Large animal models of pressure overload-induced cardiac left ventricular hypertrophy to study remodelling of the human heart with aortic stenosis

Abstract

Pathologic cardiac hypertrophy is a common consequence of many cardiovascular diseases, including aortic stenosis (AS). AS is known to increase the pressure load of the left ventricle, causing a compensative response of the cardiac muscle, which progressively will lead to dilation and heart failure. At a cellular level, this corresponds to a considerable increase in the size of cardiomyocytes, known as cardiomyocyte hypertrophy, while their proliferation capacity is attenuated upon the first developmental stages. Cardiomyocytes, in order to cope with the increased workload (overload), suffer alterations in their morphology, nuclear content, energy metabolism, intracellular homeostatic mechanisms, contractile activity, and cell death mechanisms. Moreover, modifications in the cardiomyocyte niche, involving inflammation, immune infiltration, fibrosis, and angiogenesis, contribute to the subsequent events of a pathologic hypertrophic response. Considering the emerging need for a better understanding of the condition and treatment improvement, as the only available treatment option of AS consists of surgical interventions at a late stage of the disease, when the cardiac muscle state is irreversible, large animal models have been developed to mimic the human condition, to the greatest extend. Smaller animal models lack physiological, cellular and molecular mechanisms that sufficiently resemblance humans and in vitro techniques yet fail to provide adequate complexity. Animals, such as the ferret (Mustello purtorius furo), lapine (rabbit, Oryctolagus cunigulus), feline (cat, Felis catus), canine (dog, Canis lupus familiaris), ovine (sheep, Ovis aries), and porcine (pig, Sus scrofa), have contributed to research by elucidating implicated cellular and molecular mechanisms of the condition. Essential discoveries of each model are reported and discussed briefly in this review. Results of large animal experimentation could further be interpreted aiming at prevention of the disease progress or, alternatively, at regression of the implicated pathologic mechanisms to a physiologic state. This review summarizes the important aspects of the pathophysiology of LV hypertrophy and the applied surgical large animal models that currently better mimic the condition.

Keywords: Angiogenesis; Aortic Stenosis; Cardiac Hypertrophy; Cardiac cell populations; Cardiac contractile activity; Cardiac homeostasis; Cardiac metabolism; Cardiac pathophysiology; Cardiomyocyte nucleation; Experimental surgical models; Fibrosis; Hypertrophic cardiomyocyte; Hypoxia; Immune infiltration; Inflammation; Large animal models; Left ventricular hypertrophy; Pressure overload.

Figure 1

Cardiac pathophysiology of aortic stenosis. An illustration of the cardiac phenotypes is provided, including the respective animal models where the different stages of the disease were reached/observed as validation.

Figure 2

Large animal models of left ventricular hypertrophy induced by cardiac pressure overload. Phenotypical characteristics of different animal models after inducing hypertrophy by pressure overload, and respective important scientific achievements and discoveries per animal.