Gene therapy has been used in more than 1,000 clinical trials during the last 20 years. But the U.S. Food and Drug Administration (FDA) has never approved a single application. The reason is simple: the former trials were using viruses to deliver genes to fight diseases like cancer. And viruses can be harmful. Now, MIT researchers have found a safer way to deliver genes by using biodegradable polymers. As one of the researchers said, 'What we wanted to do is start with something that's very safe -- a biocompatible, degradable polymer -- and try to make it more effective, instead of starting with a virus and trying to make it safer.' Will this new way to deliver genes to our bodies be approved one day? Time will tell.
As an example, you can see above the structure of a piece of a biodegradable polymer used for gene delivery by the MIT team (Credit: Jordan Green, MIT). Here is a link to a larger version of this image.
The majority of the MIT scientists involved in this project is working at the MIT Center for Cancer Research. Here is a short explanation of this project. "The MIT scientists focused on three poly(beta-amino esters), or chains of alternating amine and diacrylate groups, which had shown potential as gene carriers. They hoped to make the polymers even more efficient by modifying the very ends of the chains. When mixed together, these polymers can spontaneously assemble with DNA to form nanoparticles. The polymer-DNA nanoparticle can act in some ways like an artificial virus and deliver functional DNA when injected into or near the targeted tissue."
And how do they think they can improve the effectiveness of their method? "'Just by changing a couple of atoms at the end of a long polymer, one can dramatically change its performance,' said [Daniel Anderson, research associate in MIT's Center for Cancer Research.] 'These minor alterations in polymer composition significantly increase the polymers' ability to deliver DNA, and these new materials are now the best non-viral DNA delivery systems we've tested.' The polymers have already been shown to be safe in mice, and the researchers hope to ultimately run clinical trials with their modified polymers, said Anderson."
For more information, this research work has been published online in Advanced Materials under the title "Combinatorial Modification of Degradable Polymers Enables Transfection of Human Cells Comparable to Adenovirus" (September 6, 2007). Here is a link to this paper (available for US$ 25.00).
Sources: Massachusetts Institute of Technology news release, via EurekAlert!, September 7, 2007; and various websites
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