An improved method of cloning a non-human mammal by nuclear
transfer comprising
the introduction of a non-human mammalian donor cell or a
non-human mammalian donor cell nucleus into a
non-human mammalian enucleated oocyte ofthe same
species as the donor cell or donor cell nucleus to form
a nuclear transfer (NT) unit,
implantation of the NT unit into the uterus of a surrogate mother of
said species, and
permitting the NT unit to develop into the cloned mammal,
wherein the iMprovement comprises using as the donor cell or donor
cell nucleus a proliferatin2 somatic cell that has been expanded in
culture, or a nucleus isolated from said somatic cell.
Paper 7, Appendix (unpaginated, emphasis added). Strelchenko's precritical date Claim 48 provides:
48. A method for preparing a cloned mammalian embryo, compri sing the
step of a nuclear transfer between:
(a) a totipotent mammalian cell, wherein said cell is cultured and
wherein said cell is not serum starved; and
(b) an oocyte, wherein said oocyte is at a stage allowing
formation of said embryo.
Strelchenko Application 09/357,445, Paper 1, specification, p. 96 (emphasis added).
The key difference in language between the processes set out in the parties' respective claims
is the use in a nuclear transfer process of "a proliferating somatic cell that has been expanded in
culture" and the use of a totipotent cell which is cultured and which is not serum starved.
11.
The first question we address is whether "a proliferating somatic cell that has been expanded
in culture" is a material limitation. The limitation appears in all of Stice's involved claims. We hold
that the limitation is material.
A.
The record of the Stice application shows that the limitation relating to proliferating somatic
cells expanded in culture was necessary for allowance of those claims. Stice's original claims did
not include the proliferating somatic cell limitation. Stice's claims were directed broadly to the use
of differentiated cells as the donor cells in cloning. Stice Application 08/781,752, Paper I
(specification), pp. 48-61. The claims were subject to rejection on a variety of grounds including
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