Skeletal myoblasts fuse to form functional syncytical myotubes as an integral part of the skeletal muscle. During this differentiation process expression of proteins for mechanical and electrical integration is seized, which represents a major hindrance towards the application of skeletal myoblasts in cardiac regenerative cell therapy, as global heart function is dependent on intercellular communication.
We epicardially transplanted mechanically preconditioned engineered tissue constructs, containing neonatal mouse skeletal myoblasts. Y-chromosomal specific PCR was undertaken up to 10 weeks after transplantation to confirm the presence of grafted cells. Histological and electrophysiological analyses were carried out one week after transplantation.
Cells within the grafted construct expressed connexin 43 at the interface to the host myocardium, indicating electrical coupling, confirmed by sharp electrode recordings. Analyses on maximum stimulation frequency (5.65 ± 0.37 Hz), conduction velocity (0.087 ± 0.011 m/s) and sensitivity for pharmacological conduction block (0.736 ± 0.080 mM 1-heptanol) revealed effective electrophysiological coupling between graft and host cells, although significantly less robust than in native myocardial tissue (maximum stimulation frequency: 11.616 ± 0.238 Hz, p < 0.001; conduction velocity: 0.300 ± 0.057 m/s; p < 0.01; conduction block: 1.983 ± 0.077 mM 1-heptanol; p < 0.001).
While untreated skeletal myoblasts cannot couple to cardiomyocytes, we confirm that mechanical preconditioning enables transplanted skeletal myoblasts to functionally interact with cardiomyocytes in vivo and, thus, reinvigorate the concept of skeletal myoblast based cardiac cell therapy.
|Journal||The Journal of Thoracic and Cardiovascular Surgery|
|Publication status||Published - 1 Sep 2014|