A surgical mouse model of neonatal right ventricular outflow tract obstruction by pulmonary artery banding.

BACKGROUD: Diseased animal models play an extremely important role in preclinical research. Lacking the corresponding animal models, many basic research studies cannot be carried out, and the conclusions obtained are incomplete or even incorrect. Right ventricular (RV) outflow tract (RVOT) obstruction leads to RV pressure overload (PO) and reduced pulmonary blood flow (RPF), which are 2 of the most important pathophysiological characteristics in pediatric cardiovascular diseases and seriously affect the survival rate and long-term quality of life of many children. Due to the lack of a neonatal mouse model for RVOT obstruction, it is largely unknown how RV PO and RPF regulate postnatal RV and pulmonary development. The aim of this study was to construct a neonatal RVOT obstruction mouse model. METHODS AND RESULTS: Here, we first introduced a neonatal mouse model of RVOT obstruction by pulmonary artery banding (PAB) on postnatal day 1. PAB induced neonatal RVOT obstruction, RV PO, and RPF. Neonatal RV PO induced cardiomyocyte proliferation, and neonatal RPF induced pulmonary dysplasia, the 2 features that are not observed in adult RVOT obstruction. As a result, PAB neonates exhibited overall developmental dysplasia, a sign similar to that of children with RVOT obstruction. CONCLUSIONS: Because many pediatric cardiovascular diseases are associated with RV PO and RPF, the introduction of a neonatal mouse model of RVOT obstruction may greatly enhance our understanding of these diseases and eventually improve or save the lives of many children.

The implication of chromosomal abnormalities in the surgical outcomes of Chinese pediatric patients with congenital heart disease.

Background: Copy number variations (CNVs) have been shown to be overrepresented in children with congenital heart disease (CHD). Genetic evaluation of CHD is currently underperformed in China. We sought to determine the occurrence of CNVs in CNV regions with disease-causing potential among a large cohort of Chinese pediatric CHD patients and investigate whether these CNVs could be the important critical modifiers of surgical intervention. Methods: CNVs screenings were performed in 1,762 Chinese children who underwent at least one cardiac surgery. CNV status at over 200 CNV locus with disease-causing potential was analyzed with a high-throughput ligation-dependent probe amplification (HLPA) assay. Results: We found 378 out of 1,762 samples (21.45%) to have at least one CNV and 2.38% of them were carrying multiple CNVs. The detection rates of ppCNVs (pathogenic and likely pathogenic CNVs) were 9.19% (162/1,762), significantly higher than that of the healthy Han Chinese individuals from The Database of Genomic Variants archive (9.19% vs. 3.63%; P = 0.0012). CHD cases with ppCNVs had a significantly higher proportion of complex surgeries compared to CHD patients with no ppCNVs (62.35% vs. 37.63%, P < 0.001). Duration of cardiopulmonary bypass and aortic cross clamp procedures were significantly longer in CHD cases with ppCNVs (all P < 0.05), while no group differences were identified for complications of surgery and one-month mortality after surgery. The detection rate of ppCNVs in the atrioventricular septal defect (AVSD) subgroup was significantly higher than that in other subgroups (23.10% vs. 9.70%, P = 0.002). Conclusions: CNV burden is an important contributor to Chinese children with CHD. Our study demonstrated the robustness and diagnostic efficiency of HLPA method in the genetic screening of CNVs in CHD patients.

Molecular Changes in Prepubertal Left Ventricular Development Under Experimental Volume Overload.

Background: Left ventricular (LV) volume overload (VO), commonly found in patients with chronic aortic regurgitation (AR), leads to a series of left ventricular (LV) pathological responses and eventually irreversible LV dysfunction. Recently, questions about the applicability of the guideline for the optimal timing of valvular surgery to correct chronic AR have been raised in regard to both adult and pediatric patients. Understanding how VO regulates postnatal LV development may shed light on the best timing of surgical or drug intervention. Methods and Results: Prepubertal LV VO was induced by aortocaval fistula (ACF) on postnatal day 7 (P7) in mice. LV free walls were analyzed on P14 and P21. RNA-sequencing analysis demonstrated that normal (P21_Sham vs.P14_Sham) and VO-influenced (P21_VO vs. P14_VO) LV development shared common terms of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) in the downregulation of cell cycle activities and the upregulation of metabolic and sarcomere maturation. The enriched GO terms associated with cardiac condition were only observed in normal LV development, while the enriched GO terms associated with immune responses were only observed in VO-influenced LV development. These results were further validated by the examination of the markers of cell cycle, maturation, and immune responses. When normal and VO-influenced LVs of P21 were compared, they were different in terms of immune responses, angiogenesis, percentage of Ki67-positive cardiomyocytes, mitochondria number, T-tubule regularity, and sarcomere regularity and length. Conclusions: A prepubertal LV VO mouse model was first established. VO has an important influence on LV maturation and development, especially in cardiac conduction, suggesting the requirement of an early correction of AR in pediatric patients. The underlying mechanism may be associated with the activation of immune responses.

Association Between Preoperative Factors and In-hospital Mortality in Neonates After Cardiac Surgery in China.

Background: Little is known about preoperative factors affecting cardiac surgery outcomes of neonates in China. We sought to examine the association between characteristics of neonates with congenital heart disease (CHD) and early postoperative outcomes after cardiac repair in a tertiary care paediatric hospital. Methods: A single-centre retrospective cohort study of neonates who underwent cardiac surgery between January 2006 and December 2019 was performed. Demographic, institutional, and surgical characteristics of neonates were examined and their association with in-hospital mortality was analysed using multivariable logistic regression models. Results: During the study period, we analysed the outcomes of 1,078 neonates. In-hospital mortality decreased to 13.8% in the era 2017-2019. The overall in-hospital mortality rate was 16.3%. Normal weight at surgery [odds ratio (OR), 0.63; 95% confidence interval (CI), 0.47-0.85; P = 0.003] was associated with lower mortality risk. Poor health status (emergent: OR, 3.11; 95% CI, 1.96-4.94; P < 0.001; elective: OR, 1.63; 95% CI, 1.11-2.40; P = 0.013), higher Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) categories (STAT 5 category: OR, 2.58; 95% CI, 1.04-6.43; P = 0.042), and limited individual surgeon experience (surgeon with 5-10 operations per year: OR, 1.43; 95% CI, 1.06-1.95; P = 0.021) were associated with higher odds of early death. Conclusion: In-hospital mortality after neonatal cardiac surgery remained high in our centre over the past 10 years. Some preoperative aspects, including low-weight at surgery, poor health status, increased surgical complexity, and limited surgeon experience were significantly associated with higher mortality. Based on the observed associations, the necessary practises to be modified, especially in preoperative care, should be identified and assessed in future research.

Preoperative Vitamin D Deficiency Is Associated With Higher Vasoactive-Inotropic Scores Following Pediatric Cardiac Surgery in Chinese Children.

The relationship between vitamin D and cardiovascular health in children remains unclear. Vitamin D deficiency (VDD) is supposed to be a potential risk factor associated with poorer outcomes after congenital heart disease (CHD) surgery. The maximum vasoactive-inotropic use after cardiac surgery is considered to be a good predictor of adverse outcomes. We aimed to assess the correlation between preoperative VDD and the maximum vasoactive-inotropic score (VISmax) at 24 h postoperatively. Nine hundred children with CHD were enrolled in this study, and preoperative total serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by liquid chromatography-tandem mass spectrometry. Related demographic and clinical characteristics were collected. A total of 490 boys (54.4%) and 410 girls (45.6%) with a mean age of 1 year (range: 6 months-3 years) were enrolled. The median 25(OH)D level was 24.0 ng/mL, with 32.6% of patients having VDD [25(OH)D < 20 ng/mL]. The univariate analysis indicated that VDD [odds ratio (OR): 2.27; 95% confidence interval (CI): 1.48-3.50] is associated with a risk of increased VISmax at 24 h postoperation. Multivariate analysis revealed that VDD (OR: 1.85; 95% CI: 1.09-3.02), a Risk-adjusted Congenital Heart Surgery score of at least three points (OR: 1.55; 95% CI: 1.09-2.19), and cardiopulmonary bypass time (OR: 1.02; 95% CI: 1.01-1.02) were independently associated with an increased VISmax within 24 h after cardiac surgery. VDD in pediatric patients before cardiac surgery is associated with the need for increased postoperative inotropic support at 24 h postoperation.

Postnatal Right Ventricular Developmental Track Changed by Volume Overload.

Background Current right ventricular (RV) volume overload (VO) is established in adult mice. There are no neonatal mouse VO models and how VO affects postnatal RV development is largely unknown. Methods and Results Neonatal VO was induced by the fistula between abdominal aorta and inferior vena cava on postnatal day 7 and confirmed by abdominal ultrasound, echocardiography, and hematoxylin and eosin staining. The RNA-sequencing results showed that the top 5 most enriched gene ontology terms in normal RV development were energy derivation by oxidation of organic compounds, generation of precursor metabolites and energy, cellular respiration, striated muscle tissue development, and muscle organ development. Under the influence of VO, the top 5 most enriched gene ontology terms were angiogenesis, regulation of cytoskeleton organization, regulation of vasculature development, regulation of mitotic cell cycle, and regulation of the actin filament-based process. The top 3 enriched signaling pathways for the normal RV development were PPAR signaling pathway, citrate cycle (Tricarboxylic acid cycle), and fatty acid degradation. VO changed the signaling pathways to focal adhesion, the PI3K-Akt signaling pathway, and pathways in cancer. The RNA sequencing results were confirmed by the examination of the markers of metabolic and cardiac muscle maturation and the markers of cell cycle and angiogenesis. Conclusions A neonatal mouse VO model was successfully established, and the main processes of postnatal RV development were metabolic and cardiac muscle maturation, and VO changed that to angiogenesis and cell cycle regulation.

Periconceptional use of cod liver oil, a vitamin D source, could decrease the risk of CHD in offspring.

OBJECTIVE: To explore if there is association between vitamin D supplementation through cod liver oil ingestion around the periconceptional period and the risk of developing severe CHD in offspring. Furthermore, we would examine the interaction between vitamin D and folic acid supplementation in the association. METHODS: A case-control study was conducted in Shanghai Children's Medical Center, in which, a total of 262 severe CHD cases versus 262 controls were recruited through June 2016 to December 2017. All children were younger than 2 years. To reduce potential selection bias and to minimise confounding effects, propensity score matching was applied. RESULTS: After propensity score matching, vitamin D supplementation seemed to be associated with decreased odds ratio of severe CHD (odds ratio = 0.666; 95% confidence intervals: 0.449-0.990) in the multivariable conditional logistic analysis. Furthermore, we found an additive interaction between vitamin D and folic acid supplementation (relative excess risk due to interaction = 0.810, 95% confidence intervals: 0.386-1.235) in the association. CONCLUSION: The results suggested that maternal vitamin D supplementation could decrease the risk of offspring severe CHD; moreover, it could strengthen the protective effect of folic acid. The significance of this study lies in providing epidemiological evidence that vitamin D supplementation around the periconceptional period could be a potential nutritional intervention strategy to meet the challenge of increasing CHD.

Neonatal surgical outcomes after prenatal diagnosis of complex congenital heart disease: experiences of a perinatal integrated diagnosis and treatment program.

BACKGROUND: This study aimed to evaluate neonatal surgical outcomes of patients diagnosed with complex congenital heart disease (CHD) during pregnancy and treated by the newly initiated "perinatal integrated diagnosis and treatment program (PIDTP)". METHODS: We reviewed clinical data of 207 neonates (surgical age ≤ 28 days) who underwent cardiac surgeries in a single center from January 2017 to December 2018, including 31 patients with referrals from the "PIDTP" (integration group) and 176 patients with routine referral treatment (non-integrated group). RESULTS: In the integration group, median admission age was 0 days and median age at surgery was 4 days. In the non-integrated group, median admission age was 8 days (P = 0.001) and median age at surgery was 13 days (P = 0.001). The emergency surgery rate in patients with duct-dependent defects was 36% in the integration group and 59% (P = 0.042) in the non-integrated group, respectively. The in-hospital mortality was 16% in the integration group and 14% (P = 0.78) in the non-integrated group. The 2-year cumulative survival rate after surgery was 83.9% ± 6.6% in the integration group and 80.3% ± 3.1% (P = 0.744) in the non-integrated group. According to multivariable regression analysis, independent risk factors for early mortality of overall neonatal cardiac surgery were low body weight, high serum lactate level, postoperative extracorporeal membrane oxygenation (ECMO) support and prolonged cardiopulmonary bypass (CPB) time. CONCLUSIONS: PIDTP shortens the postnatal transit interval, reduces the emergency operation rate of neonatal critical CHD, and provides better preoperative status for surgery. Patients treated by the PIDTP tend to have more complicated anatomical deformity and a greater requirement for the operation and postoperative management, but early outcome and follow-up prognosis are satisfactory.

Hypoxia-induced ARHGAP26 deficiency inhibits the proliferation and migration of human ductus arteriosus smooth muscle cell through activating RhoA-ROCK-PTEN pathway.

The Rho family plays crucial roles in O2 -induced vasoconstriction, cell proliferation, and migration. Rho GTPase-activating protein 26 (ARHGAP26) is a GTPase-activating protein for the small GTPases of the Rho family. Our previous studies have demonstrated that ARHGAP26 expression was significantly downregulated in patent human ductus arteriosus (DA) tissue. However, its role underlying the maintenance of DA patency is unclear. In this study, patent (fetal) and constricted (newborn) mouse DA tissues were harvested to confirm the differences in the levels of expression of ARHGAP26. Human DA smooth muscle cells (DASMCs) were isolated and cultured in vitro and used to test the function of ARHGAP26. The expression of ARHGAP26 was significantly lower in patent (fetal) than constricted (newborn) mouse DA. ARHGAP26-knocked-down human DASMCs showed reduced proliferation and migration, which are both crucial to anatomic closure of DA. Moreover, after culturing under hypoxic conditions, the expression of ARHGAP26 in human DASMCs was significantly lower and hypoxia-induced ARHGAP26 deficiency activated the phosphorylation level of phosphatase and tensin homolog (PTEN) in DASMCs by mediating the activity of RhoA and RhoA-associated kinase 1 (ROCK1). Use of Y27632, an inhibitor of ROCK which further reduces the phospholipid activity of PTEN can reverse the inhibitory effect of PTEN on the proliferation and migration of human DASMCs. This provides insight into the molecular regulation of the RhoA-ROCK-PTEN pathway in DA smooth muscle cells, which may be a suitable therapeutic target or diagnostic biomarker for perinatal DA tone management.

Bioresorbable electrospun gelatin/polycaprolactone nanofibrous membrane as a barrier to prevent cardiac postoperative adhesion.

Post-cardiac surgical sternal and epicardial adhesions increase the risk and complexity of cardiac re-operative surgeries, which represent a significant challenge for patients with the congenital cardiac disease. Bioresorbable membranes can serve as barriers to prevent postoperative adhesions. Herein, we fabricated a bioresorbable gelatin/polycaprolactone (GT/PCL) composite membrane via electrospinning. The membrane was characterized in terms of morphology, mechanical properties, and biocompatibility. We then evaluated its efficacy as a physical barrier to prevent cardiac operative adhesions in a rabbit model. Our results showed that the membrane had a nanofibrous structure and was sturdy enough to be handled for the surgical procedures. In vitro studies with rabbit cardiac fibroblasts demonstrated that the membrane was biocompatible and inhibited cell infiltration. Further application of the membrane in a rabbit cardiac adhesion model revealed that the membrane was resorbed gradually and effectively resisted the sternal and epicardial adhesions. Interestingly, six months after the operation, the GT/PCL membrane was completely resorbed with simultaneous ingrowth of host cells to form a natural barrier. Collectively, these results indicated that the GT/PCL membrane might be a suitable barrier to prevent sternal and epicardial adhesions and might be utilized as a novel pericardial substitute for cardiac surgery. STATEMENT OF SIGNIFICANCE: Electrospinning is a versatile method to prepare nanofibrous membranes for tissue engineering and regenerative medicine applications. However, with the micro-/nano-scale structure and high porosity, the electrospun membrane might be an excellent candidate as a barrier to prevent postoperative adhesion. Here we prepared an electropun GT/PCL nanofibrous membrane and applied it as a barrier to prevent sternal and epicardial adhesions. Our results showed that the membrane had sufficient mechanical strength, good biocompatibility, and effectively resisted the sternal and epicardial adhesions. What's more, the membrane was bioresorbable and allowed simultaneous ingrowth of host cells to form a natural barrier. We believe that the current will inspire more research on nanomaterials to prevent postoperative adhesion applications.

Parental attitudes and willingness to donate children's biospecimens for congenital heart disease research: a cross-sectional study in Shanghai, China.

OBJECTIVES: To assess attitudes and willingness of parents of children with congenital heart disease (CHD) regarding donating biospecimens for future CHD research, and to identify factors associated with biospecimen donation. DESIGN: Face-to-face cross-sectional survey data were analysed using logistic regression. SETTING: Cardiothoracic Surgery Inpatient Department, Shanghai Children's Medical Centre. PARTICIPANTS: Parents of children attending the cardiothoracic surgery inpatient department at Shanghai Children's Medical Center, 1 March-31 December 2016. PRIMARY AND SECONDARY OUTCOME MEASURES: Willingness and motivation regarding donating children's biospecimens, and ethical and legal considerations concerning children's future willingness to donate. RESULTS: Of 550 parents, 508 completed the questionnaire (response rate=92.4%). Overall, 69.1% (n=351) were willing to donate their children's biospecimens for medical research. Multivariate analysis indicated higher education level (college/graduate degree: OR 2.435, 95% CI 1.221 to 4.857, p=0.012; high school: OR 1.827, 95% CI 1.190 to 2.804, p=0.006) and children's hospitalisation history (OR 1.581; 95% CI 1.069 to 2.338, p=0.022) were positively associated with willingness to donate. The most common motivation for donation was potential benefit to other children with CHD (81.2%, n=285). The main barriers to donation were physical discomfort to their children (52.3%, n=54) and concerns about personal privacy (47.1%, n=48). Most parents (86.0%, n=302) wanted to be informed of research results using their children's donated biospecimens, and 34.8% (n=177) believed that children aged 10-18 years had the right to consent independently to research participation. CONCLUSIONS: Nearly 70% of the parents in this study were willing to donate their children's biospecimens for future CHD research. Parents' education level and children's hospitalisation history influenced willingness to donate. Most parents wanted to receive the research results related to their children's biospecimens.

A neonatal rat model of increased right ventricular afterload by pulmonary artery banding.

OBJECTIVE: To construct a neonatal rat model of increased right ventricular (RV) afterload for studying the pathophysiological remodeling of the right ventricle in patients with congenital heart disease with increased RV afterload. METHODS: Surgery was performed within 6 hours after birth. Horizontal thoracotomy was performed by dissecting the intercostal muscles and splitting the sternum. The PA was then banded with 11-0 nylon thread. At postnatal day 7 (P7), constriction of PA was confirmed by echocardiography. The RV systolic and diastolic pressures were measured by cardiac catheterization. The RV end-systolic volume, end-diastolic volume, end-diastolic diameter, and free wall thickness were assessed by magnetic resonance imaging. The histological changes in sham-operated and PA-banding (PAB) hearts were evaluated by hematoxylin and eosin staining. RESULTS: Increased RV afterload was established by constriction of the PA in neonatal rats within 6 hours after birth. The survival rate was 75% at P7. Relative to the sham group, the peak pressure gradient across the PA constriction and RV systolic and diastolic pressures, end-systolic volume, end-diastolic volume, end-diastolic diameter, and free wall thickness were significantly increased in the PAB group at P7 (P < .01). Consistently, histological examination showed that the RV free wall was significantly hypertrophic in the PAB group. CONCLUSIONS: We successfully established a neonatal RV afterload increase model through PAB within 6 hours after birth, which can be used to study the pathophysiological changes in congenital heart diseases with increased RV afterload.

Age-Dependent Oxidative DNA Damage Does Not Correlate with Reduced Proliferation of Cardiomyocytes in Humans.

BACKGROUND: Postnatal human cardiomyocyte proliferation declines rapidly with age, which has been suggested to be correlated with increases in oxidative DNA damage in mice and plays an important role in regulating cardiomyocyte proliferation. However, the relationship between oxidative DNA damage and age in humans is unclear. METHODS: Sixty right ventricular outflow myocardial tissue specimens were obtained from ventricular septal defect infant patients during routine congenital cardiac surgery. These specimens were divided into three groups based on age: group A (age 0-6 months), group B (age, 7-12 months), and group C (>12 months). Each tissue specimen was subjected to DNA extraction, RNA extraction, and immunofluorescence. RESULTS: Immunofluorescence and qRT-PCR analysis revealed that DNA damage markers-mitochondrial DNA copy number, oxoguanine 8, and phosphorylated ataxia telangiectasia mutated-were highest in Group B. However immunofluorescence and qRT-PCR demonstrated that two cell proliferation markers, Ki67 and cyclin D2, were decreased with age. In addition, wheat germ agglutinin-staining indicated that the average size of cardiomyocytes increased with age. CONCLUSIONS: Oxidative DNA damage of cardiomyocytes was not correlated positively with age in human beings. Oxidative DNA damage is unable to fully explain the reduced proliferation of human cardiomyocytes.

Total Anomalous Pulmonary Venous Connection: The Current Management Strategies in a Pediatric Cohort of 768 Patients.

BACKGROUND: Total anomalous pulmonary venous connection (TAPVC) is a rare form of congenital heart disease. This study describes current surgical treatment strategies and experiences in a cohort of patients from 2 congenital cardiac centers in Shanghai and Guangdong in China. METHODS: This retrospective study included 768 patients operated on between 2005 and 2014. Although most patients (n=690) underwent conventional repair, a sutureless technique was used in 10% (n=78) of cases. A multilevel mixed-effects parametric survival model and a competing-risk analysis were used to analyze associated risk factors for death and recurrent pulmonary venous obstruction (PVO), respectively. Kaplan-Meier analysis was used to analyze the overall survival. The Nelson-Aalen cumulative risk curve was used to compare distributions of time with recurrent PVO. RESULTS: The mean surgical age and weight were 214.9±39.2 days and 5.4±3.6 kg, respectively. Obstructed TAPVC (PVO) was documented in 192 (25%) of the 768 patients. There were 38 intraoperative deaths and 13 late deaths. A younger age at the time of repair (P=0.001), mixed (P=0.004) and infracardiac (P=0.035) TAPVC, preoperative PVO (P=0.027), prolonged cardiopulmonary bypass time (P<0.001), and longer duration of ventilation (P=0.028) were associated with mortality. The median follow-up was 23.2 months (range; 1-112 months). Among the 717 survivors, recurrent PVO was observed in 111 patients (15%). Associated risk factors for recurrent PVO included preoperative PVO (P<0.001), infracardiac TAPVC (P<0.001), mixed TAPVC (P=0.013), and prolonged cardiopulmonary bypass time (P<0.001). Sutureless technique was associated with a lower restenosis rate compared with conventional repair in patients with preoperative PVO (P=0.038), except in newborn patients (P=0.443). Reintervention for restenosis was performed in 24 patients. The function of most survivors (91%) was classified according to the New York Heart Association as functional class I or II. CONCLUSIONS: Surgical correction in patients with TAPVC with a biventricular anatomy can achieve an acceptable outcome. Risk factors such as a younger age at the time of repair, infracardiac and mixed TAPVC, and preoperative PVO were associated with a poorer prognosis.

GSK-3ß Inhibitor CHIR-99021 Promotes Proliferation Through Upregulating ß-Catenin in Neonatal Atrial Human Cardiomyocytes.

BACKGROUND: The renewal capacity of neonate human cardiomyocytes provides an opportunity to manipulate endogenous cardiogenic mechanisms for supplementing the loss of cardiomyocytes caused by myocardial infarction or other cardiac diseases. GSK-3ß inhibitors have been recently shown to promote cardiomyocyte proliferation in rats and mice, thus may be ideal candidates for inducing human cardiomyocyte proliferation. METHODS: Human cardiomyocytes were isolated from right atrial specimens obtained during routine surgery for ventricle septal defect and cultured with either GSK-3ß inhibitor (CHIR-99021) or ß-catenin inhibitor (IWR-1). Immunocytochemistry was performed to visualize 5-ethynyl-2'-deoxyuridine (EdU)-positive or Ki67-positive cardiomyocytes, indicative of proliferative cardiomyocytes. RESULTS: GSK-3ß inhibitor significantly increased ß-catenin accumulation in cell nucleus, whereas ß-catenin inhibitor significantly reduced ß-catenin accumulation in cell plasma. In parallel, GSK-3ß inhibitor increased EdU-positive and Ki67-positive cardiomyocytes, whereas ß-catenin inhibitor decreased EdU-positive and Ki67-positive cardiomyocytes. CONCLUSIONS: These results indicate that GSK-3ß inhibitor can promote human atrial cardiomyocyte proliferation. Although it remains to be determined whether the observations in atrial myocytes could be directly applicable to ventricular myocytes, the current findings imply that Wnt/ß-catenin pathway may be a valuable pathway for manipulating endogenous human heart regeneration.

Computational haemodynamic analysis of left pulmonary artery angulation effects on pulmonary blood flow.

OBJECTIVES: To study the effect of the angulation between the left pulmonary artery (LPA) and the main pulmonary artery on pulmonary haemodynamics. METHODS: A 3D model of patient-specific pulmonary artery (PA) was reconstructed as an original model. Four models with descendent LPA angulation equalled to 120°, 110°, 100° and 90°, were reconstructed by computer-aided design for the virtual simulation of the pulmonary flow under different surgical strategies. Computational fluid dynamics was introduced to calculate the pulmonary blood flow in five models. Streamlines, wall shear stress, energy loss and flow distribution ratio were calculated and compared to determine the better haemodynamics in the pulmonary artery. RESULTS: Vortices were formed at the lower wall of the opening of right PA and LPA in models with LPA angles equal to or less than 100° (Models 3 and 4). Relative high wall shear stress areas at the lateral and lower wall of LPA opening had an ascendant tendency as the angle declined. Decreased flow distribution ratio to left lung (original model: 0.58, Model 1: 0.63, Model 2: 0.586, Model 3: 0.564, Model 4: 0.55) and increased energy loss (original model: 385.2 mV, Model 1: 239.4 mV, Model 2: 384.3 mV, Model 3: 430.9 mV, Model 4: 439.8 mV) in a cardiac cycle were noted as the angle reduced. CONCLUSIONS: Acute LPA angulation is associated with adverse haemodynamic performance. This should be particularly addressed during the reconstruction of pulmonary artery in the repair of tetralogy of Fallot.

A gain-of-function ACTC1 3'UTR mutation that introduces a miR-139-5p target site may be associated with a dominant familial atrial septal defect.

The ostium secundum atrial septal defect (ASDII) is the most common type of congenital heart disease and is characterized by a left to right shunting of oxygenated blood caused by incomplete closure of the septum secundum. We identified a familial form of isolated ASDII that affects four individuals in a family of five and shows autosomal dominant inheritance. By whole genome sequencing, we discovered a new mutation (c.*1784T > C) in the 3'-untranslated region (3'UTR) of ACTC1, which encodes the predominant actin in the embryonic heart. Further analysis demonstrated that the c.*1784T > C mutation results in a new target site for miRNA-139-5p, a microRNA that is involved in cell migration, invasion, and proliferation. Functional analysis demonstrated that the c.*1784T > C mutation specifically downregulates gene expression in a luciferase assay. Additionally, miR-139-5p mimic causes further decrease, whereas miR-139-5p inhibitor can dramatically rescue the decline in gene expression caused by this mutation. These findings suggest that the familial ASDII may be a result of an ACTC1 3'UTR gain-of-function mutation caused by the introduction of a new miR-139-5p target site. Our results provide the first evidence of a pathogenic mutation in the ACTC1 3'UTR that may be associated with familial isolated ASDII.

Cardiomyocytes in Young Infants With Congenital Heart Disease: a Three-Month Window of Proliferation.

Perinatal reduction in cardiomyocyte cell cycle activity is well established in animal models and humans. However, cardiomyocyte cell cycle activity in infants with congenital heart disease (CHD) is unknown, and may provide important information to improve treatment. Human right atrial specimens were obtained from infants during routine surgery to repair ventricular septal defects. The specimens were divided into three groups: group A (age 1-3 months); group B (age, 4-6 months); and group C (age 7-12 months). A dramatic fall in the number of Ki67-positive CHD cardiac myocytes occurred after three months. When cultured in vitro, young CHD myocytes (≤ 3 months) showed more abundant Ki67-positive cardiomyocytes and greater incorporation of EdU, indicating enhanced proliferation. YAP1 and NICD-important transcript factors in cardiomyocyte development and proliferation-decreased with age and ß-catenin increased with age. Compared with those of older infants, cardiomyocytes of young CHD infants (≤ 3 months) have a higher proliferating capacity in vivo and in vitro. From the perspective of cardiac muscle regeneration, CHD treatment at a younger age (≤ 3 months) may be more optimal.