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
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,
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.