Figure 3.

Collagen is inhibitory to myoblast fusion and mechanical strain-induced growth in vitro. Experimental design for in vitro mechanical stimulation of myotubes with modification of substrate (A). After 2 d of culture, C2C12 myoblasts were differentiated for 2 d in the presence of LM-111 only or a LM-111-collagen mixture in the presence of low-magnitude uniaxial strain (10%) to induce myotube alignment (perpendicular to strain). After 3 days of rest, aligned myotubes were rotated 90° and exposed to 20 min of high-magnitude uniaxial strain (18%) (Post Strain Group) or remained unstrained (Control), then evaluated 24 h later. Myoblast tube development was reduced with the addition of collagen (B, C), and myotube diameter was suppressed in response to strain with the addition of collagen (D). The number of myotubes in the range of 20–30 µm were robustly increased in the presence of laminin only, but suppressed with the addition of collagen (E). n = 6/group. ^‡ vs all groups. All values are mean ± SEM. Data are expressed relative to laminin only control.