Origin and Background of HEK 293 Cells
The HEK 293 cell line was originally cultured by Alex Van der Eb in the 1970s. However, it was Frank Graham who revolutionized the cell line by inventing the calcium phosphate method for cell transfection. These cells were sourced from a healthy aborted fetus.
To immortalize the cell line, Graham transfected DNA from adenovirus type 5 into human chromosome 19 of the HEK cells. This integration of Ad5 into the genome of the cells prevented apoptosis, allowing for the continuous production of the cell line. It took Frank Graham 293 experiments before achieving success, hence the name HEK 293.
While initially believed to derive from the fetal kidney's endothelial, epithelial, or fibroblastic cells, recent evidence suggests that these cells may have originated from neuronal fetal kidney cells.
HEK 293 Cell Size, Genome, and Chromosome Number
HEK 293 cells typically have a diameter ranging from 11-15µm, depending on the culture conditions. Cells grown in a monolayer culture tend to be flatter and have a larger diameter compared to cells cultured in suspension.
HEK 293 cells are hypotriploid human cell lines, meaning they carry 64 chromosomes and three copies of the X chromosome. The incorporation of 4 kbp Ad5 into chromosome 19 of the HEK 293 genome indicates cytogenetic instability.
Culturing Information and Requirements for HEK 293 Cells
HEK 293 cells are considered low-maintenance and robust, making their culturing requirements relatively straightforward. These cells have a rapid doubling time of approximately 34 to 36 hours.
HEK 293 cells can be cultured as either adherent or suspension cells, although they are typically grown as an adherent monolayer. A high-glucose cell culture media is used to sustain their viability, and the media should be replaced every 2-3 days. To facilitate their growth, HEK 293 cells require a humidified incubator set at 37°C and supplemented with 5% CO2.
For long-term storage, HEK 293 cells should be stored in their liquid nitrogen vapor phase rather than at -80°C since the latter can compromise their viability over time. Freezing should be done slowly using a freezing media that includes a complete growth media supplemented with 5% cryoprotectant, such as Dimethyl sulfoxide. Thawing should be done quickly by gently disturbing the cells for two minutes in a 37°C water bath before adding them to a pre-warmed medium. With the presence of adenovirus in the cells, HEK 293 is classified as Biosafety Level 2 (BSL-2).
Advantages and Limitations of Using HEK 293 Cells
Like any cell line, HEK 293 cells have both advantages and limitations. Understanding these can help researchers make informed decisions regarding their use.
Advantages of HEK 293 Cells:
- Consistent and reproducible results
- Highly efficient at producing recombinant proteins in large quantities, making them valuable in therapeutic agent development
- Suitable for both stable and transient gene expression
- Responsive to various transfection methods, allowing for flexibility in experimentation
Limitations of HEK 293 Cells:
- Prone to bacterial contamination
- Susceptible to viral contamination
- Prolonged culturing can lead to cell degradation
Applications of HEK 293 Cells
HEK 293 cells have found extensive use in various research areas, thanks to their unique properties. Some notable applications include:
Receptor Signaling: HEK 293 cells are commonly employed for heterologous expression of ion channels and cell membrane receptors. Researchers use these cells to study G protein-coupled receptor signaling pathways, which play a crucial role in disease. Additionally, HEK 293 cells are utilized for characterizing olfactory receptors in diverse organisms.
Protein Production: The exceptional efficiency of HEK 293 cells in yielding recombinant proteins has made them a preferred choice for protein production. Several vaccines and biotherapeutic proteins have already been developed using HEK 293 cells.
Cancer Research: Due to their tumorigenic nature, HEK 293 cells are frequently employed in cancer research. Studies have explored the role of these cells in elucidating the effectiveness of cancer treatments, such as Metformin, in inhibiting cell migration and suppressing chemokine interleukin-8 expression. HEK 293 cells are also frequently used as control cells in studies investigating the effects of various treatments on cancer-specific cells.
Development of HEK 293 Cells
A derivative of the HEK 293 cell line called HEK 293T has been recently developed. HEK 293T cells carry the SV40 large T antigen, enabling them to yield recombinant proteins in plasmid vectors containing SV40 promoters. These cells are widely used for viral particle production, including lentiviral particles, which are utilized for transducing non-dividing cells.
In conclusion, the HEK 293 cell line has proven to be an invaluable tool in biotechnology and research. Its unique characteristics, including fast growth, robustness, and protein production capabilities, have made it a go-to choice for various research applications. Understanding the origin, culturing requirements, advantages, and limitations of HEK 293 cells allows researchers to harness their potential effectively.