I am working on MSCs culture and to normalise the data, I am doing Picogreen DNA quantification. However, the total amount of DNA is downgraded by 30% when I repeated the quantification using stored cell lysate after a week time (-80 degree) and after 2 weeks, further decline was observed. So, is this trend is normal or quantification on the fresh cell lysate is always better to avoid this kind of change in data. Please share your opinions. Thanks