Rtca sp system

The label-free dynamic monitoring of cell proliferation and viability in real time was done by using the xCELLigence technology of the RTCA SP system (ACEA Biosciences, Ozyme, Saint-Cyr-L’Ecole, France). Cells were seeded in 96-well microplates (E-Plates). Attachment of the cells was followed every 5 min over 24h, and cell proliferation was then monitored daily every 15 min until cell confluency. Cell-sensor impedance was expressed as cell index values that were normalized using the RTCA Software 2.0. Briefly, the software automatously and uniformly transforms the cell index values in different wells at the base-time, defining as the first measurement after starting treatment as 1. This made the normalized cell index more comparable between wells. The resulting normalized cell index was actually the relative cell impedance, presented as the percentage of the value at the base-time.

Impedance-based real time detection of cell proliferation and viability was done using the xCELLingence technology of the RTCA SP system (ACEA Biosciences, Ozyme, France). 4T1 or MDA-MB-231 breast cancer cells were seeded in E-Plate 96-well plates (5 × 10³ cells/well) for 24 hours, and were treated with metformin 1–7.5 mM alone, propranolol 10 μM alone, or their combinations. At cell seeding and after drug administration impedance changes were monitored every 5 minutes for 8 hours, and every 15 minutes for the rest of the experiment. Cell index (CI) values derived from the recorded impedance data, were normalized (NCI) using the RTCA Software 2.0 (ACEA Biosciences, Ozyme, France). Data of each single well were normalized to the first measurement after starting treatment using the equation NCI_(time) = CI_time/CI_{nml time}.