Jeanne Loring holds a petri dish with induced pluripotent stem cells from a Parkinsons patient.

A nine-year legal challenge to human embryonic stem cell patents ended Tuesday, when the Supreme Court declined to hear the case.

The decision means the Wisconsin Alumni Research Foundation, or WARF, will get to keep its patent rights for the cells, which were discovered in 1998 by University of Wisconsin - Madison scientist James Thompson.

However, the challengers succeeded in preventing WARF from gaining rights over another important type of stem cells called induced pluripotent stem cells, said Jeanne Loring, a stem cell scientist at The Scripps Research Institute in La Jolla who was part of a coalition contesting the WARF patents.

IPS cells act much like human embryonic stem cells, and are being researched as an alternative for stem cell therapy. Loring is working with a group that seeks to use them to treat Parkinson's disease.

WARF maintains it has the right to license use of human embryonic stem cells, because Thompson developed the methods to isolate them from embryos, which had not been previously done. Loring said the derivation is an obvious extension of methods used to derive non-primate embryonic stem cells, and therefore not patentable.

Loring and two public interest groups, Consumer Watchdog and the Public Patent Foundation, challenged the patents in 2006, and in 2007 succeeded in narrowing WARF's claims to exclude the IPS cells. Loring and the groups continued the challenge on the grounds that as a product of nature, human embryonic stem cells are not patentable.

The U.S. Patent and Trade Office turned down that challenge, and the case reached the Supreme Court last year. By not hearing the case, the Supreme Court let that decision stand.

"They still own human embryonic stem cells," Loring said. "But the way their patents were originally written, they would have also been able to own IPS cells. If there's one success that I would point to, that was worth all the effort, it's that they can't. And the reason they can't is because we challenged the patent."

Calls and an email sent Tuesday to WARF headquarters in Madison, Wis., were not immediately returned.

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Supreme Court rejects stem cell patent case