A patent challenge for human embryonic stem cell research;

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A scientist describes how she decided that a legal fight would advance science

Nature Magazine

At 9 p.m. on 9 August, 2001, US President George W. Bush announced the first opportunity to obtain federal funding for experiments on human embryonic stem cells (ES cells). Because funding was limited to lines already established at that time, Bush’s executive order is perceived to be a constraint on this research. In fact, more restrictive decisions have already been made by another US government agency.

On 1 December, 1998, the US Patent and Trademark Office (USPTO) issued a patent that covers all primate (including human) embryonic stem (ES) cells. This patent, entitled ‘Primate Embryonic Stem Cells’ (Patent 5,843,780), was followed on 13 March, 2001 by a second (Patent 6,200,806) with the same title, but limited to human ES cells. Unlike a scientific publication, which encourages other scientists to reproduce a researcher’s work, a patent has the force of law to exclude others from working with the patented invention or material. In this case, the patents are quite broad. Through a “composition of matter” claim, the patents would cover even human ES cells that were not derived through James Thomson’s method, on whose work the patent is founded.

I was already working on deriving human ES cell lines, as were several of my colleagues in the field, when I learned about the patents, and I began to worry about what impact this monopoly would have. My concern about the patents grew as it became clear that the patent holder intended to exploit its monopoly, charging for licences to use human ES cells. I started seriously researching patents and came across an article1 about Dan Ravicher, an attorney who had founded the Public Patent Foundation in New York to challenge patents that threatened the public interest. I called him for advice, and within a month he had become my teacher and partner in the challenge to the patents that we brought in the summer of 2006 (refs 2’4).

The effects of a patent on research depend on the motives of the patent holder: the owner of a patent can sell it, mandate the terms under which it is licensed, or simply deny everyone else the chance to use the technology. In this case, the owner of the ES cell patents is the Madison-based Wisconsin Alumni Research Foundation (WARF), a technology-licensing organization associated with the University of Wisconsin, with US$1.6 billion in assets, that also holds patents for vitamin D and warfarin, a blood-thinning drug marketed in the United States as Coumadin. WARF requires a license from every academic investigator who uses human ES cells in the US, thus restricting collaboration even within the same institution, and demands large licensing fees and royalty payments from companies that wish to use human ES cells for reagent or drug development (5).

The 1998 patent (5,843,780) was based on monkey ES cells derived around 1994 by James Thomson at the Wisconsin Regional Primate Center (now the Wisconsin National Primate Research Center). The second patent was a “divisional” patent that claimed only human, not all primate ES cells.

These two patents and a third issued on 18 April, 2006 (7,029,913) form the basis for WARF‘s monopoly on human ES cells in the United States (Table 1). Under the law, WARF can exclude everyone else in the country (or anywhere the patents are enforced) from making, using, selling, offering for sale or importing any cells that fall under the patent claims. The broadest of these claims “composition of matter” of primate ES cells. The 1998 patent reads as follows:

We claim: 1. A purified preparation of primate embryonic stem cells which (i) is capable of proliferation in an in vitro culture for over one year, (ii) maintains a karyotype in which all the chromosomes characteristic of the primate species are present and not noticeably altered through prolonged culture, (iii) maintains the potential to differentiate into derivatives of endoderm, mesoderm and ectoderm tissues throughout the culture, and (iv) will not differentiate when cultured on a fibroblast feeder layer.

The research that formed the basis of the 1998 patent was supported by a grant from the US National Institutes of Health (NIH) to John Hearns, the director of the Primate Center. This is important, because it means the government automatically has a license to this patent as well as rights to force broad licensing terms if deemed necessary in the public interest. (The government has never exercised these “march-in rights” for biological patents.) The patent issued in 2001 excluded the NIH-supported work, as the claims were only for work on human ES cells supported privately by the biotechnology company Geron, based in Menlo Park, California.

Anyone who believes that a patent should not have been issued can ask the patent office to re-examine a patent. The patent office will agree to do this only if there is a reason to believe that it was not able to consider all of the information available at the time the patent was in its first examination. After a few months of Dan teaching me about patent law and me teaching him about ES cells, we set out to make the case to the USPTO that these patents should never have been awarded.

To issue a patent, examiners must determine that a process, machine, material or other ‘invention’ is novel, useful and non-obvious. Of these, ‘obviousness’ is the most difficult decision to make. Patent examiners generally look for ‘prior art’, that is, publications that singly or in combination contain all features of the invention being considered. Next, the examiner considers whether “one of ordinary skill in the art” at the time of the application would have found the ideas underlying the invention obvious.

The USPTO receives hundreds of thousands of patent applications each year. A successful application is examined for an average of two years, during which time overworked examiners can devote an average of only 18 hours to each patent application. Patent attorneys do not have such constraints on their time, so in the sense that obtaining a patent is a debate between lawyer and examiner, the lawyer has the advantage. After months of investigation, we came to understand the events that led to the issuance of these patents.

We scrutinized the patents themselves as well as the ‘file wrappers’, the documents exchanged between the USPTO and the applicant (6). For the primate ES cell patents, the patent history was a stack of paper about 10 centimeters high. Most consisted of badly photocopied scientific manuscripts, patents and other dated material such as newspaper clippings. By sifting through this pile, I learned that the USPTO rejected the first patent application on primate ESCs that WARF submitted, and that the patent that did get issued had squeaked through because of an administrative oversight.

A primate ES cell patent application was first submitted by WARF in January 1995, but failed to convince the patent examiner that the work was patentable, and this application was finally abandoned in December 1997. However, in January 1996, WARF submitted the same patent application a second time. In effect, WARF had two copies of the same patent in prosecution at the same time. A lawyer friend of mine tells me this not that unusual. Applicants who fear they have been assigned to a tough examiner can resubmit the patent to get a different one.

The file wrapper shows that this second attempt was more successful. The examiner this time criticized WARF for double patenting during the period that both applications were live, and WARF abandoned its first submission. If the appeal on the first patent application hadn’t been turned down, WARF would likely have withdrawn the second submission, and so obtained an earlier filing date, which creates earlier ‘prior art’ and so provides a stronger position for intellectual property.

Among the interesting items in the file is an undated page from Thomson’s lab notebook, used as evidence that he derived monkey ES cells before a newspaper article announcing their success in 1994. More importantly, the file contains a letter from the director of the patent examiners’ group, written after the examiner had approved the patent. This letter, dated 18 November, 1998, requests the patent printing office to delay issuing the patent so it could be further examined. However, the letter did not arrive in the printing office in time, and the patent was issued on 1 December, 1998. This patent remains in effect until 2016, 20 years after its filing, and the later patents will stretch some of WARF‘s claims even longer. WARF has tried to get the same patent issued in multiple countries and failed. Other countries have not even allowed patenting of human ES cells.

On 17 July, 2006, three of us — Dan and I, and John Simpson of the Foundation for Taxpayer and Consumer Rights in Santa Monica, California — requested that three “Primate Embryonic Stem Cell” patents be re-examined on the grounds that the claims were obvious. We cited several publications from the 1980s that described the precise recipe for ES cell derivation that Thomson used, and I wrote a declaration explaining that I thought that using the published methods for mouse ES cell derivation was an obvious approach for primate ES cells. On 30 March, 2007, the USPTO completed its re-examination and soundly rejected all of the claims in all three challenged patents. The examiners even came up with additional evidence of obviousness that we had not provided (8). The rejection does not mean the end of the patents, however, because WARF is appealing the decision, and the patents remain in force until WARF exhausts its appeals or decides to let the PTO’s decision stand.

In WARF‘s official response to the rejections, it included a declaration from Colin Stewart, a stem-cell researcher at the Institute of Medical Biology in Singapore, who argued that he did not think the approach was obvious. WARF also used the publicity surrounding Thomson’s publications as an argument that his work was patentable. We responded by obtaining declarations from three other stem-cell scientists stating that the successful derivation of primate ES cells depended on availability of resources, not novel ideas.

We were surprised when WARF responded with a press release saying, correctly, that I and the other scientists also have patents. This isn’t relevant to the validity of the WARF patents, and seems to be an attempt to undermine our credibility. Our patents, like Thomson’s, are assigned to companies or to our universities, and we have little control over how they are enforced. We are not challenging Thomson; we’re challenging the patent owner, WARF.

It’s important to remember that the patents remain in force until the challenge is resolved, but we think that our challenge is already having a positive effect. In January 2007, WARF changed their licencing policy for academics, allowing them more freedom to share human ES cell lines, and to accept funding from companies for their research. Still, only a few companies have taken licences because they feel that WARF is demanding unreasonable licencing and royalty terms. Geron, because of their investment in Thomson’s research, retains an exclusive licence for therapeutic use of neural, pancreatic and cardiac derivatives of human ES cells.

Despite the rising clamour, WARF is vowing to hang on to the patents at all costs. At the beginning of October, it filed amendments with the USPTO in an effort to strengthen its case that the patented discoveries differ from prior art. Dan, John and I, along with an increasing number of scientists, ethicists, and lawyers, will continue to maintain that the work is unpatentable. Notably, a Nobel Prize was awarded this year to the three scientists who actually did invent ES cell technology (see Nature 449, 642; 2007). Early in the 1980s, Martin Evans, Mario Capecchi and Oliver Smithies developed the technology that all of us, including Thomson, have used to derive ES cell lines ever since.

I do not get paid for our work on this challenge. I did not set out to become an expert in patent law, and it is still very much outside my comfort zone. I’d rather be spending my time learning more about the molecular interactions that make human ES cells pluripotent. But the spirit of scientific inquiry often requires us to venture beyond our areas of expertise, and I think that scientists have an obligation not only to perform research but to make sure that our research can benefit the society that supports it.


1. Kintisch, E. A ‘Robin Hood’ declares war on lucrative U.S. patents. Science 309, 1319 (2005).
2. Loring, J. F. & Campbell, C. Science and law. Intellectual property and human embryonic stem cell research. Science 311, 1716’1717 (2006).
3. Kintisch, E. Groups challenge key stem cell patents. Science 313, 281 (2006).
4. Somers, T. Foundation’s stem cell patents impede research, scientists say. San Diego Union Tribune 30 July (2006).
5. Regalado, A. & Hamilton, D. P. How a university’s patents may limit stem-cell research. The Wall Street Journal 18 July (2006).
6. All patent-challenge documents are available from the Public Patent Foundation website: http://www.pubpat.org. Official correspondence and documents (called File Wrappers) are available at: http://portal.uspto.gov/external/portal/pair.
7. Kaplan, K. U.S. invalidates three human stem cell patents. Los Angeles Times 3 April, 2007.
8. Check, E. Patenting the obvious? Nature 447, 16’17 (2007).

Author affiliation: Jeanne Loring is director of the Center for Regenerative Medicine at The Scripps Research Institute

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