Scientists have developed a genetic therapy to treat two rare childhood diseases using a component of the HIV virus.

The research, which was detailed in two studies published in Science on June 11, showed that scientists were able to use an HIV virus vector -- which acts as a tool to help put genetic material into cells -- on three children with metachromatic leukodystrophy and three others with Wiskott-Aldrich syndrome. Their diseases have stopped progressing and some of the patients have stopped showing symptoms for 18 to 32 months following the therapy.

Using a vector of the virus, the mechanism in which it gets into cells, is not the same as giving the children the actual HIV virus.

"Three years after the start of the clinical trial, 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," author Luigi Naldini, a researcher from the San Raffaele Telethon Institute for Gene Therapy, said in a press release.

Metachromatic leukodystrophy is an inherited genetic mutation that causes fats called sulfatides to collect in cells, especially in those that produce a substance that surrounds and protects nerves, called myelin. In patients with the disorder, the sulfatide collection ends up destroying the white matter that makes up part of the nervous system. This affects the brain, spinal chord and sensory cells that registered touch, pain, heat and sound.

Eventually the patients no longer have cognitive functions or motor skills, and they cannot feel different sensations. Other symptoms include seizures, paralysis, inability to speak, blindness, hearing loss and eventually loss of awareness. There is currently no cure.

About one out of 40,000 to 160,000 people worldwide have the disorder, the National Institutes of Health reports. The most common form of the condition, called late infantile form, affects 50 to 60 percent of people with the disorder starting at about 2 years old. Twenty to 30 percent of patients will have a juvenile form which begins to manifest around the age of 4 through adolescence. The adult form affects 15 to 20 percent of patients with metachromatic leukodystrophy, and starts appearing during teenage years or later.

People with Wiskott-Aldrich syndrome do not have a normal immune system and have a harder time creating blood clots. The disease, which is caused by an inherited genetic mutation on the X chromosome, causes abnormal or nonfunctional white blood cells, which puts the patients at risk of immune and inflammatory disorders.

The condition is typically found in males, and has an incidence of 1 to 10 cases per one million males, the NIH said. It is rarely found in women. Wiskott-Aldrich can be treated if the patients receive a bone marrow or stem cell transplant, which can work very well if the donation is a close match.

The researchers used an HIV virus vector to insert a corrected form of defective genes at the root of these diseases into the patients' own blood stem cells. Then, the healthy blood stem cells were surgically implanted in to the subject.

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Gene therapy using part of HIV virus treats two rare childhood diseases

Italian researchers have used a defanged version of HIV to replace faulty genes and eliminate devastating symptoms in children suffering two rare and fatal genetic diseases.

Improved gene therapy techniques prevented the onset of metachromatic leukodystrophy in three young children and halted the progression of Wiskott-Aldrich syndrome in three others.

The advance represents a major stride for a field that has struggled to translate experimental successes in lab animals into safe and effective treatments for people, experts said. Researchers may be able to use the team's method as a template, modifying it to treat a variety of diseases.

This is "ammunition for the gene therapy world," said Dr. Theodore Friedmann, a pediatric gene therapist at UC San Diego, who was not part of the study. "The field is slowly but surely making impressive advances against quite untreatable diseases."

The scientists published results from the two clinical trials Thursday in the journal Science.

Metachromatic leukodystrophy affects just 1 in 40,000 to 1 in 160,000 people worldwide; Wiskott-Aldrich syndrome, only 1 to 10 per million males. But both illnesses are devastating. Children with late infantile metachromatic leukodystrophy, the most common form of that disease, begin having trouble walking about a year old and soon after experience muscle deterioration, developmental delays, paralysis and dementia. Most die within a few years of onset.

Kids with Wiskott-Aldrich syndrome suffer from eczema, bruising, nosebleeds and recurrent infections. Most develop at least one autoimmune disorder. A third get cancers, such as lymphoma and leukemia. Life expectancy ranges from 15 to 20 years.

The disorders are challenging when not impossible to treat. No therapy exists for metachromatic leukodystrophy. A bone marrow transplant can stop disease progression for the few Wiskott-Aldrich patients with an immunologically matched sibling, but they may experience severe side effects or death if the donor is not as close a match.

Both diseases are caused by inherited genetic mutations that disrupt the body's ability to produce crucial enzymes. In each trial, researchers took the normal form of the faulty gene and attached it to a virus derived from HIV that had been modified so that it could no longer cause AIDS.

The researchers removed bone marrow stem cells from the patients and then used the lentivirus to infect those cells with the normal genes.

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Gene therapy using HIV helps children with fatal diseases, study says