Gene therapy safe for regenerating gum tissue

Scientists at the University of Michigan (U-M) have developed a method of gene delivery that appears safe for regenerating tooth-supporting gum tissue -- a discovery that assuages one of the biggest safety concerns surrounding gene therapy research and tissue engineering.

Gene therapy is an accepted, viable therapeutic concept, but safety is a major hurdle, said William Giannobile, D.D.S., DMSc, professor at the U-M School of Dentistry, in a university press release. The most notable incident highlighting the safety concerns of gene therapy research and treatment occurred several years ago when a teenager died after being given the adenovirus during a gene therapy clinical trial at the University of Pennsylvania.

The U-M therapy also uses the adenovirus, Dr. Giannobile said, but uses a different application method and a much lower dose. Instead of injecting the genes -- in this case, platelet-derived growth factor-B (PDGF) -- into the blood vessels, U-M scientists put the genes on a localized area, directly on the tissue during surgery much like a paste.

Microcomputed tomographic images of regenerated periodontium following delivery of PDGF genes. Image courtesy of the University of Michigan.

"What the U-M study showed is (the topical method) is very well contained and doesn't distribute throughout the body," Dr. Giannobile said. "This approach alleviates the safety concern about negative reactions within the body. This is the first study of periodontal disease therapy that demonstrates the distribution of these genes is very safe, suggesting that it could be used in the clinic for clinical application."

The next step is to begin human clinical trials, he added.

His group's paper, "Adenovirus Encoding Human Platelet-Derived Growth Factor-B Delivered to Alveolar Bone Defects Exhibits Safety and Biodistribution Profiles Favorable for Clinical Use," will appear in the May issue of Human Gene Therapy.

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