DNA Manipulation, also known as genetic
engineering is the modification of an organism’s genes via biotechnology. Genetic
engineering has been applied in fields such as research, agriculture, and
medicine. In research Genetically Modified Organisms (GMO’s) are used to study
gene function and expression through loss of function, and gain of function
experiments. The first company to focus on genetic engineering, Genentech, was
founded in 1976 and created human protein production. DNA Manipulation helped
with the creation of insulin in 1978 and the bacterium that produced the
insulin were commercialized in 1982. There has been a rise in crop yield in the
last few decades with the help of genetic engineering. There has been great controversy surrounding
Through the Years
Modified Organisms (GMOs) were first created by Herbert Boyer and Stanley Cohen
in 1973 when they engineering bacterium.
Herb Boyer was born in Derry, Pennsylvania and attended St. Vincent
college to be a doctor. It turns out
that Boyer did not want to pursue a career as a doctor and in 1958 he graduated
with a B.S. in biology and chemistry, so he pursued a research career (Macy,
n.d.). He did graduate level work at the
University of Pennsylvania and post-graduate work at Yale. Boyer was interested in E. coli and restriction
enzymes that came from E. Coli. Stanley
Cohen was born in Brooklyn in 1922 to Russian and Jewish emigrants. Stan went through the New York City public
school system and was accepted at Brooklyn College. Stanley focused on cell biology and the
mysteries of embryonic development while majoring in both Biology in
Chemistry. In 1948 Stanley graduated
from the University of Michigan with a Ph.D. thesis on the metabolic mechanism
on which the end product of nitrogen metabolism in the earthworm is switched
from ammonia to urea during starvation (Cohen, 1986). In the early 1970s Boyer met Stanley Cohen
who was then working on plasmids.
Plasmids are circular rings of extrachromosomal DNA. The two have been recognized for many awards
for their discovery of successfully creating an organism using recombinant DNA
One of many uses of
DNA modification is to genetically engineer plants. There are risks to genetic engineering in
plants such as the plant becoming an invasive species or the plant acquiring
antibiotic resistance. However there are
also benefits to genetically engineered plants.
The agriculture industry has debated on bringing GMOs to the community
for years due to the varying support of advantages and disadvantages. When a plant is modified, there is a chance
that the organism may become an invasive species. An invasive species is a non-native organism
that can hurt the ecosystem that it is introduced to. When invasive species are introduced they
tend to take over the area and degrade the natural ecosystem. Altering a plants genotype may be beneficial
to the agricultural industry, but those species are known to be more aggressive
than those that occur naturally. (Wolfenbarger & Phifer, 2000, n.p).
A risk that needs
to be calculated with genetically modified plants is the possibility that the
plant may develop a resistance to antibiotics.
When gene transfer of an organism is observed there are two traits that
are under observation; antibiotic resistance and herbicide tolerance. When herbicides and an antibiotic solution
are engineered into the plant, the solution will terminate the cells that did
not have the resistance and tolerance genes.
The cells that survived were deemed to have the DNA sequence for
antibiotic and or herbicide resistance.
To farmers, herbicide and antibiotic resistance can help solve bugs and
pesticides, problems that have plagued them for years. The risk that comes from resistance is when
the plant is consumed by a human or animal.
If there is an antibiotic that is commonly used with treating a specific
disease, and the organism has antibiotic resistant pathogens for that disease,
the person could die (Fox, 2001, p. 24).
There is also a chance that the antibiotics may mutate and create other
antibiotic resistant cell types.
Through all of the
risks with genetically engineered plants, there are benefits from the process
as well. Genetically, altered plants do
not require as many pesticides as normal plants which is a good thing because
pesticides contain chemicals that can hurt the environment. When the seed has the new DNA sequence in its
genome then it will automatically pass it down to its offspring. In 1998 the genetic engineering of food
expanded greatly, with corn being the most successful crop. A study found that 8.2 million pounds of
pesticides were not used due to the genetic altering of corn (Wolfenbarger
& Phiefer, 2000, n.p.). A major reason
for the genetic engineering of food is because of an increased crop yield
(Wilson, 2014, n.p.). Genetic
engineering also affects human beings.
This leads to a significant ethical dilemma known as designer babies.
A designer baby is defined as a baby whose
genetic makeup has been selected in order to eradicate a particular defect, or
to ensure that a particular gene is present (Oxford Dictionary, 2015). The idea of genetically engineering embryos
is derived from preimplantation genetic diagnosis. Preimplantation genetic diagnosis allows
expecting parents to screen for over 100 diseases before being implanted into
the mother during in vitro fertilization.
Embryos can be modified during PGD using a third parent. The nucleus of an extracted egg is placed
into the enucleated egg of another woman, which has her mitochondria. The mitochondria contain genes of the third
parent and will have the “desirable traits” that parents can fix into a child
(Center for Genetics and Society, 2015).
The advantages and
disadvantages have to be considered when talking about creating designer
babies. It is easy to see how this
process is beneficial when it is creating an exact match so an ill child can
have an organ donor or bone marrow donor.
Another benefit to the genetic alteration of human embryos is when the
PDG shows a defective gene and doctors are able to correct the problem before
the baby is born. The idea of
eliminating a familial disease is very appealing and is a huge benefit to the
discussion of designer babies.
An issue with the
creation of designer babies is the manipulation of nature. Parents who are able
to decide that the natural gender of an unborn child is different than what
they want are playing God. When parents
choose to focus on fixing the gender of a child because they have the money,
will only create segregation in society.
Not all families will be able to afford a modified child. The families who can afford the modified
child will be looked at as greater while regular humans will be the lesser
Parents will also
have to consider the relationships that will arise with altered genome children. What if the child did not turn out how the
parents expected? This procedure could
be a major disappointment. If the
parents paid large amounts of money for a child who was supposed to have
incredible talents that were not achieved, the parents may shun the child. Also, if a child found out that they were
genetically altered and not accepted for how they were originally created it
could cause many acceptance problems.
The last ethical
problem is how the technology can be implemented for future uses. Who says when the screening is
appropriate? What is done to healthy
embryos that do not have a “desirable” genetic profile? (Kirk, 2000). Pushing the envelope on screening and
modification of embryos can lead to the pushing of other medical
boundaries. The intentions of the
science behind designer babies are good, the potential for abuse is too great
for human temptation.
The most important
and interesting aspect of DNA manipulation is what it can offer in the world of
medicine. There are more studies being conducted
on the effects of gene therapy on cancer as the years pass. Immunotherapy uses modified cells with viral
particles to stimulate the immune system to destroy cancer cells. Gene transfer is a more recent treatment that
introduces new genes into a cancerous cells or surrounding tissues that prompt
the cells death or slow metastasis. This
treatment is considered very flexible so a wide range of vectors have seen
success in clinical trials. When
scientists understand more about these therapies they may be used by themselves
or in combination to help manage and cure cancer.
defined as boosting the immune system to target and destroy cancer cells, and has
been pursued by researchers for over a century.
There has been little success as cancerous cells tend to evolve to avoid
immune detection. Many gene therapy
techniques are being used to bypass this limitation. In previous years clinical trials for cancer
vaccines have shown bright spots on the horizon for cancer treatment. These vaccines are different than vaccines
for infectious agents because vaccines for infectious agents are meant to
prevent the disease, cancer vaccines are meant to cure the disease. The cancer vaccine will make its patients’
immune system recognize the immortal cells by showing it as highly antigenic
and immunostimulatory cellular debris.
First the cancer cells are taken from a patient then grown in
vitro. Then the cells are terminated and
their contents are inserted into a vaccine. Another immunotherapy method is to
alter someone’s immune system to help sensitize it to cancerous cells. One study conducted used bone marrow from a
patient. Then a tumor is added to the
cell type. The altered cells are now
primed to cause immune reactions to cancerous cells leading to the removal of
cancer (Cross, 2006). The gene can also
be added in vivo if there is a target delivery system, such as an altered viral
Some of the first
trials using the cancer vaccines have given mixed feedback, highlighting the
potential of the vaccines and the areas that need more work before they become
a standard part of cancer treatment.
Murine models that use carcinoembryonic antigen (CEA) showed tumor
reduction and a lasting immune response when immunized with a vaccinia virus
designed to express CEA. When the same
type of treatments was used on patients with breast cancer, no responses had
In current clinical
trials vaccines that have engineered cells are showing promise for treatment of
cancer compared to conventional therapy.
For example, vaccine treatment for non-small cell lung cancer has had
wonderful results in clinical trials.
More clinical trials are showing the effects of unmasking the tumor from
immune invasion. MDA-7, a cytokine that
prompts cancerous cells to die, is currently in clinical trials for its ability
to cause an immune reaction in melanoma patients. PANVAC-VF is a vaccine that is modified to
deliver Muc-1 and CEA with the other immunostimulatory genes. The vaccine is coupled with a fowl pox virus
that is engineered the in same matter.
This method has recently completed a phase 3 trial in pancreatic
cancer. Future clinical trials of
vaccines can look to a few areas of improvement. The vaccines of the future may be able to
focus on a personal vaccine for the patient instead of using autologous cells.
A newer tool called
CRISPR-Cas9 has helped researchers edit genomes so that
immune cells have the ability to kill cancerous cells in mice (Staff, 2017). CRISPR-Cas9 works by introducing a mutation
into the DNA with two molecules Cas9 and gRNA.
Cas9 is an enzyme that cuts strands of DNA at an exact location in the
genome and allow for editing (CRISPR-Cas9, 2016). The next molecule is gRNA, a small piece
of a pre-engineered RNA that is around
twenty bases long inside of a longer segment of RNA. The longer segment of RNA binds to DNA and
the pre-engineered sequence helps the Cas9 find its way to the correct area in
the genome. This method makes sure that
the Cas9 cuts at an exact point in the genome. The fact that the RNA is an exact match means
that the RNA will not bind to other areas of the genome that can cause
mutations, unlike previous methods of gene editing. Once the two molecules make it to the
location the Cas9 makes cuts across both strands of DNA and the cell recognizes
and repairs the damaged DNA. This method
was derived from some bacteria because of their built-in gene editing systems.
Cells in studies
were engineered to express the surface proteins known as chimeric antigen
receptors (CARs). Chimeric antigen
receptors allow cells to recognize and attack cancer cells that express a
specific antigen. In trials it was found
that immune cells that had been altered by CRISPR to express CARs were more
adapt to killing cancerous cells than the immune cells engineered conventionally.
that was used in the previous study is known as CAR T-cell therapy. In CAR T-cell therapy utilizes adoptive cell
transfer. Patients have their own T cells collected. The T cells are then engineered to attack
tumor cells, expanded in the lab, and injected back into the patient. Previous methods of manipulating T cells to
express a CAR used a retrovirus to return the gene, leaving the gene inserted
at a random point in the genome. Not
being able to select exactly where the CAR gene inserts itself could disrupt
the normal genome and cause the host problems from mutations. Using CRISPR the doctors are able to
specifically place where they would like the CAR gene, which is typically the
T-cell receptor alpha chain (TRAC) gene.
The TRAC portion of the genome includes the gene for T-cell receptors
which helps immune cells detect invading molecules. CRISPR removes a portion of the TRAC gene
allowing CAR to be inserted. Scientists
looked at the two types of CAR T-cell models and concluded that the gene that
was placed on the TRAC locus by way of CRISPR was more adapt at eliminating
cancerous cells than that who was inserted by a retrovirus. There is a phenomenon called “exhaustion”
where the CAR T-cells will stop recognizing and destroying tumor cells after a
certain amount of time. The researchers
found that expression levels given from CAR on the TRAC locus from CRISPR
depleted the exhaustion greatly, giving a greater tumor eradication.
manipulation will need to be used in the future because all of the positive
implications that are associated with it. There are risks that come along with
the rewards of genetically engineering plants and human beings. Genetically
altered plants have a chance of turning into an invasive species that can
destroy an ecosystem. For plants there is also a chance that antibiotic
resistance will be passed through generations. Genetically engineered plants
require significantly less pesticides making the environment a cleaner place.
The plants with alteration also help out
the problem of food shortage by increasing crop yield. The science behind gene
editing for designer babies is good, but there is too much potential for
community segregation for humanity to handle. I believe that the technology
should be used but there should be a concordance throughout the world on what
exactly should be allowed to undergo editing. Humans are increasingly close to
the line of playing god. CRISPR-Cas9 is showing as an effective method of
editing cells to remove cancer and it is interesting to see what will happen in
the future with the technology. As science evolves, so will the field of DNA
manipulation. In the future humans will look back at the “cutting-edge”
technology and methods and wonder how we lived with such basic practice.