Skeletal muscle tissue engineering using functional magnetite nanoparticles

Skeletal muscular tissues were constructed using magnetic force-based tissue engineering (Mag-TE) techniques. Mouse myoblast C2C12 cells labeled with magnetite cationic liposomes (MCLs) were seeded into a well of 24-well ultra-low cell attachment culture plates. When a magnet was positioned underneath the well, cells accumulated evenly onto the culture surface and formed a multilayered cell sheet. Furthermore, because an angiogenic potential of transplants is considered to be important for the long-term maintenance of cell survival and tissue functions, a vascular endothelial growth factor (VEGF) gene-modified C2C12 (C2C12/VEGF) cell sheets were also fabricated by the Mag-TE technique. The secretion level of C2C12/VEGF sheets was 3.0 ng/day, indicating that VEGF gene-expressing cell sheets were successfully fabricated. Since the shape of artificial tissue constructs can be controlled by magnetic force, a cellular string-like assembly was formed by placing a linear-shaped magnetic field concentrator with a magnet. These cellular sheets and strings shrank and did not maintain their shapes for an additional in vitro culture period during myogenic differentiation. On the other hand, when a silicone plug was positioned at the center of well during the fabrication of cell sheets, the cell sheets shrank and formed a ring-like assembly around the plug. After 6-d cultivation of cell rings in differentiation medium, the C2C12 cells differentiated to form multinucleated myotubes. Thus, these procedures can provide a novel strategy for skeletal muscular tissue engineering.