Einstein Science Reporting for Kids
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Contact: Science Press Package
American Association for the Advancement of Science

Good news for gene therapy?

A machine engineering HIV viruses that are shuttled to the affected brain by a rollercoaster, which represents both the vasculature routing the genetically engineered hematopoietic cells to the brain as well as the DNA helix into which the virus insert its therapeutic genetic cargo. The choice of objects, background color, and the intense stare of the treated boy communicate a sense of wonder as well as awareness of the implications of the bold, new gene therapy attempt.
[Image courtesy of Günter Pusch (http://www.gunter-pusch.com)]

Gene therapy--a process by which healthy "replacement" genes are infused into patients who have inherited faulty copies of the genes--seems to work well in animal models of diseases. But, moving from animal research to the clinic has proved extremely challenging: The transplanted genes rarely express the right amount of proteins in human patients, and in some cases the treatment leads to negative side effects, like leukemia.

Now, however, two gene therapy studies that used vectors, or delivery agents, from a lentivirus (instead of the usual retrovirus) have produced some promising results. These two collaborative studies suggest that lentiviral vectors may be safer and more effective in human gene therapy than the standard retroviral vectors.

In the first study, Alessandra Biffi and colleagues removed special stem cells, known as hematopoietic stem cells (HSCs), from young patients with a rare disease called Metachromatic Leukodystrophy. The researchers then introduced new genes into the HSCs with a lentiviral vector and infused the cells back into the patients. Two years after one patient received the treatment—and 18 months after two others received it—the researchers found that their gene therapy had stopped the progression of the disease in all the patients.

In the other study, Alessandro Aiuti and colleagues describe how they performed a similar gene therapy approach in three children with a rare disorder known as Wiskott-Aldrich Syndrome. The researchers also used a lentiviral vector to insert functional genes into the patients' HSCs and then re-infused the cells into the patients. Symptoms of the disease, such as recurring infections, had vanished between 20 and 32 months after the gene therapy treatments, they say.

But, both research teams say that longer follow-up times and more analyses are needed to confirm the safety and effectiveness of the approach. For now, these new results provide some hope.