Myoblast-mediated fusion-injection: a new technique for introduction of macromolecules specifically into living skeletal muscle cells.

A new technique for the introduction of macromolecules specifically into living skeletal muscle cells has been developed by a modification of the red blood cell ghost-mediated fusion-injection technique [M. Furusawa (1980) Int. Rev. Cytol. 62, 29-67]. Fluorescein-labeled bovine serum albumin (FITC-BSA) was introduced into chicken skeletal muscle myoblasts by the human red blood cell-mediated fusion-injection method in the presence of polyethylene glycol. Myoblasts loaded with FITC-BSA were then purified by a fluorescence cell sorter and cocultured with myotubes. Specific cell fusion between myoblasts and myotubes occurred under normal culture conditions and BSA was successfully introduced into living myotubes. This technique may provide a new method not only for the study of a given macromolecule's function in living muscle cells but also for therapeutic purposes such as muscle-specific drug delivery.