Modeling the mechanics of fibrous-porous scaffolds for skeletal muscle regeneration.

The scaffolds for skeletal muscle regeneration are designed to mimic the structure, stiffness, and strains applied to the muscle under physiologic conditions. The external strains are also used to stimulate myogenesis of the (stem) cells seeded on the scaffold. The time- and location-dependent mechanics inside the scaffold determine the microenvironment for the seeded cells. Here, fibrous-porous cylindrical scaffolds under the action of external cyclic strains are considered. The scaffold mechanics are described as two-phase (poroelastic) where the solid phase is associated with the fibers and the fluid phase is associated with the liquid-containing pores. In response to an applied cyclic strain, pressure oscillates and fluid moves radially toward and away from the axis of the scaffold. We compute the directions and magnitudes of the radial gradients of the poroelastic characteristics (solid-phase displacement, strain, and velocity; fluid-phase pressure and velocity; relative fluid-solid-phase velocity) determined by the boundary conditions and geometry of the scaffold. Several kinds of the external cyclic strain are analyzed and the resulting poroelastic functions are found. The poroelastic characteristics are obtained in closed form which is convenient for further consideration of myogenesis of the seeded cells and ultimately for the design of the scaffolds for skeletal muscle regeneration. Graphical abstract.