Rheological Properties of Growth-Arrested Fibroblast Cells under Serum Starvation Measured by Atomic Force Microscopy

The rheological properties of growth-arrested and quiescent (G0 phase) mouse fibroblast cells under serum starvation were investigated by atomic force microscopy (AFM) with a microarray technique. The number distribution of complex shear modulus, $G^{*}$, of quiescent cells at the serum concentration, $C_{\text{S}}=0.1$%, followed a log-normal distribution, and the frequency dependence of $G^{*}$ exhibited a power law behavior, which were similar to those under a control condition at $C_{\text{S}}=10$%. On the other hand, we found that the Newtonian viscosity coefficient of the quiescent cells significantly increased, and the distribution broadened, as compared with the control cells, whereas the power-law exponent was unchanged. The result indicated that the rheological properties of quiescent fibroblast cells were not identical to those in the G1 phase during cell cycle. This finding suggests that the Newtonian viscosity of cells is one of the useful indicators for evaluating growth-arrested cells under serum starvation.