Genetic engineering and stem cells can be used to bolster immune system defenses.
April 07 2006 4:16 PM EST
April 07 2006 8:00 PM EST
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Genetic engineering and stem cells can be used to bolster immune system defenses.
About 70 HIV-positive adults in California are participating in a clinical trial that combines stem cell technology and genetic engineering to create what researchers call a "parallel immune" system to fight the disease, the San Francisco Chronicle reports. About half of the study participants have received injections of their own blood cells that have been engineered to contain a gene that blocks HIV. The goal is to create an array of long-lived cells that will fight HIV and outlast natural blood cells that are targeted by the virus.
The key to the therapy is inserting an engineered enzyme called ribozyme, which does not exist naturally in the body, into immune system cells. The enzyme destroys one of HIV's key genes when the virus tries to copy itself, essentially preventing HIV from spreading in the body. Researchers attach the enzyme to an engineered mouse virus and expose human stem cells culled from bone marrow and the bloodstream to the virus. The mouse virus carries the enzyme into a cell, where it becomes part of the cell's natural machinery and fortifies it against any attempts by HIV to infect it and begin making viral copies. The stem cells are then reinserted into the donor's body, where they begin making numerous copies of immune system cells that are resistant to HIV.
Study participants must sit through two eight-hour sessions in which their blood is filtered to isolate the stem cells. Once the stem cells are removed, they are exposed to the ribozyme-carrying mouse virus, and three days later are injected back into the donors.
Lead researcher Ronald Mitsuyasu of the University of California, Los Angeles's Center for Clinical AIDS Research and Education says that while he doesn't think the approach will eventually replace standard antiretroviral therapy, it could be useful for HIV patients resistant to anti-HIV medications or those experiencing AIDS-related complications.
The clinical trial's preliminary results will be reported in February 2007.
A similar clinical trial is being conducted by a research company in Sydney, Australia, that is owned by Johnson & Johnson. (The Advocate)