Magneto-mechanical Stimulation of Bone Marrow Mesenchymal Stromal Cells for Chondrogenic Differentiation Studies

Mechanical interaction of cells and their surroundings are prominent in mechanically active tissues such as cartilage. Chondrocytes regulate their growth, matrix synthesis, metabolism, and differentiation in response to mechanical loadings. Cells sense and respond to applied physical forces through mechanosensors such as integrin receptors. Herein, we examine the role of mechanical stimulation of integrins in regards to their mechanotransduction ability to promote chondrogenesis. For this purpose, magnetic nanoparticles were chemically bonded to cell membrane mechanoreceptors and stimulated. Histological results showed the endocytosis of nanoparticles over the experimental period, pointing out the inefficient mechanical stimulation of the mechanoreceptors. Moreover, gene expression analysis only showed significant upregulation for SOX9, whereas type II collagen and aggrecan gene expression were not significantly different from the control group. Our results suggest that magneto-mechanical stimulation studies using magnetic nanoparticles should not only focus on the mechanical aspects, but also the interaction of magnetic nanoparticles with intracellular machinery should be investigated as well.