Researchers at Progenitor Inc. believe that the impracticalitiesof short-term gene therapy may be surmountable.

Currently in gene therapy, genes are introduced to human cellsthrough retroviral vectors (deactivated viruses that carry DNAfragments into cells). Unfortunately, according to Progenitor ofColumbus, Ohio, this method creates a permanent change in thealtered cells and has the potential to damage existing geneswithin human cells. This is why gene therapy is now beingdeveloped for chronic conditions that require permanentintroduction of a new gene rather than for acute or short-termconditions.

Progenitor researchers presented preclinical data this week atthe Keystone Symposia on Gene Therapy in Colorado on the T7vector, a non-viral vector that can be used to introduce a genedirectly into the cytoplasm of a cell. This results in geneexpression of short duration -- only one to two weeks.

Doros Platika, Progenitor's vice president of research, toldBioWorld that the T7 vector addresses safety concernsassociated with viral or retroviral gene transfer, including thepossibility of infection with an active virus or damage of a cell'sexisting gene structure. Unlike viral or retroviral vectors, hesaid, the T7 vector can be introduced into any cell, not just adividing cell. It is "self-stimulating," he explained, expressinggenes at up to 100 times the rate found with standardretroviral transfer.

Progenitor, a majority-owned subsidiary of InterneuronPharmaceuticals Inc. (NASDAQ:IPIC) of Lexington, Mass., said ithopes to use the vector to develop therapies for cancer,inflammation and viral infection, which will require geneexpression for only a limited time. In retroviral transfer, thegene introduced will theoretically express itself forever,although in actuality it tends to do so for only about sixmonths, Platika said.

Progenitor also hopes therapies based on the T7 vector can beused in recurring conditions or for multiple treatments. Thecompany's data indicate that the T7 vector does not create anantibody response when introduced to the body as do someviral and retroviral vectors, Platika said. After the body hasproduced antibodies to a vector, it cannot be introduced again.

The T7 vector technology was licensed in May 1993 from itsdiscoverer and Progenitor's founder, Thomas Wagner of OhioUniversity's Edison Biotechnology Institute. The company isalso developing products based on retroviral gene transfer.

-- Karl A. Thiel Associate Editor

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