Myocardial angiogenesis : Aspects on endogenous determinants and effects of stimulation

Background: Therapeutic angiogenesis using i.e. VEGF and FGF have shown beneficial effects, however, delivery routes and other modulating agents have not been thoroughly investigated. In this study the efficacy of adenovirus gene transfer was compared to plasmid gene transfer. The angiogenic effects of ephrinB2 were explored, as were the cardioprotective effects of erythropoietin and estrogen, with angiogenic effects in focus. Since hypoxia is the key regulator of angiogenesis, the studies were performed in an ischemic setting with a myocardial infarction model. Results: Intramyocardial AdhVEGF-A165 transfer induced higher hVEGF-A protein expression than PhVEGF-A165 in rat myocardium (p<0.001). PhVEGF- A165 and AdhVEGF-A165 stimulated angiogenesis and improved left ventricular function to similar extent. AdhVEGFA165 induced more apoptotic cells (p<0.001) and higher ectopic expression of VEGF-A165 than PhVEGF-A165 gene transfer. Treatment with darbepoietin-alpha did not alter capillary density after myocardial infarction in a mouse myocardial infarction model. Cell proliferation was higher in the periinfarct area compared to the non infarcted area. Darbepoietin-alpha treatment gave a decreased cell proliferation (BrdU, p< 0.02) and apoptosis (TUNEL, p<0.005) with 30% in the periinfarct area. Darbepoietin-alpha and VEGF-A165 both induced angiogenic sprouting from cultured murine aortic rings. The ephrin/Eph system was expressed in murine myocardium and altered as regards the ephrinB2/EphB4 expression after myocardial infarction (p<0.005). Modulation of ephrinB2 with fusion protein tended to increase mitosis, measured by BrdU incorporation in the periinfarct area, and also increased capillary density in the periinfarct area. EphrinB2 induced proliferation in human aortic endothelial cells (p<0.0005) and aortic ring sprouting (p<0.05) to a similar extent as VEGF-A165. In ERbetaKO mice the downregulation of ERalpha and the absence of functional ERbeta and in ERalphaKO the absence of functional ERalpha and the downregulation of ERbeta did not influence myocardial angiogenesis or arteriogenesis after myocardial infarction. In the periinfarct area of ERalphaKO mice the number of macrophages was lower compared to control (p<0.05). Conclusions: AdhVEGF-A165 does not have any obvious superior angiogenic efficacy compared to PhVEGF-A165 but more side effects in a rat myocardial infarction model. Darbepoietin-alpha induces endothelial sprouting in a murine aortic ring culture, but in this model darbepoietin-alpha decreases cell proliferation and apoptosis in the periinfarct area with capillary and arteriolar densities unchanged. The ephrin/Eph system is present in the myocardium, and alters after myocardial infarction. EphrinB2 Fc tends to increase the mitotic activity and prevents a decrement in capillary density in the periinfarct area. Also ephrinB2 Fc induces endothelial cell proliferation in vitro, and stimulates angiogenic sprouting in an aortic ring model. mRNA expression of estrogen receptors are present in the myocardium. After myocardial infarction in ERbetaKO ERalpha mRNA and in ERalphaKO ERbeta mRNA are downregulated, without any influence on angiogenesis or arteriogenesis

Incidence and surveillance of acute cardiovascular toxicities in paediatric acute lymphoblastic leukaemia: A retrospective population-based single-centre cohort study

Aim: Here, we studied the incidence of acute cardiovascular toxicities in children treated for acute lymphoblastic leukaemia (ALL). Methods: We performed a population-based single-centre longitudinal retrospective cohort study in 70 children diagnosed and treated with anthracycline-containing therapy against ALL at Karolinska University Hospital during 2015–2019 with a follow-up period of at least three months. Cardiovascular surveillance for these patients included echocardiography with measurements of left ventricular ejection fraction (LVEF) and shortening fraction (LVSF), electrocardiography and non-invasive blood pressure monitoring. Results: No patient experienced a significant decrease in LVEF or LVSF during or early after primary cancer treatment including anthracyclines. Surveillance with LVEF and LVSF was unable to predict the trajectory to severe clinical heart failure in one patient following treatment. Pericardial effusion prior to therapy initiation occurred in 13.6% of the patients. The incidence of intracardiac thrombosis and arterial hypertension was 8.5%, and 20%, respectively. Conclusion: Early cardiovascular toxicities were common in this paediatric ALL cohort. We confirm that early routine LVEF and LVSF assessments were insufficient to identify patients at risk of subsequent treatment-related heart failure. This underlines the unmet need of more sensitive methods for cardiovascular surveillance in children treated for cancer to reduce the burden of cardiovascular morbidity and mortality

High cardiomyocyte diversity in human early prenatal heart development

Summary: Cardiomyocytes play key roles during cardiogenesis, but have poorly understood features, especially in prenatal stages. Here, we characterized human prenatal cardiomyocytes, 6.5–7 weeks post-conception, by integrating single-cell RNA sequencing, spatial transcriptomics, and ligand-receptor interaction information. Using a computational workflow developed to dissect cell type heterogeneity, localize cell types, and explore their molecular interactions, we identified eight types of developing cardiomyocyte, more than double compared to the ones identified in the Human Developmental Cell Atlas. These have high variability in cell cycle activity, mitochondrial content, and connexin gene expression, and are differentially distributed in the ventricles, including outflow tract, and atria, including sinoatrial node. Moreover, cardiomyocyte ligand-receptor crosstalk is mainly with non-cardiomyocyte cell types, encompassing cardiogenesis-related pathways. Thus, early prenatal human cardiomyocytes are highly heterogeneous and develop unique location-dependent properties, with complex ligand-receptor crosstalk. Further elucidation of their developmental dynamics may give rise to new therapies

Longitudinal strain analysis for assessment of early cardiotoxicity during anthracycline treatment in childhood sarcoma: A single center experience

Abstract Background The growing population of long‐term childhood cancer survivors encounter a substantial burden of cardiovascular complications. The highest risk of cardiovascular complications is associated with exposure to anthracyclines and chest radiation. Longitudinal cardiovascular surveillance is recommended for childhood cancer patients; however, the optimal methods and timing are yet to be elucidated. Aims We aimed to investigate the feasibility of different echocardiographic methods to evaluate left ventricular systolic function in retrospective datasets, including left ventricular ejection fraction (LVEF), fractional shortening (FS), global longitudinal strain (GLS) and longitudinal strain (LS) as well as the incidence and timing of subclinical left ventricular dysfunction detected by these methods. Methods and Results A retrospective longitudinal study was performed with re‐analysis of longitudinal echocardiographic data, acquired during treatment and early follow‐up, including 41 pediatric sarcoma patients, aged 2.1–17.8 years at diagnosis, treated at Astrid Lindgren Children's Hospital, Stockholm, Sweden, during the period 2010–2021. All patients had received treatment according to protocols including high cumulative doxorubicin equivalent doses (≥250 mg/m2). In 68% of all 366 echocardiograms, LS analysis was feasible. Impaired LS values (40%, with concomitant impairment of either LVEF or FS in 20% and combined impairment of both LVEF and FS in <10%. Importantly, there were no cases of abnormal LVEF and FS without concomitant LS impairment. Conclusion Our findings demonstrate feasibility of LS in a majority of echocardiograms and a high incidence of impaired LS during anthracycline treatment for childhood sarcoma. We propose inclusion of LS in pediatric echocardiographic surveillance protocols

Controller and battery changes due to technical problems related to the HVAD® left ventricular assist device - a single center experience

Abstract Background The use of left ventricular assist devices (LVADs) has increased in the last decade. Major complications have been well described, but there is no data on device alarms and actual or threatening malfunction which impair quality of life and may impair outcomes. This study describes the technical problems related to the use of the HVAD® left ventricular assist device in a single center. Methods We retrospectively reviewed device malfunctions and outcomes in 22 patients with HVAD® left ventricular assist device followed at Karolinska University Hospital between 2011 and 2016. Device malfunction was defined by INTERMACS as a failure of one or more of the components of the LVAD system. The primary outcome was defined as death or hospitalization or unplanned urgent clinic visit due to device alarm of unknown significance or actual or threatening malfunction. Separate secondary outcomes were malfunction resulting in controller exchange and malfunction resulting in battery change. Exploratory outcomes were death, transplantation, or explantation because of recovery. Results Median age was 59 years and 19% were women. Over a mean follow-up time of 1.7 years (37 patient-years), the primary outcome occurred 30 times (0.8 events per patient-year; 0 deaths, 2 hospitalizations and 28 un-planned clinic visits). Secondary outcomes were 41 device malfunctions for 14 patients requiring 45 controller exchanges in 12 patients (1.1 events per patient-year) and 128 battery changes in 12 patients (3.5 events per patient-year). Exploratory outcomes were 8 deaths (36.4%), 7 transplantations (31.8%) and 2 explants due to recovery (9.1%). Conclusion The use of HVAD® was associated with technical problems requiring frequent un-planned clinic visits and changes of controller and/or batteries. There were no deaths due to device malfunction. Further studies are warranted to evaluate the risk of device malfunction and associated reductions in quality of life and cost

Circulating neuregulin1-beta in heart failure with preserved and reduced left ventricular ejection fraction

International audienceAims - Neuregulin1-β (NRG1-β) is released from microvascular endothelial cells in response to inflammation with compensatory cardioprotective effects. Circulating NRG1-β is elevated in heart failure (HF) with reduced ejection fraction (HFrEF) but not studied in HF with preserved EF (HFpEF). Methods and results - Circulating NRG1-β was quantified in 86 stable patients with HFpEF (EF ≥45% and N-terminal pro-brain natriuretic peptide >300 ng/L), in 86 patients with HFrEF prior to and after left ventricular assist device (LVAD) and/or heart transplantation (HTx) and in 21 healthy controls. Association between NRG1-β and the composite outcome of all-cause mortality/HF hospitalization in HFpEF and all-cause mortality/HTx/LVAD implantation in HFrEF with and without ischaemia assessed as macrovascular coronary artery disease was assessed. In HFpEF, median (25th-75th percentile) NRG1-β was 6.5 (2.1-11.3) ng/mL; in HFrEF, 3.6 (2.1-7.6) ng/mL (P = 0.035); after LVAD, 1.7 (0.9-3.6) ng/mL; after HTx 2.1 (1.4-3.6) ng/mL (overall P < 0.001); and in controls, 29.0 (23.1-34.3) ng/mL (P = 0.001). In HFrEF, higher NRG1-β was associated with worse outcomes (hazard ratio per log increase 1.45, 95% confidence interval 1.04-2.03, P = 0.029), regardless of ischaemia. In HFpEF, the association of NRG1-β with outcomes was modified by ischaemia (log-rank P = 0.020; P = 0.553) such that only in ischaemic patients, higher NRG1-β was related to worse outcomes. In contrast, in patients without ischaemia, higher NRG1-β trended towards better outcomes (hazard ratio 0.71, 95% confidence interval 0.48-1.05, P = 0.085). Conclusions - Neuregulin1-β was reduced in HFpEF and further reduced in HFrEF. The opposing relationships of NRG1-β with outcomes in non-ischaemic HFpEF compared with HFrEF and ischaemic HFpEF may indicate compensatory increases of cardioprotective NRG1-β from microvascular endothelial dysfunction in the former (non-ischaemic HFpEF), but this compensatory mechanism is overwhelmed by the presence of ischaemia in the latter (HFrEF and ischaemic HFpEF)

Sublethal caspase activation promotes generation of cardiomyocytes from embryonic stem cells.

Generation of new cardiomyocytes is critical for cardiac repair following myocardial injury, but which kind of stimuli is most important for cardiomyocyte regeneration is still unclear. Here we explore if apoptotic stimuli, manifested through caspase activation, influences cardiac progenitor up-regulation and cardiomyocyte differentiation. Using mouse embryonic stem cells as a cellular model, we show that sublethal activation of caspases increases the yield of cardiomyocytes while concurrently promoting the proliferation and differentiation of c-Kit+/α-actininlow cardiac progenitor cells. A broad-spectrum caspase inhibitor blocked these effects. In addition, the caspase inhibitor reversed the mRNA expression of genes expressed in cardiomyocytes and their precursors. Our study demonstrates that sublethal caspase-activation has an important role in cardiomyocyte differentiation and may have significant implications for promoting cardiac regeneration after myocardial injury involving exogenous or endogenous cell sources

New insights into the human heart development using a combined spatial and single-cell transcriptomics approach

Meeting Abstract: A123</p

Opposing effects of caspase inhibition on cardiac progenitor cell and differentiation markers expression.

<p>Relative mRNA levels of α-MHC (A), Nkx 2.5 (B), Isl1 (C), c-Kit (D) and Oct-4 (E) in EBs exposed to control vehicle or 10 μM Q-VD-OPH for the indicated times and then cultured for additional 7 days. * p<0.05 vs control, ** p<0.01 vs control.</p