Thursday, June 17, 2010

genetic fix for hiv?

The Scientist | Genetically modifying the stem cells of HIV patients may one day prove to be an effective, one-time therapy against the hard-to-kill virus, according to the results of a proof-of-principle trial published this week in Science Translational Medicine.

In contrast to the widely used highly active antiretroviral therapy (HAART), which patients must continue for their entire lives to control the virus, such a genetic treatment has the potential to be "a single administration therapy," said bioengineer David Schaffer of the University of California at Berkeley, who was not involved in the trial, "where you introduce [a gene] into somebody's cells, and it stays there the rest of their lives. [That] has the potential to be a major plus," eliminating many of the toxic effects and financial costs of HAART.

Because of these potential advantages, gene therapy -- the integration of new genetic material into a patient's genome -- has been proposed as a treatment for HIV. In past clinical trials, however, the new genetic material has failed to persist more than 8 months or a year. But taking advantage of a golden opportunity in which a handful of HIV patients had to undergo bone marrow transplants, molecular geneticist John Rossi of the City of Hope cancer center in California and his colleagues introduced three different therapeutic genes into patients' blood stem cells, then found evidence of those genetic elements in the blood up to 24 months later.

"It showed us that you can introduce genes into somebody's blood cells, and it can stay around for years," said Schaffer, who wrote a perspective about the paper.

"That's a major finding," Rossi added. While the number of cells expressing those genes was too low to provide any therapeutic benefit, it's "proof of principle" that gene therapy may provide long-term HIV treatment, he said.