Myocardial Tissue Engineering

Many lives are lost due to heart diseases including myocardial infarction and cardiomyopathy. Recent reports have demonstrated that regenerative medicine has promising potential for recovering severe heart failure. Regenerative therapies for heart failure include cytokine, gene and cell therapy. Because many types of cardiovascular stem cells have been identified and their clinical potentials have been demonstrated for the past decade, cell injection therapy has most attracted both researchers and clinicians (Wollert 2008). On the other hand, significant cell loss due to washing out and cell death has become problematic in cell injection technique. So, as next generation of regenerative therapy for impaired heart, transplantation of myocardial patches fabricated by tissue engineering technology are emerging and are clinically applied. Furthermore, several challenges for fabricating functional myocardial tissues/organs, which are electrically communicated, pulsate synchronously and evoke contraction power, have also started (Zimmermann, Didie et al. 2006). These ambitious challenges may lead to reconstruction of malformed hearts and become alternative therapy for heart transplantation. Heart tissues are composed of high-dense cylindrical cardiomyocytes and fibroblasts with abundant vascular network and collagen-based extracellular matrix (ECM). Cardiomyocytes pulsate via sodium and calcium ion transient through cell membrane. They are also electrically coupled by gap junctions composed of connexion 43 and rapid electrical propagation realizes simultaneous beating as a whole. Continuous blood flow supplies oxygen and nutrition, and withdraw the waste for high metabolic demand of heart tissues. These structure and function produce mechanical contractions as a blood pump. Therefore the researchers should take into account high density culture of cardiomyocyte and surrounding cells, sufficient micro blood vessel fabrication, cell/ECM orientation and proper cell-to-cell coupling for engineering heart tissues/organs. Here, previous and current status of cell injection therapy, myocardial patch transplantation and pulsatile myocardial tissue fabrication is described with some future views.