Effect of cell senescence on the impedance measurement of adipose tissue-derived stem cells

Label-free and real-time monitoring of stem cells based on electrical impedance measurement is increasingly utilized for the quality control of the isolated stem cells to be used in stem cell-based tissue therapy or regenerative medicine. In spite of that the proliferative capacity and multipotency of stem cells are dependent on the type and age of the source tissue, however, the effect of the cell senescence on the impedance measurement of stem cells has not yet been studied. We investigated whether the senescence of adipose tissue-derived stem cells (ADSCs) can be detected by electrical impedance spectroscopy. For this, ADSCs at passage 9 and 31 were prepared and those genetic characteristics and growth kinetics were evaluated by quantitative polymerase chain reaction and cell counting. While the identified ADSCs were grown on the indium tin oxide electrodes, the impedance spectra were measured and interpreted by fitting analysis with an equivalent circuit model. ADSCs at passage 9 adhered on the electrode were small and spindle-shaped whereas the cells at passage 31 were flattened and larger than younger cells. At the beginning of culture time when the cell adhesion occurred, the resistance at 4.6 kHz of passage 31 cells was higher than passage 9 due to the larger size of older cells. Afterwards, the value of passage 9 cells increased higher than passage 31, since younger cells proliferated more than old cells. Therefore, the impedance measurement could characterize the proliferative capacity of ADSCs during expanded culture.