The afterlife of Henrietta Lacks

In February 1951, Henrietta Lacks, a thirty-year-old mother of five, went for an examination at the John Hopkins hospital after noticing blood stains on her underwear. Doctors were quick to conclude that she had most likely contracted cervical cancer. To confirm their diagnosis they took a sample of her tissue and had it analyzed. The news was anything but encouraging: the tumor contaminating the cervix turned out to be malignant. In October, the same year, and only after a few months’ struggle with the disease Henrietta Lacks died.

Immortal cells of a dying patient

Even though Henrietta and her family could not have realized this fifty years ago, her body did not finish its life just yet. Some of the cells are alive even to this very day, more than half a century after their owner’s death. They are being carefully grown in numerous laboratories across the world and have even reached outer space after being sent into the orbit on a satellite, enabling researchers to observe the effect of zero gravity on cell growth. In fact, if we were to weigh all Henrietta’s surviving cells together, they would probably largely exceed the weight of her entire body fifty years ago.

The fascinating journey of Henrietta’s cells began in 1951 when a part of her tumor’s tissue was sent to the laboratory of Otto Gey, a researcher at John Hopkins University who had been striving for decades to find a solution to growing human cells in a laboratory in order to facilitate cancer research. He struggled to find the solution for a long time, but the cells simply refused to grow and divide in an artificially created environment. That was until he came across the cells from Henrietta’s tumor and decided to give them a go.

Miraculous HeLa cells

Even after spending several days in an artificial culture medium, Henrietta’s tumor cells continued to divide successfully and there was no indication of them growing old and dying as was common for all the previous experiments. Gey named them after his patient: HeLa cells. He concealed the identity of his patient with great care and it was only revealed after his death.

However, as rapidly as HeLa cells multiplied in Gey’s laboratory in 1951, they multiplied inside Henrietta’s body. Even though the patient died because of uncontrollable multiplication of tumor cells in her body only half a year after her first visit to the hospital, the very cells that did her so much harm were soon helping to save many other lives.

In the 50s the vaccine for polio was already developed with the help of HeLa cells which have to this day enabled an abundance of researches that have led to the discovery of many important facts about life and the workings of the human body.

Immortal cell lines

Henrietta’s cells were the first to be successfully grown in artificial, laboratory conditions and later used to create an immortal cell lines which is a term used for describing cells that can – in an appropriate feeding environment – continue to divide outside the body without aging. In normal circumstances, cells can only divide for a limited number of times (ten or more) before losing this ability and slowly dying.

Programmed cell death after a certain number of divisions was in fact what stopped Gey from creating an immortal cell line from normal cells in the human body. It was only Henrietta’s cells that had the ability to divide indefinitely. That was because they lacked the mechanism responsible for stopping an uncontrolled multiplication. Its inactivity failed to trigger cell death after a certain amount of duplication.

Cell aggression beats the competition

As HeLa cells turned to be very useful in numerous researches, Gey simply mailed them to his colleagues all across the world so they could grow and use them in their work. Soon, other scientists started reporting having created their own immortal lines of human cells. However, it soon turned out that these so-called new lines were really just a form of Henrietta’s cells. These were found to be very aggressive, as they were capable of infecting other cell cultures and eventually eliminating the competition even when applied in extremely small doses.

In 1972, for example, Russian scientists sent their American colleagues six different lines grown in various parts of the former Soviet Union, but it was discovered that all of them were actually HeLa cells. Americans did not prove to be any more successful either: in 1968 they tested 34 lines and proved that 24 of those were actually derived from Henrietta’s cells.

Growing patient cells

As scientists perfected the methods of growing human cells and cells of other mammals in laboratories, they quickly began to wonder whether it was possible to create immortal lines for specific individuals as well. Organ transplantation always entails a risk that the immune system will reject a transplanted heart or liver. Doctors try to overcome this with special medications that the patient with a transplanted organ has to take regularly for the rest of his or her life as well as by observing the similarities between the organ donor and the organ recipient. The transplant is done only if the donor organ and the recipient are a close enough match to assure a good chance to battle rejection with drugs.

Donor organ transplantations can always entail some problems and risks, so researchers started to think about ways to grow healthy cells of a failing organ in a laboratory and reinsert them into the patient later on. This would prevent the risk of a rejection of foreign tissue, as the artificially grown cells would not differ in any way from those of the patient, already within his body.

Today, skin and bone marrow growing therapies are already available. A sample of cells is taken from the patient and multiplied in sufficient amounts in a laboratory only to be transferred back into the patient later on. Skin growing can prove to be particularly difficult, taking several weeks to produce enough for transplantation, which might already be too late for the heavily injured.

Cells adapt to specific tasks

Another problem with growing ordinary cells present in different tissues of the adult human body is that cells can only perform a limited number of divisions. Sooner or later the process comes to an end or the cells produced do not respond to our needs.

Even though the genetic code of every cell contains all the information it requires for development, most of the cells that make up an adult body have already lost the ability to use the entire code. In the environment of a specific organ, cells adapt to perform a specific task and this adaptation is usually irreversible.

When a cell takes on a function within a blood vessel, the heart, the skin or the nervous system of an individual it can not "change its mind" and take on a different role. Scientists have not yet figured out what exactly happens within a cell when it is adapting to a specific task, but the fact remains: a part of its genetic code shuts off for good.

The mother of all cells

However, not all the cells within the human body have this one-way limitation in terms of their function. Those that have the ability to develop into other types are called stem cells. Their main characteristic is the option to develop into more specialized cells. The bone marrow, for example, contains special stem cells, capable of producing red blood cells that transport oxygen throughout our bodies. Similar stem cells that can produce other specific cells have also been found in various organs.

The capability to develop into every single one of several hundred cell types within the human body is possessed only by very young stem cells that can be found in the first days following fertilization in a group of some ten cells that constitute an embryo. These are called embryonic stem cells and are the only ones with the rare capability of developing into any cell type in different environments.

Immortal stem cell lines

Another important feature of embryonic stem cells is that they can be used to create a cell line. If grown correctly, they can multiply indefinitely without growing old and dying after some ten divisions, as is usually the case with already differentiated cells, such as skin or bone marrow cells. The first line of human embryonic stem cells was created in 1998 in the US.

Today, several hundred exist in the world. In the US, however, following the president George W. Bush’s decree, public research funds can only be used on the 22 lines created before the beginning of his mandate in 2001. This issue is once again gaining importance as the president vetoed the act that would approve the continuation of federal funding of this important/vital field of science.