Automated Tracking Turns Cell Culture into Numbers Figure 13. Reliability/robustness of the validation algorithm. (A) displays the life time distribution of reference data set A (blue). Red and green data points display the results of automatic tracking with and without validation, respectively. It can be inferred from the similarity of distributions that our validation algorithm does not select for specific cells, whereas unvalidated tracking produces many artefacts. (B) An experiment showing the robustness of the method. Proliferation curves were recorded at 10 different positions (pancreatic stem cells in passage 31); the variances between them are small. (C) Life time distributions of different experiments. Dark and light blue data points are taken from data sets A and B respectively, while the yellow data points display the outcome of the validation algorithm for the 10 different positions shown in (B). Cell behaviour and the output of the validation algorithm appears to be very reproducible, even when comparing different passages and cell densities. doi:10.1371/journal.pone.0027315.g013 automated cell tracking. This also encompasses a mitosis detector, which has been shown to be an important prerequisite for the validation methods. Using automated validation we could demonstrate that even a rather basic tracking approach can lead to very trustworthy results. These results can be used to automatically derive biologically meaningful parameters for the quantitative description of cell culture. To date, cell tracking was regarded to be a powerful, but rather specialized method to investigate specific questions in develop- mental biology [5,6] or to find and explore rare events in cell culture [1,40]. However, being able to unsupervisedly track large cell populations and to derive statistical distributions of their biological properties shifts the method from being peripheral and laborious to being descriptive and automatable. The automatically PLoS ONE | www.plosone.org 14 November 2011 | Volume 6 | Issue 11 | e27315