Modeling of the Flow within Scaffolds in Perfusion Bioreactors

Abstract

Tissue engineering aims to produce artificial organs and tissues for transplant treatments, in which cultivating cells on scaffolds in bioreactors is of critical importance. To control the cultivating process, the knowledge of the fluid flow inside and around a scaffold in the bioreactor is essential. However, due to the complicated microstructure of a scaffold, it is difficult, or even impossible, to gain such knowledge experimentally. In contrast, numerical methods employing computational fluid dynamics (CFD) have proven promising to alleviate the problem. In this research the fluid flow in perfusion bioreactors is studied with numerical methods. The emphasis is on investigating the effect of the controllable parameters in both the scaffold fabrication (i.e., the diameter of scaffold strand and the distance between two strands) and cell culture process (i.e., the flow rate) on the distribution of shear stress within the scaffold in a perfusion bioreactor. The knowledge obtained in this study will allow for improved control strategies in scaffold fabrication and cell culturing experiments.

Rapid Prototyping Assisted Scaffold Fabrication for Bone Tissue Regeneration

“…Al., (2011) in which fluid flow in both perfusion and non-perfusion is modeled in computational fluid dynamics (CFD) environment and shear stresses at the surface of the scaffold were computed. It was seen that the shear stress value increased with the increase in the strand diameter in perfusion bioreactor and is very high as compared to non-perfusion and hence it detached the cells from the surface of the scaffold and cell growth is hampered (Yan, Chen, & Bergstrom, 2011). Distribution of cells after perfusion seeding in a tissue engineered scaffold is influenced by its pore architecture.…”

Fluid flow and mass transfer over circular strands using the lattice Boltzmann method

“…shear stresses, to the cells attached to the scaffolds. The perfusion bio-reactor shows significant promise compared to the other static or non-perfusion bio-reactors [1,2]. In perfusion bio-reactors, the fluid is directed to flow through a porous scaffold and the movement of the fluid inside the bio-reactor is slow, typically within the creeping flow region.…”

“…With advances in the rapid prototyping techniques, many of the tissue scaffolds are made of arrays of circular strands. The diameter of the circular strands of a scaffold varies from 0.1 to 0.4 mm, and the distance between two strands also varies from 0.1 to 0.4 mm [1]. The average velocity inside the scaffold placed in a perfusion bio-reactor is approximately 3.5 × 10 −4 m/s [1], and typically the Reynolds number (Re D ) based on the diameter of the scaffold strands ranges from 0.01 to 0.1 [1,3].…”

“…The diameter of the circular strands of a scaffold varies from 0.1 to 0.4 mm, and the distance between two strands also varies from 0.1 to 0.4 mm [1]. The average velocity inside the scaffold placed in a perfusion bio-reactor is approximately 3.5 × 10 −4 m/s [1], and typically the Reynolds number (Re D ) based on the diameter of the scaffold strands ranges from 0.01 to 0.1 [1,3]. As part of a comprehensive study of the flow and transport process through a porous tissue scaffold, this study considers the fluid flow and mass transfer phenomena over a single circular strand and between two parallel circular strands for the physical culture conditions.…”

“…In tissue engineering, scaffolds seeded with cells are typically placed inside bio-reactors to induce the generation of adequate new tissues prior to their implementation to lesion sites [1]. Bio-reactors play a very important role in this in vitro cell culture process by providing both nutrients and flow-induced mechanical stimuli, i.e.…”