Searching for Preclinical Models of Acute Decompensated Heart Failure: a Concise Narrative Overview and a Novel Swine Model.

PURPOSE: Available animal models of acute heart failure (AHF) and their limitations are discussed herein. A novel and preclinically relevant porcine model of decompensated AHF (ADHF) is then presented. METHODS: Myocardial infarction (MI) was induced by occlusion of left anterior descending coronary artery in 17 male pigs (34 ± 4 kg). Two weeks later, ADHF was induced in the survived animals (n = 15) by occlusion of the circumflex coronary artery, associated with acute volume overload and increases in arterial blood pressure by vasoconstrictor infusion. After onset of ADHF, animals received 48-h iv infusion of either serelaxin (n = 9) or placebo (n = 6). The pathophysiology and progression of ADHF were described by combining evaluation of hemodynamics, echocardiography, bioimpedance, blood gasses, circulating biomarkers, and histology. RESULTS: During ADHF, animals showed reduced left ventricle (LV) ejection fraction < 30%, increased thoracic fluid content > 35%, pulmonary edema, and high pulmonary capillary wedge pressure ~ 30 mmHg (p < 0.01 vs. baseline). Other ADHF-induced alterations in hemodynamics, i.e., increased central venous and pulmonary arterial pressures; respiratory gas exchanges, i.e., respiratory acidosis with low arterial PO2 and high PCO2; and LV dysfunction, i.e., increased LV end-diastolic/systolic volumes, were observed (p < 0.01 vs. baseline). Representative increases in circulating cardiac biomarkers, i.e., troponin T, natriuretic peptide, and bio-adrenomedullin, occurred (p < 0.01 vs. baseline). Finally, elevated renal and liver biomarkers were observed 48 h after onset of ADHF. Mortality was ~ 50%. Serelaxin showed beneficial effects on congestion, but none on mortality. CONCLUSION: This new model, resulting from a combination of chronic and acute MI, and volume and pressure overload, was able to reproduce all the typical clinical signs occurring during ADHF in a consistent and reproducible manner.

Aliskiren inhibits prorenin-induced human aortic smooth muscle cell migration.

BACKGROUND: In the present study, we investigated the potential effect of aliskiren on smooth muscle cell (SMC) migration in response to prorenin. METHODS: Cultured human SMCs were incubated with angiotensinogen (ANG) (1.5 × 10(-7)M) and increasing concentrations of aliskiren (10(-6)-10(-5)M). After 24 h, SMC migration was assessed by Boyden's chamber chemotactic assay using prorenin as chemotactic factor (10(-8)M). The effect of aliskiren on RhoA and Rac activity was also determined by G-LISA assay and the lamellipodia formation by rhodamine-phalloidin staining. Changes in cell morphology were recorded in real-time using the iCelligence system. RESULTS: Aliskiren determined, at 10(-5)M, a significant inhibition of SMC migration induced by prorenin (-66.4 ± 18.1%; p < 0.05), while no significant effect was observed when PDGF-BB was utilized as chemotactic agent. Aliskiren also reduced Rac-GTP levels in response to prorenin (-54.2 ± 5.4%) without affecting the RhoA-GTP levels. Finally, aliskiren inhibited both the lamellipodia formation and morphological changes induced by prorenin with no significant effect on PDGF-BB activity. CONCLUSIONS: Taken together, we provide the first evidence of the inhibitory action of aliskiren on SMC migration induced by prorenin.

Aliskiren reduces prorenin receptor expression and activity in cultured human aortic smooth muscle cells.

INTRODUCTION: The recent discovery of a specific receptor for renin/prorenin (PRR) has added new interest to the potential pharmacological actions of aliskiren, the first direct renin inhibitor. MATERIALS AND METHODS: In the present study, to gain new insights into the pharmacological properties of aliskiren, we investigated the effect of aliskiren on PRR expression and activity in cultured human smooth muscle cells (HSMCs). RESULTS: Co-incubation of HSMCs with angiotensinogen (ANG) (1.5 × 10(-7)M) and prorenin (10(-8)-10(-7)M) resulted in an efficient production (within 4h) of angiotensin I, almost completely inhibited by 10(-5)M aliskiren (-86.0 ± 14.0%). In HSMCs stimulated with both ANG and prorenin, a 24h incubation with aliskiren (10(-6)-10(-5)M) resulted in a concentration-dependent reduction of PRR mRNA levels (IC(50) 4.6 × 10(-6)M). The cell surface expression of PRR determined by flow cytometry analysis was also reduced after incubation with aliskiren in a concentration-dependent manner. The lower levels of PRR were associated with a reduced expression of TGF-ß, PAI-1 and type I collagen mRNA. CONCLUSIONS: These results suggest a direct pharmacological action of aliskiren on PRR expression and its signalling pathway in HSMCs. This reported action of aliskiren may reveal a new scenario of the pharmacological properties of aliskiren.