HeLa cells

Almost all scientific research in molecular biology, pharmacology, virology, genetics since the beginning of the XX century used samples of primary living cells that were obtained from a living organism and cultured with various biochemical methods that allowed them to extend their viability, that is, to share in the laboratory. In the middle of the last century, science received HeLa cells, which are not subject to natural biological death. And this allowed many researches to become a breakthrough in biology and medicine.

[1], [2], [3], [4]

Where did the immortalized HeLa cells come from?

The history of receiving these "undying" cells (immortalization - the ability of cells to endlessly fission) is associated with the poor 31-year-old patient Johns Hopkins Hospital in Baltimore - an African-American, the mother of five children named Henrietta Lacks, who, after cancer cervix for eight months and after undergoing internal irradiation (brachytherapy), died in this hospital on October 4, 1951.

Shortly before, while making efforts to treat Henrietta from cervical carcinoma, the treating physician, surgeon Howard Wilbur Jones, took a tumor tissue sample for examination and transferred to a hospital laboratory headed at that time by a bachelor of biology by George Otto Gay.

Biopsy studies stunned the biologist: tissue cells did not die in due time as a result of apoptosis, but continued to multiply, and at an astonishing rate. The researcher managed to single out one specific structural cell and multiply it. The resulting cells continued to divide and ceased to die at the end of the mitotic cycle.

And soon after the death of the patient (whose name was not divulged, but encrypted as a reduction of HeLa), a mysterious HeLa cell culture appeared.

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

The use of HeLa cells

In 1955, HeLa cells became the first cloned human cells, and the use of HeLa cells began around the world: in studies of cellular metabolism in cancer; studying the aging of cells; causes of AIDS; features of the human papillomavirus and other viral infections; effects of radiation and toxic substances; gene mapping; in trials of new pharmacological agents; testing of cosmetics, etc.

According to some reports, the culture of these fast-growing cells was used in 70-80 thousand medical studies around the world. Annually for the needs of science about 20 tons of HeLa cells culture is grown, more than 10 thousand patents are registered with the participation of these cells.

The popularity of the new laboratory biomaterial was facilitated by the fact that in 1954 the strain of HeLa cells was used by American virologists to test the polio vaccine developed by them .

For decades, the culture of HeLa cells has served as a simple model for creating more intuitive variants of complex biological systems. And the ability to clone immortalized cell lines allows you to repeatedly repeat tests on genetically identical cells, which is a prerequisite for biomedical research.

At the very beginning - in the medical literature of those years - the "endurance" of these cells was noted. Indeed, HeLa cells do not stop dividing even in a conventional laboratory test tube. And they make it so aggressively that it costs laboratory technicians to show the slightest carelessness, HeLa cells will necessarily penetrate into other cultures and will quietly replace the original cells, as a result of which the chistat of the conducted experiments is highly doubtful.

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 studies show?

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

In 2013, researchers from the European Laboratory of Molecular Biology (EMBL) reported that by using spectral karyotyping, they established a sequence of DNA and RNA in the Henrietta Lax genome. And, having compared with HeLa cells, we were convinced: between the HeLa genes and normal human cells, striking differences ...

However, even earlier, cytogenetic analysis of HeLa cells led to the discovery of numerous chromosomal aberrations and partial genomic hybridization of these cells. It was found that HeLa cells possess hypertriploid (3n +) karyotype and produce heterogeneous cell populations. More than half of cloned HeLa cells 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 anomalies. This is a violation during cell division, leading to pathological segregation of chromosomes. If the mitotic bipolarity of the fission spindle is characteristic for healthy cells, then during the division of the cancer cell a larger number of poles and fission spindles are formed, and both daughter cells receive a different number of chromosomes. And the multipolarity of the spindle with mitosis of cells is a characteristic feature of cancer cells.

Studying multipolar mitoses in HeLa cells, genetics came to the conclusion that the whole process of dividing cancer cells, in principle, goes wrong: the prophase of mitosis is shorter, and the formation of the spindle precedes the division of chromosomes; the metaphase also begins earlier, and the chromosomes do not have time to take their place, being distributed haphazardly. Well, centrosomes are at least twice as much as needed.

Thus, the karyotype of the HeLa cell is unstable and can differ dramatically in different laboratories. Consequently, the results of many studies - in conditions of loss of the genetic identity of cellular material - simply can not be reproduced in other conditions.

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