by reduced cleaved caspase 3, reduced Bax/Bcl2 ratio, reduced TdT-mediated dUTP nick-end labeling positive cells, reduced CM loss after Cd treatment, and delayed onset of cardiac dysfunction after Cd treatment. Thus, neonatal murine ECTs can serve as a robust in vitro model for heavy metal toxicity screening and as a platform to evaluate the role cardioprotective mechanisms, such as the MT-TG model, on environmentally relevant toxicants. [ABSTRACT FROM AUTHOR]

An early manifestation of coronary artery disease in advanced age is the development of microvascular dysfunction leading to deficits in diastolic function. Our lab has previously shown that epicardial treatment with adipose-derived stromal vascular fraction (SVF) preserves microvascular function following coronary ischemia in a young rodent model. Follow-up studies showed intravenous (i.v.) delivery of SVF allows the cells to migrate to the walls of small vessels and reset vasomotor tone. Therefore we tested the hypothesis that the i.v. cell injection of SVF would reverse the coronary microvascular dysfunction associated with aging in a rodent model. Fischer 344 rats were divided into 4 groups: young control (YC), old control (OC), old + rat aortic endothelial cells (O+EC) and old + GFP+ SVF cells (O+SVF). After four weeks, cardiac function and coronary flow reserve (CFR) were measured via echocardiography, and hearts were explanted either for histology or isolation of coronary arterioles for vessel reactivity studies. In a subgroup of animals, microspheres were injected during resting and dobutamine-stimulated conditions to measure coronary blood flow. GFP+ SVF cells engrafted and persisted in the myocardium and coronary vasculature four weeks following i.v. injection. Echocardiography showed age-related diastolic dysfunction without accompanying systolic dysfunction; diastolic function was improved in old rats after SVF treatment. Ultrasound and microsphere data both showed increased stimulated coronary blood flow in O+SVF rats compared to OC and O+EC, while isolated vessel reactivity was mostly unchanged. I.v.-injected SVF cells were capable of incorporating into the vasculature of the aging heart and are shown in this study to improve CFR and diastolic function in a model of advanced age. Importantly, SVF injection did not lead to arrhythmias or increased mortality in aged rats. SVF cells provide an autologous cell therapy option for treatment of microvascular and cardiac dysfunction in aged populations. [ABSTRACT FROM AUTHOR]

We have reported that sulforaphane (SFN) prevented diabetic cardiomyopathy in both type 1 and type 2 diabetes (T2DM) animal models via the upregulation of nuclear transcription factor erythroid 2-related factor 2 (Nrf2) and metallothionein (MT). In this study, we tested whether SFN protects the heart from T2DM directly through Nrf2, MT, or both. Using Nrf2-knockout (KO), MT-KO, and wild-type (WT) mice, T2DM was induced by feeding a high-fat diet for 3 months followed by a small dose of streptozotocin. Age-matched controls were given a normal diet. Both T2DM and control mice were then treated with or without SFN for 4 months by continually feeding a high-fat or normal diet. SFN prevented diabetes-induced cardiac dysfunction as well as diabetes-associated cardiac oxidative damage, inflammation, fibrosis, and hypertrophy, with increases in Nrf2 and MT expressions in the WT mice. Both Nrf2-KO and MT-KO diabetic mice exhibited greater cardiac damage than WT diabetic mice. SFN did not provide cardiac protection in Nrf2-KO mice, but partially or completely protected the heart from diabetes in MT-KO mice. SFN did not induce MT expression in Nrf2-KO mice, but stimulated Nrf2 function in MT-KO mice. These results suggest that Nrf2 plays the indispensable role for SFN cardiac protection from T2DM with significant induction of MT and other antioxidants. MT expression induced by SFN is Nrf2 dependent, but is not indispensable for SFN-induced cardiac protection from T2DM. [ABSTRACT FROM AUTHOR]

The role of hemodynamic forces within the embryo as biomechanical regulators for cardiovascular morphogenesis, growth, and remodeling is well supported through the experimental studies. Furthermore, clinical experience suggests that perturbed flow disrupts the normal vascular growth process as one etiology for congenital heart diseases (CHD) and for fetal adaptation to CHD. However, the relationships between hemodynamics, gene expression and embryonic vascular growth are poorly defined due to the lack of concurrent, sequential in vivo data. In this study, a long-term, time-lapse optical coherence tomography (OCT) imaging campaign was conducted to acquire simultaneous blood velocity, pulsatile micro-pressure and morphometric data for 3 consecutive early embryonic stages in the chick embryo. In conjunction with the in vivo growth and hemodynamics data, in vitro reverse transcription polymerase chain reaction (RT-PCR) analysis was performed to track changes in transcript expression relevant to histogenesis and remodeling of the embryonic arterial wall. Our non-invasive extended OCT imaging technique for the microstructural data showed continuous vessel growth. OCT data coupled with the PIV technique revealed significant but intermitted increases in wall shear stress (WSS) between first and second assigned stages and a noticeable decrease afterwards. Growth rate, however, did not vary significantly throughout the embryonic period. Among all the genes studied, only the MMP-2 and CASP-3 expression levels remained unchanged during the time course. Concurrent relationships were obtained among the transcriptional modulation of the genes, vascular growth and hemodynamics-related changes. Further studies are indicated to determine cause and effect relationships and reversibility between mechanical and molecular regulation of vasculogenesis. [ABSTRACT FROM AUTHOR]

Endometrial dysfunction affects approximately 1% of infertile women, and there is currently no standard therapy for improving fertility treatment outcomes in these patients. In our study, we utilized a rodent model of thin endometrium to test whether intrauterine application of adipose-derived stromal vascular fraction cells (SVF) could improve morphological and physiological markers of endometrial receptivity. Using anhydrous ethanol, endometrial area and gland density were significantly reduced in our model of thin endometrium. Application of SVF was associated with a 29% reduction in endometrial vascular endothelial growth factor (VEGF) expression and significant increases in uterine artery systolic/diastolic velocity ratios and resistance index values, suggesting reduced diastolic microvascular tone. However, no significant improvements in endometrial area or gland density were observed following SVF treatment. 3D confocal imaging demonstrated poor engraftment of SVF cells into recipient tissue, which likely contributed to the negative results of this study. We suspect modified treatment protocols utilizing adjuvant estrogen and/or tail vein cell delivery may improve SVF retention and therapeutic response in subsequent studies. SVF is an easily-obtainable cell product with regenerative capability that may have a future role in the treatment of infertile women with endometrial dysfunction. [ABSTRACT FROM AUTHOR]

Hemodynamic mechanical cues play a critical role in the early development and functional maturation of cardiomyocytes (CM). Therefore, tissue engineering approaches that incorporate immature CM intofunctional cardiac tissues capable of recovering or replacing damaged cardiac muscle require physiologically relevant environments to provide the appropriate mechanical cues. The goal of this work is to better understand the subcellular responses of immature cardiomyocytes using an in vitro cardiac cell culture model that realistically mimics in vivo mechanical conditions, including cyclical fluid flows, chamber pressures, and tissue strains that could be experienced by implanted cardiac tissues. Cardiomyocytes were cultured in a novel microfluidic cardiac cell culture model (CCCM) to achieve accurate replication of the mechanical cues experienced by ventricular CM. Day 10 chick embryonic ventricular CM (3.5 x 104 cell clusters per cell chamber) were cultured for 4 days in the CCCM under cyclic mechanical stimulation (10 mmHg, 8-15% stretch, 2 Hz frequency) and ventricular cells from the same embryo were cultured in a static condition for 4 days as controls. Additionally, ventricular cell suspensions and ventricular tissue from day 16 chick embryo were collected and analyzed for comparison with CCCM cultured CM. The gene expressions and protein synthesis of calcium handling proteins decreased significantly during the isolation process. Mechanical stimulation of the cultured CM using the CCCM resulted in an augmentation of gene expression and protein synthesis of calcium handling proteins compared to the 2D constructs cultured in the static conditions. Further, the CCCM conditioned 2D constructs have a higher beat rate and contractility response to isoproterenol. These results demonstrate that early mechanical stimulation of embryonic cardiac tissue is necessary for tissue proliferation and for protein synthesis of the calcium handling constituents required for tissue contractility. Thus, physiologic mechanical conditioning may be essential for generating functional cardiac patches for replacement of injured cardiac tissue. [ABSTRACT FROM AUTHOR]

Objective: Infants with 'single ventricle' congenital heart disease are at high risk for sudden death following palliative surgical management. We developed a pilot telemedicine project to evaluate the feasibility of using Web-based daily reporting of clinical data with the goal of reducing unexpected admissions and sudden death. Subjects and Methods: We enrolled 9 subjects (enrolled subjects [ES]) following surgical palliation over 12 months. Parents electronically transmitted ES daily weight and oxygen saturation and then completed an automated 10-point phone questionnaire on nutrition, activity, and distress. Subject enrollment continued until a second surgical palliative procedure (n =5), sudden death (n =2), or disenrollment (n =2). We collected clinical data on all ES and 9 historical controls (HC) from the preceding 18 months and analyzed clinical management, including outpatient telephone surveillance success, scheduled and unscheduled office and emergency department visits, hospitalizations, procedures, and adverse events, including death. Results: Subject recruitment was more difficult than expected. Weight transmission success was high, but there was poor correlation between telemedicine system-measured oxygen saturation and a commercial monitor. The outpatient clinical telephone surveillance success rate for HC and ES was approximately 30%. After technical adjustments, parents of all ES (100%) were able to transmit questionnaire data. There were 9 emergency room visits for ES versus 11 unscheduled emergency room visits for HC. Sudden death occurred in 1 of 9 HC and 2 of 9 ES. Conclusions: Telemedicine monitoring for high-risk congenital heart disease patients is feasible but challenging, may reduce unscheduled visits, but may not impact the primary end point of preventing sudden death in this high-risk pediatric population. [ABSTRACT FROM AUTHOR]

A major challenge in cardiac tissue engineering is the delivery of hemodynamic mechanical cues that play a critical role in the early development and maturation of cardiomyocytes. Generation of functional cardiac tissue capable of replacing or augmenting cardiac function therefore requires physiologically relevant environments that can deliver complex mechanical cues for cardiomyocyte functional maturation. The goal of this work is the development and validation of a cardiac cell culture model (CCCM) microenvironment that accurately mimics pressure-volume changes seen in the left ventricle and to use this system to achieve cardiac cell maturation under conditions where mechanical loads such as pressure and stretch are gradually increased from the unloaded state to conditions seen in vivo. The CCCM platform, consisting of a cell culture chamber integrated within a flow loop was created to accomplish culture of 10 day chick embryonic ventricular cardiomyocytes subject to 4 days of stimulation (10 mmHg, ∼13% stretch at a frequency of 2 Hz). Results clearly show that CCCM conditioned cardiomyocytes accelerate cardiomyocyte structural and functional maturation in comparison to static unloaded controls as evidenced by increased proliferation, alignment of actin cytoskeleton, bundle-like sarcomeric a-actinin expression, higher pacing beat rate at lower threshold voltages, and increased shortening. These results confirm the CCCM microenvironment can accelerate immature cardiac cell structural and functional maturation for potential cardiac regenerative applications. [ABSTRACT FROM AUTHOR]

Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in the developing embryo, and observed that these two stages contained different aortic arch patterns with no inter-embryo variation. In the present study, we investigate these biomechanical events in the intermediate stage 21 to determine insights into this critical transition. We performed fluorescent dye microinjections to identify aortic arch patterns and measured diameters using both injection recordings and high-resolution optical coherence tomography. Flow and WSS were quantified with 3D computational fluid dynamics (CFD). Dye injections revealed that the transition in aortic arch pattern is not a uniform process and multiple configurations were documented at stage 21. CFD analysis showed that WSS is substantially elevated compared to both the previous (stage 18) and subsequent (stage 24) developmental time-points. These results demonstrate that acute increases in WSS are followed by a period of vascular remodeling to restore normative hemodynamic loading. Fluctuations in blood flow are one possible mechanism that impacts the timing of events such as aortic arch regression and generation, leading to the variable configurations at stage 21. Aortic arch variations noted during normal rapid vascular remodeling at stage 21 identify a temporal window of increased vulnerability to aberrant aortic arch morphogenesis with the potential for profound effects on subsequent cardiovascular morphogenesis. [ABSTRACT FROM AUTHOR]

Skeletal muscle derived stem cells (MDSCs) transplanted into injured myocardium can differentiate into fast skeletal muscle specific myosin heavy chain (sk-fMHC) and cardiac specific troponin-I (cTn-I) positive cells sustaining recipient myocardial function. We have recently found that MDSCs differentiate into a cardiomyocyte phenotype within a three-dimensional gel bioreactor. It is generally accepted that terminally differentiated myocardium or skeletal muscle only express cTn-I or skfMHC, respectively. Studies have shown the presence of non-cardiac muscle proteins in the developing myocardium or cardiac proteins in pathological skeletal muscle. In the current study, we tested the hypothesis that normal developing myocardium and skeletal muscle transiently share both sk-fMHC and cTn-I proteins. Immunohistochemistry, western blot, and RT-PCR analyses were carried out in embryonic day 13 (ED13) and 20 (ED20), neonatal day 0 (ND0) and 4 (ND4), postnatal day 10 (PND10), and 8 week-old adult female Lewis rat ventricular myocardium and gastrocnemius muscle. Confocal laser microscopy revealed that sk-fMHC was expressed as a typical striated muscle pattern within ED13 ventricular myocardium, and the striated sk-fMHC expression was lost by ND4 and became negative in adult myocardium. cTn-I was not expressed as a typical striated muscle pattern throughout the myocardium until PND10. Western blot and RT-PCR analyses revealed that gene and protein expression patterns of cardiac and skeletal muscle transcription factors and skfMHC within ventricular myocardium and skeletal muscle were similar at ED20, and the expression patterns became cardiac or skeletal muscle specific during postnatal development. These findings provide new insight into cardiac muscle development and highlight previously unknown common developmental features of cardiac and skeletal muscle. [ABSTRACT FROM AUTHOR]

Identification of cells that are endowed with maximum potency could be critical for the clinical success of cell-based therapies. We investigated whether cells with an enhanced efficacy for cardiac cell therapy could be enriched from adult human skeletal muscle on the basis of their adhesion properties to tissue culture flasks following tissue dissociation. Cells that adhered slowly displayed greater myogenic purity and more readily differentiated into myotubes in vitro than rapidly adhering cells (RACs). The slowly adhering cell (SAC) population also survived better than the RAC population in kinetic in vitro assays that simulate conditions of oxidative and inflammatory stress. When evaluated for the treatment of a myocardial infarction (MI), intramyocardial injection of the SACs more effectively improved echocardiographic indexes of left ventricular (LV) remodeling and contractility than the transplantation of the RACs. Immunohistological analysis revealed that hearts injected with SACs displayed a reduction in myocardial fibrosis and an increase in infarct vascularization, donor cell proliferation, and endogenous cardiomyocyte survival and proliferation in comparison with the RAC-treated hearts. In conclusion, these results suggest that adult human skeletal muscle-derived cells are inherently heterogeneous with regard to their efficacy for enhancing cardiac function after cardiac implantation, with SACs outperforming RACs. [ABSTRACT FROM AUTHOR]

Abstract: Although a variety of materials are currently used for abdominal wall repair, general complications encountered include herniation, infection, and mechanical mismatch with native tissue. An approach wherein a degradable synthetic material is ultimately replaced by tissue mechanically approximating the native state could obviate these complications. We report here on the generation of biodegradable scaffolds for abdominal wall replacement using a wet electrospinning technique in which fibers of a biodegradable elastomer, poly(ester urethane)urea (PEUU), were concurrently deposited with electrosprayed serum-based culture medium. Wet electrospun PEUU (wet ePEUU) was found to exhibit markedly different mechanical behavior and to possess an altered microstructure relative to dry processed ePEUU. In a rat model for abdominal wall replacement, wet ePEUU scaffolds (1×2.5cm) provided a healing result that developed toward approximating physiologic mechanical behavior at 8 weeks. An extensive cellular infiltrate possessing contractile smooth muscle markers was observed together with extensive extracellular matrix (collagens, elastin) elaboration. Control implants of dry ePEUU and expanded polytetrafluoroethylene did not experience substantial cellular infiltration and did not take on the native mechanical anisotropy of the rat abdominal wall. These results illustrate the markedly different in vivo behavior observed with this newly reported wet electrospinning process, offering a potentially useful refinement of an increasingly common biomaterial processing technique. [Copyright &y& Elsevier]

Objectives. Multiple technical difficulties are encountered when a multidisciplinary team of subspecialists begins a minimally invasive fetal cardiac interventional program. We describe the learning curve. Study Design. Ten pregnant sheep underwent ultrasound-guided balloon valvuloplasty of the aortic valve. Team members and their roles remained constant through the trial. The time between needle insertion and entrance of the left ventricle at the aortic root was recorded. F-test was used to assess significance (P ≤ .05). Results. The time required to accurately position the needle tip at the aortic root decreased significantly over the course of the trial, from 12 minutes with the first attempt to one minute with the last (P = .003). Conclusion. A significant learning curve is encountered when a multidisciplinary team begins a minimally-invasive fetal cardiac intervention program. However, technical proficiency can be achieved with practice. Institutions interested in developing such a program should consider practice in an animal model before proceeding to the human fetus. [ABSTRACT FROM AUTHOR]

The characteristic depressed hemodynamic state and gradually declining circulatory function in Fontan patients necessitates alternative postoperative management strategies incorporating a system level approach. In this study, the single-ventricle Fontan circulation is modeled by constructing a practical in vitro bench-top pulsatile pediatric flow loop which demonstrates the ability to simulate a wide range of clinical scenarios. The aim of this study is to illustrate the utility of a novel single-ventricle flow loop to study mechanical cardiac assist to Fontan circulation to aid postoperative management and clinical decision-making of single ventricle patients. Two different pediatric ventricular assist devices, Medos and Pediaflow Gen-0, are anastomosed in two nontraditional configurations: systemic venous booster (SVB) and pulmonary arterial booster (PAB). Optimum ventricle assist device strategy is analyzed under normal and pathological (pulmonary hypertension) conditions. Our findings indicate that the Medos ventricular assist device in SVB configuration provided the highest increase in pulmonary (46%) and systemic (90%) venous flow under normal conditions, whereas for the hypertensive condition, highest pulmonary (28%) and systemic (55%) venous flow augmentation were observed for the Pediaflow ventricular assist device inserted as a PAB. We conclude that mechanical cardiac assist in the Fontan circulation effectively results in flow augmentation and introduces various control modalities that can facilitate patient management. Assisted circulation therapies targeting single-ventricle circuits should consider disease state specific physiology and hemodynamics on the optimal configuration decisions. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether human embryonic stem cells (hESC) committed in culture into hematopoietic/endothelial cell progenitors can be further developed into mature blood and vascular cells following transplantation into chicken embryos. Materials and Methods: The yolk sac of 42− to 44-hour chicken embryos received yolk sac injections of unfractionated human embryoid body (hEB) cells, CD34-positive hEB cells, or CD34+CD45+ granulocyte colony-stimulating factor-mobilized human peripheral blood hematopoietic stem-progenitor cells. Human cells in the host were detected by flow cytometry and immunohistochemistry. Results: All injected cell populations engrafted chicken hematopoietic organs, as assessed by detection of CD45+ cells in the spleen, bursa of Fabricius, and thymus. CD34+ day -10 hEB cells showed the highest efficiency for producing human CD45+ cells in the hosts and yielded human glycophorin A+ erythroid, CD13+ myeloid, and CD19+ lymphoid cells in the spleen and bursa of Fabricius. Spleen cells from chimeric embryos also contained human colony-forming units-granulocyte macrophage, as assessed in methylcellulose colony-forming assays. Human endothelial cells expressing vascular endothelial-cadherin, von Willebrand factor, CD31, and the receptor for the Ulex europaeus lectin were also observed in the yolk sac vasculature following injection of either unfractionated or CD34+ day -10 hEB cells. Conclusion: Primitive angiohematopoietic stem cells (total and CD34+ day -10 hEB cells) as well as adult hematopoietic stem cells could home to intraembryonic blood-forming organs following injection into the yolk sac. These observations demonstrate the utility of the avian embryo as a convenient and reliable host to model the angiohematopoietic development of human embryonic, or other early stem cells. [Copyright &y& Elsevier]

Objectives: The aim of this study was to evaluate the therapeutic potential of human skeletal muscle-derived myoendothelial cells for myocardial infarct repair. Background: We have recently identified and purified a novel population of myoendothelial cells from human skeletal muscle. These cells coexpress myogenic and endothelial cell markers and produce robust muscle regeneration when injected into cardiotoxin-injured skeletal muscle. Methods: Myoendothelial cells were isolated from biopsies of human skeletal muscle using a fluorescence-activated cell sorter along with populations of regular myoblasts and endothelial cells. Acute myocardial infarction was induced in male immune-deficient mice, and cells were directly injected into the ischemic area. Cardiac function was assessed by echocardiography, and donor cell engraftment, angiogenesis, scar tissue, endogenous cardiomyocyte proliferation, and apoptosis were all evaluated by immunohistochemistry. Results: A greater improvement in left ventricular function was observed after intramyocardial injection of myoendothelial cells when compared with that seen in hearts injected with myoblast or endothelial cells. Transplanted myoendothelial cells generated robust engraftments within the infarcted myocardium, and also stimulated angiogenesis, attenuation of scar tissue, and proliferation and survival of endogenous cardiomyocytes more effectively than transplanted myoblasts or endothelial cells. Conclusions: Our findings suggest that myoendothelial cells represent a novel cell population from human skeletal muscle that may hold promise for cardiac repair. [Copyright &y& Elsevier]

Background: Hypertrophic (HCM) and dilated (DCM) cardiomyopathies result from sarcomeric protein mutations, including cardiac troponin T (cTnT, TNNT2). We determined whether TNNT2 mutations cause cardiomyopathies by altering cTnT function or quantity; whether the severity of DCM is related to the ratio of mutant to wildtype cTnT; whether Ca2+ desensitization occurs in DCM; and whether absence of cTnT impairs early embryonic cardiogenesis. Methods and Findings: We ablated Tnnt2 to produce heterozygous Tnnt2+/- mice, and crossbreeding produced homozygous null Tnnt2-/- embryos. We also generated transgenic mice overexpressing wildtype (TGWT) or DCM mutant (TGK210Δ) Tnnt2. Crossbreeding produced mice lacking one allele of Tnnt2, but carrying wildtype (Tnnt2+/-/TGWT) or mutant (Tnnt2+/-/TGK210Δ) transgenes. Tnnt2+/- mice relative to wildtype had significantly reduced transcript (0.8260.06[SD] vs. 1.0060.12 arbitrary units; p = 0.025), but not protein (1.0160.20 vs. 1.0060.13 arbitrary units; p = 0.44). Tnnt2+/- mice had normal hearts (histology, mass, left ventricular end diastolic diameter [LVEDD], fractional shortening [FS]). Moreover, whereas Tnnt2+/-/TGK210Δ mice had severe DCM, TGK210Δ mice had only mild DCM (FS 1864 vs. 2967%; p,0.01). The difference in severity of DCM may be attributable to a greater ratio of mutant to wildtype Tnnt2 transcript in Tnnt2+/-/TGK210Δ relative to TGK210Δ mice (2.42±0.08, p = 0.03). Tnnt2+/-/TGK210Δ muscle showed Ca2+ desensitization (pCa50 = 5.34±0.08 vs. 5.58±0.03 at sarcomere length 1.9 mm, p,0.01), but no difference in maximum force generation. Day 9.5 Tnnt2-/- embryos had normally looped hearts, but thin ventricular walls, large pericardial effusions, noncontractile hearts, and severely disorganized sarcomeres. Conclusions: Absence of one Tnnt2 allele leads to a mild deficit in transcript but not protein, leading to a normal cardiac phenotype. DCM results from abnormal function of a mutant protein, which is associated with myocyte Ca2+ desensitization. The severity of DCM depends on the ratio of mutant to wildtype Tnnt2 transcript. cTnT is essential for sarcomere formation, but normal embryonic heart looping occurs without contractile activity. [ABSTRACT FROM AUTHOR]

Caffeine consumption during pregnancy is reported to increase the risk of in utero growth restriction and spontaneous abortion. In the present study, we tested the hypothesis that modest maternal caffeine exposure affects in utero developing embryonic cardiovascular (CV) function and growth without altering maternal hemodynamics. Caffeine (10 mg·kg-1·day-1 subcutaneous) was administered daily to pregnant CD-1 mice from embryonic days (EDs) 9.5 to 18.5 of a 21-day gestation. We assessed maternal and embryonic CV function at baseline and at peak maternal serum caffeine concentration using high-resolution echocardiography on EDs 9.5, 11.5, 13.5, and 18.5. Maternal caffeine exposure did not influence maternal body weight gain, maternal CV function, or embryo resorption. However, crown-rump length and body weight were reduced in maternal caffeine treated embryos by ED 18.5 (P < 0.05). At peak maternal serum caffeine concentration, embryonic carotid artery, dorsal aorta, and umbilical artery flows transiently decreased from baseline at ED 11.5 (P < 0.05). By ED 13.5, embryonic aortic and umbilical artery flows were insensitive to the peak maternal caffeine concentration; however, the carotid artery flow remained affected. By ED 18.5, baseline embryonic carotid artery flow increased and descending aortic flow decreased versus non-caffeine-exposed embryos. Maternal treatment with the adenosine A2A receptor inhibitor reproduced the embryonic hemodynamic effects of maternal caffeine exposure. Adenosine A2A receptor gene expression levels of ED 11.5 embryo and ED 18.5 uterus were decreased. Results suggest that modest maternal caffeine exposure has adverse effects on developing embryonic CV function and growth, possibly mediated via adenosine A2A receptor blockade. [ABSTRACT FROM AUTHOR]

Objectives: We investigated whether vascular endothelial growth factor (VEGF) was associated with the angiogenic and therapeutic effects induced after transplantation of skeletal muscle-derived stem cells (MDSCs) into a myocardial infarction (MI). Background: Because very few MDSCs were found to differentiate into new blood vessels when injected into the heart, the mechanism underlying the occurrence of angiogenesis after MDSC transplantation is currently unknown. In the present study, we used a gain- or loss-of-VEGF function approach with skeletal MDSCs engineered to express VEGF or soluble Flt1, a VEGF-specific antagonist, to identify the involvement of VEGF in MDSC transplantation-induced neoangiogenesis. Methods: Vascular endothelial growth factor- and soluble Flt1-engineered MDSCs were injected into an acute MI. Angiogenesis and cardiac function were evaluated by immunohistochemistry and echocardiography. Results: Both control and VEGF-overexpressing MDSCs induced angiogenesis, prevented adverse cardiac remodeling, and improved function compared with saline-injected hearts. However, these therapeutic effects were diminished in hearts transplanted with MDSCs expressing soluble Flt1 despite successful cell engraftment. In vitro experiments demonstrated that MDSCs increased secretion of VEGF in response to hypoxia and cyclic stretch (likely conditions in ischemic hearts), suggesting that transplanted MDSCs release VEGF in vivo. Conclusions: Our findings suggest that VEGF is essential for the induction of angiogenesis and functional improvements observed after MDSC transplantation for infarct repair. [Copyright &y& Elsevier]

Objectives: Our objective in this study was to apply an elastic, biodegradable polyester urethane urea (PEUU) cardiac patch onto subacute infarcts and to examine the resulting cardiac ventricular remodeling and performance. Background: Myocardial infarction induces loss of contractile mass and scar formation resulting in adverse left ventricular (LV) remodeling and subsequent severe dysfunction. Methods: Lewis rats underwent proximal left coronary ligation. Two weeks after coronary ligation, a 6-mm diameter microporous PEUU patch was implanted directly on the infarcted LV wall surface (PEUU patch group, n = 14). Sham surgery was performed as an infarction control (n = 12). The LV contractile function, regional myocardial wall compliance, and tissue histology were assessed 8 weeks after patch implantation. Results: The end-diastolic LV cavity area (EDA) did not change, and the fractional area change (FAC) increased in the PEUU patch group (p < 0.05 vs. week 0), while EDA increased and FAC decreased in the infarction control group (p < 0.05). The PEUU patch was largely resorbed 8 weeks after implantation and the LV wall was thicker than infarction control (p < 0.05 vs. control group). Abundant smooth muscle bundles with mature contractile phenotype were found in the infarcted myocardium of the PEUU group. The myocardial compliance of the PEUU group was distributed between normal myocardium and infarction control (p < 0.001). Conclusions: Implantation of a novel biodegradable PEUU patch onto a subacute myocardial infarction promoted contractile phenotype smooth muscle tissue formation and improved cardiac remodeling and contractile function at the chronic stage. Our findings suggest a new therapeutic option against post-infarct cardiac failure. [Copyright &y& Elsevier]

Aim: We tested the hypothesis that murine embryonic cardiovascular (CV) function is vulnerable to transient changes in maternal transplacental oxygen support during the critical period of CV morphogenesis. Methods: We measured maternal heart rate (MHR), maternal blood pressure (MBP), and embryonic heart rate (EHR) during mechanical ventilatory support, then induced transient maternal hypoxia daily from gestation day (ED) 10.5 to ED16.5 in pregnant ICR mice. Hypoxia was induced by suspending mechanical ventilation for 30 s or by the replacement of inspired oxygen with nitrogen (75% or 100%) for 30 s while maintaining ventilation. Results: We noted a rapid onset of maternal hypotension in response to hypoxia that quickly recovered following reoxygenation. Following a brief lag time that was not gestation specific, EHR decreased in response to hypoxia. The magnitude of embryo bradycardia and the rate of EHR decline and recovery displayed gestation specific patterns. The magnitude of embryo bradycardia was similar from ED10.5 to ED13.5 and then increased with gestation. Before ED13.5, only 40% of embryos recovered to the baseline EHR following transient maternal hypoxia (vs 80% of embryos after ED 13.5). EHR following recovery exceeded baseline EHR after ED15.5. Nitrogen inhalation (75% or 100%) produced changes in maternal and embryonic hemodynamics similar to suspended ventilation induced hypoxia. Conclusions: The mammalian embryo is vulnerable to transient decreases in maternal oxygenation during the critical period of organogenesis and the gestational specific EHR response to hypoxia may reflect both increased embryonic oxygen demand and the maturation of neurohumoral heart rate regulation. [ABSTRACT FROM AUTHOR]

As in the adult dorsal aorta, the embryonic dorsal aorta is an important determinant of cardiovascular function, and increased stiffness may have secondary effects on cardiac and microcirculatory development. We previously showed that acutely and chronically increased arterial load via vitelline artery ligation (VAL) increases systemic arterial stiffness. To test the hypothesis that local dorsal aortic stiffness also increases, we measured aortic pulse-wave velocity (PWV) and assessed the active and passive properties (stress and strain) of isolated aortic segments. PWV along the dorsal aorta increased acutely and chronically after VAL. Analysis of isolated aortic active properties suggests that load-exposed aortas experienced higher stress, but not strain, at similar intraluminal pressures. When smooth muscle tone was relaxed, strain decreased in VAL vessels, whereas stress became similar to control vessels. Immunohistochemical analysis revealed that although aortic smooth muscle α-actin content was similar between groups, more cell layers expressed smooth muscle α-actin, and myocyte cell shape was markedly rounder in VAL embryos. Additionally, aortic and perivascular collagen type I and III content significantly increased in load-exposed VAL vessels. Increased production of these proteins is consistent with the observed increase in aortic PWV and decreased strain in VAL passive aortic segments. Thus the embryonic dorsal aorta is sensitive to increased arterial load and adapts by altering its material properties via changes in collagen content. [ABSTRACT FROM AUTHOR]

Embryonic myocardium has a high rate of cell proliferation and regulates cellular proliferation, contractile function, and myocardial architecture in response to changes in external mechanical loads. However, the small and complex three-dimensional (3D) structure of the embryonic myocardium limits our ability to directly investigate detailed relationships between mechanical load, contractile function, and cardiomyocyte proliferation. We developed a novel 3D engineered early embryonic cardiac tissue (EEECT) from early embryonic ventricular cells to test the hypothesis that EEECT retains the proliferative and contractile properties of embryonic myocardium. We combined freshly isolated White Leghorn chicken embryonic ventricular cells at Hamburger-Hamilton (HH) stage 31 (day 7 of a 46-stage, 21-day incubation period), collagen type I, and matrix factors to construct cylindrical-shaped EEECTs. We studied tissue architecture, cell proliferation patterns, and contractile function. We then generated engineered fetal cardiac tissue (EFCT) from HH stage 40 (day 14) fetal ventricular cells for direct comparison with EEECT. Tissue architecture was similar in EEECT and EFCT. EEECT maintained high cell proliferation patterns by culture day 12, whereas EFCT decreased cell proliferation rate by culture day 9 (P < 0.05). EEECT increased active contractile force from culture day 7 to day 12. The culture day 12 EEECT contractile response to the 3-adrenergic stimulation was less than culture day 9 EFCT (P < 0.05). Cyclic mechanical stretch stimulation induced myocardial hyperplasia in EEECT. Results indicate that EEECT retains the proliferative and contractile properties of developing embryonic myocardium and shows potential as a robust in vitro model of developing embryonic myocardium. [ABSTRACT FROM AUTHOR]

Abstract: Myoblast transplantation for cardiac repair has generated beneficial results in both animals and humans; however, poor viability and poor engraftment of myoblasts after implantation in vivo limit their regeneration capacity. We and others have identified and isolated a subpopulation of skeletal muscle-derived stem cells (MDSCs) that regenerate skeletal muscle more effectively than myoblasts. Here we report that in comparison with a myoblast population, MDSCs implanted into infarcted hearts displayed greater and more persistent engraftment, induced more neoangiogenesis through graft expression of vascular endothelial growth factor, prevented cardiac remodeling, and elicited significant improvements in cardiac function. MDSCs also exhibited a greater ability to resist oxidative stress-induced apoptosis compared to myoblasts, which may partially explain the improved engraftment of MDSCs. These findings indicate that MDSCs constitute an alternative to other myogenic cells for use in cardiac repair applications. [Copyright &y& Elsevier]