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In the paper, researchers implanted modified hematopoietic stem cells—in other words, cells that make blood—in two monkeys. The blood cells being made included immune system cells, like infection-fighting natural killer, or NK, and T cells. The researchers watched to see if the stem cells would stay alive inside the monkeys and if they would start producing cells that could attack cells infected with a form of HIV.
For more than two years, modified versions of blood cells were produced in the animals—which is a good sign. This kind of technique is called chimeric antigen receptor therapy, but it's better known by the acronym CAR-T.
Modifying stem cells with CAR therapy is a big advance, says study author Scott Kitchen, a researcher at the David Geffen School of Medicine at the University of California, Los Angeles. "In order to eradicate the virus, you really need an effective immune response. Because HIV attacks the immune response, that's difficult to achieve," he told Newsweek. But in theory, that's what this treatment could do. "This is step one, basically showing that we can modify stem cells, that you can get lifelong cells produced."
However, using CAR therapy to treat HIV in humans may still be far in the future, according to James Riley, an immune system and HIV researcher at the University of Pennsylvania’s Perelman School of Medicine who was not involved in the research. Some of the results were relatively subdued, he noted. Only one of the two animals that received the treatment showed a decrease in the amount of virus circulating in its blood compared to animals that did not receive the treatment. However, the amount of virus in the blood of the other monkey did still decrease compared to its own starting point.
Regardless of how effective the approach may be, completing a human study would require "heroic efforts," said Riley. Even for more traditional stem cell transplants, the process can be difficult. The study does prove that it's possible to generate these cells, implant them into monkeys and launch an attack on HIV in a way that maintains the stability of the animal. But, says Riley, using this kind of technique in people will require more work.
From HIV to Cancer to HIV
Interestingly, CAR-T, which has been making headlines for its anticancer benefits, was originally intended for the 37 million people living with HIV today. According to an article in the New England Journal of Medicine, CAR-T pioneer Carl June had been working on a way to modify the immune cells in HIV patients for most of his career until his wife was diagnosed with ovarian cancer.
That diagnosis changed the course of CAR-T research. About twenty years ago, June switched his focus to cancer. In August, the Food and Drug Administration approved the first-ever CAR-T treatment for human cancer.
For now, CAR therapies are mostly useful for blood cancers because the proteins on the surface of blood cells provide an obvious target for T-cells to attack. However, scientists are actively looking for ways to target other kinds of cancers.
This material was prepared specially for the WORLD HEALTH NEWS project by journalist Michael Kelly.
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