Cyclic Mechanical Strain on Myoblasts

Myoblasts were seeded on the elastic membrane of the Bioflex 6-well plate coated with Collagen I (Flexcell International Corporation, Burlington, NC, USA) at a cell density of 3 × 10⁵ cells per well and were left to adhere overnight. The plate was placed on a circular shaped loading post of 25 mm in diameter. In the FlexCell FX-5000 tension system (Flexcell International Corporation, Burlington, NC, USA), the membrane was pulled downwards by vacuum suction which caused the membrane to stretch across the loading post. The cells received either 5% equibiaxial dynamic strain at a frequency of 1 Hz or constant, statical strain based on protocols from the literature [48 (link),50 (link)] and preliminary data. Cells were strained for 1 h followed by a rest period of 2 h. This loading was repeated for 3 times followed by a rest period of 4 h. One cycle took in total 13 h. The protocol was repeated for 24 h or 48 h.