Chapter 24 - Cardiac responses to biomaterials

Abstract

The use of biomaterials for cardiac applications ranges from materials used in traditional medical devices such as pacemakers and implanted cardioverter defibrillators, to the use of polymeric hydrogels and nanoparticles for drug and cell delivery as part of novel tissue engineering strategies. One of the most essential requirements of a biomaterial for cardiac use is its biocompatibility. Herein we focus on the immune response to biomaterials for cardiac applications, in particular the foreign body response. This foreign body response causes early recruitment of macrophages and neutrophils to the biomaterial implantation site. This leads ultimately to the formation of a collagen and fibrin capsule around the implanted biomaterial. In traditional medical devices this has resulted in ultimate failure of the device and the requirement for replacement. In biomaterials for cell or drug delivery, such a fibrous capsule could reduce diffusion of therapy out of the device and supply of nutrients to cells within an implant, both of which could result in failure of the therapy. A number of strategies to reduce the foreign body response have been trialled including coating the biomaterial with “native” materials such as phospholipids, modulating the mechanical properties, addition of corticosteroids or angiogenic agents. Within our own group we have investigated the potential of using soft robotics to reduce the foreign body response, whereby we have developed an actuatable device that actively modulates the biomechanics of the biotic-abiotic interface by altering strain, fluid flow, and cellular activity in the peri-implant tissue. Furthermore, we have investigated the potential of taking advantage of the foreign body response to adhere materials to the heart reducing the need for sutures or adhesives. Advancing the understanding of the foreign body response will enable researchers to overcome or harness it in the development of next generation medical devices.