Figure 2.

Glycocalyx expression in C2C12 myoblasts and differentiated myotubes. (A,B) Immunofluorescent images of myoblasts cultured for 3 days and stained against hyaluronic acid (component of glycocalyx) by biotinylated hyaluronic acid binding protein (bHABP, green) and counterstained with DAPI (blue). (A) Top view image of cells after 3 days of culture show that only few myoblasts express hyaluronic acid (green). (B) Cross‐sectional image of myoblasts, as indicated by the white dotted line in figure A, shows that hyaluronic acid matrix is on top of the myoblast (white arrows). (C) C2C12 myotubes cultured for 7 days show abundant expression of hyaluronic acid. (D) Cross‐sectional image of myotubes shows hyaluronic acid at the myotube membrane (white arrows). Scale bars indicate 20 μM. These results confirm the presence of a glycocalyx on top of myotubes, whereas after 3 days of culture only few myoblasts show glycocalyx expression. For myotubes, enzymatic removal of hyaluronic acid matrix abolished the pulsating fluid shear stress induced NO production,30 indicating its importance for mechanosensing. Since most myoblasts do not seem to be covered by hyaluronic acids, mechanosensing might be different from that of cells with a well‐developed glycocalyx.