FIG. 1.

Models of tertiary bTBI. (A and B) For two-dimensional monolayer cultures, the cells are typically plated on a transparent flexible membrane and the membrane is either deformed using an air pressure pule (P, ΔP) to strain the cells in both directions (biaxial), or primarily only in one direction (uniaxial). Shown are illustrations of both techniques, with highlights of how the cells in a region of the membrane (the dark objects) are deformed from their initial shape (dashed lines), and then returned rapidly to their initial shape. (C) A less commonly used technique on monolayer cultures is using hydrodynamic shear (λ), which is applied to the surface of the cell monolayer, to induce a deformation in the cells. (D) A new three-dimensional technique to study the response of cells embedded within a three-dimensional structure is also shown. The cells (the dark spots) are within a three-dimensional hydrogel that is deformed in shear by applying a force (F(t), ΔF) to the top of the gel.