title: Combining optical and electrical impedance techniques for quantitative measurement of confluence in MDCK-I cell cultures.
abstract: A new method combining optical and electrical impedance measurements is described that enables submicroscopic cell movements to be monitored. The cells are grown on small gold electrodes that are transparent to light. This modified electrical cell-substrate impedance sensor (ECIS) allows simultaneous microscopic recording of both growth and motility, thus enabling cell confluence on the electrodes to be systematically correlated to the impedance in regular time intervals of seconds and for extended periods of time. Furthermore, the technique provides an independent measure of monolayer cell densities that we compare to calculated values from a theoretical model. We have followed the attachment and spreading behavior of epithelial Madin-Darby canine kidney strain I (MDCK-I) cell cultures on microelectrodes for up to 40 h. The studies reveal a high degree of correlation between the measured resistance at 4 kHz and the corresponding cell confluence in 4- to 6-h intervals with typical linear cross-correlation factors of r equaling approximately 0.9. In summary, the impedance measured with the ECIS technique provides a good quantitative measure of cell confluence.
authors.affiliation: Copenhagen University, Copenhagen, Denmark. birgitte.deblasio@basalmed.uio.no
authors.forename: Birgitte Freiesleben
authors.initials: BF
authors.lastname: De Blasio
authors.forename: Morten
authors.initials: M
authors.lastname: Laane
authors.forename: Thomas
authors.initials: T
authors.lastname: Walmann
authors.forename: Ivar
authors.initials: I
authors.lastname: Giaever
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004285:Dogs; D017097:Electric Impedance; D004566:Electrodes; D055095:Optics and Photonics