Arterial Delivery of Genetically Labelled Skeletal Myoblasts to the Murine Heart: Long-Term Survival and Phenotypic Modification of Implanted Myoblasts

Abstract

The ability to replace damaged myocardial tissue with new striated muscle would constitute a major advance in the treatment of diseases that irreversibly injure cardiac muscle cells. The creation of focal grafts of skeletal muscle has been reported following the intramural injection of skeletal myoblasts into both normal and injured myocardium. The goals of this study were to determine whether skeletal myoblast-derived cells can be engrafted into the murine heart following arterial delivery. The murine heart was seeded with genetically labeled C2C12 myoblasts introduced into the arterial circulation of the heart via a transventricular injection. A transventricular injection provided access to the coronary and systemic circulations. Implanted cells were characterized using histochemical staining for beta-galactosidase, immunofluorescent staining for muscle-specific antigens, and electron microscopy. Initially the injected cells were observed entrapped in myocardial capillaries. One week after injection myoblasts were present in the myocardial interstitium and were largely absent from the myocardial capillary bed. Implanted cells underwent myogenic development, characterized by the expression of a fast-twitch skeletal muscle sarcoendoplasmic reticulum calcium ATPase (SERCA1) and formation of myofilaments. Four months following injection myoblast-derived cells began to express a slow-twitch/cardiac protein, phospholamban, that is normally not expressed by C2C12 cells in vitro. Most surprisingly, regions of close apposition between LacZ labeled cells and native cardiomyocytes contained structures that resembled desmosomes, fascia adherens junctions, and gap junctions. The cardiac gap junction protein, connexin43, was localized to some of the interfaces between implanted cells and cardiomyocytes. Collectively, these findings suggest that arterially delivered myoblasts can be engrafted into the heart, and that prolonged residence in the myocardium may alter the phenotype of these skeletal muscle-derived cells. Further studies are necessary to determine whether arterial delivery of skeletal myoblasts can be developed as treatment for myocardial dysfunction.

Targeted Cell Delivery Into Infarcted Rat Hearts by Retrograde Intracoronary Infusion: Distribution, Dynamics, and Influence on Cardiac Function

“…We have shown that MPCs grafted by antegrade intracoronary infusion disseminate throughout cardiac layers, proliferate, differentiate, and integrate into host myocardium in rat. 8,9 We have further reported that antegrade intracoronary MPC transplantation results in improvement of cardiac function of doxorubicin-induced failing hearts in rat. 10 This route has recently been applied for infusion of bone marrow stem cells into infarcted human hearts.…”

“…7 Cell delivery via the intracoronary route has theoretical advantages over direct intramuscular injection in global cell dissemination within the myocardium. 8,9 This method is also likely to result in less myocardial and graft injury. We have shown that MPCs grafted by antegrade intracoronary infusion disseminate throughout cardiac layers, proliferate, differentiate, and integrate into host myocardium in rat.…”

Systems approaches to preventing transplanted cell death in cardiac repair

“…Clonal populations of C2C12 cells stably transduced with a retrovirus encoding nuclear-localized β-gal [91] were expanded for use in this assay. β-gal labeled C2C12 cells have been previously delivered to the heart and measured by histology [92,93], establishing β-gal as a high-fidelity marker for grafted cells.…”

Human Mesenchymal Stem Cells Differentiate to a Cardiomyocyte Phenotype in the Adult Murine Heart

“…We have previously demonstrated survival and differentiation toward a slow-twitch muscle phenotype of C2C12 myoblasts arterially delivered into the murine heart. 3 Subsequent work demonstrated, in addition to myoblast survival in the injured myocardium, positive effects on remodeling and improvement in left ventricle performance. 4,5 The first human cellular cardiomyoplasty was recently reported using autologous myoblasts, with encouraging results.…”