cloned embryos can also be combined with fertilized embryos to produce
chimeric embryos, fetuses and/or offspring.
Strelchenko Ex. 2001, col. 1, 11. 5-14. The use of differentiated cells is also said to significantly
simplify the cloning process involving transgenic mammals:
The present invention also allows simplification of transgenic
procedures by working with a differentiated cell source that can be clonally
propagated. This eliminates the need to maintain the cells in an
undifferentiated state, thus, genetic modifications, both random integration
and gene targeting, are more easily accomplished. Also by combining nuclear
transfer with the ability to modify and select for these cells in vitro, this
procedure is more efficient than previous transgenic embryo techniques.
According to the present invention, these cells can be clonally propagated
without cytokines, conditioned media and/or feeder layers, further
simplifying and facilitating the transgenic procedure. When transfected cells
are used in cloning procedures according to the invention, transgenic
embryos are produced which can develop into fetuses and offspring. Also,
these transgenic cloned embryos can be used to produce CICM cell lines or
other embryonic cell lines. Therefore, the present invention eliminates the
need to derive and maintain in vitro an undifferentiated cell line that is
conducive to genetic engineering techniques.
Strelchenko Ex. 2001, col, 6,11. 40-59.
The prosecution history of Stice application 08/781,752 which matured into the Stice 577
patent, similarly demonstrates that the use of differentiated rather than totipotent (undifferentiated)
cells was contemplated. Thus, the original title of the application was "Cloning Using Donor Nuclei
from Differentiated Fetal and Adult Cells." Stice Application 08/781,752, Paper 1, title page. In
response to a rejection and in summarizing a discussion with an examiner during an interview,
applicant characterized the invention as using somatic cells and that those cells were differentiated:
It was explained that the subject invention comprises a pioneering discovery,
i.e., that somatic cells or cells committed to a somatic cell lineage may be
used as nuclear transfer donors for cloning desired non-human mammals by
nuclear transfer techniques. It was indicated that this was a surprising
discovery as it was contravened by previous accepted dogma in the art.
Essentially, prior to the present invention, it was thought that once a cell
becomes differentiated that it loses its ability to be a suitable donor cell
during nuclear transfer.
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