Patenting of human embryonic stem cells in Europe

generated. Their potential to differentiate into almost any cell type raised hopes for their use in human therapy, for example to replace non-functioning pancreatic island cells to produce insulin in diabetes patients. The resources required to fund ES cell research and to develop stem cell based therapies are considerable. Academic institutions as well as companies therefore early-on applied for patents in order to secure their investments. However, hES cell research and the patenting of inventions in this field has given rise to fierce public debates1. Critics object to the destruction of embryos for the procurement of hES cells, but also to the commercial appropriation and commodification of cells which have a large developmental potential. The European Patent Office (EPO)2 has been in the centre of public attention with regard to hES cells since the year 2000 when it granted a patent on methods involving hES cells (the socalled "Edinburgh" patent was later restricted in opposition proceedings to exclude ES cells)3. The climax of this debate was probably reached with the referral of the "Thomson/WARF" case by a Technical Board of Appeal (the second instance at the EPO) to the Enlarged Board of Appeal in 2006 [2]. The Enlarged Board of Appeal of the EPO (EBoA) of the EPO has now issued a landmark decision concerning the patentability of hES cell cultures under the European Patent Convention (EPC). The decision concerns points of law that emerged in the appeal against the rejection of a European patent application4 filed by the Wisconsin Alumni Research Foundation (WARF) in 1995. The patent application ("WARF/Thomson") describes a method by which primate embryonic stem cells derived from an embryo can be maintained in vitro for a long period of time without losing their potential to differentiate into any cell of the body. In particular, the description of the patent application expressly teaches that the use of spare human embryos obtained during in vitro fertilisation (IVF) as starting material is indispensable. The (amended) patent claims do however not cover the method to obtain hES cells and are mainly directed to a cell culture comprising primate embryonic stem cells which (i) are capable of proliferation in vitro culture for over one year, (ii) maintain a karyotype in which all chromosomes normally characteristic of the primate species are present and are not noticeably altered through culture for over one year, (iii) maintain the potential to differentiate to derivatives of endoderm, mesoderm, and ectoderm tissues throughout the culture, and (iv) are prevented from differentiating when cultured on a fibroblast feeder layer. hES cells are widely believed to hold a considerable potential