By Dr. Christina Powell
Editor’s note: During last year’s elections, the ethics of stem cell research were hotly debated. Despite the national debate, the details of the promise and problems associated with stem cell research remain unknown to many Americans. Dr. Christina Powell, a medical research scientist and ordained Assemblies of God minister, was asked to provide an overview of the controversy. She is a research fellow at Harvard University and Massachusetts General Hospital as well as the founder of Life Impact Ministries, an organization aimed at bridging the gap between Christianity and science. She attends Calvary Christian Church (Assemblies of God; Timothy Schmidt, senior pastor) in Lynnfield, Mass.
Why stem cells are special
To understand the promise of stem cell research, as well as the potential ethical problems, we must start with a basic understanding of what makes stem cells so special. Stem cells have two unique abilities that make them an important target for medical research.
Unlike all the other cells in the body, stem cells have the amazing potential to develop into many different kinds of cells. Given the right conditions, a stem cell can “differentiate,” becoming a mature specialized cell, such as a muscle cell, skin cell or nerve cell. The second ability that makes stem cells special is their capability to multiply themselves. This ability allows stem cells to function as a repair system for the human body, dividing without limit to replenish other cells for as long as the person is alive.
Medical researchers desire to study the first special ability of stem cells — the capability to differentiate into the array of specialized cells that make up our bodies — for the insight it can offer into serious medical conditions such as cancer, which results when problems occur in this differentiation process. The second special ability of stem cells, the repair function, may make it possible to use stem cells to treat diseases such as Parkinson’s, spinal cord injury, diabetes, stroke, burns, heart disease and arthritis.
Types of stem cells
There are three types of stem cells: totipotent, pluripotent and multipotent. A fertilized egg belongs to the totipotent class of stem cells. The potential of the egg is total; all the different types of cells in the body plus the cells needed to form the organs necessary to support growth of a baby in the womb, such as the placenta, can arise from the egg. The second class of stem cells, pluripotent, include the stem cells isolated from human embryos that are a few days old (embryonic stem cells) and those derived from fetal tissue (older than eight weeks of development). These stem cells can give rise to all the cells in the body except those needed for the growth of the baby in the womb. The third class of stem cells, multipotent, includes stem cells that can give rise to a small number of different cell types. Included in this category are adult stem cells, such as blood stem cells found in bone marrow, and stem cells derived from umbilical cord blood.
Ethical issues surrounding embryonic stem cell research
Ethical difficulties with stem cell research concern the pluripotent stem cells isolated from human embryos or fetal tissue from abortions. The harvesting of stem cells from embryos destroys the embryo and thus a unique human life. Proponents of embryonic stem cells will point out that the primary source of embryonic stem cells are the extra embryos arising from in vitro fertilization treatments that will be destroyed anyway. These cells are used to make pluripotent stem cell “lines,” which are laboratory cultures that can serve as an ongoing source of embryonic stem cells. Currently, there are about 60 embryonic stem cell lines approved for use by federally funded researchers under the August 9, 2001, decision by President Bush to allow research using stem cell lines derived from excess human embryos prior to that date. While those stem cell lines will prove valuable for research, the development of new stem cell lines from a fresh source of embryos eventually will be necessary. Cell lines cultured in labs change over time, potentially developing harmful genetic mutations.
Beyond the “extra embryos” created during the process of in vitro fertilization treatment, other possible sources for embryonic stem cells include eggs and sperm donated specifically for research purposes from unrelated individuals with no reproductive intent. In this case, embryos would be created in the lab only to be destroyed a few days later to harvest stem cells. The ethical question that such a practice poses is whether a unique human life in its earliest stages has less value when created in the lab from the reproductive cells of strangers than a human life that arises in the womb as a result of sexual relations.
A final potential source of embryonic stem cells is a process called nuclear transplantation, which is sometimes referred to as “therapeutic cloning.” In such a procedure, the genetic blueprint (DNA) of an unfertilized donor egg would be replaced with the genetic blueprint from a patient’s own cell, such as a skin cell. The egg would then be stimulated to divide in the laboratory to form a ball of cells from which stem cells could be harvested. These stem cells would contain the patient’s own DNA, ensuring a genetic match for transplanted tissues arising from the stem cells and thus eliminating the problem of transplant rejection. The ethical question for such a procedure is whether or not at any point an embryo capable of forming a complete human life is formed during this process. If the process does not form an embryo fully capable of theoretically becoming an adult, then a unique human life would not be destroyed by this approach.
The ethical concern for a unique human life that has not developed beyond a ball of about 200 unspecialized cells can be overshadowed by the desire to provide hope for a child or adult who is suffering with disease. One child advocate for stem cell research could not understand why concerns for cells smaller than a period at the end of a sentence should stand in the way of providing hope for her. When we have a loved one plagued by a disease that could be potentially cured from a treatment developed from embryonic stem cells, the need of the patient seems foremost. Yet the lives of all of us, including the patients in need of cures, began as a fertilized egg, which then developed into a ball of cells smaller than the period at the end of a sentence. How many cells must an individual human possess in order for his or her human life to be considered of value?
Stem cell cures: Hope or hype?
Adult stem cells from bone marrow were first discovered about 40 years ago. These stem cells and those from umbilical cord blood have been used to successfully treat fatal inherited immune disorders and leukemia. Human embryonic stem cells, on the other hand, were first successfully isolated in 1998, although studies on animal embryonic stem cells have been conducted for about 20 years. Studies using mouse embryonic stem cells have shown the promise of cures for diseases such as diabetes, Parkinson’s and spinal cord injury. However, research using human embryonic stem cells is still in its early stages and potential treatments remain many years away.
It is also important to realize that embryonic stem cells may not always provide the best approach to treat a disease listed as one for which stem cells might someday provide a cure. For example, The Washington Post accurately observed soon after President Ronald Reagan’s death that Alzheimer’s disease is not likely to be cured through the use of stem cell therapy. In Alzheimer’s disease, a wide variety of nerve cell types become defective and the synaptic connections between them suffer widespread loss. The use of embryonic stem cells in the laboratory may assist our understanding of Alzheimer’s disease, but the cure for this disease most likely will come from a therapeutic approach that does not directly involve stem cells.
Since the use of adult stem cells and stem cells from umbilical cord blood do not involve the destruction of embryos, many people hope that studies on these stem cells will provide new treatments for the diseases listed as targets of stem cell research. Some early studies suggest that it may be possible to guide adult stem cells to differentiate into a wider variety of specialized cells than once thought possible; however, adult stem cells do not exist for many of the diseases that potentially could be treated by embryonic stem cells.
Sanctity of human life throughout development
While the potential uses of embryonic stem cells in medical research are exciting, we must ask ourselves two questions: When does human life begin? Do we believe in destroying life for the chance to extend the lives of others?
Human life is a continuum that starts with a single fertilized cell with its own unique genetic blueprint and proceeds through incremental development to the stage of a human adult possessing more than 10 trillion specialized cells. The sanctity of human life applies to human life at all points along this continuum. As King David so eloquently wrote, “When I was woven together in the depths of the earth, your eyes saw my unformed body. All the days ordained for me were written in your book before one of them came to be” (Psalm 139:15,16, NIV). Human life has intrinsic value even in the earliest stages of development.
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