Hey, I have worked on Mice models in toxicological screening and Genetic toxicology studies. If there is one thing that I have learnt from the data i have obtained from these studies is that the age, sex, weight, pathological state of the rodent are very very important for consistent results. As the rodent ages, the DNA damage and repair mechanisms mimic that of the Humans in the course of their life time..as in 90 days or 45 days duration studies. So it is evident that non-pathogenic cell lines is very essential for the same if we are to obtain accurate results.