Scientists have been modifying genes of animals and plants for decades now, usually in an attempt to improve crops and animal produce. However, in recent years, some scientists have shifted to a new field that could provide solutions to some of the worst health problems and diseases suffered by man. The idea is to find ways through which the genes of the body can be modified or changed such that they will contribute to curing the body from illness and disease. Such scientific attempts are still in the experimental phase and are related to as gene therapy. The effectiveness of this therapy, however, is yet uncertain, especially that it remains in the experimental phase, and particularly as it phases numerous challenges that scientists have to deal with. Yet, the idea of modifying the genes of the body such that the body will be capable of fighting its own diseases is much more of a dream especially as it promises to resolve health problems against which modern science has stood helpless for decades. Although it is still in the experimental phase and has to overcome numerous obstacles, gene therapy remains a promising development that could help cure many incurable illnesses.
What is Gene therapy
By definition, gene therapy “is an experimental medical intervention that involves modifying the genetic material of living cells to fight disease (NCI, 1). In other words, gene therapy is based on the re-engineering of the genetic makeup in the cells of a sick person such that the systems of this person will be capable of fighting the illness on their own.
In some bodies, a gene might be missing or deformed, thus resulting in an illness. The major objective of gene therapy is to provide the body cells and systems with healthy copies of these genes that may be missing or deformed. These healthy copies may then be duplicated and reproduced in order to fight the illness (NCI, 1). Another objective of gene therapy is to modify the functions of certain cells in the body. Thus, scientists may program certain cells in the body in such a way that they will build resistance against a certain chemical or illness in the body, or simply trigger these cells such that they would attack and kill cancer cells (NCI, 1).
So far, scientists have not agreed on what constitutes a best method for gene therapy. However, all scientific experiments in this field are based on a main concept of gene therapy. The concept is based on selecting a vector or carrier that will carry the modified DNA or gene into the body cells. Usually, the carrier chosen for this mission is a virus because of the ability of viruses to reach the nuclei of cells at a high speed and with little resistance from the body (NCI, 2).
The concept of the gene therapy process is based on stripping away the components of the virus that may causes diseases to the body while at the same time, adding the DNA qualities that are needed by the body (Brown, 4). The next step involves mixing this carrier with cells from the body, usually bone marrow or blood cells. The introduced gene then becomes part of the DNA of the carrier vector (NCI, 2). Once this step is complete, the package might then be injected through the veins (Brown, 84). The viral vector or carrier then flows until it reaches the desired destination, and once it is there, it starts unloading its genes into the nuclei of these cells (Brown, 84).
Scientists are hoping that in the foreseen future, they will be able to control and master the process of gene therapy such that they will be providing cure for numerous illnesses that are impossible, difficult or expensive to cure. Most studies right now are trying to find cures for certain cancers such as lung, prostate, cervical and breast cancers (Brown, 84). Other illnesses targeted by gene therapy include hemophilia, AIDS, cystic fibronis, melanoma and muscular dystrophy (Brown, 84).
In the meantime, gene therapy has been approved for the treatment of one illness known as adenosine deaminase deficiency or the bubble boy disorder (Brown, 84). This is an illness that severely affects the immune systems of children such that they become vulnerable to any illness or infection. The conventional treatment available is a chemical that has to be injected through veins, costing up to $60,000 a year and to be taken for life (NCI, 3). Gene therapy has proven to be effective for this type of illness, requiring only a weekly dose of a medicine that triggers the effect of the injected vector (Brown, 83).
However, the success with ADA remains a single story and scientists still have a long way to go, mainly due to the tricky nature of the viruses and immune systems.
The problem with most vectors is that they are too small to carry big genes that are usually necessary to activate gene therapy (Brown, 84). To resolve this problem, scientists have been trying to identify strong and vigorous viruses that are capable of carrying the larger genes without triggering reaction from defense systems in the body. An example of such a virus is adeno-associated virus (AAV) which has been attracting attention of scientists in this domain recently (Brown, 84).
Another problem with vectors is that once they are injected into the blood stream, they just wander around with no specific target to reach. As they do so, there are chances that they will unload either in some location where the gene is useless or purposeless, or in some ‘hot’ location where the gene will be over-expressed, thus triggering immediate defensive reaction from the immune systems of the body (Brown, 84). This is not to mention the fact that in most cases, the objective is to have the gene triggered at certain intervals of time and not on a continuous basis. A potential solution for this problem has been identified. For example, scientists have found out that AAV can operate in coordination with a ‘chemical switch’ known as rapamycin. Once rapamycin is introduced by means of a pill, it turns the AAV on which in turn starts unloading the genes it carries (Brown, 84-85).
Equally important is the concern of scientists about the long term effect of gene therapy. For example, there is a high possibility that the therapy might result in an unwanted genetic modification that might be inherited by the offspring of the treated person. More seriously, there is also a high potential that the new genes may reach unexpected locations in the DNA of cells and may in turn trigger cancer growth in some cells (NCI, 3).
In conclusion, gene therapy is still in the experimental phase. Little success has been achieved so far and the path of disappointments is yet a long one. However, scientists believe that they have set their feet on the right track. There still is a very long journey to take with science and medicine before we can expect gene therapy to enable us to overcome incurable illnesses. However, this is not going to happen without consuming a lot of time and money.
Brown, Kathryn. “Mending broken genes.” Popular Science, October 1999: 82-85.
National Cancer Institute (NCI). “Questions and answers about gene therapy.”
NCI Online: www.oncolink.upenn.edu/pdc/6000718.html, August 5, 2000: 1-6.