Scientists
engineer blood stem cells to fight HIV

Researchers at City of Hope, a medical research and treatment center in Duarte, Calif., report in the journal Nature Biotechnology that they have engineered blood stem cells to include three therapeutic genes that boost the body's defenses against HIV. The scientists used a harmless lentivirus to carry three genetically engineered genes into the blood stem cells to produce a two-pronged defense against the virus.

One of the genes engineered by the scientists coordinates the manufacture of small interfering RNAs, tiny segments of genetic material that prime cellular defenses that destroy viruses. The two other genes work to prevent HIV from inserting its genetic material into the cell's natural machinery, which is necessary for the virus to replicate. Together, the three genes prevent HIV from ever gaining a foothold inside immune system cells and from producing new copies of itself.

Once the protective genes are placed inside hematopoietic stem cells, which guide the production of virtually all other blood cells in the body, all of the newly formed cells will in turn carry genetic protection against HIV, the researchers say.

Using the lentivirus to deliver the genes to the stem cells is essential, says researcher John J. Rossi. Simply inserting the genes into the stem cells would have produced an immune system response that would cause the cells to self-destruct. But the harmless lentivirus can penetrate the cells without prompting an immune system attack.

The researchers next plan to study the genetically engineered stem cells in five patients who have both AIDS and AIDS-related lymphoma, a type of cancer that develops more easily when the immune system is severely damaged. (The Advocate)