Figure 1

Cell count validation protocol. According to ICH Q2, the test was performed three times under the same operating conditions by Op1 and Op2. The concentration of the cell suspension was previously quantified using the Bürker chamber. Both operators then evaluated the accuracy of the method comparing the Bürker chamber with the Fast Read 102® chamber, performing a total (non-viable) cell count. In order to evaluate the precision and the repeatability of the method, intra and inter operator CV% was calculated using a viable cell count by Trypan Blue vital dye. The acceptance criteria were: inter and intra operator CV% < 10 % (total cell count); intra and inter operator CV% < 5 % (viable cell count). For linearity, we tested serial dilutions, in the following range: undiluted, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128. Op1 and Op2 performed a total cell count three times for each dilution. On the basis of the results, the regression line was calculated and the optimal range of dilutions was determined.