President

In this document the NBC examines in detail only one form of interspecies
living being, that is, cytoplasmic hybrid embryos, or cybrids, because:
currently it seems to be one of the possibilities, maybe the only one, in
line with the cloning project through the nuclear transplant for therapeutic
purposes;
the protocol followed in creating this hybrids is sufficiently standardised
to be reproduced in a laboratory; the organisms derived can be described only
from a genetic point of view, although still, for some NBC members 33 remains
the problem of their uncertain identity.
The paragraph dedicated to bioethical reflection, refers in particular to the
creation of cybrids and, in general, to the creation of interspecies organisms;
conclusive bioethical considerations and the legal part (in appendix), for the
arguments and the problems tackled, are applied to all man/animal interspecies
organisms.
2. Cytoplasmic hybrid embryos
Commonly known with the expression “therapeutic cloning”, the SCNT
technique (Somatic Cell Nuclear Transfer) allows us, theoretically, to create
embryos with the genetic inheritance of an adult individual, using only one
gamete. This protocol involves the removal of an egg cell’s nucleus, which is
then substituted with the nucleus taken from a man adult somatic cell of the
same species. Appropriately stimulated – chemically and/or electrically – this
new cell can behave as a fertilised oocyte and can divide and differentiate until
it originates a new organism, which has the same nuclear genetic inheritance of
the donor’s adult somatic cell. 34
The main purpose of this technique is to obtain cellular lines and,
consequently, human tissues, compatible to the donor and, theoretically, useful
for eventual medical applications and, first of all, for the substitution of tissues
damaged by degenerative diseases (like, for example, Parkinson disease),
without having any rejection problems. This is a possible application of
regenerative medicine. Another purpose of these experiments is simply of a
cognitive nature, that is, aimed at exploring the mechanisms of cellular
reprogramming mediated by the egg cell’s cytoplasm. The SCNT can also be
seen as a technique that allows us to reprogram and therefore “rejuvenate” an
adult cell to its embryonic stage, through not yet clear mechanisms that involve
the activation of some genes.
33 S. Amato, A. Bompiani, R. Colombo, A. Da Re, F. D’Agostino, B. Dallapiccola, M.L. Di Pietro,
M. Gensabella, A. Isidori, A. Morresi, A. Nicolussi, L. Palazzani, V. Possenti, R. Proietti, L.
Scaraffia.
34 However it’s not a perfectly identical copy: the oocyte contains mitochondria - small
structures responsible, amongst other things, for the cellular energetic cycle – which have their
own genetic inheritance, present in the new embryo in different quantities, according to the
methods of transferral of the nucleus from the donor to the enucleated oocyte. The term
heteroplasmia indicates the presence of mitochondrial DNA with a different genetic make-up,
for example the mixture of the egg’s and the donor’s mitochondrial DNA, because of the
transferral of a residue of the adult somatic cell’s cytoplasm: in this case, both the mitochondria
of the somatic cell’s donor and those of the individual who has given the oocyte, can be found
in the new embryo.
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