Cell Passage
Passaging a cell line is a cell culture technique where the cell culture medium is removed and cells are transferred from a previous culture into fresh growth medium, a cell culture technique that enables the further growth of the cell line.
The growth of cells in culture proceeds from the lag phase following seeding to the log phase, where the cells proliferate exponentially. When the cells in adherent cultures occupy all the available substrate and have no room left for expansion, or when the cells in suspension cultures exceed the capacity of the medium to support further growth, cell proliferation is reduced or ceases entirely. To keep the culture at an optimal density for continued cell growth and to stimulate further proliferation, the culture has to be divided and fresh medium supplied.
For some cell culture techniques like transfection, it is important to have the cells in the log phase, this will improve the transfection efficiency.