Stem Cells & Public Policy

Stem cell research has the potential to produce medical miracles, but it is an ethical minefield. Here's a primer on stem cell research and current legislation.

Stem Cell Primer

Embryonic stem cells can develop into any of the approximately 300 types of cells that make up the human body, and this unique ability may be the key to repairing the damage caused by conditions such as heart disease, stroke, and Alzheimer's, or to replacing organs and limbs. Stem cells with genetic defects could be created to study how congenital diseases develop, and new drugs might be tested on human tissues grown from stem cells rather than on people or animals. Many technical hurdles have yet to be overcome, but research has progressed steadily. Researchers used stem cells to produce immature heart cells, which have the ability to develop into any of the three types of heart cells, and stem cells have also shown promise in treating several conditions, such as some cancers, spinal cord injuries, cystic fibrosis, diabetes, MS, and blood disorders.

Human embryonic stem cells were first isolated and cultured in 1998. The cells are usually harvested from unwanted embryos left over from fertility treatments, which would have been discarded. Most countries specify that only embryos that have been developing for less than two weeks can be used. At that stage of development, the embryo is an undifferentiated ball of cells about the size of a pinhead. After harvesting, stem cell lines can, theoretically, be maintained indefinitely.

Stem cells can also be obtained from the placenta, amniotic fluid, umbilical cord, and cord blood, which may be collected at birth. Adult stem cells are found in a variety of tissues, including bone marrow, the brain, the nervous system, and the skin. However, these stem cells can usually only produce cell types found in a particular tissue. For example, hematopoietic stem cells are found in the bone marrow, and can develop into any type of blood cell, but not skin or muscle cells. Unlike embryonic stem cells, adult stem cell lines cannot be maintained indefinitely.

The main controversies in stem cell research concern the destruction of human embryos and the potential for human cloning. Some believe that life begins at conception, and that the destruction of an embryo, regardless of stage of development, is unacceptable. Others believe that an embryo does not have the same status as a fetus or human being, and that using embryonic stem cells to advance medicine is similar to using the organs of the deceased for transplants.

The same methods used to produce Dolly the cloned the sheep could theoretically be used for reproductive cloning and therapeutic cloning of humans. In a process called somatic cell nuclear transfer, the nucleus (which contains DNA) from a skin or muscle cell is injected into an unfertilized egg that has been emptied of its own genetic material. The egg is then induced to divide and produce an embryo that's genetically identical to the donor. In reproductive cloning, the embryo would be implanted in a womb to produce a baby. In therapeutic cloning, the DNA would come from a patient, and embryonic stem cells would be harvested to repair the patient's damaged organs or tissues. This approach has the potential to cure currently untreatable diseases, and there would be no risk of rejection since the stem cells are genetically identical to the patient.

Current Laws and Policies

Almost all countries with laws on cloning have banned human reproductive cloning, but some permit therapeutic cloning. Currently, countries that permit regulated research into therapeutic cloning include the United Kingdom, Singapore, Belgium, Sweden, Japan, China, and South Korea. Countries that ban therapeutic cloning include Canada, Germany, and France. The United States does not currently have any laws regarding human cloning; although, there is serious opposition to reproductive cloning and much debate over therapeutic cloning. On March 8, 2005, the UN General Assembly adopted a non-binding declaration that "prohibits all forms of human cloning inasmuch as they are incompatible with human dignity and the protection of human life." The wording is ambiguous enough that member nations can decide whether or not therapeutic cloning, which aims to cure patients and thus protect human life, would be prohibited. Moreover, the declaration's provisions were only agreed to by 84 of the UN's 191 member states.

Countries are divided on what is acceptable in stem cell research, and how it should be financed. In Canada, Bill C-13: Assisted Human Reproduction Act (March 2004) prohibits reproductive and therapeutic cloning, making changes to human DNA that can be inherited, and the creation of human-animal hybrids and chimeras. The bill does permit medical and scientific research using stem cells, and unwanted embryos created by fertility clinics may be used, but new embryos cannot be created for research purposes.

In the United States, a presidential declaration exists which limits federal funding to researchers using stem cell lines created prior to August 2001. Only 22 of these stem cell lines are available, and these old cell lines are difficult to use for human therapy, since they are more likely to become cancerous, and some may have been contaminated. Certain states have enacted their own policies. In 2004, California passed Proposition 71, which pledged $3 billion for stem cell research over the next 10 years. In contrast, the federal government only pledged $25 million annually for stem cell research across the country.

The United Kingdom supports regulated stem cell research and therapeutic cloning, and policymakers have shown a willingness to consider scientists' requests. During the 2006 Review of the Human Fertilisation and Embryology (HFE) Act, researchers petitioned the government to extend the common 14-day limit on embryos to at least 20 days, but were unsuccessful. In January 2008, two teams obtained government permission to create a specific type of animal-human hybrid, or "cybrid" embryo. These embryos would be created by fusing human DNA with a cow or rabbit egg that had been stripped of its genetic material. The researchers hope to create cybrids with 99.9% human DNA, which can produce fully human embryonic stem cells. Cybrids are being investigated because animal eggs are much easier to obtain than human ones, and may speed up the research process.

Singapore is often seen as a haven for stem cell research, because the country offers generous research funding, actively recruits foreign scientists, and has liberal laws on stem cell research. In June 2002, the country's Bioethics Advisory Committee published 11 recommendations regarding stem cell research and cloning. Many of the recommendations are similar to those adopted by the UK and Canada.

Where Do We Go From Here?

Whether or not an embryo should be considered a human being is at the heart of the stem cell controversy, and it is a fundamental difference of belief that cannot be resolved. One option is to ban all research that requires human embryos, but while adult stem cells are a promising avenue of research, most scientists argue that they probably cannot replace embryonic stem cells since they do not have the same capabilities. Another option is to permit embryonic stem cell research, but to take steps to minimize the ethical concerns. Whenever possible, existing embryonic stem cell lines should be used rather than creating new ones. In the case of embryos created for fertility treatments, embryo adoption should be the first priority. Only embryos destined for destruction should be used for research, preferably with the consent of the genetic parents.

Another important question is which groups should be involved in the creation of public policy. Interested parties include politicians, researchers, medical professionals, bioethicists, patients who may benefit from potential therapies, lobby groups, religious leaders, investors, and the public.

Laws and guidelines regarding stem cell research not only need to regulate existing practices, but must also guide future developments. In order to accommodate rapid changes in science and technology, periodic reviews of legislation are necessary. Regulations must strike a balance between giving researchers freedom to work and banning dangerous or unethical practices. Where that balance lies may be different for each country. However, scientific knowledge cannot be contained by borders, and once a discovery is made, it will be known and potentially duplicated by other researchers around the world. If we want to regulate stem cell research and human cloning effectively, binding international laws will need to be established and enforced.

Stem cell research is expanding the boundaries of medical and scientific knowledge. Regulating its development will test our ability to make wise decisions in the face of conflicting values and viewpoints.

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