Human-animal combinations for biomedical research

Release of a public Consultation Paper by the BAC

The Bioethics Advisory Committee (BAC) announces the release of a Consultation Paper entitled “Human-Animal Combinations for Research". Human-animal combinations are entities resulting from the mixing of genes, cells or tissue of human origin with those of other species. The Paper discusses the ethical, legal and social issues arising from the creation and use of such entities for research.

The Consultation Paper is part of BAC’s effort to update and consolidate its recommendations for human stem cell research. The BAC considers such research to have considerable potential in the treatment of currently incurable diseases, such as diabetes, Alzheimer’s disease and Parkinson’s disease. While there have been significant advances in stem cell science and technology, research involving human-animal combinations is required for further progress, especially if we are to avoid reliance on increasing donations of human eggs for research.

The terms 'chimera' and 'hybrid' have been used to describe different types of human-animal combinations. Scientifically speaking, a chimera is any animal or human whose body contains cells, tissue or organs from another animal or human. For instance, the introduction of tissue from a human individual into an animal or another human individual would result in the creation of a chimera. A hybrid, on the other hand, is an organism whose cells contain genetic material from two or more different species. An example of a hybrid is a mule, which is created through the fertilisation of a horse’s egg with a donkey’s sperm. Another type of hybrid is the ‘cytoplasmic hybrid embryo’, where the nucleus (genetic material) of a somatic cell is transferred into an egg whose nucleus has been removed. This technique is called somatic cell nuclear transfer (SCNT).

Certain limited kinds of human-animal combinations are useful in stem cell research for several reasons. Some are chimeras created in vitro through the introduction of human stem cells into animal embryos, foetuses or post-natal animals. Using them, scientists are able to:

• test the development potential of human stem cells or their derivatives;

• evaluate the potential usefulness and safety of transplanting human stem cells for clinical treatment; and

• study the possibility of growing human tissues and organs in animals for the purpose of transplantation into humans.

Additionally, scientists have proposed creating cytoplasmic hybrid embryos as this would allow them to:

• study the processes involved in nuclear reprogramming (or how the nucleus of an adult specialised cell can be induced to regain its potential to develop into other types of cells). A recent reported advance in reprogramming adult cells into cells with properties similar to embryonic stem cells complements such research;

• derive disease-specific stem cells for studying specific disease mechanisms and methods of treatment; and

• avoid the use of human eggs, which are a limited and ethically contentious resource.

Research involving human-animal combinations has nevertheless raised several concerns. Some people say that there are health and safety risks pertaining to such research, for example, the risk of bringing about new strains of viruses and bacteria. In addition, there are those who have expressed religious and ethical concerns, which include arguments to the effect that the creation of these combinations is repugnant and amounts to 'playing God'.

One can ask if the concerns are so overwhelming that they would justify a partial or complete prohibition? Or would monitoring such research sufficiently address the concerns? A number of countries such as the UK and Canada have considered the matter and have allowed such research but under legal and regulatory purview. The situation in Singapore has yet to be decided, and the main objective of the Consultation Paper is to invite researchers, professionals, religious bodies, interested organisations and the general public to comment on:

• the creation and use of these human-animal combinations for research;

• the prohibitions, limits and regulatory mechanisms that should apply to such research in Singapore; and

• any other matter related to human-animal combinations for biomedical research.

Professor Lee Eng Hin, Chairman of the Human Embryo and Chimera Working Group, says: “Although the testing of human embryonic stem cells in animals is a relatively new area for biomedical research, human-animal combinations have existed for decades and there are many examples. While many people may not realise this, any individual who received a xenotransplant in the form of a pig’s heart value is by definition, a chimera. Since 1962, nude mice have been used in research to test the properties of human cancer cells. The transgenic mouse with human cancer genes, which was created in the late 1980s, has allowed scientists to study the early development of tumours. These advancements in science have expanded our knowledge regarding human diseases and such knowledge might eventually lead to the development of new medical treatments and cures.”

Professor Lim Pin, Chairman of the BAC, added: “Even though the wide use of human-animal combinations in research underscores the confidence in the benefits that they would bring about, there are certain ethical boundaries to the conduct of such research. For instance, even if possible, it would be ethically unacceptable for scientists to create sub-human creatures with potentially human consciousness. Furthermore, scientists overwhelmingly do want to conduct research in a way that is ethical. The outcome of this public consultation will be useful in giving guidance to the scientific community here.”

The views of the public and interested parties will assist the BAC in formulating recommendations on research involving human-animal combinations. Those interested in providing their views could obtain a copy of the Consultation Paper from the BAC website: www.bioethics-singapore.gov.sg and send their responses by 10 March 2008 to the BAC Secretariat via:

Email: contactus@bioethics-singapore.gov.sg

Post:
The Secretariat
Bioethics Advisory Committee
11 Biopolis Way
#10-12, Helios
Singapore 138667

Members of the public are also invited to:

• participate in an online discussion forum here; and

• attend a public talk on 19 January, 2008, to discuss the issues presented in the Consultation Paper. More information is available here.

For media enquiries, please contact:

Mr Calvin Ho
DID: (65) 6826 6382
calvin_ho@bioethics-singapore.gov.sg

Mr Alvin Chew
DID: (65) 6826 6291
alvin_chew@bioethics-singapore.gov.sg