1 Service de Biologie de la Reproduction SIHCUS-CMCO, 19, rue Louis Pasteur BP120, 67303 Schiltigheim, 2 Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 1, rue Laurent Fries, BP 163, 67404 Illkirch Cedex, C.U. de Strasbourg and 3 Laboratoire Marcel Mérieux, 1 Rue Laborde 69500 BRON, France
Abstract
The French law on bioethics, voted upon in July 1994, is going to be revised. This is the occasion for France to reconsider its position concerning research on human embryos, which is currently prohibited in France, as it is in Germany, Switzerland and Austria. However, such research is authorised in other European countries such as the UK, Spain, Belgium, Italy and The Netherlands. The establishment of human embryonic stem (ES) cells has reopened the debate in France because of their potential in human therapy. Indeed, ES cells, derived from early embryos (56 days old), preserve in vitro a pluripotent character, and they could provide an infinite source of different tissues that could be used in replacement therapy. This consists of ES cells differentiated in vitro into the desired tissues or cell types and grafted into the patient. The use of human ES cells in replacement therapy raises the major problem of graft rejection. One of the proposed solutions would be to carry out a `therapeutic cloning' and to derive ES cells from the embryos obtained in this way. We do consider that, for the moment, the interest of the cloning study lies mainly in the understanding of the mechanisms responsible for reprogramming the nuclei. This research can be performed first on animal models.
France is now thinking to allow human embryo research. We present here the French law proposed on human embryo research. French government is proposing to allow research exclusively on frozen supernumerary embryos, which no longer have any parental or adoption potential. Creation of human embryos for research purposes will still be prohibited. However, allowance of studies on human cloning in order to realise therapeutic cloning is mentioned in the proposal. We think that allowing research in humans on therapeutic cloning is premature and contradicts the prohibition of the creation of human embryos for research.
Key words: embryonic stem cells/ethics/human embryo research/therapeutic cloning
Following the establishment of human embryonic stem (ES) cell, the debate on human embryo research has reopened in France. It is now all the more topical as a French law on bioethics, voted upon in July 1994, is going to be, with more than 3 years delay, revised. This type of research is already authorized in some neighbouring European countries, such as the UK, Spain, Belgium, Italy and The Netherlands. However, it is prohibited, as is currently the case in France, in Germany, Switzerland and Austria (Viville and Nisand, 1997; Viville and Pergament, 1998
). Human embryo research may have a variety of objectives:
(i) Purely fundamental, which is generally badly accepted, although in a great majority of cases progress in clinical application ensues, even if this is not the initial objective.
(ii) The improvement of assisted reproductive technology (ART) and especially of IVF techniques, with a direct benefit for the embryo (e.g. implantation or development) or without any direct benefit, but with a resulting progression for all or a particular group of the couples concerned with IVF (e.g. culture medium, gametes in-vitro maturation or embryo evaluation criteria). A reduction in the number of multiple pregnancies is an evident corollary of this.
(iii) The understanding of embryonic development in the wide sense with the eventual repercussions of the emergence of new therapies. This could involve, for example, the study of the causes of miscarriage, of congenital pathologies and particularly the isolation of ES cells.
ES cells derive from the inner cell mass (ICM) of a blastocyst (56 day old embryo in human). At this stage of development, three cellular types can be distinguished: trophoblastic cells giving rise to the extra-embryonic tissues and two cellular types forming the ICM, which includes the primitive endoderm and the epiblast. The latter gives rise to the three germ layers (ectoderm, mesoderm and endoderm). The injection of ICM cells into blastocysts was first used to demonstrate their ability to participate in embryonic development and form chimeric mice (Gardner, 1968). Later on, it was demonstrated, by Brook and Gardner, that ES cells are derived from the epiblast (Brook and Gardner, 1997
). Their importance lies in the fact that they preserve, in vitro, the inherently pluripotent character of their epiblast origin. Indeed, these cells are capable of infinite self-renewal and they may differentiate in vitro and in vivo into all the somatic tissues. They represent an extremely powerful instrument for fundamental as well as clinical research. Indeed, they allow the study of human embryo development mechanisms, which were inaccessible up to now, and an analysis of cellular differentiation with all the possible implications for the understanding of the phenomenon of oncogenesis. Lastly, they will almost certainly constitute one of the therapeutic tools of the third millennium, although probably not before a decade or more. The possibility of differentiating ES cells in vitro into a given tissue raises the possibility of using them in replacement therapy protocols (Pedersen, 1999
). This consists of grafting the in-vitro differentiated ES cells to replace and/or repair an affected tissue. The most often quoted examples are neurodegenerative diseases, diabetes and heart attacks. Such cells therefore theoretically represent an infinite source of tissues, which may aid the treatment of all pathologies linked to tissue degeneration. In addition, they may be manipulated in vitro and hence represent an excellent vector for gene therapy.
In humans, such cells have recently been described (Thomson et al., 1998; Reubinoff et al., 2000
). The use of human ES cells in replacement therapy raises the major problem of graft rejection. Several solutions can be envisaged. The first is the creation of ES cell banks large enough to meet the demands of patients with different immunological backgrounds. This, combined with the progress in the treatment of graft rejections, seems to us to be the most attainable approach because of the number of frozen embryos that can be used to create a large panel of cell types presenting different histocompatibility complexes. The second solution consists of genetically manipulating an ES cell line to make it less `immunostimulant' and usable for a great variety of individuals. The last solution, which is intellectually the most elegant one but, as it seems to us, ethically and technically the least attainable, would be a `therapeutic cloning' and the derivation of ES cells from the embryos obtained in this way. Indeed, in such cases the ES cells would possess the genome of the patient being treated; therefore, the problem of rejection would not arise. This approach presents some major difficulties, which are linked to the cloning technique itself, which at present is far from being mastered. Furthermore, nothing or very little is known about the nuclear reprogramming mechanisms. It strikes us as a major disadvantage to use, in a clinical situation, a technique when, for the moment at least, so little is known about its underlying phenomena (Solter, 2000
). Finally, in a large number of cases, replacement therapy will be offered to patients suffering from a genetic disease. It seems to us to be unthinkable in such situations to use a pathological genome to generate a clone and to derive ES cells from it. For the moment, the interest of the cloning study mainly lies in the understanding of the mechanisms responsible for reprogramming the nuclei. One of the envisaged repercussions, without going via the nuclei transfer in the ovocytes, is the generation of ES cells from somatic cells. For example, such experiments can be done with mouse embryos. In no case do they justify human cloning. It seems obvious that there is no rush to allow human cloning, irrespective of the goal pursued, whether reproductive or therapeutic. It should be noted that the existence of stem cells in adults, capable also of a large spectrum of differentiation has been demonstrated (Eglitis and Mezey, 1997
; Ferrari et al., 1998
; Bjornson et al., 1999
; Carpenter et al., 1999
; Galli et al., 2000
). This is an important point, since the isolation of stem cells in an adult patient will not raise ethical concerns, since informed consent can be obtained from the patient.
It therefore seems clear that France's position of prohibiting human embryo research is paradoxical and difficult to maintain. This is for several reasons: the scientific necessity of the validation of new IVF techniques; the understanding of embryo development; and lastly and most importantly, the establishment of ES cells. Indeed, it is clear that the research will have considerable clinical and economic repercussions. By refusing human embryo research we put ourselves in a position of scientific, technical and financial dependence upon the countries who have accepted the principle of human embryo research. Such a situation may result in another ethical concern, since it may mean that we are unable to offer certain treatments to patients because research on human embryos has been forbidden.
In his intervention of November 28, 2000 at the Annual meeting of Bioethics, the French Prime Minister proposed to authorize human embryo research. A law proposal was discussed in May 2001 in the Council of Ministers and will be submitted to Parliament at the end of 2001or the beginning of 2002. In his speech, the Prime Minister considered that this research serves `two perspectives': on the one hand, improvement of ART, and on the other hand, research on stem cells. A proposal for a new bioethical law has just been submitted to the State Council and the national Ethical Committee. This proposal represents a radical change in the French position since it envisages not only therapeutic cloning, but also embryonic gene therapy. Spain is the only country going that far; all the other countries having a law or recommendations have strictly forbidden this possibility (Viville and Pergament, 1998). Such manipulations will open up the possibility of germ line transmission of such genetic modification.
Concerning research on human embryos, the proposal stipulates that research should be allowed only on supernumerary embryos without any parental or adoption potential. Furthermore it includes a new notion, reminiscent of the UK situation accepting research up to 14 days of development, which allows research up to the stage of tissue differentiation. The definition of tissue differentiation remains to be determined; is it the blastocyst stage (56 days) where three types of tissues can be distinguished, the trophoblast, the primitive endoderm and the epiblast or is it the gastrulation stage (14 days) when the trilaminar germ disc is formed? If it is the blastocyst stage then the isolation of ES cells will not be allowed. Here again, we are dealing with the question of `what is the definition of an embryo?' Do we have to consider that, at the blastocyst stage, just the epiblast has to be seen as the embryo since the other tissues will not participate to the embryo proper?
Therapeutic cloning, even if not formally mentioned, will not be forbidden. However, the creation of human embryos for research and reproductive cloning would remain strictly forbidden. As we already mentioned, the authorization, even just for cognitive studies, of cloning without therapeutic or reproductive goals, seems to us to be premature and to contradict the prohibition of the creation of human embryos for research. Therapeutic cloning involves the creation of embryos. In another part of the proposal the necessity to evaluate the innocuity of any new ART before its clinical application is mentioned. In such a case the creation of embryos will be tolerated since the wording states, `Embryos constituted for such an evaluation...' So, concerning the creation of embryos for research purposes the project is not clear and we believe that the pragmatic British approach is more appropriate.
This research would to be supervised by a controlling authority (to be created), which would have competence in the fields of human reproduction, embryology and predictive genetics. In 1994 the legislator had the judicious idea of introducing the notion of revising the law every 5 years. This power should be conferred to the new controlling authority as the Prime Minister wished to create it. We find ourselves here in a situation very similar to that of our Anglo-Saxon neighbours. Indeed, in UK the Human Fertilisation and Embryology Authority (HFEA) controls the research activity on human embryos and the Medical Research Council (MRC) may fund this type of research.
Such research will only be possible if no other alternatives exist and if they present a medical finality. This aspect, not allowing research on human embryos if animal models exist, is included in the Spanish law, in a Belgian bill and in the recommendations of the IVF Committee of the Health Council in The Netherlands (Viville and Pergament, 1998). Furthermore, this research should be authorised only to researchers having a well established expertise with animal embryos. The embryo is a unique model, and at this point it has to be mentioned that the embryo is not necessarily a ubiquitous model. In some cases, animal embryos are inappropriate to answer questions aimed at the human embryo, if we take into account specific physiological and metabolic characteristics. Lastly, there is no real warranty concerning the transposition and/or superposition of the results collected from the animal, to the human being.
For those of us committed to scientific and medical progress in this area, it is imperative that this debate, although necessary, should not delay too greatly either the vote on the law or the implementation of any changes.
Acknowledgements
We wish to thank Harriet Thompson and Dr Irwin Davidson for helpful comments on this manuscript. S.V. is supported by funds from the Association Franciaise contre les Myopathies (AFM), the Association Franciaise de Lutte contre la Mucoviscidose (AFLM-VLM), from the Centre National de la Recherche Scientifique (CNRS), the Institut National de la Santé et de la Recherche Médicale (INSERM) and the Hôpital Universitaire de Strasbourg.
Notes
4 To whom correspondence should be addressed. E-mail: viville{at}igbmc.u-strasbg.fr
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