Giving the phrases their ordinary meaning, Stice's 577 claims and Strelchenko's precritlical
date claims are directed to mutually exclusive processes of cloning. The Stice 577 claims require
the insertion of certain somatic cells into an enucleated oocyte, while Strelchenko's precritical date
claims require insertion of "totipotent cells."
C.
Our analysis, however, can not stop at this point. We must look at the parties' written
descriptions to see if they have given a different meaning to these phrases. Vitronics, 90 F.3d at
1582, 39 USPQ2d at 1577.
1
It is clear from Stice's written description that Stice did not contemplate the use of totipotent
cells as part of the claimed cloning process. As we noted above, totipotent cells are undifferentiated
cells. What Stice considered significant was the discovery that animals could be cloned from
differentiated cells. Thus, Stice states:
Prior art methods have used embryonic cell types in cloning
procedures. This includes work by Campbell et al (Nature, 380:64-68, 1996)
and Stice et al (Biol. Reprod., 54:100-110, 1996). In both of those studies,
embryonic cell lines were derived from embryos of less than 10 days of
gestation. In both studies, the cells were maintained on a feeder layer to
prevent overt differentiation of the donor cell to be used in the cloning
procedure. The present invention uses differentiated cells.
It was unexpected that cloned embryos with differentiated donor
nuclei could develop to advanced embryonic and fetal stages. The scientific
dogma has been that only embryonic or undifferentiated cell types could
direct this type of development. It was unexpected that a large number of
cloned embryos could be produced from these differentiated cell types. Also,
the fact that new transgenic embryonic cell lines could be readily derived
from transgenic cloned embryos was unexpected.
Stice 577, col. 6,11. 12-30 (emphasis added). Stice father emphasizes the use of differentiated cells:
The present invention relates to cloning procedures in which cell nuclei
derived from differentiated fetal or adult, mammalian cells are transplanted
into enucleated mammalian oocytes of the same species as the donor nuclei.
The nuclei are reprogrammed to direct the development of cloned embryos,
which can then be transferred into recipient females to produce fetuses and
offspring, or used to produce cultured inner cell mass cells (CICM). The
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