What is the Difference Between Population Doubling and Passage Number?

The difference between population doubling and passage number lies in their definitions and the information they provide about cell culture:

• Population Doubling (PD): Population doubling refers to the time taken for the cells in a culture medium to double their cell count. It is a measurement of time and provides an estimate of the cell line's age.
• Passage Number: Passage number refers to the number of times a particular cell culture is subcultured or passaged. It is not a direct measure of time and can be imprecise because different labs may use different initial cell seeding densities and recovery rates.

In summary:

• Population doubling is a time-based measurement that indicates the extent of cell proliferation in a culture.
• Passage number is a count of the number of times a cell culture has been subcultured, without considering the specific cell doubling events.

Both population doubling and passage number play important roles in determining the suitability of cells for a particular experiment or application. Regulatory agencies have specified that cellular age should be tracked during manufacturing, and while passage number has been traditionally used for this purpose, population doubling level is considered a more accurate and precise measure of cellular age.

Comparative Table: Population Doubling vs Passage Number

Population doubling and passage number are two important aspects of cell culture that help determine cell counts and the quality of cell culture. Here is a table summarizing the differences between the two:

In summary, population doubling measures the time taken for cells to double their population, while passage number denotes the number of times a cell culture has been passaged. Both measurements play essential roles in determining the suitability of cells for various applications, but population doubling level (PDL) is considered more accurate than passage number for determining cellular age.