HeLa cells represent the most famous and widely utilized human cell line in the history of biomedical research. These durable and prolific cells were the first human cells successfully grown and sustained indefinitely in a laboratory setting. Their unique properties have made them an indispensable tool, driving advancements in nearly every field of modern medicine since their isolation in 1951. Decades of research have relied on this continuous supply of human cells to study disease, test new therapies, and understand fundamental biological processes.
The Woman Behind the Cells
The origin of this scientific powerhouse traces back to Henrietta Lacks, a young Black woman who sought treatment at Johns Hopkins Hospital in Baltimore in January 1951. She was diagnosed with an aggressive form of cervical cancer at the age of 31. During her treatment, a surgeon collected tissue samples from her tumor and healthy cervical tissue without her knowledge or consent. This practice, common at the time, was done purely for research purposes.
The collected samples were sent to Dr. George Gey’s tissue culture lab, where they were labeled “HeLa,” derived from the first two letters of her first and last names. Henrietta Lacks died later that year in October, but her cells began multiplying rapidly and vigorously in the culture dish. Unlike previous human cells, which died quickly, Lacks’ cells continued to divide and grow indefinitely. This unprecedented growth capacity was recognized as a scientific breakthrough, providing researchers with a permanent, easy-to-grow human cell model.
The Biology of Immortality
The extraordinary nature of the HeLa cell line stems from a specific biological mechanism that bypasses the natural aging process of normal human cells. Most human cells are programmed to undergo a limited number of divisions before entering senescence, known as the Hayflick limit. This limit is imposed by the shortening of telomeres, the protective caps at the ends of chromosomes, which erode slightly with each replication.
HeLa cells possess an overactive version of the enzyme telomerase, a characteristic commonly found in cancer cells. Telomerase continually rebuilds the telomeres, preventing them from shortening during cell division. This constant maintenance allows the chromosomes to remain intact, effectively resetting the cellular clock after every division.
This unchecked mechanism grants the cells infinite replicative potential, classifying them as an “immortal” cell line in laboratory culture. This unique, self-sustaining property enables the cells to be grown in massive quantities and distributed worldwide. It forms the basis of countless experiments and makes them invaluable for scientific inquiry.
Major Scientific Contributions
The robust and easily cultured nature of HeLa cells quickly established them as the preferred model for a vast array of biological experiments. One of their earliest and most significant applications was in the development of the polio vaccine in the mid-1950s. Jonas Salk’s team used HeLa cells to grow large, consistent quantities of the poliovirus, enabling the large-scale testing and mass production of the vaccine.
HeLa cells also proved instrumental in cancer research, particularly in understanding the link between viruses and malignancy. Research revealed that Lacks’ original tumor contained Human Papillomavirus 18 (HPV-18), directly connecting the virus to cervical cancer. This finding laid the groundwork for the development of the HPV vaccine.
The cells have been consistently used to screen new drugs and test the effects of radiation and various toxins on human cells, contributing to advancements in chemotherapy and radiation therapy protocols. They were even sent into space on early missions to study the effects of zero gravity on human biology.
Standardization and Global Access
The demand for HeLa cells rapidly transformed their distribution from an informal exchange into a standardized logistical operation. Early on, the cells were mass-produced, such as at Tuskegee University, to meet the needs of the polio vaccine effort.
Today, the American Type Culture Collection (ATCC) serves as the primary organization responsible for maintaining and distributing the standardized HeLa cell line, cataloged as CCL-2. The ATCC ensures that researchers worldwide receive authenticated, uniform cell samples, which is necessary for ensuring the reproducibility of scientific results. This infrastructure turned the HeLa line into a commercial product, providing a reliable, consistent biological substrate for research.
The Ethical Legacy
The scientific utility of HeLa cells is inseparable from the profound ethical violation surrounding their origin. Henrietta Lacks’ tissue was taken without her knowledge or consent, and her family remained unaware of the cells’ existence or commercial use for over two decades. The subsequent commercialization generated billions of dollars for biotech companies while the Lacks family lived without compensation. This situation highlighted deep-seated issues of medical exploitation and racial inequity.
This controversy became a catalyst for reforms in medical ethics and research policy. The story was a driving force behind the formalization of informed consent procedures. It also led to the establishment of Institutional Review Boards (IRBs) to oversee and protect human research subjects.
More recently, when the full genomic sequence of the HeLa cells was published online, the Lacks family intervened, leading to an agreement with the National Institutes of Health (NIH). Under this arrangement, researchers must apply for controlled access to the genomic data. A working group that includes members of the Lacks family reviews these applications, granting them a role in governing the use of their ancestor’s genetic information.