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Stem Cells Explained


Columbia Staff

To help readers better understand stem-cell research and to address common misconceptions, Columbia interviewed Dr. David Prentice, an internationally recognized expert on stem cells and cloning. A doctor of biochemistry, Prentice was selected by the U.S. President's Council on Bioethics to write their comprehensive review of adult stem cell research in 2004. He is also a founding member of Do No Harm: The Coalition of Americans for Research Ethics and senior fellow for life sciences at Family Research Council.


Columbia: What are stem cells and what are the different types?

Prentice: Stem cells have two chief characteristics: They continue to grow and divide so there is always a pool of cells available, and they can change into any of the various tissues of the body.

There are, at present, three types of stem cells. Embryonic stem cells come from young embryos about a week after conception, and you have to destroy that young life to extract them. Besides the obvious ethical problem, they also like to grow and try to make all the tissues at once. The end result is that after 30 years of research with embryonic stem cells — first with mice and then with human embryonic stem cells — researchers still cannot control their growth. The cells tend to make tumors when injected into the lab mice. There are problems with transplant rejections and with forming mature, functional tissues. From a practical level, they are not very good cells for clinical treatments.

The second type is adult stem cells. We are born with them and continue to have them in all of our tissues and organs. They are also in umbilical cord blood and in the placenta. There is no ethical problem with adult stem cells — you don't have to harm the donor. For several decades, adult stem cells have already been proven to repair and replace damaged and diseased tissues. They have been used for many treatments over the last five or 10 years, including spinal cord injury, juvenile diabetes, heart damage and dozens of other conditions.

Finally, there is a newer type of stem cell, a somewhat intermediate type. The technical term is induced pluripotent stem (iPS) cells. They are made by taking a normal cell, such as a skin cell, and adding a few genes that reprogram how that cell behaves. They look and act like embryonic stem cells, but they can be obtained ethically for laboratory studies. There are no embryos, no women's eggs and no cloning techniques involved.


Columbia: How many adult stem cell treatments are currently being used?

Prentice: There are at least 73 that have been verified by published scientific evidence, and there are probably close to 80 now. There were, at last count, more than 50,000 patients around the globe who receive adult stem-cell transplants every year.


Columbia: How much funding and effort is put into adult stem-cell research as opposed to embryonic stem-cell research?

Prentice: From the federal government there is more adult stem cell money than there is embryonic, although that is changing. Embryonic research, over the last nine years, has received more than half a billion federal taxpayer dollars, and its rate of increase is much steeper in terms of federal support. Most adult stem cell funding is not going toward the newer studies and clinical trials for things like heart disease, stroke and diabetes. Some states have poured billions of dollars into embryonic stem cells, whereas there is not nearly as much going to adult stem-cell research.


Columbia: Why is there so much focus on embryonic stem cells?

Prentice: I think the obsession with embryonic stem cells is primarily ideological and economic. It is perhaps interesting science for some people, but it is very expensive science. It has been sold to the public, as well as to legislators, with promises of all of the cures and the eventual economic return that will come, but essentially it is like selling snake oil.


Columbia: Why would there be more of an economic motive in embryonic than adult stem cells?

Prentice: You can patent embryonic stem cell lines. Everyone that is interested in embryonic research wants to have their own line of embryonic stem cells that they can patent and then reap the profits. Even if no treatments ever happen, any scientist or company that wants to work with those cells has to pay a licensing fee. It becomes a moneymaker simply to destroy embryos, grow the cells and then market those cells for more basic lab studies.



Columbia: How do laws and treatments in the United States regarding stem-cell research compare to those overseas?

Prentice: In the United States, at the federal level, there is no legal restriction for embryonic research or even for cloning. In some countries, such as Italy, it is against the law to destroy a human embryo, whereas there are very liberal laws in other countries, including the United Kingdom and China.

America is behind in terms of adult stem cell research and treatments. Germany, which since the early 1990s has prohibited destruction of a human embryo, is one of numerous countries around the world leading in terms of new adult stem-cell treatments. In fact, some U.S. scientists first did their adult stem-cell treatments in other countries because they could not get the funding or the interest in the United States.


Columbia: Are there any other big challenges facing adult stem-cell research?

Prentice: Because the media will often just say "stem-cell research" without using an adjective, people automatically assume they are talking about embryonic. Those who support embryonic stem-cell research then claim that the "other side" is against research of any kind. But we support adult stem cells. We support anything that does not harm or destroy human life. We support real science. Embryonic stem-cell research is an obsolete science and an unethical science. The sooner we leave it behind, the better.