Application of a Parallelizable Perfusion Bioreactor for Physiologic 3D Cell Culture

It is crucial but challenging to keep physiologic conditions during the cultivation of 3D cell scaffold constructs for the optimization of 3D cell culture processes. Therefore, we demonstrate the benefits of a recently developed miniaturized perfusion bioreactor together with a specialized incubator system that allows for the cultivation of multiple samples while screening different conditions. Hence, a decellularized bone matrix was tested towards its suitability for 3D osteogenic differentiation under flow perfusion conditions. Subsequently, physiologic shear stress and hydrostatic pressure (HP) conditions were optimized for osteogenic differentiation of human mesenchymal stem cells (MSCs). X-ray computed microtomography and scanning electron microscopy (SEM) revealed a closed cell layer covering the entire matrix. Osteogenic differentiation assessed by alkaline phosphatase activity and SEM was found to be increased in all dynamic conditions. Furthermore, screening of different fluid shear stress (FSS) conditions revealed 1.5 mL/min (equivalent to ∼10 mPa shear stress) to be optimal. However, no distinct effect of HP compared to flow perfusion without HP on osteogenic differentiation was observed. Notably, throughout all experiments, cells cultivated under FSS or HP conditions displayed increased osteogenic differentiation, which underlines the importance of physiologic conditions. In conclusion, the bioreactor system was used for biomaterial testing and to develop and optimize a 3D cell culture process for the osteogenic differentiation of MSCs. Due to its versatility and higher throughput efficiency, we hypothesize that this bioreactor/incubator system will advance the development and optimization of a variety of 3D cell culture processes.