In silico analysis of a parallel plate bioreactor to reveal effects of oscillatory flow on stem cells for bone tissue engineering applications

Abstract

Worldwide, over a million bone injuries occur annually in which bone grafting procedures must be performed. A bone tissue engineering strategy offers a promising alternative to current medical treatments. Shear stress is an important mechanical stimulus that increases gene expression. Here, a computational study was conducted to validate a parallel plate bioreactor used to enhance the mesenchymal stem cells’ differentiation. The effect of different oscillatory frequencies was evaluated on the wall shear stress experienced by a cell layer cultured on a polymeric scaffold, considering the cell layer as both elastic and viscoelastic materials. The results showed that the height of the channel had a considerable impact on the wall shear stress magnitude, where the amount of the shear stress decreased by about 80 % with the increase in height from 1 to 5 mm. Moreover, the cell layer experienced the highest wall shear stress at the frequency of 2 Hz reaching 4 mPa. At the cell level, assuming an oscillatory regime would boost the von Mises stress level by approximately 41 %, representing a significant change; however, there was a slight change between the amount of strain in the steady condition and at frequencies of 0.5 and 1 Hz. This information not only validated the design criteria for the bioreactor, including geometric parameters, but it also enabled an accurate understanding of the biological reactions of MSCs when subjected to mechanical stimulations in vitro. Additionally, the findings assist tissue engineers in testing and designing a suitable bioreactor before the manufacturing process.