Evaluating any new technology and its ethical implications, especially when there are human applications, first requires clear definitions and a good understanding of the subject. Words like "human cloning" can be frightening, and if they are not correctly understood in their technical context it can become impossible to deal with their import in a reasonable way. Therefore, it is better to begin with a review of the technical aspects of cloning as well as an evaluation of the feasibility of potential applications so that the discussion will be, as far as possible, a reasoned one.

Cloning, which has been the subject of experimentation on cattle and sheep for the last ten years, is in fact the "fertilization" of an enucleated oocyte with genetic material from the nucleus of a diploid cell taken from either an embryonic or an adult donor, the latter having been achieved for the first time in Ian Wilmut's recent experiment.¹

Cloning by such "nuclear transfer" is accomplished in several steps:

1. obtaining an oocyte by the now classic methods of injecting gonadotropin hormones;
2. enucleation of the oocyte by inserting a fine pipette in order to draw out the non-condensed chromatin which is located under the polar body;
3. inserting (with another pipette) a diploid cell from the donor to be cloned under the oocyte's zona pellucida;
4. fusion of that cell to the enucleated oocyte by means of an electric pulse, which has the advantage of simultaneously activating the oocyte (a phenomenon normally triggered by contact with sperm);
5. culturing of the "fertilized" oocyte to allow the initial stages of cell division leading to the development of a blastocyst;
6. implantation in a surrogate mother who has undergone hormone treatment to prepare her to receive the blastocyst;
7.  pregnancy to term and birth of the cloned fetus.

This procedure, developed in 1985 for cows and sheep in several veterinary laboratories such as those of Neal First at the University of Wisconsin at Madison, is the same as the procedure used by Wilmut's group to produce Dolly the Lamb. The significance of this group's experiment lies in the demonstration that the nucleus of a differentiated cell derived from an adult tissue is capable of directing embryonic development.

A survey of this type of animal cloning experimentation will enable us to understand the impact of the recent accomplishments. Until recently it was believed that only nuclear transfer from very early embryonic cells could be used for cloning. Therefore, until now only cells isolated from the blastocyst stage of embryonic development were used. Even at this stage, which occurs immediately after the first cellular divisions, only the undifferentiated embryonic stem (ES) cells derived from the inner cell mass were thought to be pluripotent and thus capable of contributing all three germinal layers of the embryo which are necessary for successful development. This is because cells derived from the surface of the blastula have already advanced too far in their ectodermic differentiation and therefore, it was believed, they could no longer revert to full developmental capacity. However, with sheep there seems to be greater flexibility, and embryonic cells which had undergone even more advanced differentiation (embryonic fibroblasts) could be successfully used for nuclear transfer.

The importance of the latest advance is to establish that fertilization can be accomplished by using an adult tissue cell derived from the mammary gland of a sheep. But the technical problems in this procedure remain great, as can be seen in the following chart which summarizes cloning attempts in sheep.

This table shows the preliminary nature of research in the field and points out the technical difficulties in applying the procedure in humans. The success rate in obtaining blastocysts and in achieving implantation is low, and the number of viable animals at term is even lower. The number of human oocytes that would be required is at present much too high. There are also many other obstacles to be overcome. Genetic analysis of the clones shows that they are frequently polyploid, indicating certain aberrations in cellular division leading to an unequal complement of chromosomes in the daughter cells. In addition, the embryos are often mosaic, i.e., they exhibit polyploid cells only in certain tissues. Since polyploidy is a characteristic of cancerous cells, the fate of these tissues over the course of years remains uncertain. This is a technical problem which certainly must be overcome.

Another problem is the activation of the oocyte in order to initiate cellular division. Certain proteins in the sperm normally initiate this activation, and these proteins are of course missing when nuclear transfer from a donor cell is used for fertilization. The electric pulse which is used to initiate cellular division seems to solve the problem only partially but there might be differences here among various species. Another important difference is the condition of the chromatin: it seems that in quiescent sheep cells, produced by causing the cells to exit the growth cycle and arrest in G0, the chromatin is less modified (e.g., by methylation of the DNA) than in other species. In addition, the sheep oocyte itself may be more capable of reversing these modifications, thus explaining why Dolly could be obtained from the nucleus of an adult cell and why the use of embryonic fibroblasts resulted in at least four live lambs. With monkeys two births were obtained, but only with nuclei from pre-blastular cells.

Extrapolating these data to man is not easy. Perhaps the procedure will be easy; or perhaps it will be even more difficult to clone humans. In this regard, it is interesting to note that ICSI had been considered a very difficult procedure with animals, although it succeeds well in humans².

* a single living animal

There is another question which must be considered in evaluating the success of cloning: to what extent are the clones genetically identical? The principles of cloning ought to guarantee that the DNA sequences of the clone are identical to those of the donor of the nucleus. Animal experimentation has not yet demonstrated that this is true. Studies of genetic markers in cows have in fact shown that there could be unforeseen rearrangements. DNA sequencing techniques are still too slow and limited to allow checking whole genomes of cloned and donor animals. Epigenetic alterations in the chromatin of various chromosomes leading to alterations in the expression of gene activity cannot yet be fully detected.

Further, the oocyte contributes mitochondrial DNA, whose influence on the whole of the organism, beyond the development of the mitochondria, is still unknown. Every human being has maternal mitochondrial DNA, whereas half of his nuclear genome is contributed by the father. In cloning humans it is unknown what will happen to the at least thirty so-called "imprinted" genes whose expression depends on their paternal or maternal origin.

Taking all these problems and unknowns into consideration, First has calculated that phenotypical identity in a cloned cow could be as low as 70% with respect to the donor of the nucleus. Since one of the main reasons to clone is to preserve the identity of genetic characteristics, for example the milk production in cows, variations of 30% are surely unacceptable among clones! Even patches of colored hair on cloned animals are not identical because hair coloring does not depend solely on the genome, but is influenced by certain events in the course of embryonic tissue development. The persistence of some maternal nuclear DNA in the enucleated oocyte cannot be entirely eliminated. The influence of the surrogate mother and placental location are also variable factors. Another major cause of variation is nutrition, which is not identical even in animal twins raised in the same environmental conditions. The influence of the environment, including education, would be immeasurably more important in humans.

Genetic research has in recent years led to the use of animals in the production of pharmaceutical products. Targeting a gene for expression in the mammary gland leads to secretion of large quantities of certain desirable proteins in the animal's milk. Production rates are extremely high and can reach several dozen grams per liter, as in the case of human albumin used for transfusion, coagulation factors used in the treatment hemophilia, and other therapeutic proteins.

These transgenic animals can be maintained by sexual reproduction through mating of transgenic males and females. Nevertheless, it is impossible to guarantee perfect genetic identity for the rest of the genome, and this can be an obstacle to commercial exploitation. In fact, one of the prerequisites for obtaining authorization for new pharmaceutical products is absolute consistency in production. If a pharmaceutical product is produced by a living animal, it might be impossible to guarantee such consistency and authorization for commercial production might be required for each animal involved in production. If the animal accidentally dies, the commercial investment (clinical trial on the product) would be lost and would have to be repeated with another animal.

Cloning could in theory solve this problem. A herd of cloned animals might be considered sufficiently identical to be covered by a single authorization for drug registration. The example of Dolly demonstrates that a nucleus from a mammary gland cell possessing desirable genetic characteristics can be transferred to produce a clone.

More generally, cloning may be useful in the generation of transgenic animals. This is accomplished today by genetic manipulation of pluripotent embryonic stem cells (ES), which still have the capacity to differentiate into various specialized types of tissue elements. Introducing the genetically modified ES cells into blastocytes, one first obtains mosaic animals, from which are then selected those which have the desired gene in their gametes and can therefore transmit it to their off-spring. By crossbreeding, one can finally produce homozygous progeny.

This procedure could be simplified and shortened by transferring the nucleus of a genetically manipulated cell directly into an enucleated oocyte leading to the birth of a transgenic animal in a single step. Further, it would be unnecessary to work with embryonic stem cells, which are not the easiest to manipulate genetically. Instead the nucleus of various somatic cells, e.g., fibroblasts, could be used to lead to the birth of transgenic animals.

This is not the place to consider whether man has a right to engage in genetic manipulation of animals. Such manipulations have a very long history, having been practiced with various techniques in different historical periods. Inasmuch as the procedure does not involve additional cruelty vis-a-vis the animal, cloning should be justified under these rights.

The steps in such a therapeutic procedure would be as follows:

• A skin biopsy is taken, for example, from a seriously ill diabetic and an in-vitro fibroblast culture is prepared.
• A nucleus is transferred from a fibroblast into an enucleated, donated oocyte (acquired in the course of standard IVF).
• After the oocyte is "fertilized" by the patient's nucleus, it is cultured until it reaches the blastocyst stage but it is not implanted.
• Embryonic stem cells, which are pluripotent, are then obtained from the inner cell mass of the blastocyst and then cultured in-vitro over a feeder layer of fibroblasts.
• When the number of cells is adequate, the embryonic cells are removed from the feeder layer permitting their differentiation into somatic tissues of various types (hair follicles, skin, pancreas, teeth, nerves, etc.), as described by Thomson³.

This differentiation takes place under conditions allowing the isolation of different types of tissue so that pancreatic beta cells can be recovered and implanted into the patient. These cells will be syngeneic with the recipient, thus eliminating the problem of rejection.

• The result would be restoration of the regulated insulin secretion in the diabetic.

This scenario could be applied to other tissues and could also be used for genetic modification. For example, brain cells modified by the genes responsible for the production of dihydroxyphenylalanine (L-Dopa) and dopamine could be obtained for transplantation into the brains of Parkinson's patients. Perhaps neuron grafts could be developed for nerve or brain regeneration. Use of cytokines and other specific factors could produce various tissues such as blood vessels. Such tissues would be immunologically identical with the individual from whom the "fertilizing" nucleus was transferred.

In certain cultures and religions, and particularly Christianity, the fertilized human oocyte is thought of as possessing a soul, thus acquiring all the rights of a human being. According to this view there is no difference between killing an embryo prior to implantation and murdering a newborn infant to utilize its organs.

Other cultures and religions do not consider the early embryo to have all the rights of a human being. Judaism, and also Islam, do not confer human status on an embryo before forty days of gestation have elapsed. According to this view, the above technique of producing graftable tissue would be acceptable. Ethical guidelines accepted by the scientific community permit maintaining cultured embryos for around two weeks, that is, before they form their first nerve cells.

The complexity of the ethical issues involved here is clear and comparable with attitudes towards unneeded, frozen embryos which have been stored during assisted reproduction (IVF). Once pregnancy has been established, what should be done with the extra embryos? The recent controversy in the United Kingdom over the fate of frozen embryos after the five-year waiting period imposed by law demonstrates the diversity of opinions.

Another example would be preimplantation diagnostic testing which involves taking away about half of the embryo (at the stage of 2-3 cells) and ruining it in order to determine the presence or absence of a genetic disease so as to decide whether to implant and give birth to the other half. Here, too, a number of countries permit the technique for therapeutic purposes but other countries prohibit it. It must be noted that the possibility of preserving frozen half-embryos in order to produce tissues for transplantation, should the person born from the other half of the embryo (the twin) need such intervention in the course of his life, has been mentioned since the inception of in-vitro fertilization research by Dr. R. Edwards. Cloning would be more ethical from this point of view since it would be done only as needed in real medical situations rather than in anticipation of possible future needs.

The application of cloning that we consider here would not violate the prohibition against manipulating germ cells because there would be no changes in future generations. If the use of an embryo for such purposes is not to be considered an act of murder, the technique could perhaps be acceptable as a method of producing tissues for grafts and transplants.

Despite the attractiveness of this technique, we should not underestimate the dangers of neoplastic transformations or other mutations which could result in the course of culturing embryonic tissue. The advantages and dangers inherent in the technique must be carefully studied before applying it to man. Thomson's research on primates will possibly provide the necessary assurances.

In fertile couples where one of the spouses has a severe genetic disorder, cloning the other spouse could be considered for similar reasons.

The objection that this implies manipulating germ cells should prevent its application. However, in this case there is no insertion or deletion of a gene as in therapeutic manipulation of germ cells. It could be argued that the genetic patrimony transmitted to the offspring is unaltered, even having been "tested" in the life of the donor. The question, therefore, is whether a genome derived from a mature, adult cell is really capable of accurately reproducing embryonic development in man and whether mutations might not occur in such a genome. The dangers of polyploidy mentioned in connection with animals require great caution when applying the technique in man.

Further, the same considerations which occur in assisted reproduction, discussed above, can be applied in this case.

Cloning in order to produce a duplicate offspring to replace a deceased child would be a flagrant example of choice motivated by convenience. In addition, culturing the deceased child's cells may be an offense to the dignity of the deceased since it is not being done to save another person's life as is the case in post-mortem organ transplantation. Finally, such a practice would tend to create the impression that cloning transfers psychological and behavioral characteristics although, as studies of identical twins have shown, it is by no means clear to what extent these are genetically controlled. Figures would show that cognitive aptitudes are only about half genetically controlled². Would not physical similarity be unbearable if the cloned child does not have the desired mental characteristics?

Duplicating certain physical characteristics, like sex or size, could be desirable in producing groups of people particularly suited to certain activities (large people for certain sports or as soldiers, small people as astronauts, etc.). The ultimate aberration would be the duplication of individuals for their psychological or intellectual characteristics, assuming that genetics determines these characteristics more than education and environment.

The second is actual procreation as a means of treating sterility or guaranteeing the absence of homozygous genetic disorders in couples at risk. In these cases, the technique of assisted reproduction by cloning would be of interest in overcoming the religious objections to extramarital gamete donation.

The implementation of the technique would therefore have to respond to individual need without being arbitrary or based on mere convenience. This would eliminate non-therapeutic procedures. The dignity of the person or couple under care as well as that of the offspring would have to be respected. Before implementing the technique, it would therefore be necessary to be certain that the potential cloned offspring would be genetically and phenotypically healthy. Much further research is needed on primates to provide such safeguards.

Cloning groups of humans in order to obtain socially desirable genetic characteristics should be completely prohibited. Not only is this a violation of the individual's liberty and dignity, it is also a violation of the surrogate mother's rights. Reproduction by cloning implies that every clone has a biological mother who bore the child. This also makes unthinkable production of children by "industrial" cloning and should dissipate the fears of "baby factories."

Is cloning unnatural? Reproduction by parthenogenesis and propagation by cuttings is well known in the vegetable kingdom, microorganisms, plants, and insects. Rabbi Menachem ha-Meiri, a fourteenth-century commentator on the Talmud, relates (on Sanhedrin 67b) that reproduction without sex is part of nature. Cloning is therefore not a human innovation, rather it exists in nature and has been performed in the laboratory since the first half of this century. Jean Rostand has expressed enthusiasm about his experiments with sea urchins and frogs and since 1956 has been predicting "solitary reproduction in man."⁵

Asexual reproduction in man poses a provocative moral question. Can we imagine a world where instead of having fathers and mothers children will have older twin brothers or mothers who are also their older twin sisters? Can we imagine a world populated only by women, men having lost their biological raison d'etre? Surely the response is not evident.

If cloning remains strictly limited to individual therapeutic applications, society could, without abandoning its values, accept it as another modality of procreation. If, on the other hand, asexual reproduction by cloning becomes a fad, or even worse, an imposed norm for eugenic purposes, dehumanization will surely result. Sexuality is a cultural value in itself. But it is also a biological value, if we are to judge by the success of those species which reproduce sexually. Evolution depends on the genetic mixing which occurs during sexual reproduction. Such mixing is probably also necessary to maintain the evolved state of a species. Cumulative errors in a genome which would perpetuate itself for several generations would in all probability be disastrous. We cannot even determine whether the genome of an adult cell carries errors or physical alterations in its DNA which will come to light in the course of the clone's life.

The multiplicity of individual human genomes is a source of richness for mankind, but we grasp only poorly the function of this diversity in the evident unity of mankind. The analogy of the diversity of cultures, where every culture constitutes a part of the anthropological definition of Homo sapiens, can perhaps help in understanding the idea of diversity within the unity of a species. Cloning of one or more human genomes would necessarily involve an arbitrary and restrictive choice which, if it becomes the social norm, would be dehumanizing. Aldous Huxley's Best of All Possible Worlds eloquently portrays the dangers of controlled reproduction of alphas, betas, and gammas. Religions express the responsibility and dignity of the individual because our species cannot exist unless the individual is respected. So it is with the human genome: no individual is genetically perfect or genetically deficient. We must consider the complexity and originality of each individual⁶ . Mass production by cloning of one or several human genomes would run counter to this fundamental genetic morality.

If viewed as a part of a social order, rather than as a therapeutic approach for individuals, cloning is immoral because it implies genetic determinism. As with any eugenic measure, cloning neglects the impact of education and the transmission of knowledge and traditions in the formation of the individual and society. Cloning creates the illusion that everything is genetically determined, which is a false, pseudoscientific premise as already seen in animal cloning since cloned animals do not exhibit phenotypic identity. A fortiori, studies of identical human twins have shown the influence of the environment which impacts almost as much as behavioral genetics on individual psychology. Groups of cloned children will not be uniform because they will necessarily have different biological mothers. Their education and feelings will not be identical. However, the mere physical resemblance, if widespread (whereas twins are exceptional), could be disturbing for society. This is why it would be reprehensible to promote in public the myth of cloning as a means of replicating copies of an "ideal" genome: this is an oversimplification which offends the intelligence of geneticists who are often the first to see the limits of genetic influence in man.

Nevertheless, it would be wrong to stop scientific research on this new method of reproduction. Several nations are already considering legislation to prohibit all research leading to human cloning. It is the responsibility of national and international ethics committees to define the modalities in which such research can be pursued in accord with the principles of medical ethics and the preservation of personal dignity. Depriving humanity of a penetrating knowledge of all potentialities of the living would be counterproductive. This argument was already evoked in the debate on germ-cell genetic manipulation. Assuming that scientific research will eventually lead to a safe method of eradicating certain genetic diseases, including certain cancers, would it not be licit to at least consider genetic manipulations, cloning, or any other method which would allow such "genetic surgery"? The Human Genome Project promises to provide complete knowledge regarding human genetics. But before such complete knowledge is acquired, it does not seem possible to evaluate the risks and benefits of germ line genetic manipulation. Based on these considerations, it seems wise to adopt a moratorium on germ line genetic manipulation in humans but not an a priori prohibition. The ethical debate must be continuously renewed for, as Rostand said in the name of Canon Tiberghien:⁷ "Moralists will possibly have to express their views on these questions. But, pity on the world if consulted they cannot agree." Genesis teaches the same lesson in the episode of the tower of Babel: in its commentary, the Zohar⁸ attributes the human failure to the incapability of the builders to understand each other's language and adds that only with united hearts and minds will mankind succeed in its endeavors. Scientists, politicians, religious leaders and philosophers must learn to speak the same language and understand each other. The ethical principles inherited from our religious tradition place man as a partner in God's creation, and from there derives man's responsibility in science and technology. Mastering human genetics is a great endeavor of our time. The ethical principles which must guide us are:

1. Genetics should remain in the realm of medicine, aimed at therapy of suffering individuals.
2. Genetic decisions should be made by individuals after proper counseling and should never be imposed by society.
3. Individual needs being different, decisions should be made case by case, with respect for the dignity and rights of every member of the human family.

1. Cloning should be considered an example of germ line cell genetic manipulation and as such should fall under the current accepted moratorium. This moratorium is all the more necessary because the technique is still in its early stages of development.
2. In the future, some exceptions may be authorized to permit cloning for specifically defined therapeutic purposes pursuant to freely given informed consent by the mother or by the couple which opts for cloning as a method of treating sterility or preventing serious genetic disease while, for example, eliminating the need of an extramarital gamete donor.
3. Cloning should not be permitted for arbitrary, nontherapeutic purposes. It is essential that the dignity of the mother, of the genome donor and of the offspring be respected.
4. Cloning must never become the social norm for reproduction. It must remain an individual procedure and never be applied to "produce" groups of humans with illusive, predetermined genetic characteristics.

1. Nature 385 (1997): 810-813.
2. Govaerts, I., et al., Hum Reprod 11 (1996): 440-443.
3. Bio Reprod 55 (1996): 254-259.
4. Plomin, R., et al., Behavioral Genetics, Freeman and Co. (New York, 1997).
5. Jean Rostand, Peut-on modifier l'homme? (Gallimard), p. 13.
6. Leclerc et al., Intern J of Bioeth 4 (1993): 2889-92.
7. Ibid., p. 99.
8. Zohar, I, 76b.

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