Determination of cell differentiation by probing cell membrane stiffness

Force spectroscopy as a function in atomic force microscopy (AFM) allows us to quantitatively explore the mechanical properties of individual bio cells. In this study, we investigated the variation in membrane stiffness of human neuroblastoma SH-SY5Y cells (SH-cells) and human bone marrow mesenchymal stem cells (H-BMMSCs). First, the correlation of the stiffness of cell membrane with the degree of the cell’s differentiation was observed by using force spectroscopy. The stiffnesses of the non-differentiated, the partially differentiated, and the fully neuronal differentiated SH-cells were found to be 0.7044 ± 0.0372 nN/nm, 0.5976 ± 0.0114 nN/nm, and 0.4989 ± 0.0538 nN/nm, respectively. These values indicated that the stiffness of the fully neuronal differentiated cells was softer than that of the non-differentiated ones. Next, this method was applied to determine the differentiation of the H-BMMSCs into neural cells. We found that the stiffness of the H-BMMSCs cultured in neural induction media was 29.81% smaller than that of the non-differentiated cells. The neural differentiation of the H-BMMSCs was confirmed by using a Western blot analysis. The change in the elasticity of the differentiated cells could be explained in terms of morphological and biochemical modifications of the membrane during the differentiation process. Our study demonstrated that probing the variation in the stiffness of the cell membrane is a fruitful method to determine the cell’s differentiation.