Numerical simulation of dynamic seeding of mesenchymal stem cells in pore structure

Seeding of mesenchymal stem cells (MSC) into a porous scaffold, as the first step in bone tissue engineering, determines the initial cell spatial distribution and further generating of engineered bone grafts. The immersed boundary (IB)–lattice Boltzmann (LB) method is used to study the dynamic seeding behavior of cells in a simplified scaffold. In this method, the multiple-relaxation-time version of LB method is employed as the fluid solver. An energy constitutive model for the cell is coupled with the fluid using the IB method. An adhesive dynamics model is employed to simulate the stochastic formation and breakage of receptor–ligand bonds. The present method was first validated by studying a capsule deformation in a simple shear flow. The cell model was calibrated based on the deformation of the MSC in a constricted microfluidic channel. Then perfusion of cells into pore structures was simulated to characterize cell motion during the seeding process. The distribution of formed bonds indicates that cells most likely adhere to the pore throats. The cells present different motion characteristics due to distinct adhesion status. The number of bonds plays an important role in determining the adhesion status. The cell-scale deformation and adhesion involved in this study provide more detailed mechanism which is difficult to investigate through experiments. The present method can also be extended to large-scale realistic scaffold contributing to the optimization and development of the seeding process.