The use of anisotropic cell sheets to control orientation during the self-organization of 3D muscle tissue.

In some parts of native tissues, the orientation of cells and/or extracellular matrixes is well organized. We know that because anisotropy produces important tissue functions, an appropriate anisotropy needs to be designed to biomimetically construct complex tissue. Here, we show the unique features of anisotropic myoblast sheets for organizing the three-dimensional (3D) orientation of myoblasts and myotubes. Utilizing a micropatterned thermoresponsive surface, human skeletal muscle myoblasts were aligned on the surface, and manipulated as a single anisotropic cell sheet by reducing the culture temperature. Consequently, layering of anisotropic myoblast sheets using gelatin gel allowed 3D myotube constructs to be built up with the desired anisotropy. We also discovered a surprising myoblast behavior. An anisotropic cell sheet placed on top of other cell sheets in fabricating thick tissue was able to change the cell orientation in several layered cell sheets underneath. This self-organization is believed to provide the uniqueness required in designing 3D cell orientation architecture for reconstructed muscle tissue.