Application of biomaterials in cardiology

Myocardial ischemia is leading cause of heart failure in all over the world. Following myocardial infarction the irreparable loss or dysfunction of cardiomyocytes occurs due to sudden deprivation of oxygen supply to the heart. Heart has very limited regeneration capacity as most of the myocytes seems to be terminally differentiated, only small fraction of myocytes retain the capacity to replicate. Until now, drug therapy, percutaneous cardiology procedures (coronary artery angioplasty performed with balloons and stents), electrophysiological approaches (pacemakers and implantable defibrillators), surgical procedures (coronary artery bypass grafts, ventricular remodeling, dynamic cardiomyoplasty), organ transplantation and mechanical circulatory assistance devices are used as treatment when hearts are irreparably damaged.

It becomes evident that is a need to develop more effective, less invasive, therapeutic strategies for heart failure. Stem cells based therapies give new hope in the field of regenerative medicine, as stem cells have ability to differentiate into same as well as different tissue types and to regenerate themselves without losing their differentiation potential. This property of differentiation is being explored for the regeneration of several damaged tissues.

From Stem Cell Therapy to Tissue Engineering

It seems important to provide a safe environment (niche) for cell homing, proliferation and differentiation. The use of antioxidant, anti-inflammatory, angiogenic and antiapoptotic products may give better survival of transplanted cells.

Cardiac ECM is mainly composed of collagens, elastins, fibronectin, laminin and signaling molecules which give structural strength to the ventricles. After myocardial infarction, not only the changes affect the contractile element of the myocardium (cardiomyocytes) but also the extracellular matrix. Cardiomyocyte death and scar formation, which are caused by coronary artery occlusion, modulate cardiac remodeling: ischemic heart disease may progress inducing geometric alteration of the ventricular cavity (from elliptical to spherical), heart dilatation is a negative symptom in the evolution of heart failure patients, related with morbidity and mortality.

Natural and synthetic biomimetic scaffolds are in development, the main goal of these tissue engineered materials is to allow cell attachment and migration, deliver and retain cells and biochemical factors and enable diffusion of vital cell nutrients. These porous materials should offer a suitable microenvironment needed for cell survival and function, 3D scaffolds should mimic the natural extracellular environment features sufficiently as they would in vivo, cells in tissue are surrounded by a dynamic cell type-dependent extracellular matrix responsive to their environment. After initial development of “in-vitro tissue engineering” approaches, progress has been made by the development of “in-vivo tissue engineering” technologies, a biomimetic approach where the body is the own bioreactor. This in-vivo approach represents a new hope for the creation of bioartificial organs and biomimetic tissues, like elastomeric semi-bioabsorbable “Cardiopatch” to be used as bioartificial myocardium.