Stem cell research

Stem Cell Research, Cloning, and Genetic Engineering

G

enetics has come a long way since the Austrian monk Gregor Mendel's experi­ments with peas in the 1860s demon­strated that certain "hereditary factors" underlay the transmission of traits. Progress has accelerated since 1953, when biologists James Watson and Francis Crick determined the molecular structure of DNA, the basis of genetic information. The Human Genome Project, which mapped the entire human genome and was completed in 2000, promises even more wondrous things to come.

However, these scientific advances and their possibilities for human use have also been accom­panied by serious ethical questions. This chapter will examine several of these as they relate to five central areas: stem cell research, human cloning, genetic engineering, genetically modified plants and animals, and genetic screening.

STEM CELL RESEARCH

Recently, several public figures have made public appeals for the funding of stem cell research with its potential for treating or curing certain serious diseases. For example, Mary Tyler Moore, who has type I (insulin-dependent) diabetes and chairs the Juvenile Diabetes Foundation, brought children with this condition to testify in hearings before Congress. These children are not able to produce enough insulin to change nutrients into the energy needed for life; they must monitor their blood

sugar and be injected with the needed amount of manufactured human insulin every day. Nancy and Ron Reagan also support stem cell research and have spoken publicly about their hopes that this research can lead to cures for Alzheimer's dis­ease, which afflicted the late President Ronald Reagan and currently 4.5 million other Americans. Actor Michael J. Fox has also promoted this research as a possible cure for the Parkinson's dis­ease with which he is afflicted. Before he died, Superman star Christopher Reeve also lobbied for this research as a possible treatment for spinal cord injuries such as his.

Stem cell research is part of the field of regener­ative medicine. The hope of its supporters is that efforts here can lead to the production of new cells, tissues, and organs that can be used to treat disease or injury. Certain stem cell therapies have been around for some time. One example is the transplantation of the stem cells present in bone marrow to treat certain forms of leukemia. Another more recent example is the extraction from cadavers of certain parts of the human pan­creas for an experimental treatment of diabetes.¹

What are stem cells and how are they supposed to play a role in such efforts? Stem cells are found in the early embryo and in other parts of the human body that are not yet, or not yet fully, dif­ferentiated. In other words, they have not yet developed into specific skin, muscle, or other types

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of body cells and tissues. Embryonic stem cells are the fifty to one hundred cells that make up the inner mass of cells of the blastocyst (the rest form the outer shell that becomes the placenta) that exists in the first week of embryonic development. These cells are undifferentiated for a short period of time—approximately five to seven days after fertil­ization. They can be removed and placed in a cul­ture where they will continue to divide. They are the cells from which all of the body's organs develop and thus are called pluripotent. However, once removed in this manner, they can no longer develop into a fetus.

In the case of these embryonic stem cells (ES cells), researchers hope to be able to learn how to control the process of their differentiation so as to be able to provoke them to become, for example, the insulin-producing beta cells of the pancreas (thus effecting the cure of diabetes) or neurons for the treatment of spinal cord injuries. Stem cells themselves cannot be directly implanted into the pancreas, however, because they can cause can­cerous tumors to develop. Thus, it is necessary first to direct them into becoming the specialized cells that are needed.

On April 2, 2007, medical researchers from Britain reported that they had "grown human heart valve tissue from stem cells." If this is true, the replacement tissue generated could be used for heart disease patients within a few years.²

There are many practical problems with this process, among which are developing more effi­cient ways to obtain these cells, determining how to get them directed into such specialization, and controlling this process. Some researchers have pointed out that in the case of some diseases such as Lou Gehrig's disease and other autoimmune diseases, replacing the damaged cells may not help the patient because it is "the cellular environ­ment" that is the problem, and the newly added cells could be damaged as well. The source of the problem with the environment would need first to be addressed.³

Just as problematic are the ethical problems that are raised by ES cell research. Among the central ethical issues is the moral status of the early embryo. Those who believe that a human

being exists from the time of conception also hold that the blastocyst, although a ball of cells smaller than a grain of sand, has full moral status. As such, they believe it wrong to use these embryos, even to save another life. (See Chapter 9 on abor­tion for the arguments regarding the moral status of the embryo.) Supporters, however, point out that leftover embryos now stored in fertility clinics (approximately half a million are now frozen in the United States) could be used because they are often otherwise destroyed, and using them could do some good.

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