New criteria for determining the death of the early human embryo have been proposed by Donald W. Landry and Howard A. Zucker, a team of bio-engineers from Columbia University. Their purpose was to find a justification for pursuing research on human embryonic cells without causing the death of an embryo.1 They hold that an embryo that, at the four - eight cell stage, has irreversibly lost the capacity of continued and integrated cellular division, growth and differentiation, is "organismically dead." They claim that a system of chemical communication and surface recognition integrates the cells of the developing embryo. Lack of this integration is said to cause irreversible arrest of cell division, which is the cause, not of the death of all of the cells, but nonetheless, of the death of the organism. Some of the remaining cells are "likely donors of blastomeres", suitable for stem cell research.
• Landry and Zucker admit that no method exists to objectively determine whether an embryo has died. They suggest the study of cleavage in large numbers of in vitro embryos and also of biochemical defects that preclude further growth. As a justification for their theory of when an embryo is organismically dead, they state that a general consensus has been reached on when life ends: life ends when there is loss of integrative function of the human organism when the criteria for brain death are met.
• One may question the validity of the Landry-Zucker hypothesis. The biological mechanisms integrating the development of the single-cell embryo through to the 50 to 100 trillion cell human adult stage is of stupendous complexity. Literally, billions of biochemical interactions occur every fraction of a second in this process. How can one, at the present time, claim to know with adequate precision and moral certainty, when integrative unity has been lost by so complex an organism? Loss of chemical communication and surface recognition between the four to eight cells, even if known to have occurred, may represent only a disordered process in a living organism that may precede death of the organism, but not indicate that death has already occurred.
• It was proposed that a study should be made of the natural history of cell cleavage in large numbers of embryos and also that there should be a study of biochemical defects in those embryos. Will these studies result in the death of those embryos?
• The fact that objective criteria of organismical death of the embryo is not established means that to use any embryo for the purpose of determining whether there is communication between the cells, would be morally unacceptable if it led to the death of the embryo.
• The very creation of in vitro embryos is in itself an intrinsic evil.
• The basis on which organismical death is justified is still an open question. It was assumed by Landry and Zucker that the As Hoc Committee at Harvard Medical School provided criteria for brain death which indicated that it was equivalent to actual death. This is incorrect. The Committee provided criteria for irreversible coma, a situation in which, they assumed, that the person was for all practical purposes (i.e. organ retrieval), dead. They recommended that a patient be declared dead before a respirator is turned off. The reason given for that advice was that it would provide a greater degree of legal protection to those involved. The Harvard Ad Hoc Committees 1968 definition implied that brain death should be regarded as death because it inevitably leads to death; and that the person in irreversible coma is, for all practical purposes, if not in reality, dead. Untold semantic confusion has followed this oxymoronic notion2.
• Many persons declared brain dead have retained free-water homeostasis vasopressin, which controls the body's ability to excrete water. The brain is the only source of the regulated secretion of vasopressin. Some show electrical activity in their electro-encephalograms. Some react to surgical incision with a rise in heartbeat and blood pressure, indicating possible neurological function at the supraspinal level. Some have a heartbeat, digest food, and may even bring a pregnancy to term. The brain integrates the functions of breathing, diaphragm movement, eating, chewing and swallowing. It does not integrate absorption of nutrients, elimination and detoxification of cellular waste, or gestation of a fetus. Enough evidence therefore exists to cast doubt on the standard definition of "brain death" as the irreversible absence of all functions of the brain. Furthermore, the criteria for brain death vary, are not consistent, and are even increasingly ignored. A 2002 Neurosurgery study by Michael Wang et al. showed poor compliance with accepted guidelines of "brain death" in his institution. In the same year, E. Wijdics (Neurology) surveyed "brain death" criteria throughout the world, and found that "brain death" was accepted as a fact but that there was no global consensus on the diagnostic criteria. In 1999, W. Haupt and J. Rudulf (Journal of Neurology) found that the guidelines for determining "brain death" in all European countries were different in the various countries. American physicians assumed that irreversible loss of all functions of the entire brain and brain stem is necessary before death can be declared. In Britain, "brain death" is defined as complete and irreversible loss only of brain stem function. In 2001, Dr. Neil Lazar (Canadian Medical Association Journal) stated that "brain death", as a criterion for determining the death of a person, "is perhaps justification in the context of organ donation and transplantation." He did not state that "brain death" criteria determined the "death of a person," nor definitely justify the removal of organs and their transplantation. The New England Journal of Medicine published and article in 2001 stating that the consensus in regard to the equation of "brain death" with actual death is not free of metaphysical, cultural, legal and medical controversy.
• Pope John Paul 11, in August 2000, in his address to the thirteenth International Congress of the Transplantation Society, implied that there were "clearly determined parameters, commonly held by the scientific community which allow a physician to declare a person 'brain dead', and by implication, actually dead. At a recent special meeting of medical experts in February, 2005, at the Vatican, Bishop Marcelo Sanchez Sorondo, Chancellor of the Pontifical Academy of Sciences, stated that Pope John Paul 11 called for the meeting "in order to re-study the signs of death and verify at a purely scientific lever, the validity of the criterion of brain death."
Landry and Zucker's contention that an early embryo at the four to eight cell stage can be declared "organismically dead" and yet contain at the same time viable blastomeres, which are useful for, and may be morally used, for stem cell genetic engineering and research is based on questionable assumptions. 1. That, even though they are not yet established, criteria for the establishment of organismical death will be found. 2. That enough is known or will be known in the future, by the biological processes involved to justify their theory. 3. That their criteria will in fact, be empirically proven to justify the statement that they destroy the integrative function of the embryo.
Landry and Zucker claim that "just as the nervous system integrates the activities of the developed organism, so a system of chemical communication and surface recognition integrates the cells of the developing organism." The former is not established. The latter has not yet been demonstrated.
In the light of the many dubia facti involved in this theory of "organismical death", it would appear that the case that one may use the early embryo, so classified, for the purposes of research, is not morally justified. The uncertainty with regard to whether the human individual (the early embryo defined as "organismically dead") is not an abstract doubt regarding a theory, principle, or doctrinal position (dubium iuris); it is a doubt about a fact concerning the life of a human being, his existence "here and now" (dubium facti). As such, it creates the same obligation as certainty.3
1 Donald W. Landry and Howard A. Zucker, Embryonic Death and the Creation of Human Embryonic Cells, J. Clin. Invest. 2004, Nov. 1; 114 (9): 1184-1186. [Back]
2 D. Alan Shewmon, MD, Recovery From 'Brain Death'. A Neurologist's Apologia. The Linacre Quarterly. Vol. 64. Feb. 1997, 30 - 95. [Back]
3 Mauro Cozzoli, The Human Embryo: Ethical and Normative Aspects, The Identity and Status of the Human Embryo, p.271. Liberia Editrice Vaticana, 1999, second edition. [Back]