One of three stem cell patents held by the Wisconsin Alumni Research Foundation (WARF) is valid, according to a non-final ruling issued on Monday by the United States Patent and Trademark Office.

The three WARF patents have been under examination by the USPTO, beginning in October, 2006, when challenges were brought by the Public Patent Foundation in New York and the Foundation for Taxpayer and Consumer Rights (FTCR) in Los Angeles. Decisions on the other two patents are still pending.

"We're pleased with the decision and how thorough and detailed the decision is," Carl Gulbrandsen, managing director of WARF told The Scientist in regard to the USPTO ruling. Last fall, WARF issued amendments to the patents that helped in the approval process, Gulbrandsen added. He hopes that the two other patent decisions will come soon and will be as positive as the first. "We've said from the beginning we think ultimately we'll prevail on this. We've always believed that Dr. Thomson's discovery is patentable."

The valid patent -- known as "913" (U.S. Pat. 7,029,913) -- and the other two patents cover discoveries by James Thomson, a University of Wisconsin, Madison, researcher whose group was the first to isolate human embryonic stem cells in 1998. Patent 913 covers the development of a cell culture of human embryonic stem cells that have been derived from a pre-implantation embryo.

If this ruling was to be made final, the FTCR would certainly issue an appeal, John Simpson, director of the stem cell project at FTCR told The Scientist. " We think we have a very good case."

The watchdog group has opposed the patents from the beginning, arguing that they impede stem cell science and that they cover research concepts that had been established in the 1980s. Simpson added that the amendments made to the patents by WARF last October were already a victory, in that they narrowed the scope of the patents to stem cells derived from preimplantation embryos. Under the original language, all three patents would apply to stem cells derived from fetal tissue or therapeutic cloning.

In response to allegations that the patents inhibited stem cell science, WARF loosened some of the patent restrictions in January, 2007. "We have been terrific proponents of disseminating this technology to researchers," Gulbrandsen said. He added that restrictions in federal funding for stem cell research have been far more obstructive than the WARF patents.