The stimulation of myoblast differentiation by electrically conductive sub-micron fibers.

Myotubes assemble with bundles of myofibers to form the structural units in skeletal muscle. Therefore, myotube formation plays an important role in restoring muscular functions, and substrates to promote the differentiation of myoblasts to myotubes need to be developed for muscle tissue engineering. In this study, we developed electrically conductive composite fibers of poly(L-lactide-co-epsilon-caprolactone) (PLCL) blended with polyaniline (PANi) using an electrospinning method, and then investigated the effect of these composite fibers on the differentiation of myoblasts. The prepared PLCL/PANi fibers showed no significant difference in fiber diameter or contact angle, regardless of the incorporation of PANi. The fibers containing 30% PANi (PLCL/PANi-30) maintained elastic properties of maximum elongation at break (160+/-14.4%). The composite fibers were cytocompatible, as the DNA content on each fiber was similar for up to 8 days of C2C12 myoblast culture. After 4 days of culture, the number of cells positive for sarcomeric myosin was 3.6-times greater on the electrically conductive fibers (21+/-1 and 19+/-2 for PLCL/PANi-15 and -30 fibers, respectively) than on the PLCL/PANi-0 fibers (6+/-2). Furthermore, the level of myogenin expression detected on day 8 of culture on PLCL/PANi-15 was approximately 1.6-fold greater than the PLCL/PANi-0 fibers. Similar results were observed for the expression of other genes including troponin T (2-fold greater) and the myosin heavy chain gene (3-fold greater). These results indicate that electrically conductive substrates can modulate the induction of myoblasts into myotube formation without additional electrical stimulation, suggesting that these fibers may have potential as a temporary substrate for skeletal tissue engineering.