Science in Christian Perspective
Potential Life-Saver or Just "Playing God?"
Kenneth E. Roth,
Assistant Professor of Biology,
Eastern Mennonite University, Harrisonburg, VA
From: PSCF 51 (December 1999): 222-223.
Recent advances in the isolation and culture of human pluripotent stem cells have opened the doors to avenues of research not previously investigated. The possibilities afforded by these advances may be met by both excited enthusiasm on the one hand, and a degree of fear and hesitation on the other. While the medical applications are potentially great, one must also remain aware of the equally great potential for abuse.
Stem cells are defined as cells that are both self-renewing and also able to give rise to other more specialized types of cells. Totipotent stem cells are those that can differentiate into all the different cell types of the mature organism. For example, a human fertilized ovum has the ability to form an entire human being (it has total potency). While viable human offspring have resulted from the implantation of such a fertilized ovum into the uterus of a suitable woman, the technology does not presently exist that would enable us to create a human being without her. However, the possibility of developing that technology raises obvious ethical issues that will likely one day need to be addressed. This discussion will focus on a different type of stem cell, the pluripotent stem cell, which can give rise to many types of cells in the organism, but not all types.
Human pluripotent stem cell lines have been derived from cells taken from the inner cell mass of human embryos at the blastocyst stage and from fetal tissue obtained from terminated pregnancies. The continued use of either of these sources will certainly lead to some level of disapproval from the public, and will undoubtedly require substantial justification and documentation on the part of the investigator (informed consent, etc.). Another option for deriving pluripotent stem cells is the use of somatic cell nuclear transfer (SCNT). In this procedure, which is still being developed, the nucleus is removed from a normal animal egg cell, and what remains is fused with a somatic cell from the same animal. The resulting fused cell is believed to be totipotent and can soon form a blastocyst. Pluripotent stem cells can then be isolated from the inner cell mass.
The uses of pluripotent stem cell research are potentially valuable. Stem cells can help us gain a better understanding of human development. The "signals" that cause a stem cell to differentiate along a given lineage are largely unknown. Identifying microenvironmental factors that dictate these decisions may prove helpful in developing therapies for medical conditions such as cancer and birth defects that are due to abnormal cell differentiation and cell division.
Stem cell research will allow the preliminary stages of drug testing to be conducted in tissue culture flasks, rather than in laboratory animals or humans. Using pluripotent stem cells in these tests will not replace testing at the organismal level, but it can be used to screen candidate drugs so that only those deemed the safest would be used in animal or human testing.
After the necessary decision-making signals are discovered, a more exciting consequence of stem cell research is that many different types of cells and tissues can be grown in the laboratory. The laboratory cultures may be used to restore tissue that has been damaged due to injury or disease. The applications are wide-ranging. One possibility is transplanting cultured heart muscle cells to restore cardiac function in patients with chronic heart disease or following myocardial infarction. This type of transplant has already been done successfully in mice. Other possibilities include treatment of spinal cord injuries, stroke, diabetes, Alzheimerís disease, burns, arthritis, and many others.
I believe that the positive outcomes of stem cell research are very promising and should be pursued. Yet, this research must be tempered by an awareness of the potential for its abuse. For example, one might envision the engineering of taller and stronger athletes by the implantation of additional pituitary gland somatotrophes and muscle cells, for example. With minimal strain on the imagination, a long list of such abusive applications easily comes to mind. For this reason, research in this area should be carefully monitored and regulated to ensure that it is both ethical and scientifically valid.