Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers report major advance in gene therapy technique

04.06.2004


Despite a roller-coaster ride of ups and downs during the past 15 years, gene therapy has continued to attract many of the world’s brightest scientists. They are tantalized by the enormous potential that replacing missing genes or disabling defective ones offers for curing diseases of many kinds.



One group, consisting of researchers from the University of Wisconsin Medical School, the Waisman Center at UW-Madison and Mirus Bio Corporation of Madison, Wis., now reports a critical advance relating to one of the most fundamental and challenging problems of gene therapy: how to safely and effectively get therapeutic DNA inside cells.

The Wisconsin scientists have discovered a remarkably simple solution. They used a system that is virtually the same as administering an IV (intravenous injection) to inject genes and proteins into the limb veins of laboratory animals of varying sizes. The genetic material easily found its way to muscle cells, where it functioned as it should for an extended period of time.


"I think this is going to change everything relating to gene therapy for muscle problems and other disorders," says Jon Wolff, a gene therapy expert who is a UW Medical School pediatrics and medical genetics professor based at the Waisman Center. "Our non-viral, vein method is a clinically viable procedure that lets us safely, effectively and repeatedly deliver DNA to muscle cells. We hope that the next step will be a clinical trial in humans."

Wolff conducted the research with colleagues at Mirus, a biotechnology company he created to investigate the gene delivery problem. He will be describing the work on June 3 at the annual meeting of the American Society for Gene Therapy in Minneapolis, and a report will appear in a coming issue of Molecular Therapy. The research has exciting near-term implications for muscle and blood vessel disorders in particular.

Duchenne’s muscular dystrophy, for example, is a genetic disease characterized by a lack of muscle-maintaining protein called dystrophin. Inserting genes that produce dystrophin into muscle cells could override the defect, scientists theorize, ensuring that the muscles with the normal gene would not succumb to wasting. Similarly, the vein technique can be useful in treating peripheral arterial occlusive disease, often a complication of diabetes. The disorder results in damaged arteries and, frequently, the subsequent amputation of toes.

What’s more, Wolff says, with refinements the technique has the potential to be used for liver diseases such as hepatitis, cirrhosis and PKU (phenylketonuria).

In the experiments, the scientists did not use viruses to carry genes inside cells, a path many other groups have taken. Instead, they used "naked" DNA, an approach Wolff has pioneered. Naked DNA poses fewer immune issues because, unlike viruses, it does not contain a protein coat (hence the term "naked"), which means it cannot move freely from cell to cell and integrate into the chromosome. As a result, naked DNA does not cause antibody responses or genetic reactions that can render the procedure harmful.

Researchers rapidly injected "reporter genes" into a vein in laboratory animals. Under a microscope, these genes brightly indicate gene expression. A tourniquet high on the leg helped keep the injected solution from leaving the limb.

"Delivering genes through the vascular system lets us take advantage of the access blood vessels have - through the capillaries that sprout from them - to tissue cells," Wolff says, adding that muscle tissue is rich with capillaries. Rapid injection forced the solution out of the veins into capillaries and then muscle tissue.

The injections yielded substantial, stable levels of gene activity throughout the leg muscles in healthy animals, with minimal side effects. "We detected gene expression in all leg muscle groups, and the DNA stayed in muscle cells indefinitely," notes Wolff.

In addition, the scientists were able to perform multiple injections without damaging the veins. "The ability to do repeated injections has important implications for muscle diseases since to cure them, a high percentage of therapeutic cells must be introduced," he says.

The researchers also found that they could use the technique to successfully administer therapeutically important genes and proteins. When they injected dystrophin into mice that lacked it, the protein remained in muscle cells for at least six months. Similar lasting power occurred with the injection of erythropoietin, which stimulates red blood cell production.

Furthermore, in an ancillary study, the researchers learned that the technique could be used effectively to introduce molecules that inhibit - rather than promote - gene expression, a powerful new procedure called RNA interference.

"This could be very useful if you want to down-regulate a protein that’s causing a muscle disorder, such as with myotonic dystrophy," says Wolff.

In the late 1980s, Wolff and his UW-Madison colleagues surprised the scientific world with their discovery that they could get genes to express in muscle cells simply by injecting naked DNA into rodent muscle. The Wisconsin Alumni Research Foundation (WARF) licensed the technology to Vical, a California biotechnology company.

Once Wolff created Mirus, a local company, he and his colleagues turned their attention to the vascular system, a conduit to multiple leg and arm muscles they felt would work more efficiently than direct injection into muscle. WARF licensed the vascular technique to Mirus, which now holds the patent and continues to commercialize the technique.

In their first studies, the researchers focused on arteries, but then began to concentrate on veins. "Injecting any substance into arteries carries a degree of risk since, unlike veins, only one artery feeds a whole limb," notes Wolff.

In a related procedure, they experienced excellent results with high-pressure injection of genes into the tail veins of rodents, a technique that yielded extensive gene expression in the animals’ livers.

"We think the genes traveled from the capillaries through the relatively large holes that exist in liver cells," Wolff says, adding that the technique has become a successful research tool for many laboratories around the world.

"For delivering genes to limb muscles, the vein approach is so simple," he says. "We never expected it to work so well."


Collaborating on the study were James Hagstrom, Julia Hegge, Mark Nobel, David Lewis and Hans Herweijer, from Mirus Bio; and Guofeng Zhang and Vladimir Budker, from the Waisman Center.

Dian Land | EurekAlert!
Further information:
http://www.wisc.edu/

More articles from Health and Medicine:

nachricht The end of pneumonia? New vaccine offers hope
23.10.2017 | University at Buffalo

nachricht Scientists track ovarian cancers to site of origin: Fallopian tubes
23.10.2017 | Johns Hopkins Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>