Real-Time,Label-Free Monitoring of 3T3-L1 Preadipocyte Differentiation by a Bioelectrical Impedance Assay

Monitoring the differentiation of preadipocyte cell lines is critical for investigating the adipogenesis process and drug screening. In this study, a biosensor known as an electric cell-substrate impedance sensor was employed to monitor the entire process of 3T3-L1 preadipocyte differentiation. The magnitude of the impedance mirrors the differentiation status of cells in real-time. Before differentiation, 3T3-L1 preadipocytes were cultured on the surface of the microelectrode array until full confluence. Differentiation was then induced by hormone treatment, and the magnitude of the impedance of the differentiated cells significantly decreased. The differentiation process was identified by Oil Red O staining at the process end-point. We further employed a type of retinoic acid (TTNPB) that inhibits preadipocyte differentiation and assessed its effects on impedance changes. TTNPB was simultaneously added to the culture medium with the hormone inducer of differentiation. There was a good linear correlation between the reciprocal of the average impedance value and the end-point Oil Red O staining assay when different concentrations of TTNPB were added. Importantly, this is the first study to demonstrate that the inhibition of the dynamic morphological changes by TTNPB during preadipocyte differentiation is not a monotonic process, which presumably reflects the timing of intracellular molecular events.