The Biology of HeLa Tamar Gartenberg - PowerPoint Presentation

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The Biology of HeLa

Tamar Gartenberg

History

Discovery

HeLa cells were discovered by Dr. George

Gey

, the head of tissue culture research at Johns Hopkins,

in 1951

.

George

Gey

and his wife Margaret were working on discovering a way to grow malignant cells outside of the body. Most cells died too quickly to be of use, so

gey

wanted to create

a line of

immortal

cells that would continuously divide from one sample and never die.

In 1943 it was proven possible using mouse cells by researchers at the National Institute of Health,

Gey

was attempting to replicate this with human cells

.

The original sample of HeLa cells came from a patient named Henrietta Lacks who was being treated for cervical cancer at Johns Hopkins.

One of her doctors, Dr. Richard

TeLinde

was attempting to find a way to grow living samples of cervical cells to compare normal cervical cells, carcinoma in situ, and invasive carcinoma to try and prove his findings about cervical cancer and the best course of treatment.

TeLinde

provided

Gey

with a steady supply of cervical cancer cells from the patients at Johns Hopkins, including Henrietta.

Discovery

Shortly after being procured by the

Geys

, Henrietta’s cells were observed to be growing.

While some cells in culture continued to grow for a brief period of time, Henrietta’s cells grew at an astounding rate, doubling every twenty-four hours.

They grew 20 times the rate of Henrietta’s normal cells.

Following the apparent discovery of the first immortal human cells,

Gey

began sending them in response to colleagues’ requests to study the cells and use them in research.

The cells were used in countless experiments and shipped all over the world – after all, there was an endless supply.

Henrietta’s cells were invaluable to researchers because they allowed scientists to conduct experiments that would have been impossible without live, human cells.

Cell Immortality

Typically

, cells age and become more unstable the more they

divide sometimes causing toxins to form. The aging process of cells is called cellular senescence.

Eventually the cell is unable to replicate or divide further and it dies which is known as programmed cells death or apoptosis. This is part of the normal life of a cell.

Unlike

typical somatic cells, which undergo

cellular

aging (senescence) and lose the ability to divide and replicate after

a certain number of times known as the

Hayflick

limit, HeLa cells never stop dividing. Since they are tumor

cells, HeLa cells also do not die from

apoptosis.

HeLa

cells thus became the first line of human cells to survive indefinitely in vitro (under proper culture-growing conditions

).

Research

Cell DeliveryFrom the time of their discovery, HeLa cells have been in high demand all over the world. At the time, it was not common to send cells from one location to another.

Gey

developed methods of

sending the cells to other laboratories and researchers while keeping

them alive by

putting them in tubes with culture medium to keep them alive. Pilots or stewards would keep the tubes in their pockets to maintain the cells’ temperature.

Using HeLa cells, scientists were able to discover methods of

freezing and shipping

cells, which is now common practice today. Live cells are often shipped from large supply companies and between laboratories

.

In 1952, HeLa cells became the first living cells to be shipped by postal mail.

How are HeLa cells useful in research despite being cancerous?

Although they

are cancerous

,

HeLa cells share the same basic characteristics and behave

similarly to healthy cells in many

ways. They produce

proteins and

communicate

with one another like normal cells, they

divide

and

generate

energy, they

express and regulate genes,

and they

are susceptible

to

infections.

Because they are cancerous, they are often even more helpful in research because they will produce results even more quickly than normal cells.

Researchers have been using them since the 1950s to discover how cells behave in

certain

environments, react

to

specific chemicals,

or

produce

certain

proteins.

Because they are susceptible to infection, they are ideal for synthesizing

and studying

bacteria, hormones, proteins, and viruses in culture.

Polio VaccineAt

the end of 1951 was the largest polio epidemic in history. In February 1952, Jonas Salk announced that he had developed a vaccine, but in order to administer the vaccine, it needed to be tested on a large scale.

Millions of neutralization tests, which mixed blood serum from vaccinated children with live poliovirus and examining the results under a microscope, needed to be conducted.

Millions of neutralization tests, which mixed blood serum from vaccinated children with live poliovirus and examining the results under a microscope, needed to be conducted

.

Originally, Rhesus monkey cells were used to measure the antibodies produced by the polio virus, but the large quantities required for vaccine testing could not be procured because the monkeys were killed in the neutralization tests.

Polio VaccineHeLa

cells were remarkably susceptible to the poliovirus and highly proliferative which made them a suitable, cost-effective alternative

. Unlike other culture cells, they also weren’t limited by space because they didn’t need to grow in a single layer on glass, they could be grown floating in culture medium.

Shortly after the HeLa cell strain was chosen as an alternative source to Rhesus monkey cells, the NFIP proposed the establishment of a central source to supply HeLa cultures to meet the anticipated needs of researchers testing the vaccine

.

They planned to create a HeLa factory which would produce trillions of HeLa cells per week. A HeLa distribution Center was created at the Tuskegee Institute. In addition to being used to test the polio vaccine, the cells were shipped to many other researchers.

Cell Line ContaminationIn September 1996, at

the Second

Decenniel

Review Conference on Cell Tissue and Organ

Culture,

a geneticist named Stanley

Gartler

explained tha

t in the process of looking for genetic markers, he had discovered that the 18 most commonly used cell lines all contained a rare genetic marker almost exclusively found in black Americans (though many of the cell lines came form Caucasians).

Though many scientists doubted him, they were unaware that HeLa cells were able to travel through the air on dust particles and travel from culture to culture on hands, pipettes, lab coats, etc.

Since

HeLa

cells grow

so aggressively without

many of the factors that limit the growth

of other cells, they began to pose a problem for scientists

. Because they are so strong, even one HeLa cell can completely take over another culture.

If

laboratory workers are not extremely careful to avoid cross-contamination, HeLa cells can invade other

cultures, replacing

the original

cells.

Estimates

in the 1970s suggested that 10–20% of all cultured lines may have been contaminated by HeLa cells.

Why was this significant?The fact that so many cell lines were corrupted was a HUGE scientific discovery that affected numerous research projects and scientific findings.

The

work and effort scientists had put into all of these projects had been put to waste because many of their findings were

invalidated

– along with millions of dollars invested in research.

For example, Robert Change, a researcher at Harvard’s Chang Liver Cell line was listed as contaminated. If the cells had actually come from Henrietta’s cervix, all of Chang’s research was worthless.

The American Type Culture Collection (ATCC) had collected dozens of different types of cells, all guaranteed to be uncontaminated, but at least 6 of the contaminated cell lines came from the ATCC.

Cells in SpaceIn April 1961, when Yuri Gagarin made his historic, orbit a team of microbiologists

from the Institute of Experimental Biology of the Soviet Academy of Medical

Sciences also sent HeLa cells into orbit to examine the impact of space travel on cells

.

Though this was a short flight, they were sent into space numerous other times along with other cell samples and the results show that HeLa cells on several of the journeys divided faster and more powerfully in space than on Earth as opposed to normal cells which divided at the same rate. On other trips, though, HeLa divided at the same rate.

HeLa was very important as

the first immortal human cell line in the history of space

microbiology, but the results from HeLa’s space travel are seemingly inconclusive.

Other Scientific BreakthroughsIt

was on HeLa cells that scientists first examined the human cell division in

detail.

HeLa cells were

the first human cells to be

cloned.

Using HeLa cells, scientists were able to generate an accurate

calculation of

chromosomes.

HeLa cells were the first

to be put to

centrifuge, under

the

sea, and in space.

H

eLa cells were instrumental in studying and developing and testing vaccines for numerous diseases and including Polio and Parkinson’s.

In

1965 scientists fused them with mouse cells and created the first cross-species hybrid.

Ethics

Responses to Ethical Questions

Scientists were often the ones to justify seemingly unethical behavior because of the important impact of their work. The more freedom they had in collecting samples and test subjects, the easier it was for scientists to conduct research.

“To use the dreaded word ‘cancer’ in connection with any clinical procedure on an ill person is potentially deleterious to that patient’s well-being, because it may suggest to him (rightly or wrongly) that his prognosis is poor...medically

nonpertinent

details...best tradition od

responsible

clinical

practice

” -

Chester

Southam

“If the issue were stated that bluntly so people could really understand what

’

s happening and they’re okay with it, that would make me more comfortable with what we’re currently doing. Because what’s happening now is not what people think is going on” – Ellen Wright Clayton

“These tissues enter a pipeline of millions of other samples. How are you going to distinguish, well, this patient said we can study colon cancer; the next one said we can do anything we want, but we can’t commercialize it. I mean, do they all have to be color coded?” – Wayne

Grody