Human cloning and genetic engineering: the case for proceeding cautiously.

• Author: Brown, Barry L.

The irony inherent in the debate on "whole human" reproductive cloning is the amount that has been written and the emotions that have been stirred regarding a scientific advance that has not yet occurred (1) and that, at present, is only a potential threat to family and social structures. (2) This article is in no way intended to minimize the fears raised in the ongoing discussion regarding the potential for superhuman or subhuman replicants, (3) or the potential adverse impact upon the family from the need to nurture genetic duplicates of one or two parents. (4) This paper is merely presented as one alternative to the entertainment industry's popular depiction of the horrors of cloning (5)--a depiction that has the effect of detracting from a debate that is, potentially, highly productive. Arguably, a more realistic focus upon the beneficial, as well as on the destructive, potentials of human cloning would permit the evolution of a reasoned set of legal controls designed to protect the interests of individuals, the family, and society.

A debate motivated by fear is more likely to result in extreme solutions or absolute prohibitions; these are unlikely to withstand the test of time. Enforcement of absolute limitations in the face of continuing scientific curiosity and societal needs will ultimately fail. (6) Laws that attempt to ban what people want to have (7) or to find out about (8) are, generally, honored only in their breach. To presume that the enactment of laws prohibiting the application of scientific advances will end the debate on human cloning, is, in this author's belief, the height of folly. Our curiosity regarding the essential elements of our physical being have led us to the strands of DNA and, even deeper, to the basic protein structures of which those strands are composed. (9) Human cloning is merely a predictable tangent to the study of the human genome. (10)

The purpose of this article is to suggest that an absolute prohibition against human cloning is unworkable and ill-conceived; and, further, that there is sufficient time to engage in a reasoned debate to develop the type of restrictions upon cloning practices that will protect the interests of individuals, families, and the human species, while permitting an exploration of the potential benefits of cloning technologies. The first part below briefly discusses the scientific history of cloning and how this has led to present efforts to clone higher animals. The second part identifies the risks that have been identified in the current debate, and also considers some of the potential benefits implicated by both therapeutic and reproductive cloning. The third part presents a constitutional framework for either supporting or denying an individual right to engage in human cloning. The fourth part considers the present national legislative response to the prospect of both therapeutic and human reproductive cloning. Finally, this paper presents suggestions for the continuing debate and argues for the imposition of a more logical framework in order to achieve a reasoned result in light of the inevitable advances being made in the science of human cloning.

1. BACKGROUND

   Scientific advances allowing the cloning of plant and lower animal structures are longstanding. (11) The replication of organisms for agricultural purposes has been commonplace for many years. (12) Similarly, cloning of certain animals, particularly for food production, has become commonplace, if not universally accepted. (13)

   The progress heretofore made with respect to plants and lower animals was dramatically enhanced with the public disclosure that researchers in England had successfully cloned a female sheep by transplanting the nucleus of a cell--removed from an adult sheep's udder--into an enucleated egg cell from an adult female sheep. (14) After 277 attempts, scientists at Roslin Institute utilizing the process of somatic nuclear transfer succeeded in producing the genetic twin of the sheep whose nucleus was transplanted into the donee egg cell. (15) Out of twenty-nine live embryos, only one successful offspring was achieved. (16) Nonetheless, Dolly, as the first viable mammal cloned from the nucleus of an adult cell, became the internationally recognized symbol for the future potential of cloning and the spark for the debate on the efficacy of cloning humans.

   Predictably, successful mammalian cloning culminating in the birth of Dolly has also heightened both the temptation of scientists and the consternation of ethicists regarding the application of similar procedures in humans. (17) It is not simply the success of Dolly, however, that has incited the curiosity of researchers. Rather a confluence of circumstances and discoveries has occurred during the last half-decade of the millennium--causing the prospect of human cloning to have value apart from, or perhaps in the face of, ethical concerns. These concerns include (1) advances and discoveries with respect to stem cells, (2) the mapping of the human genome, and (3) the integration of these achievements into the science of human cloning.

   1. Stem Cells

      Potential applications for human cloning have been enhanced by discoveries and advances in stem cell technology. In fact, as noted below, the avowed purpose of those who have announced the first cloned human embryo is to utilize this technology for the production of human stem cells.

      Two types of stem cells--totipotent and pluripotent--originate from the embryo. (18) After fertilization, division of the egg begins and the initial cleaving produces two totipotent stem cells. Each totipotent stem cell possesses the capability to develop into a full human being. An example of the totipotent nature of these cells exists in the incident of identical twins. Identical twins form as a result of a separation of these two cells after the first cleavage. At approximately four days after fertilization, the dividing cells form a hollow sphere called an early blastocyst. (19)

      As the blastocyst develops, two layers become evident: an outer layer of cells, called the outer cell mass (OCM); and an inner layer of cells, called the inner cell mass (ICM). At this point in time, the OCM becomes destined to develop into the placenta and other sustaining tissues. These cells will not differentiate into the embryo proper, but only into tissues that support fetal development in utero. The ICM consists of the cells that will eventually develop into the tissues of the human body, i.e., the embryo proper. (20) By this time in development, the cells of the ICM have lost their totipotent capabilities and have become what are known as pluripotent stem cells. Although the embryo will be formed from these cells, if isolated from the OCM and implanted into the uterus they would never develop into a fetus. (21) These stem cells nevertheless hold the capability to develop into numerous types of cells if properly induced.

      1. Characteristics

         In addition to the key characteristic of potentiality, the ability to differentiate into various cells, embryonic stem cells boast other characteristics that distinguish them from the other cells of the body. First, these stem cells have a higher resistance to senescence, or cell aging and death. (22) This is advantageous because stem cells can be maintained longer in culture for use in experiments and research. Next, stem cells have the ability to continually reproduce with little mutation occurring between generations. (23) The combination of these two traits would enable researchers to keep a library of stem cells. (24)

         After the completion of the initial collection of stem cells, their replication through many generations would create a large supply of viable, usable stem cells. Successfully maintaining such a cell line could reduce or potentially eliminate the need to collect stem cells from embryos or fetuses. In addition, the storage of stem cells would decrease the time between problem identification and treatment via donation. (25)

         Lastly, stem cells obtained from embryos and/or fetuses may be less immunogenic in nature. Due to their immaturity, scientists believe that stem cells may cause less of an immune response in donees than mature, specialized cells taken from an adult or child. (26) These three unique characteristics viewed in totem demonstrate that stem cells hold significant value as potentially important medical technologies.

      2. Proposed Uses

         Scientists hypothesize numerous clinical and research uses for embryonic pluripotent stem cells. One such use involves tissue transplantation. Traditionally, whole organs and tissues have been harvested to replace diseased or damaged tissues. In order to decrease rejection by the patient, the closest possible matching of types, including histocompatibility, was paramount. (27) Yet finding a perfect organ match is an arduous task, and the wait for a match is often very long. (28) The implementation of stem cell storage would lead to both a decrease in the amount of time for a patient to wait before a transplant, and an increase in the chance for donee acceptance. (29) Thus, stem ceils have the potential for being especially useful in treating diseases in which there is a shortage of suitable tissue for transplant, such as Type I diabetes in children. (30)

         Another possible stem cell use being tested involves the implantation of fetal stem cells into the brain of Parkinson's disease patients. (31) Though still in the early stages of experimentation, evidence shows some effective replacement of lost nerve ceils in these patients. Further, researchers are optimistic about translating these methods to patients suffering from Alzheimer's disease and other degenerative nervous system diseases. (32) The National Institutes of Health (NIH) suggests that embryonic stem cells could have possible utility in drug development. (33) New drugs could be tested on tissues generated from stem cells, rather than on actual...