Myocyte replacement therapy: skeletal myoblasts.

Skeletal myoblasts function as precursors to adult skeletal myocytes. More so than other muscle progenitors, their capacity for de novo self-renewal and their positive functional effects in the cardiac environment have been demonstrated, even though they do not attain a cardiomyocyte phenotype. Autologous skeletal myoblasts are easily procured by established methods and can be administered into diseased myocardium safely and without technical difficulty, features that at this time set them apart from any other myogenic cell. Clinical studies in patients with chronic myocardial disease have consistently reported modest improvements in ventricular function and clinical status. Data from the Myogenesis Heart efficiency and Regeneration Trial (MYOHEART) trial are currently being evaluated. Larger, randomized, placebo-controlled studies in patients with congestive heart failure due to postinfarction systolic left ventricular dysfunction are under way, such as Myoblast Autologous Grafting in Ischemic Cardiomayopathy (MAGIC) and Multicenter Study of the Safety and Cardiovascular Effects Of Myoblasts in Congestive Heart Failure (MARVEL). The future role of skeletal myoblasts in the clinical setting will be determined by the results of randomized trials as well as by the investigation of subsequent generations of myoblasts, engineered for enhanced efficacy.