Munich

A controversial patent covering technologies for purifying human and animal stem cells has been restricted in scope by the European Patent Office (EPO).

In a ruling issued on 24 July, the EPO's oppositions division narrowed the patent held by the University of Edinburgh's Centre for Genome Research, invalidating all claims involving animal and human embryonic stem cells.

The patent, which details techniques for isolating and propagating genetically engineered adult or embryonic stem cells, generated widespread complaints when it was granted in December 1999.

Starting in March 2000, 14 parties, including Greenpeace and the German, Italian and Dutch governments, filed objections. Most opposed the patent because it involved techniques for working with human embryonic cells (see Nature 404, 3–4; 200010.1038/35003701). The DFG, Germany's main research funding agency, objected on technical grounds, claiming that the University of Edinburgh had not revealed enough technical information about the methods involved.

Shortly after the objections were filed, the university withdrew parts of the patent that covered technologies that could be used to alter the composition of the human germ line. But the EPO's ruling on the formal objections has gone further, leaving only claims covering adult stem cells intact.

The patent office says that its decision was partly based on ethical grounds — uses of human embryos are excluded from patentability according to EPO rules — and partly due to the patent's failure to disclose sufficient information for the techniques to be repeated by stem-cell experts.

Oliver Brüstle, a stem-cell researcher at the University of Bonn, fears that the ruling will send a negative signal to researchers. “It could mean that it will be difficult for researchers to get protection for intellectual property on human embryonic stem cells in the future,” he says.

But Bernard Huber, a lawyer for the DFG, points out that the EPO's decision applies only to this particular case, and so cannot be generalized.