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Questions and answers on issue of stem cell research
archived from: 2007-01-17

Stem cells are once again in the headlines. Similar to many previous reports from those detailing the effective use of stem cells ethically derived from adult and post-natal sources, scientists from the Institute for Regenerative Medicine at the Wake Forest University School of Medicine reported Jan. 7 that amniotic fluid is rich in flexible stem cells (can mature into all of the major types of cells) that could be used to treat a variety of diseases. A story on the study appeared locally, and although the first part of the story treated the report as novel, the truth is that stem cells from post-natal sources (including amniotic fluid) have been providing positive results for years.

This newest study comes as members of the 110th Congress have announced they will make the funding and support of embryonic stem-cell research a priority for their legislative agenda, despite the decades of positive research with practical application that has taken place through the use of adult stem cells. They hope to pass legislation in January that funds and supports the unethical and destructive research in embryonic stem cells.

Because successes in adult stem-cell research are frequently depicted merely as stem cell research, many falsely believe that without supporting and funding embryonic stem-cell research the future of stem cell medicine would cease to exist or succeed. Clearly, the issue of stem cell research is misunderstood. Below is a brief series of questions and answers to aid you in understanding this important issue and its implications for the future of medicine.

What is a stem cell?

A stem cell is essentially a cell that is capable of regenerating and becoming one or more differentiated cell types of the body.

Why are stem cells important?

Stem cells are used to replace or heal damaged tissues or cells in the body.

How many sources of stem cells are there and how are they harvested?

The two broad classes of stem cells are defined by their origin: embryonic stem cells and adult stem cells.

Where do embryonic stem cells come from?

Embryonic stem cells and embryonic germ cells are harvested from living human embryos very early in life. The process of harvesting those cells kills the human embryo.

Where do adult stem cells come from?

• Umbilical cords, placentas and amniotic fluid: Adult-type stem cells can be derived from various pregnancy-related tissues.

• Adult tissues: In the human body, stem cells are present within various tissues and organ systems and can be resourced without adverse effect to the donor. These include bone marrow, liver, epidermis, retina, skeletal muscle, intestine, brain, dental pulp and elsewhere. Even fat obtained from liposuction has been shown to contain significant numbers of adult-type stem cells.

• Cadavers: Neural stem cells have been removed from specific areas in post-mortem human brains as late as 20 hours following death.

After more than 20 years of research, what is our understanding of how embryonic and adult stem cells compare?

Adult stem cell advantages:

1. No harm done to donor.

2. Adult-type stem cells have proven to be significantly more flexible than originally anticipated, and various stem cells can be differentiated into other needed cell types (e.g., bone marrow donor stem cells have been morphed into bone marrow, bone, cartilage, tendon, muscle, fat, liver, nerve/brain and blood cells).

3. Cells from pregnancy-related (post-natal) tissues contain useable stem cells in abundance. These cells have been differentiated successfully into numerous other cells and have yielded treatments or therapies that are beneficial to humans.

4. Not immunogenic: Recipients of adult stem-cell treatments and therapies often receive the products of their own stem cells and, therefore, do not experience immune rejection.

5. Relative ease of procurement: Some adult stem cells are easy to harvest (skin, muscle, marrow, fat), while others may be more difficult to obtain (brain stem cells). Umbilical and placental stem cells have proven to be readily available.

6. Non-tumorigenic: Tend not to form tumors, unlike embryonic stem cells, which are highly tumorigenic.

Adult stem cell disadvantages:

1. Limited quantity: Can sometimes be difficult to obtain in large numbers from the human body. Exception note: Stem cells from pregnancy-related tissue are available in abundance.

2. Finite: May not live as long as embryonic stem cells in culture.

3. Not infinitely flexible: Despite ongoing successes with related cell type differentiation, already differentiated stem cells in the human body cannot become every cell type. Exception note: This disadvantage is not true of stem cells from pregnancy-related tissues, which are very flexible.

Embryonic stem cell advantages:

1. Flexible: Because, in the natural growth and development process, embryonic stem cells give rise to all the differentiated cells in the human body, it has been hypothesized that scientists can coax these cells into becoming any desired cell type. However, to date, attempts have been wholly unsuccessful.

2. Immortal: One embryonic stem cell line potentially can provide an endless supply of cells with defined characteristics.

Embryonic stem cell disadvantages:

1. An innocent human life is destroyed in the process of harvesting the stem cells.

2. It is extremely difficult (if not impossible) to differentiate embryonic stem cells uniformly and homogeneously into a target tissue.

3. Availability is an issue as embryos would have to be provided from in vitro fertilization clinics or created through a cloning process.

4. Immunogenic: Embryonic stem cells from a random embryo donor are likely to be rejected after transplant.

5. Tumorigenic: Embryonic stem cells are likely to form tumors or promote tumor formation.

Why are adult stem cells preferable to embryonic stem cells?

Adult stem cells naturally exist in our bodies, and they provide a natural repair mechanism for many tissues of our bodies. They belong in the microenvironment of an adult body. On the other hand, because embryonic stem cells belong in the microenvironment of the early embryo, when they are used in an adult body they tend to cause tumors and immune system reactions.

Most importantly, adult stem cells already have been successfully used in numerous treatments and therapies that benefit humans for many years. To date, no therapies in humans have been successfully carried out using embryonic stem cells. New therapies using adult stem cells, on the other hand, are being developed all the time. Currently, adult stem-cell therapies provide benefit to humans suffering from 72 diseases and conditions. One doesn’t need to look very far to see the many examples of success stories using adult stem cells.

What is the best course of action for future stem cell medicine?

There is, without a doubt, urgency to this issue for so many who are waiting for cures to debilitating diseases. The efforts and resources of our scientific community should focus on those ethical avenues of research that are proving so effective at alleviating symptoms and curing diseases and injuries. It would be a mistake to continue to foster false hope or waste time and money by supporting the ineffective and unethical practice of embryonic stem-cell research.

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