Biomedical research extensively relies on cell cultures to unravel intricate biological phenomena and devise innovative therapeutic approaches. Among the diverse cell culture options available, cell lines and primary cells occupy prominent positions. While serving as indispensable tools, these two cell types significantly differ in their origin, characteristics, and applications.
Cell lines
Cell lines are usually derived from tumor samples thereby naturally evading mechanisms governing cellular senescence and growth regulation. Consequently, most cancerous cell lines proliferate incessantly, ensuring an ample and convenient resource for experimental purposes.
Distinctive Characteristics of Cell Lines:
Proliferative Capacity: Most cell lines possess theoretically an infinite proliferative potential, facilitating large-scale cultivation and long-term storage, ensuring a constant supply for experimental investigations.
Genetic Stability Concerns: Extended cultivation durations cause cell lines to accumulate genetic alterations over time, leading to heterogeneity within cell line populations. Such genetic disparities can impede experimental reproducibility and potentially introduce confounding artifacts; therefore it is recommended to authenticate the cell lines’ identity through STR analysis every once in a while (we recommend every 10 passages) to make sure the cell lines did not accumulate additional mutations or have been contaminated by another, faster growing, cell line.
Altered Phenotype: cancerous cell lines frequently exhibit distinctive characteristics that deviate from their original tissue counterparts. They may manifest abnormal gene expression patterns, altered cellular signaling pathways, and morphological transformations, reflecting phenotypic modifications imposed by in vitro culture conditions and/or their cancerous origin.
Primary cells
Primary cells, in contrast, are directly isolated from living tissues or organs. Cultured for a limited number of passages, these cells maintain the genetic and phenotypic traits of the original tissue, rendering them valuable models for deciphering physiological processes and elucidating disease mechanisms.
Distinctive Characteristics of Primary Cells:
The authenticity of Source: Primary cells offer an authentic representation of the tissue of interest. They retain the genetic and phenotypic features of their tissue of origin, enabling researchers to explore cellular behaviors and responses in their natural state. Furthermore, using primary cells allows the researcher to choose cells from different donors (age, sex and in certain cell types of area in the body from where the cells were isolated) to see if these characteristics affect the cells’ biological response to different experimental conditions. HLA typed cells are also available. Additionally, pools of cells from several donors, intended to neutralize donor to donor variations are also available for some primary cell types.
Heterogeneity: Primary cells encompass inherent diversity akin to living tissues. Specific cell types, such as epithelial, endothelial, or immune cells, can be isolated and cultured separately, or structured together to create 3 dimensional organoids enabling investigations into cell-specific functionalities and intricate cellular interactions. In some cases, different cell types from the same donor are available.
Limited Lifespan: Primary cells exhibit finite lifespans in culture due to replicative senescence or the gradual loss of tissue-specific functions. Both ATCC and Promocell commit to a minimum of 15 population doublings for most primary cell lines. Consequently, a restricted number of experiments can be conducted with a single batch of cells, necessitating periodic sourcing from fresh tissues.
Immortalized cell lines
Immortalized cells are a third option encompassing the best of both worlds. These cells are primary normal cells that have undergone genetic to make them immortal.
Distinctive Characteristics of Immortalized Cells:
Immortalization process: There are several methods for cell immortalization, the most common ones are achieved by introducing specific viral vectors, such as retroviruses or lentiviruses, carrying genes that inhibit senescence or promote cell division. For example, the viral gene products, such as SV40 large T antigen or human papillomavirus (HPV) E6/E7 proteins, can bind to and inactivate tumor suppressor proteins like p53 and pRB, which allows cells to bypass senescence and continue proliferating.
Another common method is introducing the telomerase gene (TERT) into primary cells, which enables telomeres to be extended, and overcome replicative senescence.
Enhanced Characteristics of Immortalized Cells: Immortalized cell lines offer a unique combination of physiological features seen in primary cell lines and the extended culture lifespan observed in continuous cell lines. They circumvent the limitations of replicative senescence found in primary cells and the unstable karyotype commonly associated with continuous cell lines.
Applications
Both cell lines and primary cells find distinct applications in research endeavors:
Cell lines are extensively employed in high-throughput screening, drug discovery, and biopharmaceutical production, owing to their inexhaustible proliferative potential.
Primary cells are preferred for investigations necessitating faithful representations of in vivo conditions. They are particularly valuable for scrutinizing tissue-specific functionalities, cellular interactions, and disease pathogenesis.
In summary, cell lines and primary cells stand as indispensable tools in scientific research, each offering unique advantages and limitations. Cell lines provide unlimited proliferation capabilities, ease of use, and high availability. Conversely, primary cells preserve the authenticity of tissue sources, allowing for investigations into physiological processes and disease mechanisms in a faithful manner, while immortalized cell lines offer the advantages of using normal healthy cells with high proliferative capacity. Researchers should meticulously select the appropriate cell type based on their specific research objectives, ensuring the relevance and validity of their findings.
The next time you approach your research, choose carefully which type of cells to use.
And if you need help, our team of experts is here to advise you.
Click to see our collection of primary cells by PromoCell.