Biotechnology is the use of living organisms like use of plants, animals and micro-organisms, such as bacteria or enzymes to create products or to do things for humans CSIRO, 2008). Also it can be used for solving problems and to conduct research. Biotechnology formed the basis of learning about people and disease and it also underpinned the development for treatments. Genetic engineering is the alteration of a genetic code by artificial means and is therefore is different from traditional selective breeding (Patrick Dixon, 2010).
Genes that carry chromosomes are the basic physical and functional units of heredity. Genes are the specific sequences of bases for encoding instructions, for making proteins (H, Huan, 2009). The proteins perform most life functions and make up the majority of the cellular structure. If the genes are altered so that the encoded proteins are unable to perform their function genetic disorders occur. Gene therapy is the experimental, treatment and application of gene technology that involves, introducing genetic material into a persons cell to fight or prevent from disease and to replace faulty genes. Gene therapy simply gives the human body the advantage and ability to produces its own cure quickly, safely and effectively. Gene therapy is not based on altering the human germ line which is normal misconception.
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Scientists are studying gene therapy for immuno-deficiencies such as hemophilia, cancer and HIV through different ways of delivering the gene into the cell. It was first envisioned to treat or cure genetic disorders but could treat a wide range of diseases, including those that resist conventional treatment. The gene can be delivered into a cell by using a vector (H, Huan, 2009).
Figure 1: The DNA being inserted into virus and into human.
Vectors that are most commonly used in gene therapy are viruses. Viruses are genetically altered to make the virus carry the human DNA. Once the virus has been genetically altered, it is safe to insert, although some risk still exists because the technology is still in the infancy stage but has been successful (M, Walter & L, Huxley, 2005). There are numerous gene therapy approaches such as:
Replacing the mutated gene that is causing disease and replacing it with a health copy of the gene. This enables the transfer of DNA into the patient's cells by a process called transfection.
Inactivating, knocking out the mutated gene which is functioning improperly.
Introducing a gene to help fight the disease.
The Abnormal gene is swapped for a normal gene through homologous recombination.
The Abnormal gene is repaired through a selective reverse mutation which then returns the genes to normal function.
Researchers have also been experimenting with a 47th chromosome which will be introduced into the target cells. The chromosome exists autonomously alongside the 46th chromosome not affecting its work or mutating it. This large vector would be capable o carrying substantial amounts of genetic code (D, Williams, 2010).
The gene can not be directly inserted into he person's cell but can be delivered into the cell by using a carrier, called a vector. Vector systems can be divided into two groups:
Non viral vectors
The most common type of vector is viruses but liposome and variety of other molecular transporters can be used. Virus vectors are used because they can be genetically altered to carry normal DNA (F, Stacy, 2010). Viruses have a way of encapsulating and delivering their gene to the human cell through a pathogenic manner. The scientists have taken the advantage of this capability and manipulated the viruses' genome and remove its disease genes and insert the therapeutic gene (H, Huan, 2009). The viruses that are used in gene therapy vectors:
Retroviruses: class of viruses that can create double stranded DNA copies and their RNA genomes. These copies of the genome are integrated into the chromosomes of the host cells. The human immune-deficiency virus (HIV) is a retrovirus.
Adenoviruses: class of viruses that have double stranded DNA genomes which cause respiratory, intestinal, eye infections in humans. The common cold is an adenovirus.
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Adeno-associated viruses: class of viruses that have a small single stranded DNA.
Herpes simplex viruses: class of viruses with a double stranded DNA. This virus infects a particular type of cell neuron. Cold sores are caused by herpes simplex type 1 is a common human pathogen.
Figure 3: Process of gene therapy using an adenovirus, http://www.pharmaprojects.com/contentimg/0409/gene_therapy.jpg
The vector is introduced into a sample of the patient's cells which are cultured to amplify the correct gene. Scientists have tried to harness the ability by manipulating a viral genome, to remove disease causing genes and insert a therapeutic one instead. Target cells are injected with the vector and into the patient's liver or lung cells, where the vector uploads the genetic material containing therapeutic gene (H, Huan, 2009). The functional protein product from the therapeutic gene restores the target cell and restores it back to normal. Altered stem cells instead of mature somatic cells have achieved longer lasting results in patients. The treatment of somatic cells or stem cells maybe therapeutic but the change is not inherited but germline therapy enables genetic change to be passed on. There has been limited success with gene therapy because the transfection of the target cells is inefficient and the side affects can be severe to fatal. There has been a small success with the treatment of one form of SCID, which is a genetic disease affecting the immune system.
Another approach to gene therapy besides the virus mediated gene delivery systems; there are several non viral options. The simplest method is to directly introduce t he therapeutic DNA into the target cells (N, Ananth, 2002). This approach is limited in application because it only works on certain tissues and requires a large amount of DNA. An additional non viral approach to gene therapy, involves the creation of artificial lipid sphere which has an aqueous core. The liposome is the carrier of the therapeutic DNA which is capable of passing the DNA through the target cell's membrane. Once the therapeutic DNA gets inside the target cell's membrane it chemically links to molecules that bind to special receptors (F, Stacy, 2010). When bounded to the receptors the therapeutic DNA constructs are engulfed by the cell membrane and then it is passed into the interior of the target cell. This is less effective than the other methods.
One of the diseases that can be cured is cancer. There has been much research done on this topic and experimental practice on gene therapy for cancer. Gene therapy is used as an approach to target health cells and enhance the ability to fight cancer or target the cancer cells which will either prevent growth or destroy tumour (National Cancer Institute, 2006). This can be done by replacing a missing gene for altering genes to make them health. A missing or altered gene may cure cancer by substituting working copies which may treat cancer.
Researchers have been studying new ways to improve the immune response to cure cancer by using gene therapy. Gene therapy is used tot stimulate the body's natural ability to attack cancer cells and this method takes a sample of blood from the patient and insert genes that cause each cell to produce T-cell receptors (T-lymphocytes) into the white blood cells(National Cancer Institute, 2006) . The blood is given back and injected back into the body. Then the T-cell receptors (TRC) attach to the outer surface of the white blood cells. The TRC's recognise certain molecules found on the surface of the cancer cells, which activates the white blood cells attack and kill the cancer cells (National Cancer Institute, 2006). This process is shown below.
Figure2: process of gene therapy
Figure2: process of gene therapy
http://library.thinkquest.org/28000/media/genetherapy/l_gene.therapy-ms.gifThis new technology is great and but not everyone approves of it, whether it is ethical issues, scientific issues or religious issues. Firstly people think that this new technology is too much like playing God. Many religious people have problems with scientists manipulating the genetic makeup of people's genes, changing who they really are. Also people feel if that people use gene technology to change a genetic disorder or makeup it is like questioning God's methods for making people that certain way (D, Bose, 2009). Secondly the ethical issues are that gene technology will be expensive which means only richer people can afford the benefits of this technology, and it will only make the rich richer and the poor poorer (D, Bose, 2009). Another ethical issue is the perfection is the only way and that it is the only acceptable way cause many people to have gene therapy used on them making a superior race f humans. Thirdly the scientific issues are not fool proof because this technology is only in the infancy stage still. The popular method of using a viral vector to treat the genes is not fool proof because it can not be placed in the specific point in the genome where the correct gene needs to be introduced. There is not grantee that the viral enzyme will introduce the correct gene in the specific spot in the host chromosome (Suzanne Clancy, 2008). If this does not happen then an error in process can occur and result in an error in genetic makeup of the cells causing serious disorders. Another problem with using a viral vector is that the body's immune system may detect this vector as a foreign body; it will try and destroy it. If these hurdles can be overcome then the long term benefits will help patients with genetic disorder and will help to fight diseases.
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Gene therapy is a perfect temporary treatment for disease and disorders. Scientists believe that gene therapy method may help people with disabilities or danger from harmful diseases (D, Bose, 2009). This is a powerful technology that if mastered could help millions of people and why would anyone not want to help people. Humans have been under continuous onslaught from disease and once a cure is found, a new more violent virulent form of germ is discovered (E, Bushelle, 2003). This could be treated with a gene therapy. It is also important that scientists use the best available treatment methods.
Gene therapy has been bantered by many groups of people saying that it is unethical but this technology is used too help people with genetic disorders and to help fight diseases. This technology should only be used for those things and not modifications of human capabilities. If these things can be done then gene technology should be researched, then experimental treatments and if there is success with the experimental treatment then the gene therapy should be used to treat on patients.