Delivery of primary autologous skeletal myoblasts into rabbit heart by coronary infusion: A potential approach to myocardial repair

Myocardial repair after injury is limited because the adult heart cannot regenerate. We propose using autologous skeletal muscle cells (myoblasts) as a source of reserve cells for repair of regions of damaged myocardium. This report examines two potential methods for the transfer of cells to the myocardium: selective coronary catheterization, and myoblast infusion or myoblast injection directly into the left ventricular wall. Autologous, primary rabbit skeletal myoblasts were harvested, were transduced ex vivo with adenoviruses expressing the Escherichia coli β-galactosidase (β-gal) gene, and were infused selectively into the coronary circulation or injected directly into the myocardial wall. After either delivery method, β-gal expression was detectable at the earliest times examined (3 days) and persisted for several weeks. The method of delivery influenced the spatial pattern of β-gal expression. After direct injection, a localized concentration of myoblasts that decreased with distance from the injection site was visible primarily in the myocardial layer of the ventricle, although occasional staining could be detected in other layers. After coronary infusion, discrete punctate or linear foci of β-gal expression were found throughout the distribution of the left coronary circulation in all cardiac layers. After infusion or injection, β-gal-positive cells were seen in direct physical apposition to cardiocytes; interestingly, β-gal could be detected also in some branched cells with clear cross-striations. Autologous myoblasts survived with no obvious dysrhythmic effects despite their presence in extensive or discrete loci in the myocardium. These observations provide the first evidence that myoblast transfer is possible by catheter-based methods, and they create the basis for studies to investigate the functional consequences of myoblast infusion in damaged heart.