HeLa cells are the first “immortal” line of human cells cultured in a laboratory, originally isolated from a woman’s cervical cancer in 1951. Their ability to divide indefinitely outside the body revolutionized scientific study. The American Type Culture Collection (ATCC) is a biological resource center that acquires, authenticates, and distributes standardized cell lines. The ATCC provides researchers with reliable biological materials to ensure experimental consistency.
The Standardization of HeLa by ATCC
The widespread use of HeLa cells created a problem of cross-contamination. Because HeLa cells are robust and fast-growing, they frequently contaminated other cell cultures. This issue invalidated research findings, as scientists who believed they were studying one type of cell were working with HeLa. This crisis showed the need for a verified, uncontaminated source of cells to ensure the reproducibility of experiments.
To address this, the ATCC established a “gold standard” reference stock of HeLa cells, designated ATCC CCL-2. By creating a thoroughly authenticated and pure stock, the ATCC offered a solution to the contamination problem. The availability of a certified HeLa line meant that scientists could be certain they were working with the correct cells, allowing for accurate comparison of results across different studies and laboratories.
Authentication and Quality Control Protocols
The ATCC uses rigorous procedures to guarantee the identity and purity of the HeLa CCL-2 line. A primary method is Short Tandem Repeat (STR) profiling, a genetic fingerprinting technique that analyzes short, repetitive DNA sequences. By generating a unique STR profile for the HeLa cells, the ATCC can confirm their identity and ensure the line has not been compromised by other human cell lines.
In addition to genetic authentication, the ATCC performs extensive testing for biological contaminants. This quality control includes detecting mycoplasma, a genus of bacteria that lack a cell wall, making them resistant to many antibiotics. Mycoplasma can alter cell metabolism, growth, and gene expression, invalidating results. The ATCC uses sensitive methods like PCR-based assays to ensure its HeLa cell stocks are free from these microorganisms.
Recommended Culture and Handling Procedures
Specific protocols are recommended for culturing ATCC CCL-2 to ensure optimal growth. The designated base medium is ATCC-formulated Eagle’s Minimum Essential Medium. This base must be supplemented with 10% fetal bovine serum to create the complete growth medium. Following this formulation maintains the cell line’s health and characteristics.
The cells require an incubator that maintains a constant temperature of 37°C and an atmosphere of 5% CO2. For subculturing, it is recommended to act when cultures are between 70% and 80% confluent. This process involves using a reagent like Trypsin-EDTA to detach the cells from the flask surface. The detached cells are then diluted and re-seeded at a density of 10,000 to 30,000 cells per square centimeter.
Research Significance of Standardized HeLa Cells
The standardized HeLa cell line from ATCC has been foundational to many scientific advancements. These cells played a role in the development of the first polio vaccine, as their ability to be cultured on a large scale allowed for the necessary viral studies. Beyond virology, HeLa cells have been central to decades of cancer research, genetics, and the understanding of human cellular processes.