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From a prosecutor’s standpoint, the ‘231 patent (link at bottom of this post) has “dream claims” to a new class of stem cells. Claim 1 reads:

An isolated adipose-derived stem cell that can differentiate into two or more of the group consisting of a bone cell, a cartilage cell, a nerve cell, or a muscle cell.

Adipose is “fat”, and because there is so much of it around, and it is easy to obtain, it may nearly be an ideal source for “pluripotent stem cells.” During prosecution, the inventors had to convince the Examiner that these fat-derived stem cells were patentably distinct from mesenchymal stem cells (MSC). Other groups had derived these pluripotent MSCs from bone marrow, and they could be induced to form the same tissue types. Several companies are investigating the use of these cells to repair heart attack damage. For those two or three of you who have not been keeping up with stem cell technology and patent developments, I refer you to my article in JPTOS, vol. 83, 830 (2001).

An inventorship dispute arose between the two inventors who began the work that led to the ‘231 patent at the University of Pittsburgh, and a visiting scientist who worked at Pittsburgh and then returned to UCLA and worked with another scientist to further characterize the cells. Although Pittsburgh listed both their inventors and the two UCLA inventors on a provisional, a PCT and the application that issued as the ‘231 patent, Pittsburgh tried to remove the two UCLA inventors from the ‘231 patent shortly after it issued. Not surprisingly, the UCLA inventors resisted being removed. (Decision is App. No. 2008-1468, July 23, 2009, a link is provided at the bottom of this post.)

The Federal Circuit found sufficient evidence to hold that the two Pittsburgh inventors had conceived of the claimed invention prior to the involvement of the UCLA researchers. The fact that the UCLA researchers confirmed certain properties of the cells was not a contribution sufficient to make them co-inventors, and ultimately, the court held that, while the Pittsburgh inventors were not certain that the stem cells would behave as expected, nonetheless they had the “firm and definite idea that these properties existed in [the cells].” At this point, work by others that confirms your educated guess is simply part of reduction to practice.

As interesting as is the resolution of the inventorship dispute, the resolution of the claim construction issue occupies almost four pages of the decision, and helps expand the notion of “patent profanity” that I discussed in the earlier post about the Sandoz decision. Here, the UCLA scientists urged a more limited definition of “adipose-derived stem cell” that they believed would encompass their contributions: “a species of stem cell distinct from the mesenchymal stem cell (MSC) that is obtainable from bone marrow tissue.”

The Federal Circuit affirmed that the plain meaning of the claim term was simply “derived from fat tissue.” The court then examined the specification and prosecution history to determine if there were any contradictory definitions in the specification or a “unmistakable disavowal” of the plain meaning by applicants during prosecution. The court found that the proposed narrower definition would require that the cells be a “separate species” than MSCs and that the specification did not assert that this was the case (even though the fat-derived stem cells have different isolation requirements).

Notably, even though the applicants submitted evidence derived from work at UCLA to establish that the cells were patentably distinct from MSCs, and the Examiner relied on this submission, the court specifically held: “This is not a disavowal.” The court found only a “weak inference from the summary [by the Examiner] that adipose-derived stem cells in this invention must be a different species from mesenchymal stem cells and a clear and unmistakable disavowal as required to limit a claim term.” The court even delved into the science to support its holding, stating that there was a theory that MSCs could travel to fat tissue and be changed by the new environment they encountered. (Are all adult stem cells the same cell?)

If there is a take-away lesson here, it is that unmistakable disavowal of otherwise undisturbed plain meaning must be really unmistakable before it will be used to narrow claim scope. Here, the patentee was saved from the effects of “patent profanity” because they apparently did not urge during prosecution that the claimed cells were a “distinct species” of stem cell, as opposed to simply having some distinct properties. A close call, but in the end, the Pittsburgh inventors were “safe” and the UCLA inventors were out at the plate.

Patent 206777231
Univ of Pittsburgh v Hedrick


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