Approaches for automized expansion and differentiation of human MSC in specialized bioreactors

Abstract

A main challenge in cell therapies and other tissue regeneration approaches is to produce a therapeutically significant cell number. For expansion of mesenchymal stem cells (MSC) the cultivation on 2D plastic surfaces is still the conventional procedure, even though the culture conditions differ significantly from the 3D environment in vivo. Additionally, static amplification of MSC is a labour-intensive procedure. We therefore used a specialized rotating bed bioreactor in order to maximize ex vivo expansion of MSC. MSC were isolated from umbilical cord (UC) by explant method approach under xeno-free conditions. UC-MSC were thereafter expanded under dynamic conditions in a novel rotating bed bioreactor. The bioreactor system was designed to enable integration of sensors for online monitoring of various parameters (e.g. pH, pO2, pCO2) and hence, allow ensured cultivation under well controlled and reproducible conditions. Beside cell expansion, directed differentiation of MSC was also achieved in bioreactors. MSC lack the ability to grow in 3D direction and build functional tissue in vitro. Thus, it is necessary to seed and culture MSC on 3D matrices to obtain functional implants. For guided differentiation towards the osteogenic lineage, MSC were cultivated on ceramic porous matrices under dynamic conditions. Custom-made miniaturized perfusion bioreactors for parallel testing were designed and optimized for that purpose.