Scientists at the UCLA Eli and Edythe Broad
Center of Regenerative Medicine and Stem Cell Research are one step
closer to engineering a tool that could one day arm the body's immune
system to fight HIV, and win. The new technique harnesses the
regenerative capacity of stem cells to generate an immune response to
the virus.
"We hope this approach could one day allow HIV-positive individuals
to reduce or even stop their current HIV drug regimen and clear the
virus from the body altogether," said Scott Kitchen, the study's lead
author and a member of the Broad Stem Cell Research Center. "We also
think this approach could possibly be extended to other diseases."
Kitchen also is a member of the UCLA AIDS Institute and an associate
professor of medicine in the division of hematology and oncology at the
David Geffen School of Medicine at UCLA.Kitchen and his colleagues were the first to report the use of an
engineered molecule called a chimeric antigen receptor, or CAR, in
blood-forming stem cells. Blood-forming stem cells are capable of turning into any type of blood cell, including T cells, the white blood cells
that are central to the immune system. In a healthy immune system, T
cells can usually rid the body of viral or bacterial infection. But HIV
is too strong and mutates too rapidly for T cells to fight against the
virus.The researchers inserted a gene for a CAR into blood-forming stem
cells in the lab. The CAR, which is a two-part receptor that recognizes
an antigen, was engineered to be carried by T cells and direct them to
locate and kill HIV-infected cells. The CAR-modified blood stem cells
were then transplanted into HIV-infected mice that had been genetically
engineered with human immune systems. (As a result, HIV infection
causes disease similar to that in humans.)
The researchers found that the CAR-carrying blood stem cells
successfully turned into functional T cells that could kill HIV-infected
cells in the mice. The result was a decrease in HIV levels of 80 to 95
percent.
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