ON CLONING EMBRYOS FOR RESEARCH
'Reproductive' and
'therapeutic'
cloning:
What's the
difference?
By ROLAND CHIA
A RECENT article in The Straits
Times announced the intention of a group of researchers at the
National University of Singapore to clone a human embryo for research
(Straits Times, Wednesday, Dec 25, 2002, H8). This announcement
was made in the wake of a similar initiative to be undertaken
by scientists from the prestigious Stanford University, the first
attempted by a United States university.
Commenting on the objective of therapeutic cloning, Professor
Ng, who heads the NUS team of researchers, told The Straits Times:
"My team hopes to develop cells through nuclear transfer
for clinical trials in patients with irreversible brain or spinal
damage, and possibly in diabetes and liver diseases." He
added that he and his team were "not interested in human
productive cloning, nor are we allowed to do so".
This position is in line with that of the Bioethics Advisory Committee
(BAC) whose recommendations on ES Cell Research were accepted
by the Singapore Government. In its report, the BAC makes the
distinction between "therapeutic cloning" and "reproductive
cloning". While opposing reproductive cloning, the BAC recommended
that therapeutic cloning be allowed under stringent conditions.
Much depends on the difference between "reproductive"
and "therapeutic cloning". Reproductive cloning, according
to some scientists, is the process by which an embryo is created
by nuclear transfer and implanted into a woman's womb in the hope
of bringing it to term. Therapeutic cloning, on the other hand,
is the process by which an embryo is created through nuclear transfer
in order to obtain stem cells from it. The preparation of human
embryonic stem cells by therapeutic cloning requires the development
of the embryo to the stage of initial blastocyst. The embryoblast
or inner mass (ICM) is then isolated - a process that implies
the destruction of the embryo - and cultured on a feeder.
According to the above definitions, the distinction between the
"reproductive" and "therapeutic" cloning has
to do with the purposes to which the clone will be put to use
and not the nature of the clone. In either case, an embryo is
cloned. In either case, one is dealing with the reality of a human
being, who is the subject of human rights, the most fundamental
of which is the right to live.
This raises the question whether the blastocyst
is indeed a human being who must be accorded with the same rights
and dignity as every human being. Scientists who maintain that
human life begins at about 14 days when "individuation"
occurs have made the distinction between a "re-embryo"
and an "embryo". These and other euphemisms that have
entered the discussion - "totipotent cell", "clump
of embryonic cells", "unfertilised oocyte", etc
- have clouded the issue. Thus, scientists who oppose the cloning
of "human beings" and "persons" reserve the
right to clone embryos or blastocysts as long as they are not
allowed to survive to birth.
Scripture and tradition hold that life begins from conception,
and that the embryo, from the moment it is formed from the union
of the gametes, is a human subject with a well-defined identity.
Therefore the zygote, from its conception, is a human being made
in the image of God and should therefore be accorded the same
respect and dignity as all human beings.
This position can be defended philosophically as well as scientifically.
It can be argued that the human zygote is a human being because
it cannot articulate itself into some other animal. Conversely,
it can be argued that the human zygote will articulate itself
into a mature human being because it is already one from its conception.
There are many established embryologists and scientists who hold
that human life begins at conception.
Writes Marjorie England: "Development of the embryo begins
at Stage 1when a sperm fertilises an oocyte and together they
form a zygote." In similar vein Keith Moore maintains that
"human development begins after the union of male and female
gametes or germ cells during a process known as fertilisation
(conception)." In "Cloning Human Beings", a report
of the National Bioethics Advisory Commission in Rockville, an
embryo is defined as "the developing organism from the time
of fertilisation until significant differentiation has occurred,
when the organism becomes known as a fetus".
'No' to sacrifice a human life
for benefit of others
William Larsen describes the zero point of embryonic development
thus: "The chromosomes of the oocyte and sperm are
respectively enclosed within female and male pronuclei. These
pronuclei fuse with each other to produce the single, diploid,
2N nucleus of the fertilised zygote. This moment of zygote formation
may be taken as the beginning or zero time point of embryonic
development." "If it's not an embryo," Jonathan
Van Blerkom, the embryologist at University of Colorado asks,
"what is it?"
Finally, in "Human Embryology & Teratology", Ronan
O'Rahilly and Fabiola Müller contend that "although
life is a continuous process, fertilisation is a critical landmark
because, under ordinary circumstances, a new genetically human
organism is thereby formed
The combination of 23 chromosomes
present in each pronucleus results in 46 chromosomes in the zygote.
Thus the duploid number is restored and the embryonic genome is
formed. The embryo now exists as a genetic unity."
This textbook describes "pre-embryo" as "ill-defined
and inaccurate" and lists it among "discarded and replaced
terms". This chorus of voices should at least caution against
regarding too hastily what appears to be an abstract and arbitrary
distinction as a dogma that has achieved widespread consensus
among members of the scientific community.
The refrain that "the advantages of therapeutic cloning or
embryonic stem cell research to mankind far outweighs the ethical
considerations" has been repeated so often that it has almost
become axiomatic. Killing a healthy adult and quarrying his organs
for transplant may save the lives of numerous others who will
otherwise die. It may be argued that the therapeutic potentials
and advantages (saving numerous lives) far outweigh the ethical
considerations (taking the life of just one human being). But
no society would countenance this utilitarian calculus that prizes
the lives of many over the life of one human being. Yet, scientists
could without difficulty apply this principle to human embryos.
From the standpoint of Christian ethics it is never ethical to
sacrifice one human life for the real or potential benefit of
others. No end can be deemed good if the means by which it is
achieved is itself wrong. The human embryo is a living human being
from the moment of conception, and therefore, it has inviolable
dignity. It must not be treated as a means to an end: it is an
end in itself.
It merits our fullest respect, the same respect that we accord
to the newborn babe, the child, the adolescent, and the adult.
It may not be cloned and killed in order that parts of its body
may be used for the benefit of another person.
Dr Roland Chia, a lecturer at Trinity Theological College, is also the Director of the Centre for the Development of Christian Ministry at TTC. He is a member of Fairfield Methodist Church.