Embryo Research

Author: Eustace de Souza


by Dr. Eustace J. de Souza

Modern technologies in reproductive biology, as well as the possible uses for foetal tissue in brain implants, have brought embryo research into sharp focus. The by-product of "in vitro" fertilization, "embryo transfer" and the myriad permutations envisaged by surrogacy have caught the scientific and legal world by storm.

It is natural that in the midst of scientific jargon and legal quibbling the layman is bewildered and confused. The exciting facilities now made available are also tinged with apprehension at the awesome possibilities that make the horrors of Aldous Huxley's "Brave New World" pale in comparison. To those who sit and think, the caution of Sir Thomas More comes to mind: "It is not the question of what the king can do, but rather what he may . . . " (emphasis not in the original).

Human Fertilization and Embryo Research

The British Parliament has accepted a bill, "Human Fertilization and Embryo Research," which seems to stress that the rights of human personhood are not inherent but rather those that can be conferred by human law makers. This legislation was accepted in spite of a plea from a member of the Church of England Synod that human life began at the moment of fertilization. In effect, the bill declares that the embryo of not more than fourteen days is not a person but only a thing, and therefore a fit subject for immolation on the altars of the "Great God Of Research!"

Some Catholic theologians too show a strange dichotomy in their approach to the problem. They would hotly deny that human personhood is a right that can be conferred, and yet they would deny full human status to this early human embryo. They hold that the zygote, at this early stage, is worthy of "utmost respect" but this respect is proportionate and therefore subservient to a greater good! This greater good may be relief of the trauma of rape or even the severe social ostracism of an unwed mother or the serious physical or mental health of the woman. In the same breath these theologians, in a belated concession to "Donum Vitae" will not accept embryo research on the early conceptus as an adequate good in the realm of "utmost respect."

In this thicket of contradictions let us see what are the "goods" of embryo research and the cases made for it.

The Greater "Good"

The enthusiasm for vital and exciting knowledge can easily cloud moral thinking. It can happen that the great ends of immediate scientific gain can obscure the morality of means. There are many who would insist that means are neither good nor bad in themselves but must be viewed in a total context. Some would insist that it is the situation that determines the ethic.

It was the spin-off from "in vitro" fertilization that provided valuable material for embryo research. For successful "take" at "in vitro" fertilization (even though this "take" is limited) several ova have to be induced by hormone or chemical super-ovulation. These multiple ova are artificially fertilized "in vitro." The resultant early embryos, called blastocysts at this stage, are microscopically scrutinized for obvious defects. From those considered suitable, some are used for implanting into the woman. The rest are frozen for subsequent use in case the first crop of implants do not "take." If the first implant succeeds, the frozen embryos are "spare." What is to be done with these spares? They can be stored for a next pregnancy or discarded!

Then comes the apparently innocuous request from the researcher: "Rather than throw them down the drain, why not use them for research or experimentation that can benefit mankind? Why lose such valuable material?" In a similar vein, the blastocysts that were considered unacceptable for implantation can be more valuable for research. They can provide valuable pointers of altered growth, maybe even clues to the great scourge of cancer, which is indeed growth gone awry. Is not the world spending millions on cancer research? Is not tissue culture research one of the important tools in this field?

After all, the law has declared that this cluster of cells is devoid of the rights of human personhood. Does it not therefore have the same status as a cluster of human tissue culture cells? Is not the great aim of research more than that of "utmost respect?" Surely, once we have denied its human value, we have greased the skids on the slippery slope!

Another advantage of such embryo research is that we have at hand sibling material to study the "why"--and even possibly the "what to do"--for those who are more tangibly with us as more developed beings. For instance, the embryo can be a valuable model or experimental material providing data or clues on what to do for a haemophilic child.

Even more valuable as far as research is concerned would be cloned blastocysts. Here we have the ideal, experimental twin brother--only we do not call him "brother"--rather he is called the "pre-embryo." Such a nice semantic twist from biological fact to philosophic uncertainty! Just the change of a word or the passage of legislation, and another child is deprived of his/her right to enter this world.

Cloning and Natural Twinning

It is true that human cloning is precluded in the enacted British "Embryo Research" legislation, as are experiments involving cross species hybridization using human embryos. Once the technology is available, however, it is almost certain that either human cupidity or curiosity will tempt someone to jump the gun.

While cloning generally means the production of an identical twin embryo, there are several allied experimental possibilities each with its specific implications. Since they have a relationship to natural twinning as well as to other problems of early embryonic development such as mosaicsm and chimeras, it may be worthwhile to consider this in some detail.

There are two varieties of natural twinning both of which may have some genetic basis. In one variety, the woman releases more than one ovum at the same time. Since millions of sperm are available, the ova can be fertilized each by an individual sperm. These are "fraternal" twins.

On the other hand, a single ovum, fertilized by a single sperm, can form a zygote which develops in such a way that, after the first division, each of the resultant cells develops into a complete individual. These will be "identical" or monozygotic twins. They will be of the same sex, blood group and share at least ten genetic traits such as skin, eye and hair color, etc.

The "zona pellucida" of the ovum or the egg shell plays a very important part. Once a sperm crosses it, the process of division to form the new individual of the same species is set into motion. Division and differentiation is initiated using the diploid material (i.e. a double set of chromosomes) for further replication. So two things are necessary: a zona pellucida and diploid genetic material within it. It does not matter whether any genetic material came originally from within its own zona pellucida, or from another. Once there is a diploid set of genetic material within the zona pellucida, the signal is given for repeated mitotic divisions and differentiation into a new individual as coded in this genetic blueprint or genome.

The blueprint is the finalized set of instructions from the new combination of paternal and maternal complementary haploid (half) set. Since sperm and ova have infinite variations the "resultant" gets a "shuffled" new set of combinations from the father and mother. That is why two brothers or a brother and a sister through sharing components from the same parents can be so different while each shows characters in common with their parents. The shuffling is nature's way of ensuring survival of the species. That is why consanguinity among closed groups can ultimately be harmful as it works against adequate shuffling.

On the other hand, identical twins, since they possess identical sets of chromosomes (identical genomes) have almost all genetic traits in common. The differences therefore, are those induced by environment.

Cloning is the technique used to reproduce a genome in a new entity who will possess all characters in common with the individual from whom this genome set was taken. Embryo research can be directed and classified into several categories. The first of these involves study of basic principles of development and differentiation with no direct and immediate application envisaged.

Experimental Models

Let us review the work as a series of experiments or models. In the first group a cell may be taken out from the inner cell mass of blastocyst A--and inserted into a second zona pellucida B--from which the nucleus has been removed. This transplanted cell is an experimentally produced identical twin or clone of A. The new embryo or clone, possessing the identical genetic blueprint or genome of A, has the same sex, blood group, and disease patterns.

Within the second model, cells from two shells A and B, are cross transferred. We now have two, new, complete individuals who are patchwork crosses of A and B. They can each be considered as AB and BA chimera. This can account for naturally occurring chimeras or "twin recombinations."

The next model involves the removal of the nucleus from an ovum and implanting it into a vacant shell, the diploid nucleus from the body cell (i.e. intestinal cell) of an adult. This implant develops into the identical twin or clone of the individual from whom the somatic or body cell was taken.

A hypothetical model envisages experimental parthenogenesis where the haploid nucleus of an ovum is experimentally stimulated into a division resulting in a diploid nucleus within a single zona pellucida. This diploidy in the zona pellucida will now divide like a zygote. No reports are currently available of such experimental work--and certainly not in any higher species.

Obviously, any experimentation as indicated above on the human embryonic "spares" would be to underscore the extrapolation from animal models.

Research Rationale

Human embryo research is primarily directed toward two ends. The first of these is to improve the "takes" in "in vitro fertilization;" or to check out the genetic make-up of an identical or near identical twin to ensure the survival or absence of defect or deformity of the implanted "in vitro embryo." The method could be used to look for chromosomal defects or sex of the embryo if suspected of sex linked diseases like haemophilia or Duchenne muscular dystrophy. The more distant goal of the basic work is to understand the processes of growth, development and disease, with the hope that this knowledge can be turned to more productive or directly applicable means of obviating deformity and preventing disease.

The morality and ethics of this experimentation on human beings must come to terms with the morality of means and ends. At some stage there is the obligation not to deny the developing human his future. Where shall the line be drawn?

Entry into the zona pellucida pulls the switch that ensures the future development of the product of human sperm and human ovum into a living member of the species homo sapiens and no other species. Is it not a little perverse to postulate a somehow living but not human something, belonging to the species homo sapiens but not yet human?

To deny that the abortion issue does not figure in the debate is to be naive. To justify early abortion for whatever reason and then object to embryo research is inconsistent. There is a connection between the two issues and it is consistent to hold that all human life, whatever its stage of development is equally worthwhile and therefore equally inviolable.