A computational simulation to reveal effects of oscillatory flow on MSCs on polymeric scaffolds under dynamic culture condition

Worldwide, over a million bone injuries occur annually, in which bone grafting procedures have to be performed. A bone tissue engineering strategy suggests an auspicious alternative to current medical treatments. Shear stress is a dominant mechanical stimulus that increases the gene expression. The role of mechanical stimuli in Mesenchymal stem cells (MSCs) differentiation has been well explored. However, the effects of oscillatory flow on the biological cellular processes at the cell level: osteogenic differentiation, migration, and proliferation are poorly understood. In the present study, we used a fluid-structure interaction method to investigate the effects of the shear stress being applied to both poly (polyol sebacate) (PPS) and poly (lactic acid) (PLA) scaffolds as cell culture substrates under oscillatory fluid flow regimes, which are considered to be 0.5, 1, and 2 Hz within a parallel plate bioreactor. This system is designed based on an experimental study aimed to apply shear stress to MSCs seeded on a polymeric scaffold. However, the role of the oscillatory flow regime within it remains unclear. Our findings demonstrate that oscillatory fluid flow improve cellular activities. At the frequency of 0.5 Hz there was a more significant amount of WSS in both polymeric membranes. However, all the regimes were confirmed to be in the range of osteogenic differentiation (>0.001dyn/cm
²
). Furthermore, the PPS scaffold’s maximum and minimum wall shear stress was 0.2 and 0.05 dyn/cm
²
, respectively. The amount of wall shear stress was 0.04-0.3 dyn/cm
²
in the PLA scaffold. These promising results provide a numerical basis for exploring the MSCs fate on different polymeric scaffolds and frequencies.