Because the adult heart cannot regenerate itself following acute myocardial infarction, the organ is irreversibly damaged, often resulting In severely diminished performance. None of the therapeutic options currently employed are directed toward reversing or repairing the injury which occurs at the cellular level. A relatively new therapeutic option in development, cellular cardiomyoplasty (CMM) or transplantation of autologous primary skeletal muscle cells into the myocardium, offers potential for augmenting cardiac function in previously infarcted myocardium. In a rabbit model, our laboratory has previously demonstrated the successful engraftment of skeletal myoblasts in infarcted myocardium, which resulted in an improvement in both systolic and diastolic regional myocardial performance. Because of these promising findings there is potential clinical usefulness of this therapy. As a first step in translating these data from bench to bedside, this project is designed to extend findings made in a infarcted rabbit model to a large animal such as a pig, and to develop a basis for the use of cellular cardiomyoplasty in human cardiac disease including acute myocardial infarction.