Featured Research

from universities, journals, and other organizations

Stanford Researchers Develop Gene Therapy Technique That Sharply Cuts Risks

Date:
October 14, 2002
Source:
Stanford University Medical Center
Summary:
Researchers at Stanford University Medical Center have devised a new gene therapy technique that appears to eliminate one of the major health risks linked to gene therapy. The technique, published in the Oct. 15 advanced online edition of the journal Nature Biotechnology, overcomes the need for viral vectors that have plagued gene therapy trials, while retaining the ability to insert therapeutic DNA into specific sites in the chromosomes.

STANFORD, Calif. - Researchers at Stanford University Medical Center have devised a new gene therapy technique that appears to eliminate one of the major health risks linked to gene therapy. The technique, published in the Oct. 15 advanced online edition of the journal Nature Biotechnology, overcomes the need for viral vectors that have plagued gene therapy trials, while retaining the ability to insert therapeutic DNA into specific sites in the chromosomes.

"Our approach provides an alternative that didn't exist before," said Michele Calos, PhD, associate professor of genetics at the School of Medicine and lead author on the study.

The goal of gene therapy is to insert a healthy copy of a gene into a cell where it can take over for a faulty version. If the therapeutic DNA does not integrate into the human chromosome, it produces its protein for a short time before being turned off or broken down within the cell. For a long-term cure, the gene has to wedge itself into a chromosome where it remains indefinitely integrated, getting passed on when the cell divides.

Current gene therapy approaches that cause genes to integrate use a viral vector to sneak the therapeutic DNA into the host cell, Calos said. However, the DNA inserts itself into the chromosome at random positions. In one recent French gene therapy trial, the randomly inserted DNA apparently activated a neighboring oncogene, causing a patient to develop leukemia. "That sort of puts another cloud over the existing gene therapy trials," Calos said.

Calos' technique avoids the pitfalls of other gene therapy approaches by integrating DNA without using viral vectors, inserting the DNA at known locations. This new technique can also handle genes that are too large to fit into a viral package, such as the gene for Duchenne's muscular dystrophy, Calos said.

In developing this new approach, Calos hijacked a mechanism used by a bacteria-infecting virus (called a bacteriophage) to integrate its genes into bacteria. The bacteriophage makes a protein called integrase that inserts the viral genes into a specific DNA sequence on the bacteria chromosome. It turns out that humans also have a version of that DNA sequence. When the researchers insert a copy of the therapeutic gene and a gene coding for integrase into a human cell, the integrase inserts the gene within the human sequence.

Calos and members of her lab, in collaboration with Mark Kay, MD, PhD, professor of pediatrics and genetics, tested the technique using a gene that makes Factor IX - a protein that is missing in the blood of people with one form of hemophilia. They injected mice with a piece of DNA containing the Factor IX gene plus a stretch of DNA that acts as an "insert me" signal to integrase. At the same time they injected a gene for integrase.

Within a week, mice that received this injection made 12 times more Factor IX than their littermates that received the injection without the integrase. Further experiments confirmed that the Factor IX gene had successfully integrated into the mouse DNA.

Although the mouse genome contains at least 53 potential integration sites, Calos and her team found the Factor IX gene in only two locations, with one location by far the more common. She said that for each tissue there may be a particular site that is the most likely insertion point. Her group is testing the technique in different tissue types to ensure that no human integration site is near a potential oncogene. "We need to look in different tissues to see where the hot spot is," Calos said.

Calos is also modifying the integrase so it targets specific integration sites that her team knows are safe. "We mutated the enzyme and evolved it so it will prefer one place over another," she said.

Calos said this approach should be effective for treating diseases in several different human organs including skin, retina, blood, muscle and lung. She hopes to start human trials for the technique in a fatal childhood skin disease called recessive dystrophic epidermolysis bullosa, which she has already treated in mice. "If that trial shows that it is safe then that will open the door for trials in other diseases," Calos said. She has collaborations underway testing the technique for use in Duchenne's muscular dystrophy and cystic fibrosis, among others.

###Contributing researchers to the study include Stanford graduate students Eric Olivares and Thomas Chalberg, and post-doctoral scholar Roger Hollis, PhD.

Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at http://mednews.stanford.edu.


Story Source:

The above story is based on materials provided by Stanford University Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

Stanford University Medical Center. "Stanford Researchers Develop Gene Therapy Technique That Sharply Cuts Risks." ScienceDaily. ScienceDaily, 14 October 2002. <www.sciencedaily.com/releases/2002/10/021014071708.htm>.
Stanford University Medical Center. (2002, October 14). Stanford Researchers Develop Gene Therapy Technique That Sharply Cuts Risks. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2002/10/021014071708.htm
Stanford University Medical Center. "Stanford Researchers Develop Gene Therapy Technique That Sharply Cuts Risks." ScienceDaily. www.sciencedaily.com/releases/2002/10/021014071708.htm (accessed September 2, 2014).

Share This




More Health & Medicine News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Get on Your Bike! London Cycling Popularity Soars Despite Danger

Get on Your Bike! London Cycling Popularity Soars Despite Danger

AFP (Sep. 1, 2014) Wedged between buses, lorries and cars, cycling in London isn't for the faint hearted. Nevertheless the number of people choosing to bike in the British capital has doubled over the past 15 years. Duration: 02:27 Video provided by AFP
Powered by NewsLook.com
Can You Train Your Brain To Eat Healthy?

Can You Train Your Brain To Eat Healthy?

Newsy (Sep. 1, 2014) New research says if you condition yourself to eat healthy foods, eventually you'll crave them instead of junk food. Video provided by Newsy
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Liberia Continues Fight Against Ebola

Liberia Continues Fight Against Ebola

AFP (Aug. 30, 2014) Authorities in Liberia try to stem the spread of the Ebola epidemic by raising awareness and setting up sanitation units for people to wash their hands. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins