December 8, 2009
Researchers Engineer HIV-Killing Cells From Stem Cells
Researchers at the University of California in Los Angeles (UCLA) have demonstrated it is possible to engineer new HIV-specific killer CD8 cells from stem cells in the blood, according to an announcement by UCLA. The novel treatment approach, introduced in December in PLoS One, has a long way to go before it could be tested in humans, but it shows promise to fight other illnesses in addition to HIV/AIDS.
People who are naturally able to control HIV for long periods of time have high numbers of a type of an immune cell known as a cytotoxic T-lymphocyte (CTL) that is specific to HIV. Conversely, low levels of HIV-specific CTLs have been associated with more rapid disease progression. Researchers have attempted to increase a person’s HIV-specific CTL numbers by expanding the population of cells outside the body and then reinfusing them, but this process didn’t work because the cells did not live long and function fully.
To determine whether it might be possible to generate a large population of fully functional and long-lived HIV-specific CTLs, Scott Kitchen, PhD, and his colleagues at UCLA cloned a T-cell receptor from an HIV-specific CTL and then used it to engineer human stem cells that could fight HIV. The new HIV-specific CTLs were grown in human thymus tissue implanted in specially bred mice.
Kitchen’s team found that the cells lived long, reproduced and appeared to recognize HIV.
Challenges remain, however. First, according to Kitchen and his colleagues, expanded CTLs will have to be cloned and expanded for each individual, a time-consuming and costly process. One person’s CTLs cannot be used in another person. Second, because HIV can escape existing CTLs by mutating, it might be necessary to expand a variety of CTL populations in an individual in order to control HIV. Third, researchers must next demonstrate in more sophisticated models whether it is possible to engineer functional cells that can reproduce and thrive in humans.
Despite these challenges, the team is encouraged by this initial success. “This approach could be used to combat a variety of chronic viral diseases,” said study coauthor and fellow UCLA professor Jerome Zack, PhD. “It’s like a genetic vaccine.”
Search: Stem cells, cytotoxic T-lymphocytes, CTL, CD8, killer cells, Scott Kitchen, Jerome Zack
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