Tensile strain and magnetic particle force application do not induce MAP3K8 and IL-1B differential gene expression in a similar manner to fluid shear stress in human mesenchymal stem cells.

Mechanical forces, important in a variety of cellular processes, including proliferation, differentiation and gene expression, are also key in the development, remodelling and maintenance of load-bearing tissues such as cartilage and bone. Thus, there is great interest in using in vitro mechanical conditioning of mesenchymal stem cells (MSCs), multipotent adult stem cells, for tissue engineering of these tissues. In a previous gene expression study, we reported a potentially important role for mitogen-activated protein kinase kinase kinase 8 (MAP3K8) and interleukin-1β (IL-1B) in MAPK signalling in MSCs exposed to fluid shear stress. In this follow-up study, we examined the expression of these genes in MSCs exposed to other types of mechanical force: uniaxial tensile strain (3% cell elongation) and forces generated through the exposure of magnetic particle-labelled MSCs to an oscillating magnetic field (maximum field strength 90 mT). Exposure to both types of mechanical force for 1 h did not significantly alter the gene expression of MAP3K8 or IL-1B over the 24 h period subsequent to force exposure. These data demonstrate that uniaxial tensile strain and magnetic particle-based forces do not induce MAP3K8-related MAPK signalling in the same manner as does fluid flow-induced shear stress. This illustrates divergence in the process of mechanotransduction in mechanically stimulated MSCs.