Antisenescence in vitro potency of extracellular vesicles secreted by cardiosphere-derived cells predicts the antihypertrophic effect in a rat model of cardiac ageing

Background

Cardiac ageing is characterized by hypertrophy and diastolic dysfunction and related with heart failure with preserved ejection fraction, an unmet medical need for treatments development. Cardiosphere-derived cells (CDCs) have demonstrated glimpses of efficacy in old animals with cardiac dysfunction, however variability of effect among different CDC-donors is observed.

Purpose

To identify markers of in vitro potency of CDCs and to test it in an in vivo model of cardiac ageing.

Methods

CDCs were derived from cardiac biopsies of forty patients (age range 0 - 81 years old, 16 females) who underwent cardiac surgery for other reasons. CDC-secreted extracellular vesicles (CDC-EVs) were purified and used in in vitro and in vivo experiments. Since anti-ageing effect was targeted in vivo, in vitro potency of CDC-EVs was checked in terms of their anti-senescence bioactivity. A panel of six parameters (genetic, secretory and cellular) related with cellular senescence were analysed in vitro for all 40-donors CDC-EVs and those with most favourable and unfavourable profiles were classified as potent (P-EVs) and non-potent (NP-EVs), respectively. P-EVs and NP-EVs were then tested in vivo in 25 rats with D-galactose-induced cardiac ageing and 7-healthy controls in a randomized blinded study.

Results

In vitro, despite variations in the extent of the observed effect, all CDC-EVs significantly reduced cellular senescence and increased IL-6 secretion of human cardiac stromal cells. Most CDC-EVs decreased the expression of senescence-related genes (p21, p16, p53, TGF-b). Based on the observed profiles as P-EVs were selected CDC-EVs from 75- and 14-years old donors and as NP-EVs from 73-years old. In vivo, 3-months old SD-rats (30% female) after 3-months of daily intraperitoneal injections of saline (healthy control) or D-Gal, were randomly allocated (D-Gal group) to receive intraperitoneal injection of saline (sham control, n=12), P-EVs (n=7), NP-EVs (n=6) and followed-up for one month. While sham control group developed myocardial hypertrophy compared to healthy control animals (heart/body weight 2.7 vs. 2.2 mg/gr, p=0.03), this effect was prevented by P-EVs but not by NP-EVs (2.5 vs. 2.9 mg/gr, p=0.02). This finding was in parallel to the levels of serum antioxidants which were increased in sham vs healthy (p=0.02) and in sham vs. P-EVs (p=0.01) but levels in NP-EVs were similar to the sham group.

Conclusions

Anti-senescence in vitro effect of CDC-EVs is correlated to their therapeutic efficacy in vivo model of cardiac ageing. The relevance of this study is double: identification of senescence-related markers as determinant of therapeutic potency of the tested product and confirming the potential utility of CDC-EVs as therapy for cardiac ageing-related pathologies.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III, Ministerio de Ciencia e Innovaciόn,CIBERCV, Spain

Extracellular vesicles secreted by human cardiosphere-derived cells attenuate electrophysiological remodelling in an in vitro model of atrial fibrillation

Background

Stem cells and their secreted extracellular vesicles (EVs) have shown different cardioprotective effects. However, their impact on the electrophysiological properties of the heart tissue remains controversial. While the use of some progenitor cells seems to have antiarrhythmic potential, the use of cardiomyocyte-like cells may be proarrhythmic. The mechanisms behind, and whether these effects are linked to cell engraftment and not to their secreted products is not fully known.

Purpose

The aim of this study was to investigate the electrophysiological modifications induced by extracellular vesicles secreted by human cardiosphere-derived cells (CDC-EVs) in an in vitro model of atrial fibrillation in order to explore their potential antiarrhythmic effect.

Methods

CDCs were derived from cardiac biopsies of patients who underwent cardiac surgery for other reasons. Purified CDC-EVs resuspended in serum-free media (SFM) vs. SFM alone were added to HL-1 atrial myocyte monolayers presenting spontaneous fibrillatory activity. After 48 hours, the monolayers were fully confluent, and the electrophysiological properties were analysed through optical mapping in both the treated (n=9) and control plates (n=9). Optical mapping recordings of the monolayers were analysed with Matlab for the activation frequency, activation complexity, rotor dynamics (curvature and meandering) and conduction velocity.

Results

CDC-EVs reduced activation complexity of the fibrillating atrial monolayers by ∼40% (2.74±0.59 vs. 1.61±0.16 PS/cm2, p<0.01). This reduction in activation complexity was accompanied by larger rotor meandering (1.47±0.82 vs. 4.32±2.25 cm/s, p<0.01) and decreased curvature (1.79±0.40 vs. 0.87±0.24 rad/cm, p<0.01) in the treated group. Despite reduction in the activation complexity, activation frequency did not change significantly between both groups. This could be in part because CDC-EVs increased conduction velocity by 80% (1.32±0.57 vs. 2.65±0.87 cm/s, p<0.01). Low conduction velocity has been linked to higher reentry recurrence, and lower meandering and higher curvature to higher rotor stability and harder AF termination. Therefore, CDC-EVs seem to drive cardiomyocytes to a less arrhythmic profile reducing activation complexity and preventing remodelling by increasing conduction velocity and modifying rotor dynamics.

Conclusions

CDC-EVs significantly modify conduction velocity and rotor dynamics, therefore reducing fibrillation complexity and remodelling to drive atrial myocytes to a less arrhythmogenic profile. Testing CDC-EVs in more robust models of atrial fibrillation, the most common sustained arrhythmia in humans with significant morbidity and mortality, is of special interest.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III, Ministerio de Ciencia e Innovaciόn,CIBERCV, Spain Figure 1

Sex differences in patients with ischemia and no obstructive coronary disease subjected to intracoronary acetylcholine test in a multicenter registry

Background

Ischemia with no obstructive coronary disease (INOCA) is increasingly diagnosed because of wide performance of coronary angiography. Prevalence of INOCA is higher in women than in men, however the exact pathophysiological mechanisms which may explain this phenomenon are still not very well understood.

Objective

To evaluate differences in clinical and procedural characteristics between men and women with INOCA subjected to intracoronary acetylcholine test (Ach).

Methods

A total of 210 women and 148 men with INOCA diagnosed with coronary angiography, were prospectively enrolled in a multicenter, observational registry. Ach test was performed according to clinical indications in all included patients. After 1-year patients were re-evaluated for major cardiovascular events, angina symptoms and prescribed medical treatment.

Results

Mean age of 60.6±13.6 years old was similar in both populations, but differences were observed in the prevalence of risk factors: active smoking was more frequent among men (43% vs. 17%, p<0.001), who had also a higher number of associated risk factors (≥3 risk factors were present in 31.2% of men vs. 20.2% of women, p<0.01) and more frequent history of percutaneous coronary revascularization (14.2% vs. 6.7%, p=0.03). Women were more prone to have dyspnea than men (35.5% vs. 20.8%, p=0.01). Men had more coronary atherosclerosis in angiography (57.9% vs. 43.7%, p=0.01) and more slow flow in the left anterior descending artery (21.6% vs. 9.0%, p=0.001). Ach was positive in 36.5% of patients, similar in both sexes, with no differences in the type of induced coronary spasm. Among those with a positive Ach test, at one-year, 36% of women vs. 43.6% of men were on optimal medical treatment for vasospasm although the difference was not statistically significant. Importantly, 41.5% of women and 38.1% of men experienced severe symptoms of angina during follow-up.

Conclusions

Although men with INOCA have a higher risk profile than women and more coronary atherosclerosis, one third of patients present endothelial dysfunction, similar in both groups, indicating that probably other pathophysiological mechanisms are responsible for it in females. Treatment in these patients remains suboptimal and associated with highly impaired quality of life.

Funding Acknowledgement

Type of funding source: None

Clinical profile and predictors of positivity of acetylcholine test in patients with angina and no obstructive coronary artery disease. Results of a multi-center mediterranean registry

Background

Coronary endothelial dysfunction and vasospasm are potential causes of ischemia in no obstructive coronary disease (INOCA) and are now known to be associated with an increased risk of major cardiovascular events (MACE) and impaired quality of life. The recent guidelines recommend the use of intracoronary acetylcholine to unravel the underlying pathophysiology of INOCA, by identifying those with endothelial dysfunction, and to guide future treatment in these patients.

Objective

To evaluate the clinical profile and prevalence of endothelial dysfunction in patients with INOCA, and to identify the predictors of positivity of the acetylcholine test.

Methods

A total of 358 patients with INOCA were prospectively enrolled in a multicenter observational study. Coronary angiography and acetylcholine test were performed according to clinical indications in all included patients. Patients were followed-up for 1-year for MACE and clinical reevaluation of symptoms.

Results

Patients' mean age was 60.6±13.5 y.o. and 58.7% were females, with no previous history of coronary heart disease in 76% of cases. Regarding clinical presentation, 56.9% had angina at rest, 59.9% exertional angina, and 29.5% dyspnea. In 39% the EKG was abnormal, and in 10.9% there was a troponin rise.

Coronary endothelial dysfunction –defined as a vasoconstriction over 30%– was observed in 129 (36%) patients, and severe vasoconstriction (>70%) in 75 (21%). Of positive cases, 47 (36%) focal vasoconstriction, and 90 (70%) diffuse. On follow-up, patients with a positive Ach test were treated differently, with a lower prescription of betablockers (12% vs. 24%, p=0.01) and a higher use of vasodilators (47% vs. 28.5%, p=0.001). Guidelines-recommended optimal treatment was prescribed to 39.2% of patients with a positive acetylcholine test. Patients with positive acetylcholine test were more prone to having worsening angina (25.6% vs. 12.8%, p<0.01) and minimal exertion angina (40% vs. 26.7%, p=0.03) on follow-up. Multivariable regression analysis showed that acetylcholine test positivity was predicted by the presence of diabetes (OR 1.7, p=0.04), exertional angina (OR 1.2, p=0.04), coronary atherosclerosis (OR 1.8, p=0.02) and coronary milking (OR 2.6, p=0.04).

Conclusions

Endothelial dysfunction detected by acetylcholine test was present in one third of patients with INOCA and was associated with more severe and worsening symptoms. Although Ach test positivity influenced the pharmacological treatment at discharge, a large room for optimization still remained.

Funding Acknowledgement

Type of funding source: None

Lack of effect of the ghrelin gene-derived peptide obestatin on cardiomyocyte viability and metabolism

Obestatin is a recently discovered peptide encoded by the ghrelin gene that opposes ghrelin effects on food intake and gastrointestinal function. The biological activity of obestatin depends on amidation at its carboxyl terminus and on its postulated binding to the orphan G protein-coupled receptor 39 (GPR39). We have previously demonstrated that ghrelin is synthesized by cardiomyocytes and has direct effects on its viability. Our aim was to know if obestatin, derived from the same gene as ghrelin, also affects cardiomyocyte physiology. By RT-PCR and immunocytochemistry we have demonstrated that murine cardiomyocytes cultured in vitro and human atrial tissue express GPR39 receptor. Competitive binding studies with radioiodine 125I-labeled obestatin recognized specific binding sites for this peptide in the murine cardiomyocyte cell line HL-1. However, obestatin did not modify the cell cycle or viability of these cells, and it was not able to prevent the cytosine arabinoside-induced apoptosis of HL-1 cardiomyocytes, as assessed by Hoechst dye vital staining, flow cytometry analysis and determination of lactate dehydrogenase in the culture media. Finally, treatment with obestatin did not affect fatty acid or glucose uptake by HL-1 cardiomyocytes. In conclusion, obestatin is not a relevant metabolic or viability modifier for cardiomyocytes.

Heart failure in patients with preserved and deteriorated left ventricular ejection fraction

OBJECTIVES

To determine clinical and prognostic differences between preserved and deteriorated systolic function (defined as left ventricular (LV) ejection fractions > or = 50% and < 50%, respectively) in patients with heart failure satisfying modified Framingham criteria.

PATIENTS AND METHODS

Records were studied of 1252 patients with congestive heart failure (CHF) (mean (SD) age 69.4 (11.7) years; 485 women, 767 men) who had been admitted to a cardiology service for CHF in the period 1991-2002 and whose LV systolic function had been echocardiographically evaluated within two weeks of admission. Data were collected on the main clinical findings, supplementary examinations, treatment, and duration of hospitalisation. Whether the patient was alive in the spring of 2003 was evaluated by searching the general archives of the hospital and by telephone survey.

RESULTS

LV systolic function was preserved in 39.8% of patients. Age, female to male sex ratio, and prevalence of atrial fibrillation, valve disease, and other non-ischaemic, non-dilated cardiopathies were all significantly greater in the group with preserved systolic function. New York Heart Association functional class IV, third heart sound, jugular vein congestion, cardiomegaly, radiological signs of lung oedema, pathological Q waves, left bundle branch block, sinus rhythm, ischaemic cardiopathy, and dilated cardiomyopathy were all significantly more prevalent in the group with deteriorated systolic function, as was treatment with angiotensin converting enzyme inhibitors and most other antihypertensive drugs on discharge from hospital. There was no significant difference in survival between the groups with preserved and deteriorated systolic function (either survival regardless of age at admission or in subgroups aged < 75 and > or = 75 years at admission). In the whole group, survival rates after one, three, and five years were 84.0%, 66.7%, and 50.9%, respectively.

CONCLUSION

In view of the poor prognosis of patients with CHF with preserved LV systolic function, who are currently treated empirically, it is to be hoped that relevant controlled clinical trials under way will afford information allowing optimisation of their treatment.

Atomic arrangement of iodine atoms inside single-walled carbon nanotubes

We report atomic resolution Z-contrast scanning transmission electron microscopy images that reveal the incorporation of I atoms in the form of helical chains inside single-walled carbon nanotubes. Density functional calculations and topological considerations provide a consistent interpretation of the experimental data. Charge transfer between the nanotube walls and the I chains is associated with the intercalation.