Fibrosis is an accumulation of proteins including collagen in the extracellular space, which has previously been considered as irreversible damage in various cardiovascular diseases including heart failure and hypertension. The pathophysiology of fibrosis is currently better understood and can be evaluated by non-invasive methods. Here, the authors present briefly the impact and molecular mechanisms of fibrosis in the myocardium and the promising therapeutic candidates including anti-hypertensive therapies, heart-rate lowering drugs, anti-inflammatory agents, as well as other innovative approaches such as inhibitors of growth factors, miRNA or cell therapy. Surrogate end points allow for larger clinical trials than previously possible with endomyocardial biopsies, and magnetic resonance and molecular imaging should open new fields of research on cardiac fibrosis. Several pre-clinical findings are very promising, and some clinical data support the proofs of concept, mainly those with inhibitors of the renin-angiotensin system. These approaches open the field for regression of fibrosis and include the following: first, some of these drugs are widely used like renin-angiotensin system inhibitors; second, inflammation modulators; third, in near future entirely new approaches targeting the TGF-β pathways, or others like cell therapies or genetic interventions.

Coronary artery disease is characterized by atherosclerotic plaque formation. Despite impressive advances in intravascular imaging modalities, in vivo molecular plaque characterization remains challenging, and different multimodality imaging systems have been proposed. We validated an engineered bimodal intravascular ultrasound imaging (IVUS) / near-infrared fluorescence (NIRF) imaging catheter in vivo using a balloon injury atherosclerosis rabbit model. Rabbit aortas and right iliac arteries were scanned in vivo after indocyanine green (ICG) injection, and compared to corresponding ex vivo fluorescence and white light images. Areas of ICG accumulation were colocalized with macroscopic atherosclerotic plaque formation. In vivo imaging was performed with the bimodal catheter integrating ICG-induced fluorescence signals into cross-sectional IVUS imaging. In vivo ICG accumulation corresponded to ex vivo fluorescence signal intensity and IVUS identified plaques.

BackgroundThe toxicity of doxorubicin, leading to an irreversible heart failure, limits its use as chemotherapeutic agent. The beneficial effects of early administration of β-blocker were reported in patients with heart failure due to doxorubicin, suggesting an important role of β-adrenoceptors (β-ARs). This study aimed to identify a putative target (β-AR and/or its effectors) at the early phase of a chronic doxorubicin-induced cardiomyopathy (Dox-CM) in a rat model.MethodologyDox-CM was induced by six doxorubicin injections (cumulative dose: 15 mg.kg−1) and validated by echocardiography and left ventricle (LV) catheterization. The β-AR protein expressions in LV were evaluated by western-blot at days 35 (d35) and 70 (d70) after the first doxorubicin injection. Ex vivo cardiac contractility (dP/dtmax, dP/dtmin) was evaluated on isolated heart in response to specific β-AR stimulations at d35.ResultsAt d35, Dox-CM hearts were characterized by mild LV systolic and diastolic dysfunctions, which were exacerbated at d70. In Dox-CM hearts, β3-AR expression was only decreased at d70 (-37±8%). At d35, β1-AR expression was decreased by 68±6%, but ex vivo β1-AR function was preserved due to, at least in part, an increased adenylyl cyclase response assessed by forskolin. β2-AR expression was increased both at d35 (+58±22%) and d70 (+174±35%), with an increase of ex vivo β2-AR response at d35. Inhibition of Gi protein with pertussis toxin did not affect β2-AR response in Dox-CM hearts, suggesting a decoupling of β2-AR to Gi protein.ConclusionThis study highlights the β1/β2-AR imbalance in early Dox-CM and reveals the important role that β2-AR/Gi coupling could play in this pathology. Our results suggest that β2-AR could be an interesting target at early stage of Dox-CM.