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Because biotechnology's application to medicine is relatively new-only approximately a century old, this field does not have a very rich history. However, the origin of medical biotechnology can be traced back to the famous accidental discovery of penicillin by Alexander Fleming in 1928. Performing research at St. Mary's Hospital in London, Fleming was observing a sample, or culture, of harmful bacteria known as Staphylococcus aureus. While in the lab, he noticed that one of his cultures had been accidentally contaminated with a species of Penicillium, a type of blue-green fungus. Examining it further, he noticed that this fungus was severely inhibiting the growth of the bacteria. While this effect had been examined much earlier than Fleming, many researchers had simply discarded their findings, never pursuing further interest in the matter. Unlike the rest, Fleming was the first to bring penicillin to the center stage in the medical field by publishing a paper on his findings in 1929 ("The Story of Penicillin, Wonder Drug" 1). Noticing the therapeutic significance of Fleming's research, countless scientists tried to develop penicillin into a viable drug. In 1939, Dr. Howard Florey was finally able to do so. While performing research on penicillin at Oxford, he refined the fungus into a practical antibiotic with the capacity to fight off infectious bacteria in the human body. However, he ran into the problem of mass producing the drug. In 1941, Andrew J. Moyer was able to increase the growth rate of penicillin to the point where mass production of the drug was obtainable ("The Story of Penicillin, Wonder Drug" 1). As such, penicillin grew to become one of the most widely used medicinal treatments for disease with its unmatched ability to inhibit the growth of bacteria. Moreover, its discovery and development led to the antibiotics that keep countless individuals free from disease. Without these antibiotics, a case of strep throat or even a simple cut that becomes infected could result in death. However, while the significance of these antibiotics is almost indescribable, they cannot fight off every disease. Thus, scientists are turning to other means in which to cure such diseases.
Today, to cure diseases, pioneering medical biotechnology fields try to exploit the fundamental building block of all life: Deoxyribonucleic Acid, also known as DNA. Located in every nucleus of every cell in a living organism, DNA is the genetic material that serves as a sort of code or set of instructions in the creation and development of every living organism. One piece of DNA is comprised two long strands of nucleotides side by side, each nucleotide with one phosphate, one sugar, and one of the four possible chemical bases-Adenine, Guanine, Cytosine, and Thymine. These bases couple with each other, Adenine with Thymine and Guanine with Cytosine, to form base pairs. As discovered by James Watson and Francis Crick in their examination of DNA in 1953, these two long strands of nucleotides wind up to form the shape of a double helix (Hyde and Setaro 98). The order in which the base pairs appear in the DNA, known as the genetic makeup, determines what proteins will be produced in the building process of an organism. In turn, these proteins determine the characteristics of the organism such as its eye color, hair type, and skin color. The ability for DNA to replicate itself in the process of cell division is vital to sustain an organism. Each strand of DNA in the double can serve as a basis for creating another strand of DNA with an identical sequence of bases (Hyde and Setaro 99). With the knowledge of these properties, biotechnologists can theoretically change an organism's characteristics by changing the sequence of these base pairs in the DNA.
Beginning in October 1990 and ending in 2003, the United States funded a research program known as the Human Genome Project that served to determine the sequence of nearly "three billion chemical bases" in one strand of human DNA. In essence, the project was able to identify the genes--made up of 3,000 bases on average--that control the characteristics of a human. However, what scientists have yet to discover is the "function of over 50% of discovered genes" (Hyde and Setaro 94). The project also found that humans have 99.9% of the same sequence of bases, implying that only .1% of DNA separates one human from another (Hyde and Setaro 94). It is in this .1% of varying DNA that medical biotechnologists are searching for the genes that control diseases stemming from genetic disorders. By examining the sequence of DNA that controls a genetic disorder in a patient with the disorder and a patient without the disorder, scientists could be able to see how they vary. Subsequently, by altering this sequence of DNA in the patient with the disorder through a revolutionary new process known as gene therapy, scientists could eradicate the diseases stemming from genetic disorders.
While still in its early stages of development, gene therapy is becoming widely researched and practiced by countless medical biotechnologists. Though it is still considered to be extremely risky, the potential benefits could prove to be ground-breaking in the medical field, paving the way for a disease-free world. In essence, gene therapy is the use of genes in the DNA to correct or prevent genetic disorders instead of using drugs. The most common and widely studied form of gene therapy is the process of replacing the disease-causing gene with a normal, functional one. In these cases, a vector, the molecule that carries the therapeutic gene, bi-passes through the selectively permeable membrane of the targets cells until it reaches the nucleus where the DNA is housed ("Gene Therapy" 1). Because it is so difficult to find a substance or object that can act as a vector to reach the DNA, medical biotechnologists are now trying to exploit the uncanny ability of viruses to pass through the selectively permeable membrane. Viruses have progressed in a manner that allows them to reach the DNA and deliver their harmful genes to a cell-the reason as to why they are so deadly and difficult to eradicate. With gene therapy, medical biotechnologists are using viruses in a beneficial manner to deliver therapeutic genes instead of harmful ones ("Gene Therapy" 1). Thus, instead of deadly genes reproducing, therapeutic genes will multiply and ultimately heal the patient with the genetic disorder. With new improvements in technology, medical biotechnologists are finally able to apply this revolutionary practice as a means to advance the field of medicine.
With the steady development of gene therapy over the last few decades, medical biotechnologists are now readily turning to and applying this cutting-edge technique in the hope that one day, a cure will be found for the myriad of existing diseases. One quite common disease that scientists are concentrating their efforts toward is diabetes. For centuries, this disease plagued the lives of innumerable individuals. Today, it affects 25.8 million Americans alone--8.3 % of the population in the United States ("Diabetes Basics" 1). Still, in this modern era of advanced technology, the cure for diabetes is nowhere to be found. There is only treatment, which involves taking shots every day at a specific time, to lessen the debilitating effects of it. Essentially, diabetes is an overarching term to describe a collection of diseases that prevent the creation or inhibit the use of insulin, a hormone produced in the pancreas that helps cells in the body obtain the glucose from food needed for survival. Specifically, diabetes can be broken down into two basic subgroups: type 1 and type 2. Occurring more often in children, type 1 diabetes arises when the body's immune system intentionally attacks the beta cells in the pancreas that are responsible for the production of insulin. As such, the glucose and starches from the intake of food cannot be broken down, rendering it impossible for the cells to obtain essential nutrients ("Diabetes Basics" 1). On the other hand, type 2 diabetes, a much more common type of diabetes as compared to type 1, occurs when the insulin is produced just as any normal human being, but the body simply ignores it and never uses it. Similar to type 1 diabetes, the cells in the body will not obtain the insulin needed and thus are unable to break down the complex sugars and starches from food. Moreover, because the insulin remains unused in an individual with type 2 diabetes, it will build up in the blood stream along with the glucose, causing further complications such as high blood pressure ("Diabetes Basics" 1). While lifestyle factors influence the presence of diabetes, genetics ultimately determines whether or not an individual is able to obtain both types of this disease. Thus researchers are now trying to manipulate the human genome through gene therapy as a means to completely eradicate this disease from existence.
To combat type 1 diabetes, researchers are applying different techniques of gene therapy, and with increased efficacy in current studies, there arises hope for a cure in the near future. Because type 1 diabetes cannot be pinpointed to one faulty gene, medical biotechnologists in the past have had trouble in trying to cure such a deceptive disease. Now, they are looking to clever new ways in which to circumvent these problems but still reverse the effects of the disease. A Baylor team of scientists, led by Vijay Yechoor, believes they may have the answer. In their study, they used 27 mice diagnosed with type 1 diabetes. The scientists then treated the mice with a gene called neurogenin3 injected through the liver. Here, the gene acts to produce and develop new islets-clusters of cells that include insulin-producing beta cells-in the pancreas. However, just giving the mice this gene only solves one part of the problem. When these new islets form in the body, they are attacked and destroyed T cells acting on behalf of the immune system. Therefore, in order for these new islets cells to be viable and able to produce insulin, the team had to inject a new gene so as to deactivate the T cells only when they reached the new islets ("Gene Therapy Reverses Type 1 Diabetes in Mice" 1). If they deactivated the whole immune system, the process of reversing type 1 diabetes would be counterproductive as the patients would easily suffer from immunodeficiency. The only protective gene that had any success in deactivating the T cells only when they came into contact with the newly-formed islets was CD274. Adding this gene to the neurogenin3, the researchers were able to achieve a 78% success rate in curing the diabetic mice long-term. Currently they are working to produce a 100% success rate. Some problems have stemmed from the complex ways in which the immune system acts to kill these new islets; the beta cells themselves may be self-destructing ("Gene Therapy Reverses Type 1 Diabetes in Mice" 1). Thus, they are trying to cut off all the paths in which these islets may die off. Nonetheless, this gene therapy technique has a great potential to work in humans.
Scientists at the University of Florida, led by Satya Kalra, are taking a similar clever approach in trying to cure type 2 diabetes using gene therapy. Like the study at Baylor, Kalra's team of researchers used mice diagnosed with type 2 diabetes. When the mice were fed a high-fat diet, their bodies, not surprisingly, produced too much unused insulin that did not break down the glucose. As a result, the mice suffered from in high blood insulin levels as well as high blood glucose levels. To combat these effects, the researchers injected a gene into the brain of the mice using a harmless virus that codes for an increase in the production of leptin. Secreted through the hypothalamus in the brain, leptin is a hormone that is known to aid in controlling the appetite ("UF Study Shows Leptin Could Combat Type 2 Diabetes" 1). However, in the study, they found that leptin can also act to help regulate insulin secretion as well as reduce the blood glucose levels. In patients with type 2 diabetes, the overproduction of ineffective insulin is common, resulting in high blood glucose levels. Because of this, the patients are susceptible to a wide range of other ailments including blindness and cardiovascular disease. Thus, by reducing blood insulin and glucose levels through increased leptin production using gene therapy, the effects of type 2 diabetes can be reversed ("UF Study Shows Leptin Could Combat Type 2 Diabetes" 1). While this treatment still needs to be researched and studied before it can be used in humans, it is a huge step forward in combatting type 2 diabetes, a disease that affects innumerable lives throughout the world.
Another quite common disease that medical biotechnologists are looking to cure through gene therapy is cystic fibrosis. However, unlike diabetes, cystic fibrosis is caused by just one specific gene, the Cystic Fibrosis Transmembrane Regulator (CFTR) gene, that has been mutated, resulting in what is called a genetic disorder. Patients with this genetic disorder experience malfunctioning in their secretory glands responsible for mucus and sweat production because the "CFTR protein is defective and the cells do not release chloride and other ions" ("What Is Cystic Fibrosis?" 1) In patients without cystic fibrosis, their muscles naturally make mucus, a moist, wet substance that lines many organs such as the lungs to prevent infection. However, in patients with cystic fibrosis, the mucus produced is quite thick with a high level of viscosity. As a result, this mucus builds up in the lungs, preventing air from coming in and out of the body. Moreover, patients with cystic fibrosis are more prone to recurrent lung infections as the sticky mucus allows harmful bacteria to grow and flourish. Not only does cystic fibrosis affect the lungs, it also affects the pancreas as the sticky mucus can block the tubes in the pancreas. Thus, digestive enzymes made in the pancreas that are responsible for breaking down food are unable to be transported to the small intestines. As a result, cystic fibrosis patients often suffer from malnutrition as the nutrients from the food cannot be spread throughout the body ("What Is Cystic Fibrosis?" 1). While cystic fibrosis has its most significant, life-threatening influence in the lungs and pancreas, it also affects many other areas of the body-for example, the liver or sex organs-and can cause dehydration as a result of overly salty perspiration.
Because it is derived from a faulty genetic makeup, cystic fibrosis is hereditary, meaning that the disease has been passed down from the parents to the children. Currently, approximately 30,000 Americans suffer from cystic fibrosis, but one in 31 Americans are symptomless carriers for the disease ("Learning About Cystic Fibrosis" 1). That is, cystic fibrosis is a recessive disorder: for a person to inherit the disease, both parents must possess, or carry, the defective CFTR gene. That is not to imply the parents experience the symptoms cystic fibrosis; they may have a dominant gene over-riding the recessive gene that causes the disease. Moreover, even if both parents are symptomless carriers for the gene, there is only a 25% chance that the offspring will have cystic fibrosis ("Learning About Cystic Fibrosis" 1). To date, there only exist means to diagnose and treat this disorder. Diagnostic tests for cystic fibrosis include the "sweat test" in which the amount of salt in a patient's sweat is determined. Abnormally high amounts of salt indicate that the patient has cystic fibrosis. Generally, the earlier one can diagnose cystic fibrosis, the better treatment one can receive. Treatments include daily airway clearance techniques that rid the airways of the sticky mucus and antibiotics to fight off infections in the lungs ("Learning About Cystic Fibrosis" 1). However, there is no cure for the vast amount of mutations of the CFTR gene that causes cystic fibrosis.
The technique that offers the most promise for a cure for cystic fibrosis is gene therapy as it eradicates the source of the disease. Cystic fibrosis is a single gene disease: essentially, a mutation on the CFTR gene-usually a 3-base deletion where code for the normal protein is absent-occurs ("Gene Therapy Case Study: Cystic Fibrosis" 1). Because it only occurs due to one defective gene unlike diabetes, gene therapy techniques for cystic fibrosis are more straightforward. Theoretically, by adding a normal CFTR gene to the affected tissue areas such as the lungs, it could successfully solve the problem. Consequently, in the early 1990s, researchers began applying their gene therapy techniques. To start, they built a vector using a genetically-modified Adeno-associated virus. In the virus, the researchers replaced the DNA that coded for replication with the CFTR gene. They then replicated this genetically-modified virus and injected it into the lung cells of a cystic fibrosis patient. The virus subsequently infects the cells and replaces the faulty CFTR gene with a normal gene, causing the disease to be eradicated ("Gene Therapy Case Study: Cystic Fibrosis" 1). In 1993, this exact technique was used in clinical trials on human patients, but the study observed that the CFTR gene activity levels, which measured the ability for the virus to infect the cells, were too low to have a significant impact on the state of the disease. The cause for these low gene activity levels stemmed from the immune system. When these viruses entered the body, they triggered the immune system to rid the body of them. Thus, the therapeutic gene could not reach the lung cells. In other trials, researchers tried using different vectors, but none have completely eradicated the disease in the patient for one reason or another ("Gene Therapy Case Study: Cystic Fibrosis" 1). Currently, researchers are investigating different vectors as a means to transport the therapeutic genes effectively into the patient's DNA.
In essence, medical biotechnology, from the discovery of penicillin and antibiotics to current gene therapy techniques used to try to eradicate diabetes and cystic fibrosis, attempts to fight off and cure disease using a variety of technological systems. Beginning with Fleming's discovery of penicillin, antibiotic medicines have battled many infections that could have the potential to be fatal. However, antibiotics cannot cure every disease as some are embedded in the genes of an organism. Thus, new technologies such as gene therapy are attempting to erase genetic disorders by inserting therapeutic genes into the human DNA. Two of most promising applications of gene therapy involve diabetes and cystic fibrosis. In both type 1 and type 2 diabetes, researchers are trying to create functioning beta cells within the human body so as to regulate the amount of insulin produced and the amount of glucose in the blood stream. In terms of cystic fibrosis, researchers are attempting to insert a therapeutic CFTR gene into patients with the disease using a vector in order to replace the faulty, mutated genes. While both of these applications of gene therapy appear encouraging, a cure has yet to be discovered. Nonetheless, the future of medical biotechnology promises a world where disease is prevented in the womb before birth. Most importantly though, the medical biotechnology field is inherently beneficial to human progress as it combines biology and technology in order to eliminate human suffering from detrimental diseases.