Real-time monitoring of cell growth

Cell growth was evaluated using the xCELLigence DP system (ACEA Biosciences, San Diego, CA), designed to monitor events in real time by measuring electrical impedance across interdigitated microelectrodes integrated on the bottom of tissue culture E-plates (ACEA), see http://www.aceabio.com/main.aspx [35 (link), 74 (link)]. H69 and HepG2 were seeded at 5,000 and 10,000 cells/well, respectively, into E-plates in medium supplemented with 10% fetal bovine serum (FBS), and cultured in a humidified incubator at 37°C, 5% CO₂ for one day. The cells were rinsed in PBS and medium replaced with H69 or HepG2 medium diluted 1 in 20, i.e. 0.5% FBS, for four to six hours. Thereafter, the medium was replaced with conditioned medium and the cells monitored continuously, at intervals of 15 minutes, for up to 120 hours using the RTCA Software 1.2 (ACEA), as described [37 (link), 39 (link)].