| dc.description.abstract | Myokine secretion during muscle contraction may influence bone tissue formation. In order to investigate their relationship, we would like to induce myokine secretion in in vitro plateform. Conductive polypyrrole (PPy) was deposited onto the surface of polydimethylsiloxane (PDMS) to obtain a highly stretchable conductive membrane, which was used to construct a bioreactor. C2C12 myoblasts were seeded and differentiated to form myotubes on the bioreactor, which can be electrically stimulated to induce active contraction or cyclically stretched to allow passive cellular deformation. Both IL-6 and CXCL-1 myokines can be secreted from myotubes under electrical stimulation, which be maintained for 24 hours and their secretion increased with voltage. As we performed continuous cyclic stretching or electrical stimulation to myotubes for 24 h, and the qPCR results showed that many myokines could be up-regulated by both stimuli, but some can only be boosted through cyclic stretching. These conditioned media were used to differentiate osteoblasts and osteoclasts. Osteogenic differentiation genes can be upregulated by conditioned media, which were further promoted when the conditioned media were collected from stimulated myotubes. These trends were found in alizarin red staining and calcium quanrification experiments, and the promotion effect of cyclic stretching was better than that of the electrical stimulation. On the other hand, conditioned media down-regulated osteoclastic differentiation genes, and the results of tartrate-resistant acid phosphatase (TRAP) staining also demonstrated that osteoclast formation was inhibited by these conditioned media. Our results showed that myokine genes can be upregulated by both cyclic stretching and electrical stimulation, and their secretions not only improved bone formation but also inhibited osteoclast differentiation. Therefore, myokines are potential for the treatment of bone disease, and our developed bioreactor can be used as an in vitro platform for relative research. | en_US |