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
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

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

Tags: Health, Health

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