Alex Constantine - June 3, 2008
Dear ATCA Colleagues
[Please note that the views presented by individual contributors are not necessarily representative of the views of ATCA, which is neutral. ATCA conducts collective Socratic dialogue on global opportunities and threats.]
After 10 years of stem cell research, scientists are now facing difficulty with cell therapy from the present human embryonic stem cell experimentation.
The next phase involves human-animal combinations via Chimeras, Hybrids and Cybrids.
1. A Chimera is produced when a human embryo is fused with an animal embryo;
2. An Hybrid is produced when a human female egg is fertilised with animal sperm or vice-versa; and
3. A "Cybrid" is produced when an animal cell's genetic material is removed and replaced with human genetic material.
Some key questions arise:
1. Should human genetic material be fused with animal cells to create clones of hybrids and cybrids for research?
2. Are human body replacement parts which are part human and part animal appropriate?
Whilst this human-animal combination may open up more potential for future cell therapy and cures for serious illnesses like cancer, there are clear asymmetric threats emerging for humanity. At the same time, it is not clear that if we create human-animal combinations as test beds for research into cancer or other deadly diseases, any success in identifying new treatments will necessarily replicate reliably in the context of the human species. We may indeed have found solutions for the artificially created human-animal synthetic species which may completely fail on the classic "human being." Hence defeating the purpose of the entire exercise.
Reflects on the perils of creating human-animal synthetic organisms.
Why is there a rising need for human-animal combinations for biomedical research? Scientists are facing difficulty getting volunteers to donate human donor eggs for cell based research and therapeutic cloning as egg donation is a procedure which poses some risks to a healthy human female's life. The fusion of human genetic material with animal ova is thought to produce cells which behave in a manner identical to human embryos obtained from in vitro fertilisation (IVF). In IVF obtained embryos, the inner cell mass (ICM) of these minute human embryos would normally differentiate to form various organs of the human body. But when the ICM is removed for human therapeutic cloning experiments including embryonic stem cell research, the human embryo must die. This is the major moral and ethical objection of therapeutic cloning in regard to human embryos.
Rabbit-human hybrid embryos
In August 2003, Hui Zhen Sheng of Shanghai Second Medical University, China, announced that rabbit-human 'cybrid' embryos had been created. Researchers fused adult human material with rabbit eggs stripped of their original genetic material and created rabbit-human hybrid embryos which developed to approximately the 100-cell stage, after about four days of development. Moreover, the scientists claimed to derive stem cells from these embryos similar to conventional human embryonic stem cells.
Historic attempts at human-ape
There are well-documented reports that a few scientists in the mid-1920s made serious attempts to create a half-human, half-chimpanzee. One of the Soviet Union's top scientists, Professor Ilya Ivanov, tried to impregnate female chimpanzees with human sperm in Africa in order to create a human-chimpanzee hybrid (a humanzee). experiments were unsuccessful, but at the time many colleagues believed it was probably feasible in the future. The "Humanzee" is becoming possible in the 21st century.
A chimera of either form of hybrid will have both human and animal tissues. Examples of classic chimeras include the mule, which is a cross between a horse and a donkey. Mythical examples of chimeras include the Merlion (human and a fish) and Centaur (body of a horse and a human head).
The Asymmetric Threats from Human-Animal Synthetic Organisms
1. Medical science has repeatedly shown that animal diseases can be transmitted into humans by any remnant animal protein or genetic fragment, especially from animal protein or genetic material remaining in the egg of the animal. Such diseases can include cancer, leukaemia, or even Alzheimer dementia and mad cow disease by difficult-to-detect prion protein.
2. Serious animal infections, presently confined only to the animal kingdom, can cross the species barrier and infect humans. For example, the HIV virus was transmitted from chimpanzees to humans. It was absent prior to the 1950s but started appearing in Africa either when some tribes ate infected chimps or was passed by errant researchers using chimpanzee serum for human treatment. Chicken eggs may contain the fatal avian virus, and poultry hepatitis B viruses which cause liver cancer.
3. If a human being is created in the Chimera form, and then its life is terminated, this could be legally and ethically unjustifiable.
4. It may be said that any form of mixing violates natural boundaries -- it breaks the species barrier. To pursue this, however, we need to increase our understanding of the strengths and weaknesses of the concept of species boundaries. Although it is rare for species to interbreed, the 'barrier' is in reality difficult to define.
5. If each species has a clearly defined genome, then mixing species means mixing up two distinct genomes. With the human genome, things are not that clear. To start with, around half the genes in human cells create proteins that keep cells alive and growing. These genes are found in many different living organisms where they vary only slightly, if at all, from the versions found in humans. This is why people quote figures such as "humans are 50% bananas!" It is therefore difficult to describe these so-called 'housekeeper' genes as belonging to any particular species.
The word 'science' derives from the Latin scientia, knowledge, and science is rightly concerned with 'the systematic study of the nature and behaviour of the material and physical universe, based on observation, experiment and measurement'. However, questions like whether to create human-animal embryonic combinations require more than knowledge, they require wisdom. Wisdom is knowledge tempered by judgment. Science cannot simply pursue the acquisition of knowledge without any consideration of the means involved; it must operate within legal and ethical boundaries. What if the human-animal combinations fail to find cures for any illness but unleash a whole series of new fangled problems and diseases in runaway chain reaction experiments? The regulatory system may fail at some point and the scheduled termination of human-animal synthetic organisms may not take place. What happens then? What if the new synthetic speci
es grows in confinement to full form and escapes into the wider world?
ATCA is pro-science and we need to look for ways of conducting science within a legally and ethically justifiable framework for the long term. ATCA recognises that direct human and animal experimentation is becoming increasingly difficult for the scientific community in the current climate because of STRICT government restrictions enforced by tight legislation as well as human rights and animal rights groups.
Therefore, the scientific community is left with limited options such as pursuing research at a cellular level to create human-animal synthetic organisms in order to understand and to find cures for debilitating diseases. However, if the world's scientific community were to make the brave decision not to pursue this particular direction of human-animal synthetic research, then new avenues would almost certainly open up and lead to alternative modes of finding cures and treatments. Rather than being a panacea the human-animal synthetic organisms could be the opening of the genetic equivalent of pandora's box!