HeLa cells

Almost all scientific research in molecular biology, pharmacology, virology, genetics since the beginning of the 20th century used samples of primary living cells, which were obtained from a living organism and cultivated by various biochemical methods, allowing to extend their viability, that is, the ability to divide in laboratory conditions. In the middle of the last century, science received HeLa cells, which are not subject to natural biological death. And this allowed many studies to become a breakthrough in biology and medicine.

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Where did immortalized HeLa cells come from?

The story of obtaining these “undying” cells (immortalization is the ability of cells to divide infinitely) is connected with a poor 31-year-old patient of Johns Hopkins Hospital in Baltimore – an African-American woman, mother of five children named Henrietta Lacks, who, having suffered from cervical cancer for eight months and having undergone internal radiation (brachytherapy), died in this hospital on October 4, 1951.

Shortly before this, while trying to treat Henrietta for cervical carcinoma, the attending physician, surgeon Howard Wilbur Jones, took a sample of tumor tissue for examination and sent it to the hospital laboratory, then headed by George Otto Gey, a bachelor of biology.

The biologist was stunned by the biopsy: the tissue cells did not die after the allotted time as a result of apoptosis, but continued to multiply, and at an astonishing rate. The researcher managed to isolate one specific structural cell and multiply it. The resulting cells continued to divide and stopped dying at the end of the mitotic cycle.

And soon after the death of the patient (whose name was not disclosed, but encrypted as the abbreviation HeLa), a mysterious culture of HeLa cells appeared.

Once it became clear that HeLa cells – available outside the human body – were not subject to programmed death, the demand for them for various studies and experiments began to grow. And further commercialization of the unexpected discovery resulted in the organization of serial production – for the sale of HeLa cells to numerous scientific centers and laboratories.

Using HeLa cells

In 1955, HeLa cells became the first human cells to be cloned, and HeLa cells have been used worldwide to study cell metabolism in cancer; the aging process; the causes of AIDS; the characteristics of the human papillomavirus and other viral infections; the effects of radiation and toxic substances; gene mapping; testing new pharmaceuticals; testing cosmetics, etc.

According to some data, the culture of these fast-growing cells has been used in 70-80 thousand medical studies worldwide. About 20 tons of HeLa cell culture are grown annually for scientific needs, and more than 10 thousand patents involving these cells have been registered.

The popularization of the new laboratory biomaterial was facilitated by the fact that in 1954 the HeLa cell strain was used by American virologists to test the polio vaccine they had developed.

For decades, HeLa cell culture has been widely used as a simple model for creating more visual versions of complex biological systems. And the ability to clone immortalized cell lines allows for repeated analyses on genetically identical cells, a prerequisite for biomedical research.

At the very beginning – in the medical literature of those years – the “stamina” of these cells was noted. Indeed, HeLa cells do not stop dividing even in a regular laboratory test tube. And they do it so aggressively that if lab technicians show the slightest carelessness, HeLa cells will definitely penetrate other cultures and calmly replace the original cells, as a result of which the purity of the experiments is highly questionable.

By the way, as a result of one study, which was conducted back in 1974, the ability of HeLa cells to “contaminate” other cell lines in scientists’ laboratories was experimentally established.

HeLa cells: what did the research show?

Why do HeLa cells behave this way? Because they are not normal cells of healthy body tissues, but tumor cells obtained from a cancerous tumor tissue sample and containing pathologically altered genes of continuous mitosis of human cancer cells. In essence, they are clones of malignant cells.

In 2013, researchers at the European Molecular Biology Laboratory (EMBL) reported that they had sequenced the DNA and RNA in Henrietta Lacks' genome using spectral karyotyping. And when they compared it with HeLa cells, they found that there were striking differences between the genes in HeLa and normal human cells...

However, even earlier, cytogenetic analysis of HeLa cells led to the discovery of numerous chromosomal aberrations and partial genomic hybridization of these cells. It turned out that HeLa cells have a hypertriploid (3n+) karyotype and produce heterogeneous cell populations. Moreover, more than half of the cloned HeLa cells were found to have aneuploidy - a change in the number of chromosomes: 49, 69, 73 and even 78 instead of 46.

As it turned out, multipolar, polycentric or multipolar mitoses in HeLa cells are involved in the genomic instability of the HeLa phenotype, the loss of chromosome markers and the formation of additional structural abnormalities. These are disturbances during cell division, leading to pathological segregation of chromosomes. If mitotic bipolarity of the division spindle is characteristic of healthy cells, then during the division of a cancer cell, a greater number of poles and division spindles are formed, and both daughter cells receive a different number of chromosomes. And the multipolarity of the spindle during cell mitosis is a characteristic feature of cancer cells.

Studying multipolar mitoses in HeLa cells, geneticists came to the conclusion that the entire process of cancer cell division is, in principle, incorrect: the prophase of mitosis is shorter, and the formation of the division spindle precedes the division of chromosomes; metaphase also begins earlier, and chromosomes do not have time to take their place, distributing themselves haphazardly. Well, the number of centrosomes is at least twice as large as necessary.

Thus, the karyotype of the HeLa cell is unstable and can vary greatly between laboratories. Consequently, the results of many studies - given the loss of the genetic identity of the cellular material - are simply impossible to reproduce under other conditions.

Science has made great strides in its ability to manipulate biological processes in a controlled manner. The latest example is the creation of a realistic model of a cancerous tumor using HeLa cells using a 3-D printer by a group of researchers from the US and China.