Categories of cell culture: Primary Cells vs. Cell Lines
The 2 main types of cells used in laboratories are primary cells and established cell lines.
Primary cells, also known as finite cells, are cells that are directly prepared from an organism’s tissues . If grown under the right conditions primary cells will grow and proliferate, but they are only able to do so a finite number of times . This number is known as the Hayflick limit . The Hayflick limit is related to the telomere length at the end of the cell’s DNA. As cells undergo each cell division, a small segment of the telomere is lost after each time DNA is duplicated. This process eventually leads to a stage of senescence, where the cells can no longer divide. Continuous cell lines, on the other hand, are able to escape the normal constraints of the cell cycle and grow indefinitely, making them extremely useful for long-term research . Whereas primary cells are obtained directly from donor tissues, cell lines can be derived from clinical tumors, or created from transforming primary cells with viral oncogenes or chemical
It is important to note that not all immortalized cells will retain the same characteristics as the primary cells and often times characterization experiments are performed on the newly established cell lines to determine their usefulness in research settings.