From Science News Online

September 15, 2004

The research on aging treatments is progressing rapidly. The

development of this gene therapy technique is particularly important

for the prospect of treating and reversing aging. The article

mentions this:

" The same gene-delivery method could prove useful for treating a

variety of muscular disorders, including heart disease and muscle

wasting associated with aging, Rando says. "

Walford could foresee the development of this type of technology.

Thanks,

Doug

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Science News Online

Week of Aug. 7, 2004; Vol. 166, No. 6

Gene Delivery: Mouse study shows new therapy may reverse muscular

dystrophy

Lock

For people with the most common type of muscular dystrophy, one

faulty gene wreaks devastating consequences. Researchers have now

found a way to deliver a working copy of the gene to the entire

muscular system in mice that suffer from the muscle-wasting ailment.

With one injection into the bloodstream, the animals' conditions

improved markedly.

[iMAGE] REVERSING DAMAGE. Quadriceps muscle of a normal mouse (top),

a mouse with Duchenne muscular dystrophy (middle), and a mouse that

had received gene therapy 6 weeks earlier (bottom). Dystrophin

protein (green) outlines cells.

Nature Medicine

" No one's been able to get a delivery system to work very well

before, " says S. Chamberlain of the University of Washington

in Seattle. " We were able to show a very significant effect in

halting and reversing this disease. "

To the genome of a virus that doesn't trigger an immune response or

replicate in mice or people, the researchers added the dystrophin

gene, the faulty version of which causes Duchenne muscular dystrophy.

The investigators also included a promoter gene that ensured that

only muscle cells would manufacture the protein encoded by the

dystrophin gene.

That protein acts like a girder in a building, providing structural

support to muscle cells. Without it, muscle tissue develops holes and

tears.

The researchers injected the engineered virus, along with a chemical

to facilitate its diffusion through blood vessels, into mice with

muscular dystrophy. Weeks later, the scientists examined these

animals' muscles, including those in the arms, legs, and ribs, and

compared them with muscles of similar mice that hadn't received an

injection.

" The [treated] muscles looked tremendously better under the

microscope, " says Chamberlain. He and his colleagues report their

results in the August Nature Medicine.

One injection into the bloodstream spread the virus & #151;and the

dystrophin gene it carries & #151;to skeletal muscles and the heart.

" This research shows that it's possible to deliver a therapeutic gene

throughout the body, " comments A. Rando of Stanford

University, who studies muscle diseases. " That's been a real hurdle. "

Because the dystrophin protein in the test functioned only in muscle

cells, the procedure overcomes an additional obstacle to gene

therapy & #151;limiting a therapeutic gene's activity to the desired

cells and tissues.

Other experimental attempts at gene therapy for muscular diseases

rely on local injections directly into muscle, and any beneficial

effects are limited to that area. This research sets a new standard

for gene delivery to the entire muscular system, says Rando.

The same gene-delivery method could prove useful for treating a

variety of muscular disorders, including heart disease and muscle

wasting associated with aging, Rando says.

Adding to the technique's promise is evidence that the virus

infiltrated many organ systems. To target genetic therapies to

disorders of organs such as the liver and kidney, investigators might

load viruses with different combinations of healthy genes and

promoters, Chamberlain speculates.

While the treatment appears to be safe and effective in mice, it's

too soon to say whether it will be suitable for use in people.

Chamberlain is embarking on safety studies in larger mammals and

hopes to begin human-safety studies in a few years.

Well before the results become available, this new method will

provide laboratory and clinical researchers with a powerful new means

of gene delivery, says P. of the University of Iowa in

Iowa City.

If you have a comment on this article that you would like considered

for publication in Science News, send it to editors@....

Please include your name and location.

References:

Gregorevic, P.... and J.S. Chamberlain. 2004. Systemic delivery of

genes to striated muscles using adeno-associated viral vectors.

Nature Medicine 10(August):828-834. Abstract available at

http://dx.doi.org/10.1038/nm1085.

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