Argumenty bioetyki 2012

wykład 15

KLONOWANIE W CELACH

BADAWCZYCH

[źródła zarodkowych komórek

macierzystych]

• - zarodki pozostałe po kuracji in vitro
• - zarodki utworzone techniką in vitro

specjalnie w celach badawczych

• - zarodki utworzone w celach badawczych

metodą klonowania terapeutycznego

(SCNT), tj. przez transfer jądra ludzkiej

komórki somatycznej do ludzkiej komórki

jajowej

• - zarodki utworzone w celach badawczych

przez transfer jądra ludzkiej komórki

somatycznej do zwierzęcej komórki jajowej

• Devolder, Katrien, "Cloning", The

Stanford Encyclopedia of Philosophy

(Fall 2010 Edition), Edward N.

Zalta (ed.), URL =

http://plato.stanford.edu/archives/fal

l2010/entries/cloning/

• President's Council on Bioethics

(PCBE) (2002), Human Cloning and

Human Dignity: An Ethical Inquiry.

Washington D.C.: PCBE.

• Hansen, J.E. (2002) “Embryonic stem cell production

through therapeutic cloning has fewer ethical

problems than stem cell harvest from surplus IVF

embryos”, Journal of Medical Ethics, 28(2): 86–8.

• Hurlbut 2005 - William B. Hurlbut, “Patenting

humans: clones, chimeras, and biological artifacts”.

Science and Engineering Ethics (2005) 11, 21-29

• Hyun & Jung 2006 - Insoo Hyun and Kyu Won Jung,

“Human Research Cloning, Embryos, and Embryo-

Like Artifacts,” Hastings Center Report 36, no. 5

(2006): 34-41.

• McHugh, P.R. (2004) “Zygote and ‘clonote’—the

ethical use of embryonic stem cells”, New England

Journal of Medicine, 351(3): 209–11.

klonowanie - znaczenia

stworzenie genetycznej kopii sekwencji

NA lub całego genomu organizmu

przeniesienie jądra komórki

somatycznej (do opróżnionej z jądra

komórki jajowej) - somatic cell

nuclear transfer (SCNT)

klonowanie terapeutyczne (w

celach badawczych)

klonowanie reprodukcyjne

PCBE 2002 – medyczne cele

klonowania

• 1. Klonowanie w celu lepszego

zrozumienia ludzkiej choroby

• 2. Klonowanie w celu wynajdywania

nowych terapii ludzkich chorób

• 3. Klonowanie w celu wytwarzania

tkanek do przeszczepów nie

odrzucanych przez system

odpornościowy

• 4. Klonowanie wspomagające terapię

genową

klonowanie terapeutyczne –

argumenty przeciw

• szkody wyrządzane klonowanym

zarodkom

• szkody wyrządzane dawczyniom

oocytów

• szkody wyrządzane społeczeństwu

stanowiska w sprawie

etycznej oceny klonowania

• I. klonowanie terapeutyczne i tworzenie zarodków in

vitro w celu badawczym to praktyki etycznie

równorzędne, a mianowicie
A. równie dopuszczalne
[B. równie niedopuszczalne]

• II. klonowanie terapeutyczne jest etycznie bardziej

kontrowersyjne niż tworzenie „badawczych”

zarodków in vitro (ze względu na niebezpieczeństwa

równi pochyłej)

• III. klonowanie terapeutyczne jest etycznie mniej

kontrowersyjne niż tworzenie „badawczych”

zarodków in vitro (ze względu na niższy status

sklonowanych zarodków)

ad III. zarodek sklonowany a

zarodek zapłodniony

• Hansen, J.E. (2002) “Embryonic stem cell production

through therapeutic cloning has fewer ethical

problems than stem cell harvest from surplus IVF

embryos”, Journal of Medical Ethics, 28(2): 86–8.

• Hurlbut 2005 - William B. Hurlbut, “Patenting

humans: clones, chimeras, and biological artifacts”.

Science and Engineering Ethics (2005) 11, 21-29

• Hyun & Jung 2006 - Insoo Hyun and Kyu Won Jung,

“Human Research Cloning, Embryos, and Embryo-

Like Artifacts,” Hastings Center Report 36, no. 5

(2006): 34-41.

• McHugh, P.R. (2004) “Zygote and ‘clonote’—the

ethical use of embryonic stem cells”, New England

Journal of Medicine, 351(3): 209–11.

Hansen 2002

• The genetic complement of the fertilised egg is a

unique result of a fusion of a sperm cell and an egg

cell, and this may naturally evolve into an embryo, a

fetus, and eventually an infant. This is not the case

with an enucleated egg cell that has been

transplanted with the nuclear material from a

somatic cell. Neither is the genetic content unique,

for it is identical with the nuclear donor; nor is it

occurring naturally, with a natural potential of

evolvement into an embryo. It is entirely artificial

and leads its life in the laboratory unless somebody

chooses to implant it into a susceptible female

uterus before it can develop to the blastocyst stage,

when stem cell harvest is possible. (s. 86)

brak niepowtarzalności

• in my opinion the entire argument of deriving human

uniqueness from genetic uniqueness is flawed since

identical twins have identical genomes but are

evidently separate individuals. However, if emphasis is

none the less placed on the uniqueness of the new

genetic complement (the nuclear genome) of a

fertilised egg the differences between a fertilised egg

and a transnuclear egg cell would be significant and

the transnuclear egg cell could not be considered a

human being even if a naturally fertilised egg cell were

to be so considered. The genome of the transnuclear

egg cell already exists in the cells of the donor of the

nucleus. So either one must give up the notion that

human individuality is related to genetic uniqueness or

accept that a transnuclear egg cell is not a human

individual. (s. 87)

brak naturalności

• While the concept of natural purpose may be

dubious— consider for instance that the great

majority of naturally fertilised eggs perish before

term—the purpose of a transnuclear egg cell is

clearly not defined by nature.10 Therefore, if

emphasis is placed on the natural purpose of a

fertilised egg to evolve into an embryo and

eventually a human being, the transnuclear egg

cell would fall outside the category of human

beings as there are no natural occurrences

whereby a transnuclear egg cell develops into a

fetus. As with all other artifacts, its purpose is

properly defined through human design. (s. 87)

McHugh 2004 – zarodki in

vitro i zarodki sklonowane

• I argue that this process of SCNT, by causing the

expression of an intrinsic potential for growth and

replication that is found in every somatic cell, can

extend and expand a donor’s cellular mass into

extracorporeal space, as any form of tissue culture

does. The stem cells that issued from the process

would, in this view, be licitly used as the donor

allowed. To specify this fundamental difference

between in vitro fertilization and SCNT, I suggested

that, since we call the first cell produced by

fertilization the zygote, we dub the combination of

nucleus and enucleated ovum that launches SCNT

the “clonote.” (McHugh 2004, s. 210)

Hurlbut 2005

• The crucial principle in all such efforts, however, must be

the preemptive nature of the intervention, the intentional

construction of an entity that cannot be reasonably

designated a living being. The intervention that precludes

the possibility of human development would be undertaken

at a stage before the transition to organismal status and

thus no active potentiality, no human life in process would

be violated, mutilated or destroyed. If the artifact were

accorded a certain cautionary respect (as with all human

tissues) even though not the full protection of human life,

the consequences of such a program would not compromise

any moral principle. Just as we have learned that neither

genes, nor cells, nor even whole organs define the locus of

human moral standing, in this era of developmental biology

we will come to recognize that cells and tissues with ‘partial

developmental potential’ may be used for medical benefit

without a violation of human dignity. (Hurlbut 2005, s. 27-

28)

Hyun & Jung 2006

• Using this primate research as a point of reference,

we believe one can reasonably argue that the

squish enucleation process for creating human

SCNT blastocysts for stem cell research might very

well have the effect of simultaneously barring these

SCNT blastocysts from developing into a future

human life. For primates, unlike previously cloned

animal species, the same technology that makes

research cloning possible may also make primate

reproductive cloning impossible. Thus human

research cloning may soon emerge as scientific

reality while human reproductive cloning may

remain science fiction. (Hyun & Jung 2006, s. 38)