Department of Obstetrics and Gynaecology, Fertility and Reproductive Medicine Laboratories, Royal Free and University College Medical School, 25 Grafton Way, London WC1E 6DB, UK
Email: gulam.bahadur{at}uclh.org
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Abstract |
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Key words: assisted reproduction/cancer patients/ethics/risks/safety/testicular stem cells
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Scientific background |
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Work in other species and in humans aims to develop this strategy for practical purposes (Schlatt et al., 1999; Brook et al., 2001a
), including applications for cancer patients. It is anticipated that testicular tissue biopsies could be cryopreserved for autologous transfer when the patients are in full remission (Bahadur et al., 2000
). This method could serve as a back-up for routine semen cryopreservation already offered, as it provides the potential for reinitiating spermatogenesis, especially in boys receiving total body irradiation. The efficacy of recolonization of germ cells in rodents (Nagano et al., 1999
) provides hope for sterile men. Recently, mice have been born after the use of frozen immature testicular tissue taken from one set of mice and matured in others, and a rabbit was born after using rabbit testicular tissue that had been matured in host immunodeficient mice. The recipient host mice who had the testicular tissue transplanted into their testes had their own spermatogonial cells destroyed by cancer drugs. This study provides an important impetus for work on human testicular stem cell transplantation (Kanatsu-Shinohara et al., 2003
). In the latest innovations, testicular stem cells have been derived from embryonic stem (ES) cells in various species, leading to newer prospects for male infertility (Toyooka et al., 2003
; Clark et al., 2004
; Hong et al., 2004
; Nayernia et al., 2004
).
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Introduction |
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When working with sensitive reproductive material, it is important to understand the social, legal and ethical ramifications. This is to ensure that scientific and medical progress is made transparent, in tune with and acceptable to society's expectation. As a minimum, we need to express the value of beneficence, maleficence and autonomy concerning respect for self and autonomous choice. In order to relay a sense of public acceptance, we need to be able to either provide answers or be seen to have addressed concerns and problems well before these became a reality. On the whole, these concerns will encompass safety, commercialization, health and disturbance or deviation from normal reproduction. The public will need to be convinced of the appeal of xenotransplantation techniques (Schlatt et al., 1999; Kanatsu-Shinohara et al., 2003
) in research when clinical application is sought. Our scientific world is increasingly under public scrutiny and the public needs to have its share in decision making. Public disquiet covers wide areas of science, including genetically modified (GM) foods, nanotechnology (Glover, 2004
) and man-made pollutants; reproductive technology in humans and agricultural animals has continued to attract significant media reports, including interest in testicular stem cell medicine (Reaney, 2002
). Scientists recently have been described as a high priesthood serving a tutelary god which is science and claiming a comprehensive and exclusive understanding of God's intention (Glover, 2004
). It is therefore important that reproductive technologists retain their sense of proportionality and a perspective of public concerns while progressing with their scientific advances. The field of reproductive medicine remains highly sensitive, with complex legal and ethical issues.
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Ethical issues |
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As for injury, in the context of stem cell transplantation research, if a boy protested at having tissue taken from him, despite parental consent, then there could be scope for the charge of having caused bodily harm. This is something clearly to be avoided by engaging the child in the decision-making process, especially as the procedure to preserve and infuse testicular stem cells cannot currently be justified as essential, even if it is desirable (Bahadur and Ralph, 1999).
There are clearly unacceptable and unethical uses of human tissue or its extracts, and these may include the production of leather, cosmetic products or herbal aphrodisiacs. Perhaps more difficult to evaluate is whether human tissue can be bought and sold, and whether the donor has any rights to or say over the tissue. Practitioners are also known to court the media prematurely in order to report on unfounded or weakly based information, such as recovery of sperm after stem cell transplantation, without distinguishing this from what could be natural recovery. This type of approach can have a profound effect on vulnerable patients, especially in the commercial sector. The taking of testicular stem cells from minors after death is unacceptable as the interest of the patient cannot be justified.. Likewise, the use of previously stored testicular stem cells from minors in posthumous procreation to recreate a lost son is unethical, given that the overriding reason is likely to be parental bereavement. Philosophers find these issues difficult to resolve, and they are discussed in the context of rights and utilitarianism or, more broadly, consequentialism.
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Legal status of stem cells |
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Children and adolescents present a new challenge to our understanding of informed consent; in the case of pre-pubertal subjects, parental or proxy consent may be inevitable. The fiduciary duties of doctors should represent a sufficient safeguard of patients' interests, but the history of reproductive medicine is littered with examples when patients' interests have not come first, such as in the misappropriation of embryos, or embryo freezing programmes disproportionate to embryos used in research.
Some cases in the USA, however, have come close to answering such questions. An individual's interest in protecting his tissue could not be granted concerning a cell line produced from a patient's tissue (Moore v Regents of University of California, 1990). In a case specifically centering on reproductive material, namely a cryopreserved embryo, a bailorbailiff relationship was deemed to have formed, which suggested a proprietary interest (York v Jones, 1989
). This suggestion was criticised in the Davis v Davis, 1992
, where the embryo was seen to be neither property or persons but sui generis.
A recognition of proprietary interests in reproductive material would not be incompatible with UK law as it stands. The fact that an embryo is not a legal person has been reiterated in several cases and reinforced by the Warnock Committee in the report of their enquiry into fertilization and embryology. Although it does not automatically follow that the same principles as apply to the embryo in utero should apply in vitro, it is difficult to imagine courts deciding in favour of the dichotomous legal position which would arise if the embryo in vitro were classified a person. Therefore, if not a person, the embryo risks being classified as a chattel. In addition, it should be recalled that a fetus is not accorded the status of a person. The management and trade of sperm, especially across borders, makes the treatment of it as a chattel more of a likelihood.
Against this background, public feeling is likely to be against classifying the embryo as property, which raises the spectre of commercialization of entities with the potential to become human beings. The special status accorded to embryos appears to be more a public relations exercise than one with any legal substance. It is only a matter of time before the property status of sperm, egg and embryos becomes subject to court application or clarification, especially if inheritance disputes arise.
Although it may be perceived that testicular stem cells will have a somewhat lesser status than embryos, the reality is that they are not different. Testicular stem cells generated from donated embryos may also bring an added double-edged sensitivity and attention, given the level of global attention to ES cells (Toyooka et al., 2003; Clark et al., 2004
; Hong et al., 2004
; Nayernia et al., 2004
).
If the process of testicular stem cell culture finds a use in a novel system of hormone production, for example, the issues of patenting and intellectual property rights will undoubtedly be involved. Interest will be heightened further if therapeutic gene modification occurs at the stem cell level.
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Oncology and pre-pubertal patients, adolescents and adults lacking capacity |
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Normally consent models refer to treatment but, as stated above, the freezing of sperm is preventative and normally requires no surgical intervention. The consent model which appears most appropriate to the needs of early adolescent cancer patients considering the storage of sperm is that covered in the Gillick case (Anonymous, 1985).
Interestingly, in the USA, the concept of assent has been developed. Early adolescents are considered to assent (or, its converse, dissent) when they have sufficient competence to have some appreciation of a procedure, but not enough to give fully informed consent. The age of assent is currently estimated as being 12 (Anonymous, 1977; Sigman and O'Connor, 1991
; Committee on Bioethics, 1995
).
If a patient is unable to produce semen by masturbation, the possibility of preserving testicular tissue arises, and two issues are at stake. Where the patient is pre-pubertal, and therefore the testicular tissue does not contain gametes as defined by the Human Fertilization and Embryology Association (HFEA; haploid sperm only), the legal, practical and ethical considerations are covered by the Children's Act 1989 and the Tissues Act 1961. Under these circumstances, parental consent is essential (Bahadur et al., 2000). Secondly, where in the opinion of the medical practitioner, gametes are present and the patient has reached Tanner Grade 2 maturity, then under the provisions of the UK Human Fertilization and Embryology (HFE) Act, consent must come from the patient.
A family rule model (Foreman, 1999) of consent for early adolescents has been developed. When practitioners seek consent they usually want to perform some action and the subject therefore consents to experiencing an event. Whilst this model does seem appropriate to medical intervention, it should be noted that any coercive influence affecting a decision on testicular stem cell donation and cryopreservation should be avoided; if the patient refuses, then this should be respected.
The basic abilities required to give consent are developed by 2 years of age with an understanding of basic requests and behaviour towards others. By age 7, emotional factors are more important than developmental factors in predicting comprehension of medical procedures, and the use of appropriate techniques can significantly improve younger children's comprehension of them. Children between 6 and 12 can understand, for example, the idea of psychiatric hospitalization. This fits the model age at which UK patients, parents and practitioners think children can make decisions about surgery, and the age of assent. On the other hand, early adolescents are perceived to lack the social independence needed to make a fully autonomous decision, being vulnerable to external pressures and benefiting from firm guidance (Bahadur et al., 2001).
Therefore, whilst not with respect to medical intervention per se, testicular stem cell biopsy, cryopreservation and transplantation in pre-pubertal cancer patients require delicate, sensitive handling. The UK statutory elements should be taken into account if in vitro mature, haploid, sperm cells are to be produced. We also have a duty of care to the patients' relatives and guardians, who should ultimately respect the confidentiality accorded by statute to the patient if he so chooses. If the patient refuses at any stage, then this must be respected.
It might at some time occur that an adult who is normally healthy and has the capacity to consent suddenly develops a serious illness, or is involved in an accident, which results in the loss of capacity to consent. The question of freezing ovarian or testicular tissue may arise at short notice. Although ovarian tissue is unlikely to contain gametes as defined by the UK's HFEA, adult testicular tissue may have such gametes. Strictly in the UK, no gametes can be frozen without informed written consent. However, it is thought that common law principles concerning the removal of gametes from an incapacitated adult should not be changed. If there is doubt about the person's future recovery, about the potential effects of his or her condition and/or treatment on fertility, or removal of gametes is proposed as being in the individual's best interests, the courts should determine the lawfulness of any removal. Where the courts have declared removal to be in a person's best interests, the HFEA should have the power to waive the HFE Act's consent requirements for the duration of the donor's incapacity (Anonymous, 2002). The practical downside of this is that little time is available when such requests have to be made to enable the letter of the law to be followed, and this type of problem was presented in the now well known case of Diane Blood in the UK (Bahadur, 2002
). Around the world where the consent requirements may not exist or be strict, cases need to be looked at individually and, for their own protection, practitioners should follow what they perceive as best possible practice in the interest of the incapacitated.
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Rights |
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In general, a person from whom tissue is removed has no interest in making any claim to the removed tissue. In the celebrated case of Californian John Moore, the courts decided there were no property rights. English law is silent on the issue of whether a person can claim property rights in tissue which has been removed. The Polkinghorne Committee took the view that a woman having an abortion must give express and unconditional consent to the use of aborted fetal tissue.
The HFE Act, 1990 adopted a scheme requiring consent so as to avoid addressing the issue of property and ownership. The traditional view has been that a body is not property and this view will undoubtedly be subject to further debate as new technologies and possibilities arise, especially in cases when tissue contains reproductive stem cells for personal use. It has to be said that consent to removal does not entail an intention to abandon. Still, however, some support for the property approach can be derived from the various statutes in existence. The HFE Act, 1990
considers that the control and disposal of gametes and embryos rests with the donors. It further allows for the transfer of reproductive material between those having a licence to deal with it, or granting an importexport licence.
The statutory provision, S25, of the National Health Service Act 1977 also seems implicitly to adopt a property approach. The section provides that: where the Secretary of State has acquired: (a) supplies of blood...or (b) any parts of human body..., he may arrange to make such supplies or that part available (on such terms, including terms, as charges, as he thinks fit) to any person.... The statutory language, therefore, refers to body parts as things, property or goods. Reconsidering the property status of tissue is a logical extension to according rights.
In France (Parpalaix v CECOS, 1984), the wife of a deceased sperm depositor argued that she had a right to her husband's frozen sperm, which he had deposited before cancer treatment. The court rejected the argument that frozen sperm was property, on the grounds that reproductive material was not inheritable nor an object of commerce. However, the court ruled that the sperm bank must return the frozen sperm to the wife of the depositor, as a result of an understanding between the depositor and sperm bank.
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Property and commerce |
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Perhaps the limitation of greatest concern has to do with commercial dealing in tissue. The HFE Act, 1990 provides that no money or benefit may be given or received in respect of any supply of gametes or embryos unless authorised by directions. Individual donors of gametes may be paid £15 plus reasonable expenses. The Recommendation on Human Tissue Banking of the Council of Europe's Directing Committee on public health [Recommendation No R(94)1] specifically recommends that activities associated with human tissue should be carried out by non-profit making institutions.
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Patents |
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The European Patent Office (EPO) has granted patents relating to inventions covering the use of processes from human tissue. These have included the production from human tissue of cell lines, e.g. a human lymphoblastic cell line, and a human hepatocyte culture process; human cell-derived protein products (e.g. interferon); and DNA fragments, e.g. genes coding for useful proteins such as the hormone relaxin. A highly purified sample would meet the novelty requirement, as would a glycosylated derivative of the natural form, e.g. the tissue plasminogen activator t-PA, the enzyme active in dissolution of blood clots. The use of relaxin, which relaxes the uterus in childbirth, created opposition in so far as the DNA for relaxin could be obtained from pregnant women, and the use of pregnancy for human profit was judged an offence to human dignity; patenting DNA was considered to be patenting life. The EPO rejected this opposition and noted that the original ovarian tissue had been donated during the course of necessary gynaecological operations. This use of donated tissue was no more immoral than using donated blood as a source of life-saving substances, such as blood clotting factors. It held that DNA amounted to a chemical substance rather than life.
It is not clear to what extent the exclusion of patents on grounds of morality may apply. Germ cell modification for germline therapy is perhaps one area, and advances in animal sperm modification to alter progeny is perhaps another area of contention. It is envisaged that patent applications for testicular stem cell technology will follow, especially where gene therapy may be involved, and where male infertility may be reversed (Toyooka et al., 2003; Clark et al., 2004
; Hong et al., 2004
; Nayernia et al., 2004
). Recent advances in a mouse model show that sperm cells can be derived from ES cells which, when injected into oocytes, are capable of restoring the somatic diploid chromosome complement and develop into blastocysts (Geijsen et al., 2004
; Azim Surani, 2004
). The prospect of asexual reproduction becomes possible.
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Health and safety |
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The size of the biopsy or the effect of repeated biopsies need to be assessed in terms of trauma and how this may manifest itself in the health of the testes. Taking a normal biopsy from a child with a very small gonad may border on castration, and whether there are long-term well-being implications and the need for testosterone therapy need to be discussed. There are issues for patients with blood-borne cancers and the manner in which the sample may be used or not used if transplantation of tissue has to be considered. If a disaster were to occur from the use of potentially flawed genetic material, then a wrongful birth action or wrongful life action could follow in some states of the USA. An action for wrongful birth is one brought by parents of a child born with some defect or disease, who allege that the negligence of prenatal health care providers or genetic counsellors deprived them of their ability to make an informed decision about whether to have the child who had a likelihood of being born in an impaired state (Kasama v Magat, 2002). This action is brought by parents to recover damages accruing from having to endure having an impaired child. The only way a person who had taken advantage of the proposed service would be able to sustain this cause of action is if he/she were not properly warned of the risk of passing cancer onto his/her potential child. Therefore, if practitioners properly warn of any risks associated with an individual who had cancer passing it onto his/her offspring, a wrongful birth cause of action should be precluded. A wrongful life cause of action, however, would not necessarily be unavailable. Wrongful life claims, as they would apply to this scenario, would be claims by abnormal or unhealthy children (or the parents on their children's behalf) asserting that but for the practitioner's negligent advice or treatment, the child would not have been born to experience the pain and suffering of living with such an impairment (Hayman v Wilkerson, 1987
).
The very patients' testicular stem cell technology could benefit also present a double-edged dilemma of transmitting to the offspring, for example, a cancer gene or the infertility gene, and the unavoidable application of ICSI. The transmission of the deletion on the Y chromosome too has implications for children born from testicular stem cells (Katagiri et al., 2004). We also need to recognize in relation to the indiscriminate use of ICSI that the calcium oscillation patterns which are thought to be genetic regulatory features are completely altered compared with normal IVF, and with less mature sperm (Kurokawa and Fissore, 2003
), and doubts about the long-term health of offspring produced by the procedure are constantly commented upon. Longer term but limited studies on children born from IVF technology appear to show growth retardation, although overall they are apparently fine (Koivurova et al., 2003
; Ludwig, 2004
). For patients with Sertoli cell-only syndrome or testicular cancer who could benefit from testicular stem cell technology, there may be specific observations which need to be considered. In most tubules devoid of germinal cells or lacking spermatocytes and spermatids, the Sertoli cells' nuclei showed an increase in histone H4 acetylation. A similar observation was made in the peritumoral seminiferous tubules of testicular tumour tissue that lacked germinal cells, with carcinoma in situ (CIS) cells being hypoacetylated. The global hyperacetylation of elongating spermatids during spermatogenesis could be part of an intercellular signalling pathway involving Sertoli cells and germinal cells, which could be disturbed in cases of severe spermatogenesis impairment, as well as in tubes surrounding germ cells in testicular tumours (Faure et al., 2003
).
We need to recognize that the testicular stem cells need to mature to at least the late stage haploid spermatids for ICSI to take place. Maturing the sample by orthoptic transplantation or germ cell infusion seems reasonable, and in animal models shows promise. However, such a strategy for blood-borne cancer and testicular cancer patients must be avoided, even if there are biochemical or mechanical ways of flushing out such tumour cells, as the flushing may not always be efficient. The effects of an unusual reverse re-population mechanism of germ cells into the existing testes need to be noted, as well as any long-term effects this may pose to the health of the testes. Reaction to transplantation on a non-reproductive site, such as an arm in humans, for reproductive purpose, has been mixed. With ovarian tissue, the logistics of additional internal surgery and intrusive follicle aspiration seem a practical reason, but this reasoning cannot be evenly applied to testicular germ cells. Overall, the idea of unusual transplantation sites seems to be met publicly with caution, and the effects of altering the pertinent long-term developmental genetic and biochemical switches in an unnatural biological environment seem to be ignored. Strong concerns and reservations have been expressed by the public and scientists on xenotransplantation and xenomaturation per se, and in particular the possibility of releasing a new virus or bacterium into the environment. The clinical application of producing human gametes by xenotransplantation or xenomaturation has added concerns in so far as genetic contamination or mismatches may occur, and how these may manifest in the offspring. However, research application of both these techniques, xenotransplantation and xenomaturation, ought to be allowed in a controlled environment as interesting, safe and effective developments may one day arise.
The other approach is to in vitro mature the testicular stem cells; unlike mature sperm, these cells undergo meiosis, thereby maintaining genetic diversity in the main germline. Likewise, germ cells have more potential to be altered by different maturation processes, and disruption of methylation patterns could have possible long-term health implications for the offspring, in particular in relation to genomic imprinting diseases (Clayton-Smith, 2003). Consideration of methylation patterns also applies to isolated germ cells (Aslam et al., 2000
), as any protective cells are removed thereby making the cells more prone to DNA fragmentation or chemical changes by external agents. Furthermore, the dialogue between the germ cells and Sertoli cells seems relevant (Jegou et al., 1992
). Paternal DNA integrity also appears to be important in development of the human embryo (Tesarik et al., 2004
). In this sense, it is worth noting that human testicular germ cell infusion has already been reported (Brook et al., 2001b
) with dye solution via the rete testes. Any recovery of spermatogenesis would be difficult to distinguish from normal recovery, which occurs in a number of cancer patients.
The storage of tissue, including gonadal tissue, comes under the Medical Devices Agency set up so as to ensure the safety of tissue storage and use. In the UK, it has just been announced that a new Regulatory Authority for Fertility and Tissue is to replace the HFEA and the Tissue Authority, highlighting the increasing importance of tissue (Anonymous, 2004d). Concerns are understandable, given that the donated tissue is for heterotopic transplantation and hence pharmaceutical grade tissue is required. Gonadal tissue and germ cells are likely to be used for orthotopic transplantation. There is a need to screen patients for hepatitis B, hepatitis C and human immunodeficiency virus (HIV), so that mixed storage of samples does not cause cross-contamination. Nitrogen vapour-only freezing does not give added reassurance as vapours circulate carrying any airborne pathogens. The use of automated alarms and fillers, too, has proven to offer false reassurances, and banks have gone dry due to the malfunction of complicated structures. It is important that banks are physically maintained and checked in order to avoid a false sense of security.
The Health and Safety of Work Act 1974 imposes important duties on employers with regards to health and safety. The Control of Substances Hazardous to Health (COSHH) Regulations 1994 relate to exposure of employees and their environment to toxic substances. Records and auditing of samples along with good laboratory practice and accreditation collectively contribute towards staff and patient welfare. More transparency is expected with the Freedom of Information Act. In cases of unproven technologies, it is prudent to draw up contracts which recognize the limits of the application of such reproductive germ cells for the purpose of procreation. These wider issues are equally important in ensuring standards are maintained in any testicular stem cell work.
Most recent developments in Western Europe relate to EU Directives on Tissue Banking (Anonymous, 2004c) with well meaning standards, but which most clinics in the UK are currently unlikely to attain without very significant laboratory and staffing investment. The EU commission has about 312 million Euro to deal with this tissue issue, and one can imagine the European clinics will need to match at least that sort of expenditure to fulfil their demands. One has to bear in mind that cryopreserved sperm has been used for nearly three decades and with overall satisfaction. The standards currently required for tissue appear disproportionate. It is akin to saying that if this option was the last possible option for a patient to preserve his fertility then this should not occur as the facilities are not up to scratch. From the welfare of the child consideration, this apparently translates as, his or her safety is so important that it is better not to be born. There is no basis for such a rash decision and it would appear that in the UK, no clinic has gained an ovarian or testicular tissue licence, to date. It is important that this option is made available to patients as advances seem promising. New laws cannot be applied retrospectively to already stored tissue and provisions have to be made for its use. It is important for EU politicians to understand that a pragmatic balance needs to be struck to enable laboratories and clinics to function normally, and be able offer the possibility to keep the fertility options for patients open. Clinics and laboratories are already mindful of litigations and hurt to patients. There is an increasing danger of over-regulation, where practitioners and reproductive tissue are increasingly separated by excessive paperwork and bureaucracy, notwithstanding reduced patient choice and autonomy. It is especially important that the EU commission take heed of this message.
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Practical aspects |
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When it comes to the use of such material, the transition from research phase to clinical application is always going to reveal difficult dilemmas. These may, for example, include: when do we know it is safe to use it for procreation and how many cases should be carried out before the technology can be declared safe for routine use? It would be prudent to avoid the use of dyes in cell infusions, which are inevitably carcinogenic. The various safety views and concerns need to be relayed to patients if litigation is to be avoided in future. It would always be best to consult the relevant national or professional bodies for up to date advice and guidance, and to voice local hospital and ethics committee's views. All risks, no matter how trivial or hypothetical, need to be explained for ethical and legal reasons.
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Conclusion |
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The issues of consent, rights, the application of the technology, technical preferences, commerce, property status, patents, and health and safety all raise ethical questions which need to be taken into consideration in instances of testicular stem cell transplantation. These ethical dilemmas involve considerations of respect for the patient's autonomy, the need for informed consent, and the health of any offspring resulting from such a procedure. The issue of consent is particularly complicated in the case of pre-pubertal cancer patients, for whom the technology may prove useful.
While there are no property rights in tissue under the current legislation, to treat such tissue as property might serve as a means of guaranteeing respect for patients' rights. It is likely that patent applications for testicular stem cell technology will follow. The field is in the research phase and it would be unethical to make commercial gain from those seeking help from this technology.
The emerging political position and directives in Europe need to take account of the need to enhance patient determination and autonomy in relation to the new technologies in reproductive medicine, whilst providing a pragmatic way forward to enable fertility clinics and laboratories to function. Technological advances are breathtaking and, even if the facilities were allowed freely to patients, no significant demand can be expected to put pressure on routine services. The latest proposal in the UK to merge the HFEA with a tissue authority highlights the growing importance of tissue technology in medicine.
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References |
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Anonymous (1985) Gillick v W. Norfolk and Wisbech ANA, All England Law Reports, 402.
Anonymous (2002) Human Bodies, Human Choices. Department of Health Publications, London. www.doh.gov.uk/tissue.
Anonymous (2004a) Does a foetus have a right to life? www.bbc.co.uk 9th July 2004; Europe rejects fetal rights bid. 8th July 2004.
Anonymous (2004b) Couple's joy at deep freeze baby www.bbc.co.uk 5th June 2004.
Anonymous (2004c) Directive 2004/23/EC of the European Parliament and the Council on Setting Standards of quality and safety for the donation, procurement, testing, processing, preservation, storage and distribution of human tissues and cells. Official Journal of the European Union L 102/48-102/58, 7.4.2004.
Anonymous (2004d) Response to arms length bodies review www.hfea.gov.uk 22nd July 2004.
Aslam I, Fischel S, Moore H, Dowell KK and Thornton S (2000) Fertility preservation of boys undergoing anti-cancer therapy: a review of the existing situation and prospects for the future. Hum Reprod 15, 21542159.
Averbock MR, Brinster CJ and Brinster RL (1996) Reconstitution of spermatogenesis from frozen spermatogonial stem cells. Nature Med 2, 693696.[ISI][Medline]
Azim Surani M (2004) Stem cells; how to make eggs and sperm. Nature 427, 106107.[CrossRef][ISI][Medline]
Bahadur G (2001) The Human Rights Act (1998) and its impact on human reproductive issues. Hum Reprod 16, 785789.
Bahadur G (2002) Death and conception. Hum Reprod 17, 27692775.
Bahadur G and Hindmarsh P (2000) Age definitions, childhood and adolescent cancers in relation to reproductive issues. Hum Reprod 15, 227.
Bahadur G and Ralph D (1999) Gonadal tissue cryopreservation in boys with paediatric cancers. Hum Reprod 14, 1117.
Bahadur G, Chatterjee R and Ralph D (2000) Testicular tissue cryopreservation in boys. Ethical and legal issues. Hum Reprod 15, 14161420.
Bahadur G, Whelan J, Ralph D and Hindmarsh P (2001) Gaining consent to freeze spermatozoa from adolescents with cancer: legal, ethical and practical aspects. Hum Reprod 16, 188193.
Brinster RL and Zimmerman JW (1994) Spermatogenesis following male germ cell transplantation. Proc Natl Acad Sci USA 91, 1129811302.
Brook PF, Radford JA, Shalet SM et al. (2001a) Isolation of germ cells from human testicular tissue for low temperature storage and autotransplantation. Proc Natl Acad Sci USA 98, 269274.
Brook PF, Radford JA, Shalet SM, Joyce Ad and Gosden RG (2001b) Isolation of germ cells from human testicular tissue for low temperature storage and autotransplantation. Fertil Steril 75, 269274.[CrossRef][ISI][Medline]
Clark AT, Dodner MS, Fox M, Rodriquez RT, Abeyta MJ, Firpo MT and Pera AR (2004) Spontaneous differentiation of germ cells from human embryonic stem cells in vitro. Hum Mol Genet 13, 727739.
Clayton-Smith J (2003) Genomic imprinting as a cause of disease. Br Med J 327, 11211122.
Committee on Bioethics (1995) Informed consent, parental permission, and assent in pediatric practice. Pediatrics 95, 314317.[Abstract]
Davis v Davis (1992) 842 SW 2d 588 (Tenn Sup Ct).
Deansley R (1954) Immature rat ovaries grafted after freezing and thawing. J Endocinol 11, 197201.[ISI]
Dworkin G (1991) Taking Rights Seriously. Gerald Duckworth & Co. Ltd, London.
Faure AK, Pivot-Pajot C, Kerjean A et al. (2003) Misregulation of histone acetylation in Sertoli cell-only syndrome and testicular cancer. Mol Hum Reprod 9, 757763.
Foreman DM (1999) The family rule: a framework for obtaining ethical consent for medical interventions from children. J Med Ethics 25, 491496.[Abstract]
Geijsen N, Horoschak M, Kim K, Gribnau J, Eggan K and Daley GQ (2004) Derivation of embryonic germ cells and male gametes from embryonic stem cells. Nature 427, 148154.[CrossRef][ISI][Medline]
Glover S (2004) Charles is right: scientists don't know everything. Daily Mail, Tuesday, July 13th 2004.
Hayman v Wilkerson (1987) 535 A.2d 880, 883 (D.C. 1987).
HFE Act (1990) Chapter 37. The Stationary Office, London.
Hong Y, Liu T, Zhao H, Xu H, Wang W, Liu R, Chen T, Deng J and Gui J (2004) Establishment of a normal medakafish spermatogonial cell line capable of sperm production in vitro. Proc Natl Acad Sci USA 101, 80118016.
Horne G, Atkinson AD, Pease EHE, Logue JP, Brison DR and Lieberman BA (2004) Live birth with sperm cryopreserved for 21 years prior to cancer treatment: case report. Hum Reprod 19, 14481449.
Jegou B, Syed V, Sourdaine P, Byers S, Gerard N, de la Calle JV, Pineau C, Garnier DH and Bauche F (1992) The dialogue between late spermatids and Sertoli cells in vertebrates: a century of research. In Nieschlag E and Habenicht U-F (eds). Spermatogenesis, Fertilisation Contraception. Molecular, Cellular and Endocrine Events in Male Reproduction, 4. Schering Foundation Workshop, Springer Verlag, pp. 5795.
Kanatsu-Shinohara M, Ogonuki N, Inoue K, Ogura A, Toyokuni S and Shinohara T (2003) Restoration of fertility in infertile mice by transplantation of cryopreserved male germline stem cells. Hum Reprod 18, 26602667.
Kasama v Magat (2002) 792 A.2d 1102, 1116-19 (Md.2002).
Katagiri Y, Neri QV, Takeuchi T, Schlegel PN, Megid WA, Kent-First M, Rosenwaks Z and Palermo GD (2004) Y chromosome assessment and its implications for the development of ICSI children. RBM Online 8, 307318.[Medline]
Koivurova S, Hartikainen A-L, Sovio U, Hemminki E and Jarvelin M-R (2003) Growth, psychomotor development and morbidity up to 3 years of age in children born after IVF. Hum Reprod 18, 23282336.
Kurokawa M and Fissore RA (2003) ICSI generated mouse zygotes exhibit altered calcium oscillations, inositol 1,4,5-triphosphate receptor-1 down regulation, and embryo development. Mol Hum Reprod 9, 523533.
Ludwig M (2004) Development of children born after IVF and ICSI. RBM Online 9, 1012.[Medline]
Moore v Regents of University of California (1990) 793 P 2d 479.
Nagano M, Averbock MR and Brinster RL (1999) Pattern and kinetics of mouse donor spermatogonial stem cell colonisation in recipient testes. Biol Reprod 60, 14291436.
Nayernia K, Li M, Jaroszynski L, Khusainov R, Wulf G, Schwandt I, Korabiowska M, Michelmann HW, Meinhardt A and Engel W (2004) Stem cell based therapeutical approach of male infertility by teratocarcinoma derived germ cells. Hum Mol Genet 13, 14511460.
Ogawa T, Dobrinski I, Averbock MR and Brinster RL (2000) Transplantation of male germ line stem cells restores fertility in infertile mice. Nature Med 6, 2934.[CrossRef][ISI][Medline]
Parpalaix v CECOS Gaz.Pal (1984) 2e sem.jur.560.
Parrott DVM (1960) The fertility of mice with orthotopic ovarian grafts derived from frozen tissue. J Reprod Fertil 1, 230241.[ISI]
Reaney P (2002) Young cancer patients could save sperm samples. www.story.news.yahoo.com, 29th, 2002.
Schlatt S, Rosiepen G, Weinbauer GF et al. (1999) Germ cell transfer into rat, bovine, monkey and human testes. Hum Reprod 14, 144150.
Scott G (1998) Making Ethical Choices: Resolving Ethical Dilemmas. Paragon House.
Sigman G and O'Connor C (1991) Exploration for physicians of the mature minor doctrine. J Pediatr 119, 520525.[ISI][Medline]
Toyooka Y, Tsunekawa N, Akasu R and Noce T (2003) Embryonic stem cells can form germ cells in vitro. Proc Natl Acad Sci USA 100, 1145711462.
Tesarik J, Greco E and Mendoza C (2004) Late, but not early, paternal effect on human embryo development is related to sperm DNA fragmentation. Hum Reprod 19, 611615.
Tissue Act (1961) The Stationary Office, London.
Wright PK (2004) Biopsy specimen should be legally defined as donations. Br Med J 328, 642.
York v Jones (1989) 717 F Suppl 421 (EDVa).