Title :
Assessing in vitro cytotoxicity of cell micromotion by Hilbert-Huang Transform
Author :
Yi-Ting Lai ; Chun-Min Lo
Author_Institution :
Dept. of Biomed. Eng., Nat. Yang-Ming Univ., Taipei, Taiwan
Abstract :
Electric cell-substrate impedance sensing (ECIS) is a powerful instrument for quantifying cell behavior in tissue culture. As cells attach and spread on the sensing electrode, they restrict the current flow and hence cause the increase of electrical impedance. Furthermore, cell motion may reveal itself as electrical fluctuations, which are always associated with living cells and continue even when the cells become fully confluent. The impedance fluctuation is attributed to incessant changes in the size of the cell-substrate space as cells persistently rearrange their cell-substrate adhesion sites. The magnitude of this sort of vertical motion detected by ECIS is of the order of nanometers and referred to as micromotion. In this study, Hilbert-Huang Transform was used as a micromotion analysis tool to distinguish the in vitro cytotoxicity of human umbilical vein endothelial cells (HUVECs) exposed to low levels of cytochalasin B. Hilbert-Huang Transform consists of two procedures: the empirical mode decomposition (EMD) and the Hilbert Transform. The measured impedance fluctuations due to cell micromotion were decomposed into several intrinsic mode functions (IMFs) by EMD, and then these IMFs were transferred to instantaneous frequencies by Hilbert Transform. Both amplitude and phase of instantaneous frequencies were expressed as a time-frequency spectrum, called Hilbert spectrum, which displayed different distribution pattern in response to different cytochalasin B concentration. The total instantaneous energy (IE) of each IMF was also calculated to quantify the spectral difference. In addition to the observation of a dose-dependent relationship, the IE value of the first IMF at 0.1 μM decreased to about 48% of the control value and significantly distinguished the cytotoxic effect of 0.1 μM of cytochalasin B (P<;0.05).
Keywords :
Hilbert transforms; bioelectric phenomena; biological tissues; biomedical electrodes; cell motility; electric impedance; electric sensing devices; toxicology; ECIS; EMD; HUVEC; Hilbert transform; Hilbert-Huang Transform; cell attachment; cell micromotion; cell spreading; cell-substrate adhesion sites; current flow; cytochalasin B; electric cell-substrate impedance sensing; electrical fluctuations; electrical impedance; empirical mode decomposition; human umbilical vein endothelial cells; in vitro cytotoxicity; instantaneous energy; intrinsic mode functions; sensing electrode; time-frequency spectrum; tissue culture; Fluctuations; Impedance; Impedance measurement; Sensors; Time-frequency analysis; Transforms;
Conference_Titel :
Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE
Conference_Location :
Chicago, IL
DOI :
10.1109/EMBC.2014.6944303