Abstract

Advances in material science and innovative medical technologies have allowed the development of less invasive interventional procedures for deploying implant devices, including scaffolds for cardiac tissue engineering. Biodegradable materials (e.g., resorbable polymers) are employed in devices that are only needed for a transient period. In the case of coronary stents, the device is only required for 6–8 months before positive remodelling takes place. Hence, biodegradable polymeric stents have been considered to promote this positive remodelling and eliminate the issue of permanent caging of the vessel. In tissue engineering, the role of the scaffold is to support favourable cell-scaffold interaction to stimulate formation of functional tissue. The ideal outcome is for the cells to produce their own extracellular matrix over time and eventually replace the implanted scaffold or tissue engineered construct. Synthetic biodegradable polymers are the favoured candidates as scaffolds, because their degradation rates can be manipulated over a broad time scale, and they may be functionalised easily. This review presents an overview of coronary heart disease, the limitations of current interventions and how biomaterials can be used to potentially circumvent these shortcomings in bioresorbable stents, vascular grafts and cardiac patches. The material specifications, type of polymers used, current progress and future challenges for each application will be discussed in this manuscript.

Highlights

  • The term cardiovascular disease (CVD) is used to describe a group of diseases that afflicts the structure and function of the heart or blood vessels [1], with the coronary heart disease (CHD) subset being responsible for the greatest cause of cardiovascular deaths

  • The radial strength of a stent is directly proportional to its tensile modulus, and bioresorbable scaffolds (BRS) made of poly L-lactic acid (PLLA) are about 100-fold weaker than stents made from stainless steel and cobalt chromium

  • Future implementations of biomaterials could involve a hybrid of these two sources in order to engineer specific properties that better suit their intended implantation [11]

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Summary

Introduction

The term cardiovascular disease (CVD) is used to describe a group of diseases that afflicts the structure and function of the heart or blood vessels [1], with the coronary heart disease (CHD) subset being responsible for the greatest cause of cardiovascular deaths. In cases where patients have experienced prior myocardial infarction (MI), the heart muscles are damaged and thinned [7] This will in turn result in inefficient pumping of the heart and can lead to complications such as cardiac arrythmias. The advent of tissue engineering and regenerative medicine spurred R&D efforts in producing treatment options such as bioresorbable stents, vascular grafts and cardiac patches. The adoption of polymeric biomaterials in cardiovascular applications has translated into various treatment options that can potentially improve patient outcomes [11]. The usage of polymeric biomaterials ranges from heart valve prostheses, stents, vascular grafts, cardiac patches and pacemakers. In the three subsections, the background, material considerations for choice of polymer and a brief overview on the progress will be discussed for bioresorbable coronary stents, vascular grafts and cardiac patches

Development of Coronary Stents
Polymers in BRS Application
Degradation Profile of BRS
Processing Methods
Extrusion
Dip Coating
Spinning and Braiding
Current BRS
BRS Clinical Experience
Looking Forward
Vascular Grafts
Polymers for Bioresorbable Vascular Graft Scaffold Application
Strategies and Approaches for a Bioresorbable Vascular Graft Scaffold
Fabrication of Bioresorbable Vascular Graft Scaffolds
Electrospinning
Gas Foaming
Emulsion Freeze Drying
Preclinical Studies of Bioresorbable Vascular Graft
Challenges Ahead
Cardiac Patches
Commercially Available Cardiac Patches
Material Choice for Cardiac Patches
Natural Biopolymers
Synthetic Materials
Material Fabrication—3D Bioprinting
Findings
Conclusions
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