The time course appearances of isometric contractile properties and muscle‐specific proteins in a novel three‐dimensional skeletal muscle model

Abstract

C2C12 cells were embedded in type‐I collagen gel solution at density of 1.0 × 107 cells/ml. The suspension was added to two artificial tendons(elastase treated porcine aorta). The medium was cultured for 2 days in growth medium and shifted to differentiation medium supplemented with 7% horse serum. The contraction force (F), the change ratio of contraction (dF/dt) and the change ratio of relaxation (dF/drt) were assessed at 7,14,21 days after onset of cultivation. The protein accumulation in myosin heavy chain (MHC) and electron micrograph (EM) were also assessed at 7,14,21 days after cultivation.Up to 14 days, F, dF/dt and dF/drt increased dramatically. In addition, the protein accumulations of α‐actin, fast and slow MHC also increased markedly. From 14 days to 21 days, F, dF/dt, dF/drt increased gradually, however, the protein accumulations of α‐actin, fast and slow MHC did not show remarkable change. At 21 days, the sarcomere structures and basal lamina were evident by EM.These results suggest that the appearances of contractile properties do not quite correspond to the appearances of muscle‐specific protein at latter stage in maturation of three‐dimensional skeletal muscle cells.