More on genetic engineering

Cloning

Cloning is one type of genetic manipulation, which aims to create many individuals with identical genetic structure. Media interest began with the cloning of Dolly the sheep in Scotland, and more recently in Australia, Matilda the sheep and Suzi the calf. To start cloning you need:

  1. Donor eggs

  2. Donor DNA (genetic material)

The donor eggs come from ovaries collected from slaughterhouses. The donor DNA comes from valuable animals with the characteristics you want to reproduce. It can come either from adult cells - Dolly’s DNA came from an udder cell in a mature ewe - or from cells from foetuses - Suzi’s DNA came from a 40-day old foetus. In the latter case foetuses are surgically removed from pregnant females.

The nucleus (which contains the DNA) is removed from the donor egg. The nucleus from the donor cell is injected under the outer layer of the donor egg, and is fully integrated into the egg by an electric current. If all goes well the egg begins to divide. It is kept in culture for about 7 days.

Embryos which appear normal at this stage are implanted into females, any females because the offspring won’t have their characteristics anyway. In cattle the implantation can be done through the vagina, but in sheep they are implanted surgically, either through laperoscopy or laperotomy. In both cases an incision is made in the belly of the sheep, but in laperoscopy there is usually no anaesthetic while laperotomy is done under general anaesthetic.

Implantation has a very poor success rate. Many embryos die in early pregnancy because the placenta does not develop normally. There are further late term miscarriages, at a time when the foetus is already sentient. Some animals are still- born, and of those live-born, some die in the days or weeks after birth due to respiratory failure, general weakness or deformities. Cloned animals tend to be over-sized, which produces more birth difficulties. As a result, many cloned animals are born by Caesarian section. In livestock species this often means that the offspring have to be raised by humans because, without the experience of birth, the mothers reject the offspring. The Australian researchers responsible for Suzi and Matilda report that only 6% of implanted embryos result in live-born calves (1). They report one experiment in which 22 calf foetuses were carried to term. Of these, 17 were born alive and 5 were still-born, but a further 5 of the 17 live-born calves died or were euthanased (2).

Results overseas are no better. Here are some results from recent scientific journals:

The situation with sheep is no better. Here are some examples from scientific journals:

To summarise:

  1. If donor DNA comes from a foetus, this is surgically removed from its mother.

  2. In sheep, cloned embryos are surgically implanted.

  3. Many foetuses die late in pregnancy and before/during birth.

  4. Foetuses are often larger than normal and lead to birth difficulties and surgical birth.

  5. Among cloned animals a higher than normal percentage are unhealthy, with deformities and poorly developed lungs, and there is a higher than normal death rate in the first few weeks after birth.

Transgenesis

Transgenesis is another form of genetic manipulation, where only one piece of genetic material (the transgene) is inserted into an already existing embryo. The intention is for this foreign transgene to be incorporated into the embryo's own chromosome structure.

To start transgenesis you need:

  1. Many embryos

  2. Genes (a piece of foreign DNA) that you wish to insert into the embryos.

First of all, females are superovulated by hormone injection so that they release many more eggs than they normally would. In the case of sheep (but not cattle), these eggs are surgically fertilised (laperoscopy/laperotomy), and then the embryos are surgically removed. In the case of mice, the most common transgenic animals, the mother is killed when the embryos are removed.

In the next stage the foreign genetic material (the transgene) is injected into the pronucleus of the embryo. The embryos are then implanted into surrogate mothers, again surgically in the case of sheep.

As in the case of cloning, there is a high death rate among the foetuses, and many have to be born by Caesarian section. With transgenics there is an addition problem, namely that very few of the young born will actually express the inserted gene. These animals are rejects as far as the researchers are concerned and are usually killed, even though they may be quite healthy.

The following are examples of a few studies:

Gene insertion is a very imprecise process, and even if the transgene is incorporated into the animal's DNA, researchers can't predict where or how it will be incorporated. The transgene may disrupt an existing gene or be inadequately regulated in its new environment, producing unintended side effects.

A striking example of unintended but severe side effects occurred in the "Beltsville pigs" (12). Pigs that expressed the transgene for increased growth hormone had many infirmities and died prematurely. Effects on subsequent generations were described as follows:
" The most common clinical signs of disease associated with transgene expression included lethargy, lameness, uncoordinated gait, exopthalmos, and thickened skin. The following gross and histopathologic changes were noted in some of the transgenic pigs: gastric ulceration, severe synovitis, degenerative joint disease, pericarditis and endocarditis, cardiomegaly, parakeratosis, nephritis and pneumonia. In addition, gilts were anestrus and boars lacked libido. "

To summarise:

  1. Females are superovulated to produce more eggs, then in the case of sheep these eggs are surgically fertilised.

  2. Embryos are surgically removed from the mothers in some species - mice are killed at this point.

  3. Genetically manipulated embryos are surgically implanted into surrogate mothers in some species (vaginally with epidural injection in cattle)

  4. Many foetuses die, and those that survive to term are often born by Caesarian section.

  5. The vast majority of animals are not transgenetic and are killed.

  6. Some effects of the transgene, both intended and unintended, cause suffering. Transgenetic animals produced as models of disease suffer in the same way as humans with the disease, and unintended suffering can result when transgenes are incorporated and expressed in unpredictable ways.

Purposes of genetic manipulation

  1. To produce livestock with more desired characteristics more quickly than through conventional breeding. Examples include finer wool, milk with more protein or less fat, beef with a particular fat content, sheep with faster growing wool, and so on. There is interest in producing milk without lactose, so that the milk market can be expanded to lactose-intolerant people. Some of the uses quite trivial, for example to increase casein protein and reduce beta-lactoglobulin in milk to make cheese manufacture easier. The same researcher goes on: " One possible scenario for the future is the generation of particular herds possessing specific genetic modifications in order to produce milk designed for the manufacture of high-value dairy products for niche markets ." (13) While cows probably aren’t fussed by what sort of milk they produce, consider the suffering that goes on beforehand to produce these niche-market herds in the first place.

  2. To produce biopharmaceuticals, such as blood clotting factor for haemophiliacs. This involves inserting human genes that code for these proteins into the animal embryos and then harvesting the desired protein from the milk.

  3. To produce animals that have diseases similar to humans to that proposed cures can be tested on the animals. A human gene that is thought to be responsible for a particular disease is inserted in to animal embryos. For example, there are claimed to be mouse models of cystic fibrosis and Alzheimer’s disease. There are scientific as well as ethical problems with this approach - it only has a chance of succeeding is a disease is produced by a single gene, rather than several genes, or the interaction between genes and the environment. An ECVAM Workshop concluded (14):
    " It is apparent from an analysis of some transgenic disease models that the actual benefits of using the model are rarely equivalent to the potential benefits, and that the decrease in aspects of animal welfare might be disproportionate to any benefits gained. "

    There are currently 3 so-called mouse models of cystic fibrosis, and while they problems with the digestive tract and have shortened lifespans, none have the lung congestion that afflicts human sufferers (15). The difficulty of reproducing human diseases is not surprising, since the genetic changes in even a single-gene disease are very complex. The situation is even more unpredictable in diseases that are polygenic and multifactorial. As an ECVAM workshop concluded (14):
    " There are several limitations in relation to the usefulness of the current approaches to developing transgenic disease models, particularly since many diseases are multifactorial. Problems persist when extrapolating data obtained by using such transgenic animals to the disease condition in humans. "

  4. To produce animals, particularly pigs, to grow organs for transplants. Human genes are inserted into embryos to reduce problems of rejection. However, rejection is only one problem - disease transfer is another. The genetic material of pigs contains endogenous retroviruses that have been shown to infect human cells in culture. There may also be as yet unidentified viruses, to which a transplant patient on immuno-suppressant drugs would be particularly vulnerable. As one researcher pointed out:
    " Some argue that, as pigs have lived alongside humans for so long, we would by now have picked up any of the microbes capable of infecting us. Yet pig calicivirus, closely related to human hepatitis E virus, was discovered within the last few years, and the Nipah virus, identified earlier this year, was only discovered during an outbreak of a fatal encephalitis in Malaysia. "

    Further problems with these purposes

    Supposedly the research community has embraced the 3Rs principle:

    Replace animal experiments with other methods wherever possible;

    Reduce the numbers of animals used in experiments;

    Refine procedures to minimise pain and distress.

    However, genetic engineering goes directly against the 3Rs - it is expanding the purposes for which animals are experimented on and is using larger rather than smaller numbers of animals, mainly because it is so inefficient.

    There is little emphasis on Replacement - looking for non-animal ways to achieve a purpose. Biopharmaceuticals are important, but they are already being produced in genetically modified bacteria and cell cultures. For example, human insulin for Type 1 diabetes is produced by E.coli bacteria, and human blood clotting factor for haemophiliacs is produced by cell cultures. The only advantage in producing transgenic animals is that the product will be cheaper. However, blood proteins can already be produced in cell culture at a cost comparable to harvesting them from human blood donations (17).

    Similarly, there is little effort being put into increasing the supply of human organs for transplants. Several countries have adopted the Presumed Consent principle, that is, it is assumed that everyone is an organ donor unless they explicitly refuse to be involved. Austria increased its supply of organs four-fold when this scheme was introduced. It is essential to first conduct a public education campaign so that people embrace the need for organ donation and discuss it with their next of kin, then in most cases they will be willing to participate rather than opting out. (For more detailed information, go to Organ transplants .)

    It is important not to forget that some (not all) illnesses for which transplants will be used are preventable. One NZ researcher commented on the increasing incidence of mature onset or type 2 diabetes (16), which is a classic lifestyle disease. People with the disease can suffer heart and kidney failure and then need a transplant. However, the disease can be largely prevented by good diet and exercise, and can be alleviated by a low fat vegan diet before the stage of organ failure is reached (18). Similarly, heart disease can be reversed by a vegetarian diet and exercise (19).

    Poor diet causes at least as much ill-health as smoking, yet the government has never mounted as aggressive an advertising campaign against bad eating habits as it has against smoking. Clearly the percentage of smokers in the population has steadily declined over the years, yet obesity, high blood pressure and high cholesterol continue to increase. It would make more sense to try to prevent ill-health associated with poor diet, rather than passively accept that more transplants will be needed.

    Another way in which animal use could be reduced is if early embryos could be used to produce proteins such as insulin and dopamine. (For more detailed information, go to Organs transplants .) The nucleus from a patient's cells could be transferred into a donor egg and allowed to develop into a pre-implantation embryo. Stem cells from this embryo would be differentiated into the cells required so that when reimplanted, the new cells would produce the insulin that diabetics lack, or the dopamine that people with Parkinsons lack. Because it is cells with the same DNA as the patient that are reimplanted, no anti-rejection drugs would be required. Currently there are plans to use pig islet pancreatic cells, and nerve cells from pigs. A researcher commented on the human therapeutic cloning option as follows (13):
    " This approach, involving human cloning, is bound to raise controversy but may be ethically acceptable as it generates only a very early embryo (with around 100 cells) which current ethical opinion does not consider a human being, principally because at this stage it has not yet begun to develop a nervous system. "

    The Reduction principle is also not followed in genetic manipulation research. Animals are being used for a greater variety of purposes, some of them quite trivial. More animals are being used because the procedures are so inefficient. Huge numbers of "waste" animals are being generated by transgenesis. As one animal technician commented: " My remit is to ensure that we don't overbreed animals, but with transgenics you can't do anything about the surplus. "

    In a New Scientist article called "Hidden sacrifice", this same animal technician described how she was very disturbed by being told to kill so many animals. " I go away feeling physically and emotionally exhausted and I think it’s important for people to understand how we feel. " (20)

    In terms of Refinement , it has already been pointed out that genetic manipulation involves a lot of surgical intervention in female animals, more difficult births, and a high death rate among late term foetuses and new born animals. In addition, the housing of genetically manipulated animals may be a further source of stress.

    Any animal kept for medical purposes such as transplantation would need to be housed in the sterile conditions of barrier housing, which is unlikely to allow the animals to express their behavioural needs. Litter could only be used if it had been autoclaved, and it is questionable whether researchers would bother with such “non-essentials”. Also sterile piglets are delivered by Caesarian section at best, at worst by complete hysterectomy and killing the mother. Here is one description of housing (16):

    " Pigs and piglets will be raised in secure HEPA filtered units and fed only sterile food. All material used in these facilities will be sterile or sterilisable. Piglets will be derived by hysterectomy or medicated early weaning and reared on artificial foods containing no animal proteins. Animal facilities are also expected to have isolator rearing facilities, surgical derivation areas and tissue harvest areas. "

    This same researcher notes that such barrier housing with no contact with the outside world may be counterproductive:
    " In the opinion of some veterinarians and pig breeders the proposed SPF conditions are unacceptable in terms of pig health and may actually increase the risk of infection being present in some transplant material by producing less robust and sicker pigs. "

    To summarise:

    1. Genetic manipulation is leading to an increased use of animals, often for very non-essential purposes.

    2. More effort needs to go into health education to prevent and alleviate diseases that may necessitate transplants, eg type 2 diabetes

    3. There should be an Presumed Consent system to increase human organs available for transplantation.

    4. Effort should go into making microorganism and cell culture systems as efficient as possible in producing biopharmaceuticals.

    5. Animals bred to produce organs for transplant will be kept in sterile barrier housing that is unlikely to meet their behavioural needs.

    Click here to see References for this document on genetic engineering.