Abstract
Cell behaviors such as morphology, proliferation, and differentiation, are influenced by mechanical strain applied to cells. To study these mechanical responses, cells are often cultured on an elastic membrane and deformed by stretching the membrane. Traditionally, mechanical stimuli involve repetitive stretching and contracting in the same direction. However, in vivo tensile forces can vary in direction. To address this, we developed a "rotational strain field" where the tensile direction rotates. We created a device and a square elastic chamber with an elastic membrane at its bottom to apply this strain field to an osteoblastic cell line MC3T3-E1. Unexpectedly, the cells aligned in the directions parallel to the chamber edges to form a cross pattern, suggesting that the strain field was not uniform. Analysis revealed that the chamber deformed anisotropically, with strains in the direction of the edges being only one-third of those in the diagonal direction, due to lateral bending of the chamber wall. To achieve an isotropic rotational strain field, we redesigned the chamber by adding rigid rods along the edges to prevent the bending. This adjustment resulted in nearly uniform deformation of 8.7% to 9.9% across all directions. When MC3T3-E1 cells were subjected to an isotropic rotational strain field at 60 rpm counterclockwise, they exhibited random orientation, contrasting with the aligned pattern seen under anisotropic conditions. Future research will involve detailed quantitative analysis of cell morphology changes, the effects of rotational direction and speed, and how variations in cell tension influence responses.
