'Viral vector' from the AIDS-causing virus was key to stem cell therapy that helped several children, study says
THURSDAY, July 11, 2013 (HealthDay News) -- Turning a medical foe into a therapeutic friend, Italian scientists say they used a piece of HIV to cure two rare genetic diseases affecting children.
HIV is the virus that causes AIDS.
Gene therapy using the technique proved effective in three children with metachromatic leukodystrophy and three others with Wiskott-Aldrich syndrome. After three years of treatment, all of them are now well and show significant benefits from the therapy.
"The results obtained from the first six patients are very encouraging: The therapy is not only safe, but also effective and able to change the clinical history of these severe diseases," study lead researcher Luigi Naldini, director of the San Raffaele Telethon Institute for Gene Therapy (TIGET), in Milan, said in an institute news release.
The cause of both diseases is a genetic defect that results in the deficiency of a protein essential in the early years of life. In the case of metachromatic leukodystrophy, the nervous system is affected. Babies with this previously incurable disease appear healthy at birth, but at some point they begin to gradually lose the thinking and physical skills they have developed, with no possibility of halting the decline.
Children with Wiskott-Aldrich syndrome have a faulty immune system that makes them much more vulnerable than normal to the development of infections, autoimmune diseases and cancer. They also have a defect in the platelets, which causes frequent bleeding.
In this new therapy, stem cells are taken from the bone marrow of the patient. But a viral vector -- a means of transporting an agent into a cell -- is needed to transport a corrected copy of the gene that is defective into the stem cells. The Italian team obtained just such a viral vector from HIV.
Once reinjected into the body, the treated stem cells are able to restore the missing protein to key organs, the researchers said.
"In patients with Wiskott-Aldrich syndrome, blood cells are directly affected by the disease and the corrected stem cells replace the diseased cells, creating a properly functioning immune system and normal platelets," said Alessandro Aiuti, head of research of the Pediatric Clinic at TIGET. "Thanks to gene therapy, the children no longer have to face severe bleeding and infection. They can run, play and go to school."
"In the case of metachromatic leukodystrophy, however, the therapeutic mechanism is more sophisticated: The corrected [stem] cells reach the brain through the blood and release the correct protein that is 'gathered' there by the surrounding nerve cells," colleague Alessandra Biffi said in the news release.
The studies were published July 11 in the journal Science.
The U.S. National Institute of Neurological Disorders and Stroke has more about metachromatic leukodystrophy (http://www.ninds.nih.gov/disorders/metachromatic_leukodystrophy/metachromatic_leukodystrophy.htm ) and the U.S. National Library of Medicine has more about Wiskott-Aldrich syndrome (http://ghr.nlm.nih.gov/condition/wiskott-aldrich-syndrome ).
SOURCE: San Raffaele Telethon Institute for Gene Therapy, news release, July 11, 2013