Using the human immunodeficiency virus (HIV) as a cure? It may sound dangerous and far-fetched, but Italian scientists have found a way to harness gene therapy vectors derived from HIV to cure two severe genetic diseases, metachromatic leukodystrophy and Wiskott-Aldrich syndrome.
Researchers from the San Raffaele-Telethon Institute for Gene Therapy (TIGET) and Telethon in Italy have been changing the way we think of HIV since 1996, when a team led by TIGET director Dr. Luigi Naldini found they could learn something from a virus as potent as HIV. Seventeen years later, they’ve successfully treated six children using HIV-derived genetic messengers.
“The idea of using the HIV vector came many years ago to Dr. Luigi Naldini and his team. They realized that this vector had a unique property which is highly efficient in introducing information into the cell’s specific DNA,” said Alessandra Biffi, MD, PhD, group leader at TIGET, in a press release.
HIV works by infecting and altering a cell’s DNA, but researchers realized that if they could similarly “infect” a malfunctioning cell with the genetic material it was missing, they could, in effect, cure some genetic diseases.
The scientists targeted two genetic disorders of childhood: Wiskott-Aldrich syndrome, which causes severe bleeding and infection because of defective immune function, and metachromatic leukodystrophy, which causes faulty production and maintenance of myelin, the padding that insulates nerve cells in the brain.
Hijacking a Virus
Naldini and his team realized that by stripping HIV of its harmful genetic information, they could take advantage of its delivery system and create a highly efficient vehicle for getting treatment directly into the DNA of cells.
The virus is like a delivery truck, but in this case, all the spoiled packages that would normally cause HIV infection have been removed and replaced with packages containing genetic information that is key to treating disorders, like metachromatic leukodystrophy and Wiskott-Aldrich syndrome, in which a vital piece of DNA is missing.
To harness the genetic vector, researchers withdrew stem cells from the bone marrow of 16 patients: six with Wiskott-Aldrich syndrome and 10 with metachromatic leukodystrophy. The recent study, published in Science, discusses only three patients from each group.
After the stem cells were collected, a corrected copy of the defective gene was introduced using the “cleaned” viral vectors from HIV. These stem cells were then re-injected into the patients and were "able to restore the missing protein to key organs,” the study authors wrote.
The way the HIV vectors have been manipulated makes them safe to use, and it has an enormous potential for treating patients, Biffi said. All six patients mentioned in the study are now well and living nearly normal lives.
"Three years after the start of the clinical trial," Naldini said in a press release, "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. After 15 years of effort and our successes in the laboratory, but frustration as well, it's really exciting to be able to give a concrete solution to the first patients."
HIV can be contracted through the exchange of bodily fluids, and it results in the progressive deterioration of the immune system. The immune system is our body's natural defense against viruses, bacteria, and infections.
HIV infection can result in acquired immunodeficiency syndrome (AIDS), which doesn’t kill itself, but weakens the immune system so severely that something as trivial as a cold can be deadly. In the United States alone, AIDS reportedly killed nearly 450,000 people between 1981 and 2000, according to the Centers for Disease Control and Prevention (CDC).