Cell adherence and proliferation was monitored in real‐time using the xCELLigence system E‐Plate. Different cell numbers were tested, with the optimum cell density to found to be 2.5 × 104 cells/cm2 (data not shown). Experiments were performed at different time‐points and with various percentages of media derived from OEC cultures mixed with fresh medium, with 100% of fresh medium employed as a control. The impedance value of each well was monitored by the xCELLigence system for a time of 24 hrs and expressed as a cell index (CI) value. Data for cell adherence were normalized at 16 hrs after plating. Normalized CI, representing a quantitative measure of cell number, was calculated by dividing CI at the time‐point into the CI at the normalization time‐point (time 0). The Rate of Cell Growth (RCG) was determined by calculating the slope of the line between starting point and ending point.