“Stem cells: what future for therapy?
Scientific aspects and bioethical problems”.
A summary report.
Maciej Bazela


From 14th to 16th September 2006 the Pontifical Augustinianum Institute in Rome hosted an international congress: “Stem cells: what future for therapy? Scientific aspects and bioethical problems”. The event was organized by the World Federation of Catholic Medical Associations (FIAMC)  and the Pontifical Academy for Life .
As stated by professor Gian Luigi Gigli- the out-going president of FIAMC- the main reason for the congress was to present honest, transparent and up-to-date scientific data on the research and clinical applications of adult stem cells, since there is too much partial and misleading information in the media that favors research on embryonic stem cells over adult stem cells. In addition, Gigli underlined that the Catholic physicians are deeply aware that stem cells hold great promise for many new treatments for those suffering from chronic degenerative diseases all over the world. They hope to one day provide their patients with the innovative and effective treatments that stem cell research seems to promise. At the same time, however, many doctors do not accept solutions that rely on embryonic stem cells, for such research not only provokes serious moral dilemmas, but the conference proposes are even scientifically unsound in light of the ultimate results. Similarly, the president elect of FIAMC, Jose Maria Simon de Castellvi, categorically rejected the use of embryonic stem cells, because from the Catholic point of view it would mean ‘eating from the tree of knowledge’. He also said that the congress should serve not only to share knowledge and learn, but also to meditate on the mystery of life which we still know so little about. Finally, bishop Elio Sgreccia, the head of the Pontifical Academy for Life, underlined in his opening remarks that ethics is the best ally of scientific research, for it always defends human dignity. Therefore, it protects both practitioners and their patients from potential abuses and the scientific instrumentalization that results from the pressure of vested interests and the expectation of large profits. Moreover, he informed those present that the Pontifical Academy for Life plans to hold a permanent round table to facilitate sincere dialogue among philosophers, theologians, scientists and medical doctors, to identify promising trends for further scientific research on stem cells and outline the necessary ethical conditions.
The congress was divided into three major sessions. The first was dedicated to some general aspects including an overview of the stem-cell history, the biology and physiology of stem cells, explanation of differences between embryonic and non-embryonic stem cells, and finally the economic and political implications of stem-cell research. The second session, which was the longest of the three, addressed the clinical application of adult stem cells in various fields of medical specialization. The third session focused on some alternative proposals, namely altered nuclear transfer (ANT) and the use of human parthenotes. The last session however concentrated on the anthropological and the ethical aspects of the research and therapeutic use of stem cells. The main sessions were intertwined with free communication-sequences of short presentation of particular research projects and case studies that were carried out in different laboratories and research institutes. The conference was enriched by a poster session which consisted of fifteen independent panels on which various institutions (universities, hospitals, research centers and foundations) presented their respective academic, clinical, educational and social projects. Altogether, there were nearly 30 invited speakers and 350 registered participants who took part in the congress.

1st Session: General aspects.

    In the first speech of the conference, prof. D.A Prentice from Georgetown University (USA) pointed out that the existence of stem cells had been scientifically confirmed in the mid-20th century . Nevertheless, the very first studies on the concept of stem cells can be traced back to the beginning of the last century, chiefly to the works of prof. Maximow in the year 1909. Initial experimental studies with embryonic stem cells emerged during laboratory works with teratocarcinomas in the 1950s. The first successfully grown culture of embryonic stem cells ever (mouse embryonic cells) was obtained in 1981, while human culture of embryonic stem cells was grown in the laboratory for the first time in 1998. Yet already in 1945 all major features of adult stem cells were identified. In reference to the embryonic stem cells however we had to wait until 1964 when their major characteristics were adequately described. Prof. Prentice pointed out that there has not yet been a single successful clinical application of embryonic stem cells. In contrast, adult stem cells have been used in bone marrow transplants since the 1960s and in cord blood transplants since 1980s.
    Prof. Silburn from Brisbane University (Australia) offered an impressively lucid comparative analysis of the therapeutic utility of embryonic and non-embryonic stem cells, in particular with reference to the generation of patient-specific stem cells . The generation of patient-specific stem cells is the major thrust of biomedical research today, since these cells are essential to enhancing pharmaceutical treatment, cellular transplantation and regenerative strategies. Development of case-specific stem cells can also help us to understand diverse disease phenotypes. The presentation claimed that adult stem cells are far and away more adequate for the above-mentioned goal than embryonic stem cells. The former do not present major scientific problems in terms of cell genotypic and phenotypic stability, renewability, transplant integration and avoidance of immune rejection. It is much easier to derive several specific cell lines in large numbers from adult stem-cells than from embryonic cells. Embryonic stem-cells are usually used to derive only one specific type of cells which is insufficient for treatment of many complex diseases like Parkinson or Alzheimer which require simultaneous transplantation of many different types of cells. Besides, specific cells derived from adult stem cells are known for easily engaging in cell-to-cell interactions which is crucial for the recovery of damaged organs. Eventually, their DNA is incomparably more stable and they are far less likely to be tumorgenic.
    In the third and last speech of the first session, the vice-president of the International Bioethical Committee of UNESCO spoke about economic and political aspects of stem cell research . He accentuated the shortage of public financing coupled with the lack of coherent governmental strategies jeopardize the independent and transparent character of such research, since the sector is contingent on pharmaceutical houses, private laboratories and individual donors- each one with its vested interests. What obscures transparency and accountability of stem cell research even more is the bio-ethical legislative gridlock among many members of the EU-25 and the EU altogether which is due to unbridgeable ideological gaps and moral non-cognitivism. The overall condition of European bio-ethical legislation is unsettled. One dilemma for instance is how to match the United Nations’ pronouncement regarding the inviolable character of human life with national laws that allow research on embryonic stem cells for therapeutic purpose, embryo cloning and cryopreservation. The lack of agreement on the concept of person as well as the beginning and the end of human life surface as key elements of this legislative turmoil.

2nd Session: Clinical application of stem cells.

    First and foremost, this session revealed a paradoxical discrepancy between biomedical research on stem cells and their clinical application.  Specifically, scientists that carry out biomedical research in laboratories rely in 80-90% of cases on embryonic stem cells. However, medical doctors who use stem cells for therapeutic purposes depend to the same extent on adult stem cells. There are over 70 diseases that can be treated with cord-blood stem cell transplantation, no existing therapy uses embryonic stem cells. Secondly, the session displayed a broad array of successful clinical applications of adult stem cells in such fields as cardiology, neurology, regenerative medicine, genetic disease and pre-natal medicine.
    As far as cardiology is concerned, contrary to the prevailing dogma, it has been recently revealed that the myocardium has the ability to repair itself. Several clinical tests have confirmed its regenerative capacity after stem cell transplantation. Damaged myocardium can be renewed due to the transplantation of autologous bone-marrow derived stem cells that are differentiated into cardiac cells; by cytokine-induced repair of apoptotic heart muscle cells; and by the accumulation of cardiac stem cells in the damaged heart. Moreover, the transfer of differentiated, bone-marrow derived stem cells can prevent congestive heart failure that is induced by acute myocardial infarction or ischemic coronary artery disease .
    As well, it has been discovered in recent decades that the central nervous system has inner restorative capacity, so that it is predisposed to stem cell-based regenerative therapies. Not only this, but now we also know that the human brain  contains 0.1% of its own stem cells that give birth to new neurons in the hippocampus area. Moreover, there is some clinical evidence of bone-marrow derived cells developing neuronal and vascular phenotypes that help repair an injured brain. The regenerative therapies to neurological disease include such procedures as: (1)cell therapy approach in which stem cells-derived specific cells are delivered by intravenous or intra-arterial routes; (2) stem cell mobilization in which endogenous stem and progenitor cells are mobilized by cytokines such as G-CSF or chemokines such as SDF-1; (3) trophic and growth factor support such as delivering brain-derived neurotrophic factor (BDNF) or glial-derived neurotrophic factor (GDNF) into the brain  to support injured neurons. While initially it was thought that the best regenerative results could be obtained through direct transplantation of differentiated cells into the central nerve system, now however the preferred approach is to inject such cells into the cardiovascular system so that they actively seek out damaged neurons. We also know that the stem cells-based neurological therapies require the development of many specific cell populations, since neurological disease not only damages many different parts of the nervous system, but also other systems. For instance, Parkinson’s disease degenerates dopaminergic neurons in the substantia nigra, as well as other brainstem and spinal cord regions. In strokes however, stem cells therapies need to repair both vessels and neurons. In fact, providing support to blood vessels is absolutely essential in therapies for stroke patients. Angiogenesis and neurogenesis are coupled in the brain. Therefore, stem cell-therapies have to be mutually supportive for neurons and blood vessels . Further, a group of Portuguese and American doctors presented positive results of their clinical studies in which olfactory mucosa-derived autograft stem cells were transplanted into the injured spinal cord for neural repair .
     Stem cells transplants can also find applications in regenerative medicine. Practitioners from the Imperial College in London use adult stem cells therapies to cure degenerative disorders, in particular liver disease, when organ transplantation is inappropriate or there is no donor. During laboratory studies English researchers identified a CD34+ subpopulation of adult stem cells from haematopoietic tissue, but with a morphology typical of primitive stem cells. The CD34+ cells were infused into five selected patients with liver degeneration via the portal vein and hepatic artery. Three of the five patients showed an improvement in serum bilirubin and four out of five in serum albumin. The best two responders had primary sclerosing cholangitis .
    Genetic specialists however focus on the olfactory mucosa- a small patch of nerve tissue in the nose which contains stem cells and neural progenitor cells and continuously regenerates the olfactory sensory neurons. Stem cells of the olfactory mucosa are multipotent and can be obtained from people of every age via biopsy through external naris. This type of stem cells has very particular characteristics.  Olfactory stem cells can regenerate both neural and non-neural cells. They can differentiate into a wide array of different cell types such as neurons, glia, liver, kidney, heart, skeletal muscle and fat cells, which makes them remarkably useful for the treatment of genetic and degenerative disease. Olfactory stem cells can be maintained in vitro for many generations. They are self-renewing and fast-multiplying. They can be stored frozen and recovered without loss of multipotency. On-going clinical trials show that transplantation of autologus olfactory ensheathing stem cells into the human spinal cord is safe and can bring positive results in correcting genetic defects and the treatment of genetic disease .
    Eventually, a group of Italian doctors presented some results of their on-going laboratory tests on mice and sheep that target the injection of stem cells in utero via intracelomic route as a safe and efficient method for regenerative therapies in prenatal life, in particular to support the low competence of the fetal immune system .

3rd Session: Alternative proposals.

    This session addressed potential alternative methods of obtaining pluripotent embryo-like stem cells without the destruction of human embryos. One way of doing this is via Altered Nuclear Transfer (ANT). ANT is a laboratory method that alters the DNA of mature, somatic cell and/or the cytoplasm of an oocyte. When the somatic nucleus is transferred into an enucleated oocyte, it does not form a zygote, but rather an amorphous group of stem cells. The question is whether there is a method to assure with certainty that the final product of ANT is a non-embryo, rather than a damaged or defective embryo.  It was prof. Condic from Salt Lake City University who in her speech tried to lay out such criteria. Theoretically speaking, what unequivocally distinguishes an embryo from a non-embryo is the capacity of global organization. Non-organisms do not exhibit global self-organization nor self-coordination. Although they can have local organization- development of certain organs and various cell types, they do not develop as an organized and integrated holistic structure. They do not form an organism. In other words, according to prof. Condic, a necessary and sufficient condition for an entity to be considered an embryo is that it must possess the capacity of global coordination of parts for the sake of the entity as a whole. Practically speaking, the use of ANT would require a scientific criterium to identify how much self-organization is enough to declare an entity an embryo or a non-embryo. Prof. Condic states that the first globally coordinated event in human development is the segregation of cells into the trophoblast and inner cell mass (ICM) lineages. The latest scientific evidence suggests that the formation of trophoblast and ICM indispensably requires two transcription factors: Cdx2 and Oct3/4. Consequently, the formation of trophoblast and inner cell mass via Cdx2-Oct3/4 mutual cross-repression constitutes- according to prof. Condic- both the earliest act of the embryo and one of the definitive, intrinsic powers of the embryo, such that in the absence of this power, an entity is not and cannot be an embryo. Thus, the formation of trophoblast and ICM is both necessary and sufficient criterion for distinguishing whether ANT has generated an embryo or a non-embryonic entity. Neverthless, prof. Condic underlined that what she said was just a scientific hypothesis to be verified in animal tests and that non-embryo entities created via ANT should be used only for research and not for clinical purposes .
The speaker had to face fierce criticism during question time at the end of the session. Bishop Sgreecia- the head of the Pontifical Academy for Life- who intervened first- expressed his serious doubts about ANT, because it seems to distort the teleological order of human biology, especially in reference to oocytes which as reproductive human cells directly involved in the beginning of human life should be treated with special care and their intrinsically procreative character should not be subject to manipulation.
Another alternative is to derive stem cells from parthenotes which are embryo-like structures that can be obtained from oocytes without fertilization. A group of Italian scientists from Milan carried out laboratory experiments to verify whether human parthenotes could be a source of pluripotent cell lines. Indeed, the laboratory tests showed that cell lines derived from human parthenotes display many characteristics of biparental embryonic stem cells. The ability of these cells to form teratomas is currently being tested by injection into the rear leg muscle of male mice .
Finally, to circumvent ethical difficulties that concern the use of embryonic stem cells, it is possible to generate pluripotent stem cells directly from somatic cells. This procedure requires the identification of factors that would allow us to convert somatic cells back into embryonic cells. Experimental works on this hypothesis are carried by the Institute for Frontier Medical Sciences in Kyoto (Japan).  Scientists involved in this project assume that the same factors which play important roles in the pluripotency maintenance in embryonic stem cells may play a pivotal role in nuclear reprogramming of somatic cells. The strongest candidates for reprogramming factors are Oct3/4, Sox2, Nanog and Fbx15, since all of them are transcription factors responsible for the long-term maintenance of pluripotency in embryonic stem cells. Those somatic cells which have been subject to nuclear reprogramming have so far showed morphology and proliferation similar to embryonic stem cells. Further, when transplanted into mice, they produced teratomas containing various tissues of the three germ layers .

4th Session: Anthropological and ethical aspects.

    Father Carrasco from the University of Valencia put forward general ethical principles on the use of adult stem cells. In his preliminary remarks he underlined that human will to knowledge is motivated by the hunger for knowledge in se, but also by the will to power. When the second prevails, serious ethical dilemmas regarding the meaning of scientific research immediately emerge. Secondly, he stated that human greatness is rooted in the ontological status and special dignity of the human being, rather than in his technological power. Thirdly, he formulated four basic principles that should guide research and clinical application of adult stem cells: (1) Principle of personalism-  man is always subject and never an object or means of scientific research. The human person is always the final goal, not the instrument of research; (2) Principle of prevalence- well-being and integrity of the individual always takes the upper hand over potential benefits for the society as a whole; (3) Principle of consent- anyone who takes part either in laboratory trials or clinical tests ought to give his independent and informed consent; (4) Principle of responsibility and transparence- it refers to the conscience of medical doctors who should remember that their most immediate and thus most important responsibility is to their patients. They should always provide their patient with transparent information and protect them from scientific instrumentalization .
    Father Faggioni- a bioethics professor from the Pontifical Academy for Life- addressed some ethical flashpoints in regard to production and use of embryonic stem cells . He first reminded us that it is by no means morally acceptable to  intentionally destroy human embryos for greater goals that might be good; nor is it  right to produce human embryos for mere therapeutic or scientific reasons even when it does not involve the destruction of such embryos. Moreover, therapeutic cloning of human embryos represents a greater evil than reproductive cloning. Both are morally reprehensible, and yet the latter does not manipulate the intrinsic goal of fertilization, which is to have children. Therapeutic cloning however not only uses embryos as mere means for other scopes, but also separates the act of fertilization from its teleological goal. Therefore, we can say that therapeutic cloning is doubly unethical. He also remarked that it is extremely difficult to set any positive moral standards for the scientific use of embryonic stem cells since there cannot be any “morality of immorality”. Ethical reasoning operating in this morally disordered context has difficulties in “healing the situation”, because it can be easily contaminated by the profoundly immoral character of the practices involved in production and use of embryonic stem cells.
    There is no moral clarity as to what should be done with the thousands of cryconserved embryos that end up without laboratory or clinical use. Nor is their clarity regarding the definition of embryonic death.
    Another ethical dilemma concerns the use of embryonic stem cells legally produced in some countries and then transported into others where it is forbidden. Since the production of these stem cells includes the destruction of human embryos, involvement in their trade or scientific use by “importing” institutions have the characteristics of cooperation in morally evil acts.
Moreover, there are many unsettled issues in reference to the use of human parthenotes as a source of stem cells, altered nuclear transfer (ANT) and nuclear reprogramming of somatic cells. The discussion on the biological and anthropological status of parthenotes is open. Some think that parthenotes are real embryos, because they develop as such. Others however claim that they are not, since they are incapable of growing beyond the first stage of embryonic life. Similarly, in the case of ANT we are not certain whether the biological entity that is produced is so radically different from a human embryo obtained through standard cloning procedure with nuclei transfer, and therefore to be judged a non-embryo. In reference to the reverse genetic reprogramming of somatic cells into stem cells however, we face the question whether it is morally right to set back the evolutionary character of human biology. In other words, it remains to be defined whether it is morally justified to manipulate the intrinsically teleological, linear and one-directional nature of life. Similarly to Father’s Faggioni reasoning, Dr Mauceri- a UN delegate of FIAMC- stated that any manipulation of embryos or their precursors (oocytes) such as nuclear transfer, blastomer isolation or any other technique that diverts or distorts embroy’s or gamete’s teleological order is morally problematic. The embryo should never be altered, because it possesses its proper entelechin; the proper form and goal of existence. The oocyte however should be respected in its integrity due to its ontological, life-giving power . Likewise, prof. Vout pointed out that the most fundamental question to be asked in reference to ANT is whether it in any way constitutes an appropriate use of the human reproductive capacities of oocytes and whether it is morally sound to donate oocytes for non-reproductive purposes at all .

Conclusions

(1)    The majority of speakers exhibited broad agreement that the media coverage of stem cells research is extremely partisan in favor of embryonic stem cells. Even a minor discovery or progress in the research on embryonic stem cells becomes breaking news or a headline on the front page of the most widely read newspapers. At the same time, evident clinical successes with adult stem cells therapies are hardly noticed. This ideological bias bereft of scientific grounding in data nor clinical trials has sinister socio-political implications. It leads to dis-information and the underhanded manipulation of public opinion, diverts potential funds and endowments from research on adult stem cells and encourages politicians to pass laws that legalize and support research on embryonic stem cells with public funding.
(2)    Lecturers expressed unanimous concern that the on-going, stubborn pursuit of  embryonic stem cell research despite its therapeutically disappointing laboratory trials is a lamentable waste of the time, human resources and money which should be diverted to heal other social ills like poverty, malnutrition, HIV/AIDS, etc.
(3)    Adult stem cells that come from umbilical cord blood, bone marrow, post-natal germ cells, the olfactory mucosa and fetal membranes constitute abundant and resourceful material to develop successful therapeutic strategies in many different fields of medicine. Not only this, but adult stem cells also apparently outclass embryonic stem cells in terms of genotypic and phenotypic stability, renewability, transplant integration and avoidance of immune rejection. They are far less likely to give rise to some tumor forms. They are easy to obtain and grow in large cultures, so they guarantee a proficient use of resources.
(4)    It still has not been empirically proven that embryonic stem cells are totipent. They exhibit pluripotency and omnipotency, though, which means that they are exactly as versatile as adult stem cells. To date there has not been a single clinical application of embryonic stem cells, while cord-blood derived stem cells are used to combat more than 65  different diseases.
(5)    Umbilical cord blood remains the largest and most known source of adult stem cells, since there are one hundred million children born a year and cord blood stem cells have been transplanted for 20 years. They have two distinctive advantages over other types of stem cells: the length of telomere and the protected immunological status of the developing neonatal environment which should bring down the total amount of potential mutations in comparison to adult tissues. Additionally, they are characterized by a homogenous, primitive and uncommitted phenotype with high potential for mutli-lineage tissue differentiation . However, there are many new and equally promising sources. For instance, stem cells obtained from the stromal regions of amnion and chorion of fetal placenta exhibit characteristics of mesenchymal stem/progenitor phenotype which together with their immunosuppressive proprieties after culturing- (they are not rejected, so can be transplanted in cases when autologus stem cells are not available)- makes them extremely useful for genetic therapies and tissue engineering . We should not forget either about successful clinical therapies with the olfactory mucosa and bone marrow-derived adult stem cells.

Special audience of His Holiness Benedict XVI .

At the end of the congress the invited speakers and registered participants were received in private audience with the Holly Father at Castel Gandolfo. At the beginning of His speech, the pope expressed His gratefulness to the organizers of the congress for having set up the event, since stem cells is one of the most relevant bioethical issues at present. Afterwards, Benedict XVI put forward a synthetic, Magisterial reflection on the ethics of scientific research and use of stem cells. First of all, he reminded those present that the essence of authentic progress is to endow man to growth as a human person; to improve not only his technological capacities, but most importantly his moral capacity. Consequently, scientific research on adult stem cells should be approved and encouraged as long as it can find a feasible match and positive mutual reinforcement between scientific knowledge, advanced biomedical technologies and the ethical norms that defend human life in every phase of its existence. Therefore, neither compromises nor excuses are acceptable with regards to scientific research that presupposes direct and willed suppression of human beings, in particular human embryos. Regardless of potential therapeutic benefits, this kind of science does not serve the well-being of humankind, because it involves the annihilation of human embryos that have the same dignity as other human individuals, including the researchers themselves. Science that implies destruction of human lives was condemned in the past and will always be condemned in the future, not only because it is far from God’s Light, but also because it is simply not human.  It is hard to imagine then- continued the pontiff- that society can effectively combat crime when at the same time it legally allows crime in the realm of prenatal life.
    Benedict XVI underlined also that the Church used to and still gives his constant support to biomedical research that seeks therapeutic solutions and improvement of the quality of life. However, the Church also recognizes that there is- and has to be- a sacrosanct limit to scientific experiments that we should not surpass. Precisely, individual human life in whatever stage must not be used as a means for the benefit of others. The ethical character of biomedical research is contingent not only on noble and universally valid goals like development of therapeutic solutions and efficient medical remedies, but also on morally acceptable means that bring us to such goals.
Eventually, the pope pointed out that the numerous promising results of research on adult stem cells as well as the great hope and commitment of so many people of good will who work in this field are the best evidence of the validity of the Catholic moral teaching that calls for genuine and full respect of human life from the moment of fertilization. It is evident that science itself awards with satisfactory results those who express such respect in their daily work.
    At the end, His Holiness granted to those present, their co-workers and patients an affectionate apostolic benediction and a promise of special prayer.


I would like to thank Internetowy Portal Bioetechnologiczny.pl ., namely Mr. Tadeusz Pietrucha, Ph.D whose endowment allowed me to pay the registration fee, and thereby take part in the congress.

  1. http://www.fiamc.org

  2. http://www.academiavita.org

  3. DA PRENTICE, Historical development of research on stem cells. (This and all subsequent footnotes refer to the content of particular speeches delivered during the congress).

  4. P. SILBURN, Embryonic and non-embryonic stem cells.

  5. C. HURIET, Stem cells: economic interests and political implications.

 6. B.E. STRAUER – M. BREHM, Therapeutic applications of stem cells in the cardiologic field. (Division of Cardiology, Pneumology and Angiology, Heinrich-Heine University, Dusseldorf, Germany).

  7. D.C. HESS, Stem cells and neurological diseases. (Medical College of Georgia, Augusta, USA, email: dhess@mail.mcg.edu).

  8. C. LIMA – J.P. VITAL – P. ESCADA – H. FERREIRA – C. CAPUCHO – J. PEDUZZI, Possible uses of stem cells in the lesions of the spinal cord. (Hospital de Egas  Moniz, Lisbon, Portugal and Wayne State University, Detroit, USA).

  9. N.A. HABIB – N. LEVICAR - M. PAI – J. NICHOLIS – M. GORDON, Possible use of stem cells in regenerative medicine. (Department of Surgery and Haematology, Imperial College, London, UK).

  10. A. MACKAY-SIM, Stem cells and genetic disease. (Eskitis Institute for Cell and Molecular Therapies, Griffith University, Brisbane, Australia, email: a.mackay-sim@griffith.edu.au).

  11. S. MANCUSO – G. NOIA, Regenerative medicine in prenatal life:  engraftment after in utero stem cell transplantation via intracelomic route.

  12. M.L. CONDIC, Embryonic stem cells without embryos?(Salt Lake City University, USA).

  13. T.A.L. BREVINI - V. TOSETTI – S. ANTONINI – A. PAFFONI – M. CRESTAN – G. RAGNI – F. GANDOLFI, The establishment and characterization of pluripotent cell line from human parthenotes. (Centre for Stem Cell Research, University of Milan, Italy & Infertility Unit, Department of Obstetrics, Gynaecology and Neonatology, Ospedale Maggiore Policlinico, Mangiagalli and Regina Elena, Milan, Italy, email: tiziana.brevini@unimi.it). 

  14. K. TAKAHASHI – S. YAMANAKA, Identification of factors that generate pluripotent stem cells from fibroblast culture. (Department of Stem Cell Biology, Institute for Frontier Medical Sciences, Kyoto University, Japan).

  15. I. CARRASCO, General ethical principles on the use of “adult” stem cells.

 16. M. FAGGIONI, Anthropological-ethical reflections on production and use of “embryonic” stem cells.

  17. J. MAUCERI, Embryology is teleology. (UN Delegate of FIAMC, Cephas Institute, Kingston, NY, USA,  www.cephasinstitute.org, email: drjosephmauceri@msn.com or info@cephasinstitute.org). 

  18. B. VOUT, Ethical and anthropological signifcance of form disabled human embryos or human-animal hybrid embryos as a source of human embryonic stem cells. (John Paul II Institute for the Study of Marriage and Family, Life Office, Catholic Archdiocese of Sydney, Melbourne, Australia, email: brigid.vout@sydney.catholic.org.au).

  19. C.P. MCGUCKING – N. FORRAZ, Potential for access to embryonic-like cells from human umbilical cord blood; C.P. MCGUCKING – M.O. BARADEZ – N. FORRAZ, Cord blood multi-lineage progenitor cell line: an ethical and practical stem cell source for research and development. (Newcastle Centre for Cord Blood, Stem Cell Institute, Medical School, Newcastle upon Tyne, UK, email: c.mcguckin@newcastle.ac.uk or nico.forraz@newcastle.ac.uk).

  20. O. PAROLINI, Fetal membranes from human term placenta: a source of progentior/stem cells. (Centro di Ricerca E.Menni, Fondazione Poliambulanza, Brescia, Italy, email: ornella.parolini@tin.it). The complete text of the pope’s speech can be found in L’Osservatore Romano, Anno CXLVI, N.215 (44.357), Sunday 17th September 2006, p.1.5.