Total Body Irradiation and Stem Cell Transplantation: A Cure for HIV?
written by: Leigh A. Zaykoski•edited by: Leigh A. Zaykoski•updated: 12/14/2010
Human immunodeficiency virus (HIV), the precursor to AIDS, targets the immune system and makes it difficult for the body to fight infection. Once thought incurable, scientific research indicates that a cure for HIV may be on the horizon. Learn about the possible cure and its implications.
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HIV targets the CD4+ T cells of the immune system. Also known as helper cells, the TD4+ cells help to maximize the abilities of the immune system by telling other immune cells what to do. These cells activate the infection-fighting capabilities of phagocytes and help cytotoxic T cells fight cancer. Because HIV destroys the CD4+ T cells, it weakens the immune system and renders the body unable to efficiently fight infections. Research started in 2007 shows that it is possible to cure HIV, once known as an incurable illness, with drastic measures.
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An HIV Cure?
Timothy Ray Brown underwent a stem cell transplant in 2007. Brown, who received the transplant as a treatment for acute myeloid leukemia, also underwent total body irradiation that destroyed almost all of his immune cells. Three years after receiving the transplant, testing showed no signs of HIV in his system, even though he did not take any antiretroviral drugs in the years following the procedure.
The scientists who performed the transplant chose the stem cell donor very carefully. Doctors used the bone marrow of a man with a rare genetic variation that made him almost impervious to HIV. The genetic variation, CCR5 delta 32, appears to have a protective effect again HIV and smallpox. Scientists theorize that this genetic mutation occurred during periods of widespread illness, such as during the Black Death or outbreaks of smallpox in Europe.
It appears that a CCR5 delta 32 variation results in the deletion of a 32-bp segment, resulting in a nonfunctional receptor and preventing the entry of HIV R5. One copy of this allele may slow the progression of HIV to AIDS – acquired immune deficiency syndrome – by two years. The stem cell donor selected for Timothy Ray Brown’s procedure had two copies of this allele.
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While many people are excited about the prospect of a potential cure for HIV, this is not a practical solution for widespread use. Total body irradiation and stem cell transplantation have serious risks and many people do not survive these procedures. Because of the risks, people should not consider this a cure, but a breakthrough that gives genetic researchers information they can use in the fields of stem cell research, genetic engineering and gene therapy.
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Further research in this area will focus on CCR5 delta 32 and its capabilities. In 2009, the University of Pennsylvania started enrolling patients in a clinical trial to explore the effects of the CCR5 delta 32 variation in HIV-positive people. Researchers will genetically alter the cells of participants so that the cells carry the CCR5 delta 32 variation.
Genetic research could have a global impact on the outcome of the AIDS crisis. Not only could this type of scientific research prevent HIV or at least stop the progression of HIV to AIDS, but this type of treatment could also affect the economic impact of AIDS. While antiretroviral drugs help HIV patients manage their condition, they are also very expensive and unavailable in some of the more disadvantaged parts of the world. If cell manipulation leads to a cure for HIV, the breakthrough would highlight the importance of genetic research in treating serious illnesses as well as preventing them.