The US Patent No. 6,399,349 titled "Human Aminopeptidase P Gene," which is the subject of the License Agreement, covers the XPNPEP2 gene sequenced by Dr. James Ryan, Chief Scientist of Ryogen LLC. XPNPEP2 codes for the membrane- bound aminopeptidase P (AmP). This protein is a significant marker for hypertension, angioedema, rejection of kidney transplants, certain tumors and other diseases. The patent covers the cDNA and gDNA sequences encoding AmP, a method of producing recombinant AmP, diagnostics for detecting AmP abnormalities, and prevention and treatment of medical conditions, associated with the mutation of the AmP gene.

"We are happy to extend a license under the AmP Patent to Invitrogen," said Valeria Poltorak, Ryogen's Executive Vice President. "We look forward to working with Invitrogen on making this discovery available to the research community," she concluded.

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This procedure is a form of gene therapy, a technique for correcting defective genes responsible for disease development. A similar injection procedure is currently being used in a Phase I clinical trial at Cornell University as a treatment for children with late infantile Batten disease, another lysosomal storage disease. Unfortunately, gene therapy alone didn't fully correct the disease in Twitcher mice in Sands' early experiments, and it only slightly increased their lifespan. On the other hand, decades of prior research with Twitcher mice had shown that under extreme treatment conditions bone marrow transplantation could extend the lives of these mice to an average of about 80 days (untreated Twitcher mice live to approximately 38 days).

"Lysosomal enzymes are located inside the cell, and at first glance, there's no reason to think that transplanting normal bone marrow would do anything at all," Sands says. "But it turns out that lysosomal enzymes can escape from cells and get incorporated into other cells. When bone marrow is given, the marrow cells circulate to every organ and tissue in the body, sharing their lysosomal enzymes."

However, this mechanism is relatively inefficient in the brain. Transplanted bone marrow cells have a hard time getting across the blood-brain barrier, and not much enzyme was delivered to brain cells by this treatment. So why was the treatment working for the Twitcher mice?

"We went back to the drawing board and asked what are each of these approaches doing?" Sands says.

The researchers could see that gene therapy was getting functional genes to brain cells, but they began to suspect that bone marrow transplantation was working in an entirely different way -- it was reducing inflammation in the brain by a mechanism that hasn't yet been clearly defined.

"We hypothesized that if we could supply high levels of enzyme to the brain with gene therapy and at the same time decrease inflammation in the brain with bone marrow transplantation, we might have an effect," Sands says. "However, we never imagined that the two approaches would synergize to the degree we saw."

Inflammation in the brain in Krabb?© disorder is an important factor in neural damage. Sands believes reducing inflammation allowed the gene therapy to be much more effective in the brain, even in areas far from the injection site that received low doses of the gene.

"Nothing we used here hasn't already been used for other disorders," Sands says. "We are going to work on optimizing the therapy in the lab, and I think the combination approach could potentially be in the clinic in a few years."

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