Cardiac-bio-assists: biological approaches to support or repair cardiac muscle

In contrast to those of other cardiac diseases, the morbility and morbidity of congestive cardiac insufficiency are not on the decrease, in spite of significant progress in pharmacological treatments and due to the increased life expectancy of the population. Cardiac transplant is the therapy of choice when cardiac failure becomes pharmacologically intractable, but all over the developed world (not to mention the situation in the underdeveloped countries) the number of heart transplants has reached the limit set by the availability of donor organs. Sooner or later xenotransplants could solve this problem, but even if our most optimistic hopes regarding their development and reliability are met, xenotransplants would still carry the risk of anthropozoonotic viral infections. Finally, as suggested in a recent overview, the way to the long-lasting clinical use of mechanical circulatory support is a long and winding road. Other options are related to tissue or cell cardiac bioassistance. Cardiac-bio-assists are biological approaches to the remedy of progressive cardiac failure based on autologous or heterologous tissue or cell transplantation. Some of the work hypotheses are in pre-clinical evaluation (skeletal muscle ventricle), others are under preliminary (cardiomyoplasty, myocardium reduction, implants of myoblasts derived from skeletal muscle satellite cells and implants of embryonic or adult stem cell-derived myocardiocytes, cellular cardiomyoplasty) or advanced clinical testing (dynamic aortomyoplasty and dynamic cardiomyoplasty). Dynamic cardiomyoplasty is a surgical procedure which could support myocardial function when cardiac insufficiency would become pharmacologically intractable in the mid term. In this procedure a nonessential muscle, the latissimus dorsi (LD), is diverted from its normal role, transferred into the chest, wrapped around the heart (LD wrap), conditioned to fatigue and activated during systole to provide cardiac assistance. The mechanisms of its action are discussed and the risk of myodystrophic lesions of the LD wrap which could reduce the work capability of the pericardial muscle prosthesis remains. We are now addressing some of these issues by means of clinical research on the group of Italian patients of demand dynamic cardiomyoplasty, and by means of animal experiments aimed at the development and testing of new surgical, clinical and biotechnological approaches. In particular, we will discuss whether the increase in the muscle mass of the distal part of the transposed LD is desirable and feasible or if it is mandatory.