Modulation of left ventricular dilation remodeling with epicardial restraint devices in postmyocardial infarction heart failure

Multiscale Experimental and Computational Modeling Approaches to Characterize Therapy Delivery to the Heart from an Implantable Epicardial Biomaterial Reservoir

Delivery of therapeutic-laden biomaterials to the epicardial surface of the heart presents a promising method of treating a variety of diseased conditions by offering targeted, localized release with limited systemic recirculation and enhanced myocardial tissue uptake. A vast range of biomaterials and therapeutic agents using this approach been investigated. However, the fundamental factors that govern transport of the drug molecules from the biomaterials to the tissue are not well understood. Here, the transport of a drug analog from a biomaterial reservoir to the epicardial surface is characterized using experimental techniques and microscale modeling. Using the experimentally determined parameters, a multiscale model of transport is developed. The model is then used to study the effect of important design parameters such as loading conditions, biomaterial geometry, and orientation relative to the cardiac fibers on drug delivery to the myocardium. The simulations highlight the significance of the cardiac fiber anisotropy as a crucial factor in governing drug distribution on the epicardial surface and limiting factor for penetration into the myocardium. The multiscale model can be useful for rapid iteration of different device concepts and for determination of designs for epicardial drug delivery that may be optimal and most promising for the ultimate therapeutic goal.

Polysaccharide-based strategies for heart tissue engineering

Polysaccharides are abundant biomolecules in nature presenting important roles in a wide variety of living systems processes. Considering the structural and biological functions of polysaccharides, their properties have raised interest for tissue engineering. Herein, we described the latest advances in cardiac tissue engineering mediated by polysaccharides. We reviewed the data already obtained in vitro and in vivo in this field with several types of polysaccharides. Cardiac injection, intramyocardial in situ polymerization strategies, and scaffold-based approaches involving polysaccharides for heart tissue engineering are thus discussed.

Model-based design of mechanical therapies for myocardial infarction

The mechanical properties of healing myocardial infarcts are a critical determinant of pump function and the transition to heart failure. Recent reports suggest that modifying infarct mechanical properties can improve function and limit ventricular remodeling. However, little attempt has been made to identify the specific infarct material properties that would optimize left ventricular (LV) function. We utilized a finite-element model of a large anteroapical infarct in a dog heart to explore a wide range of infarct mechanical properties. Isotropic stiffening of the infarct reduced end-diastolic (EDV) and end-systolic (ESV) volumes, improved LV contractility, but had little effect on stroke volume. A highly anisotropic infarct, with high longitudinal stiffness but low circumferential stiffness coefficients, produced the best stroke volume by increasing diastolic filling, without affecting contractility or ESV. Simulated infarcts in two different locations displayed different transmural strain patterns. Our results suggest that there is a general trade-off between acutely reducing LV size and acutely improving LV pump function, that isotropically stiffening the infarct is not the only option of potential therapeutic interest, and that customizing therapies for different infarct locations may be important. Our model results should provide guidance for design and development of therapies to improve LV function by modifying infarct mechanical properties.