HeLa cells are a type of human cell line derived from a cervical cancer patient named Henrietta Lacks in 1951. While HeLa cells originated from human tissue, they possess several unique characteristics that set them apart from normal human cells. Some of these differences are:
- Immortality: HeLa cells are considered immortal because they can divide indefinitely in laboratory conditions, unlike normal human cells that have a limited number of divisions before they undergo senescence (cellular aging). The immortal nature of HeLa cells is due to genetic alterations, including the activation of the enzyme telomerase, which maintains the protective caps (telomeres) at the ends of chromosomes, allowing the cells to bypass replicative senescence.
- Rapid proliferation: HeLa cells grow and divide much faster than most normal human cells. This rapid proliferation is due to alterations in cell cycle regulation, driven by mutations in oncogenes and tumor suppressor genes. The accelerated growth rate allows HeLa cells to quickly overtake other cell cultures, making them prone to contamination.
- Genetic instability: HeLa cells have a highly abnormal chromosome number (aneuploidy) and structure, which is a result of the genetic instability in cancer cells. This genetic instability contributes to the cells’ ability to adapt to various conditions and confers resistance to certain treatments.
- Altered metabolism: Cancer cells, including HeLa cells, often exhibit altered metabolism compared to normal cells. They typically have a higher rate of glycolysis, even under oxygen-rich conditions, which is known as the Warburg effect. This metabolic change is thought to support the rapid growth and proliferation of cancer cells.
- Loss of contact inhibition: Normal human cells usually stop growing when they come into contact with each other, a phenomenon known as contact inhibition. HeLa cells, however, lack this regulatory mechanism, allowing them to continue growing and forming multi-layered cell masses, a characteristic feature of cancer cells.
While HeLa cells have provided invaluable insights into various aspects of cell biology, cancer research, and have contributed to the development of numerous medical treatments, it is essential to recognize that they are not representative of normal human cells due to their unique properties. The differences between HeLa cells and normal human cells should be taken into consideration when interpreting the results of experiments conducted using HeLa cells.