By: Tanish Patel
What is Genetic Engineering?
Genetic engineering is “the deliberate modification of the characteristics of an organism by manipulating its genetic material” (Oxford Languages). In this practice, scientists alter an organism’s deoxyribonucleic acid (DNA) and other nucleic acids to modify it. Genetic engineering used to be known as a term used to refer to the methods used to modify organisms through reproduction and heredity, similar to artificial selection. The term also formerly encompassed biomedical techniques including fertilization outside living organisms (in vitro), cloning, and gene manipulation, among others. In the 1900s, however, genetic engineering was redefined to specifically refer to recombinant DNA technology. In these methods, DNA molecules from multiple sources combine either in cells or in vitro, are inserted into organisms, and grow.
Credit: Biology Dictionary
Recombinant DNA technology usually involves bacteria plasmids (small DNA rings outside the chromosome) being filled with foreign genes. These plasmids can direct protein synthesis and are also reproduced and inherited by the bacteria’s offspring. This way, when the bacteria reproduces, the plasmids containing the foreign genes are passed onto its offspring, allowing scientists to obtain a theoretically endless amount of copies of the foreign gene. Not only this but if the gene that was inserted into the plasmid can direct protein synthesis, the genetically altered bacteria will create the protein instructed by the new DNA.
A more recent development in the world of genetic engineering is gene editing, a method in which a technology known as clustered regularly interspaced short palindromic repeats (CRISPR) allows scientists to alter organisms’ DNA to change their genetic sequence. This technique also has several applications both inside and outside the medical field, ranging from genetically modifying crops to model organisms such as mice in laboratories.
Applications of Genetic Engineering
Gene Therapy
According to the United States Food and Drug Administration (FDA), gene therapy is a process in which a gene’s expression is altered to change the properties of living cells for therapy. Gene therapy is the application of genetic engineering as a form of therapy to cure/treat disease. Gene therapy can either replace genes that cause diseases with their healthy replica, inactivate disease-causing or malfunctioning genes, or add new/modified genes to an organism to treat diseases. Gene therapy usually refers to the addition of a normal gene into a person’s genome to fix a mutation that causes a disease. When this normal gene is inserted into a mutant nucleus, it incorporates itself into a different chromosomal site from the harmful allele, possibly repairing the mutation or creating a new one if the new gene integrates into a different functional gene. The new gene may replace the mutant allele and may cause the transformed cells to rapidly increase, making enough of the normal gene to cause the individual’s entire body to be renewed to the phenotype without the disease.
Gene therapy products are also being continuously developed and improved upon as genetic engineering advances. Apart from the previously discussed gene therapy product plasmid DNA, some products include bacterial vectors, viral vectors, human gene editing technology, and patient-derived cellular gene therapy products. In bacterial vectors, bacteria are modified to prevent them from being disease-causing and then used as vehicles (hence the name vectors) to transport helpful genes into human tissue. Viral vectors employ a similar transportation method, in which the natural capability of viruses to deliver genetic material into cells is utilized. Viruses, altered to terminate their power to carry infectious diseases, carry therapeutic genes to human cells similar to bacterial vectors. Human gene editing technology is a different form of genetic therapy, in which genes are edited to disrupt harmful genes or fix mutated ones. This technique is discussed above, as it is what is usually referenced when gene therapy is discussed. Finally, in patient-derived cellular gene therapy products, cells are extracted from patients, genetically revised (often using some sort of vector such as viral vectors), and then replaced into the individual.
Credit: FDA
Vaccines
Genetic engineering can be implemented in microbial cells (cells that respond to certain stimuli) to develop vaccines by inserting genes from harmful pathogens. These genes contain information about developing parts of pathogens that trigger responses from the immune system to fight them off. This procedure has proved effective in developing the vaccine for the hepatitis B virus (HBV), one which is widely used; the vaccine was created by using microbial cells to produce parts of the HBV. Scientists are using similar procedures to develop treatments for diseases in animals and humans, and are currently testing vaccines as genetic engineering research and technology progress.
Genetic modification techniques also enable us to create substances we can use to study diseases. The HBV virus component created through genetic engineering, for example, allows researchers to diagnose the virus and learn more about the immune system’s responses to similar viruses. This information enables scientists to develop more vaccines and treatments for diseases, thanks to the wonders of genetic engineering.
Other Applications in Medicine
In medicine and healthcare research, genetic engineering has enabled scientists to “mass-produce insulin, human growth hormones, Follistim for treating infertility, human albumin, monoclonal antibodies, antihemophilic factors, vaccines, and many other drugs” (LibreTexts). As previously stated, genetic engineering has developed drugs and hormones used in medicine. For example, gene splicing was utilized to develop large supplies of insulin from cells of the E. coli bacteria. Interferon, which is used to kill cancer cells and other viruses, and tissue plasminogen activator and urokinase (used to dissolve blood clots) were also created by way of genetic engineering. Human growth hormone (HGH), is also produced through genetically modified bacteria and yeasts. HGH is used for treating conditions such as dwarfism and the human immunodeficiency virus (HIV). Gene therapy has also been used in clinical trials to treat things like acquired immunodeficiency syndrome (AIDS), cystic fibrosis, cancer, and high cholesterol. Although there are a few drawbacks such as patients’ immune systems destroying genetically altered cells, gene therapy and genetic engineering are paving the way for new developments in the future of medicine.
Ethical Issues Surrounding Genetic Engineering
In the 1980s, new microorganisms developed through the alteration of genetic material were able to become patented, and the United States Department of Agriculture approved the first living organism that was genetically modified. This organism was a virus that was being implemented as a vaccine. This initiated an increase in genetically altered products and patents, such as those for bacteria and plants, including crops and food which would be sold and distributed to the general populace. This led to the development of public fear of genetic engineering causing dangerous and unfavourable traits to be introduced into microorganisms that used to be healthy without genetic intervention. For example, these traits comprise resistance to antibiotics, the creation of toxins, or even the capacity to cause diseases. Genetically modified crops and food products as well as animals and other organisms (such as mosquitoes, which were released into the environment to prevent disease outbreaks) were also feared for their possible effects on human and environmental health.
Gene editing in humans, specifically, has posed further ethical concerns as well. Genetic engineering can alter an individual’s innate characteristics such as beauty, and other personality traits including intelligence. Genetically modifying human sperm may enable altered genes to be passed down through generations as well, but could also be utilized to alter genes that increase cancer risk. This could potentially reduce the risk of cancer in the resulting offspring. Overall, genetic engineering has limitless possibilities, and as a result, the ethical guidelines surrounding this revolutionary technology are lacking.
Conclusion
Genetic engineering is an immensely controversial topic. It has proponents and opponents, and pros and cons. However, it is an irrefutable fact that genetic engineering has elevated the field of medicine in terms of disease identification, therapies/treatments, and pharmaceuticals. Although the field of genetic engineering requires more rigid and cohesive ethical guidelines, the possibilities of the applications of genetic engineering are almost limitless, both inside and outside the world of medicine.
References
“7.23b: Applications of Genetic Engineering.” Biology LibreTexts, 24 Dec. 2022, bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/07%3A_Microbial_Genetics/7.23%3A_Genetic_Engineering_Products/7.23B%3A__Applications_of_Genetic_Engineering#:~:text=In%20medicine%2C%20genetic%20engineering%20has,the%20functions%20of%20certain%20genes.
Center for Biologics Evaluation and Research. “What Is Gene Therapy?” U.S. Food and Drug Administration, www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/what-gene-therapy. Accessed 10 Aug. 2023.
“Genetic Engineering.” Encyclopædia Britannica, 29 June 2023, www.britannica.com/science/genetic-engineering.
PG;, Murray K;Stahl S;Ashton-Rickardt. “Genetic Engineering Applied to the Development of Vaccines.” Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, pubmed.ncbi.nlm.nih.gov/2573084/#:~:text=The%20simplest%20application%20of%20the,host%20of%20the%20pathogen%20involved. Accessed 10 Aug. 2023.
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