Seeing Through False Arguments For
Embryonic Stem Cell Research
Revised for clarity from a lecture delivered to The Bradley Institute at Belmont Abbey College, March 25, 2009.
On March 9, 2009, President Barack Obama brought stem cell research back into the news. He signed an executive order expanding government support for embryonic stem cell research (ESCR). Shortly afterwards, a family member emailed me to say he was greatly conflicted about the issue. On the one hand, stem cell research has great potential, but on the other, we all started as embryos. So is it right to destroy something we all came from to further scientific research? My relative and I did not exchange further emails and the headlines moved on, but I am sure he still thinks about the issue from time to time. Perhaps he feels as if he cannot understand the science; I certainly had to think back to high school biology as I prepared this lecture. However, with some effort, I did learn enough stem cell science to understand the issue, and in the first part of this lecture I am going to help you understand it too; in the second part, I will argue against ESCR; finally, I will suggest how Christians might think about this issue theologically. It is my hope that this address will invite non-Christians to consider the Christian point of view rationally.
Some Basics About Stem Cell Research And Policy
A little history shows that stem cell research has become a part of our social fabric by the same steps that other scientific research has: Discovery is followed by dreams of social benefits, and if subsequent ethical deliberation and debate lead to social acceptance, the government provides financial support. The medical use of stem cells began by accident in 1968 with the first successful bone marrow transplant. Twenty years later, biologist Irving Weissman discovered that the transplants worked because bone marrow contains stem cells. Stem cells can maintain their populations by cell division over decades and can develop into other types of body cells. There are three naturally-occurring kinds of stem cells (see below) and, since 2007, one man-made kind called “induced pluripotent stem cells.”
1. “Totipotent” stem cells (meaning their potential is total) can develop into any type of body cell and/or produce a new individual. (Totipotent stem cells can even produce two new individuals e.g. identical twins are formed when an embryo splits into two halves about eight days after fertilization.)
2. “Pluripotent” stem cells can develop into any type of body cell, but cannot produce a new individual. (Embryos, which are formed from totipotent stem cells, contain both pluripotent and multipotent stem cells.)
3. “Multipotent” stem cells, commonly known as “adult stem cells,” can develop into only a few types of body cells. (Our bone marrow contains multipotent stem cells that develop into our red cells, platelets and germ-fighting white cells.)
Although scientists did not realize it in the 1980’s, many adult tissues, such as brain, skin, muscle, blood, blood vessels, teeth, liver, heart, reproductive organs, and even fat contain small numbers of multipotent stem cells. Once biologists like Weissman recognized stem cell properties, they naturally imagined using them to develop therapies, to test drugs, and to conduct basic research into the beginning of life. With these great social benefits in mind, as well as hope for achieving scientific renown, scientists turned to government and capital markets to fund what appeared to be very promising research.
In 1993, Congress allowed the National Institutes of Health, which it sponsors, to conduct research on human embryos for the first time. Ethical concerns arose on all sides. A year later, President Clinton prohibited the use of federal funds to create human embryos formed by fertilizing a human egg. Nonetheless, he allowed funding experiments on “spare” embryos from in vitro fertilization, better known as IVF. IVF is used to help infertile couples have children by uniting their sperm and eggs in a petri dish. To maximize success rates and lower costs, IVF clinics typically create five to 10 embryos, implant some in the mother’s womb and freeze the others. When the couple decides not to have any more children, the remaining embryos become “spares.” The number of “spare” embryos in the U.S. as of 2009 is usually estimated to be in the hundreds of thousands. Although the Clinton Administration permitted funding research on “spares,” Congress eliminated the funding in 1996 with the Dickey Amendment to the federal budget. The Dickey Amendment, which is still the law today, made it illegal for federal funds to be used to create or destroy human embryos.
Two major discoveries in the late 1990’s led scientists and other high profile figures to pressure the government to fund human embryonic research; Englishman Ian Wilmut cloned Dolly the sheep and two other researchers “isolated” stem cells from fertilized human embryos. Since isolating stem cells means removing them from the embryo and placing them in a laboratory container, the process actually destroys the embryo, which the terminology fails to communicate. The stem cells are then “expanded,” meaning they are allowed to divide many times, creating “stem cell lines” that can be used indefinitely for research purposes. The discovery of embryonic stem cells generated some of the most absurd hype in recent scientific history. Tall tales about disabled rats walking again raised expectations that therapies would soon be within reach. To their credit, some scientists corrected such predictions, but there are still plenty of bogus stem cell therapies out there on the Internet.
Just before September 11, 2001, President George Bush found himself sandwiched between scientific pressure to fund research on human embryos and moral objections to destroying them. In response, he issued a controversial executive order that allowed federally-funded research on existing embryonic stem cell lines, but prohibited the use of taxpayer money to create new embryos or destroy existing ones. This compromise position was attacked from both sides. On the one hand, he was accused of adhering to anti-scientific religious ideology. On the other, he was vilified for condoning the past destruction of embryos and for abandoning the principle that government should not be involved in research that destroys human embryos. Congress tried to overturn the Bush policy, but President Bush vetoed that legislation, and in 2007, he issued another executive order encouraging the funding of research that was already underway to develop ethical alternatives to human embryonic stem cells.
That same year, scientist Shinya Yamanaka delivered the best ethically justifiable alternative to date, induced pluripotent stem cells, mentioned above as the only man-made type of stem cell. Induced pluripotent stem cells function like embryonic stem cells, yet are obtained without destroying any embryos. Here is how it works. Scientists already knew how to make a stem cell differentiate into a specific body cell, but Yamanaka ran the process in reverse, taking tissue cells back to a pluripotent state. The process typically uses skin cells instead of embryos and thus poses no ethical problems. Yamanaka’s own ethical concerns guided his scientific interest, as he explained in the New York Times: “When I saw the embryo, I suddenly realized there was such a small difference between it and my daughters…’I thought, we can’t keep destroying embryos for our research. There must be another way.’”
Using induced pluripotent stem cells is not only ethical, but also safer for the patient. A therapy developed from a patient’s own body cells will not be rejected by that patient’s immune system. Adult stem cell therapy already works because it uses the patient’s own cells. In fact, by 2009 adult stem cell therapies had already produced treatments for at least 60 diseases. For example, doctors rebuilt a woman’s trachea and grew an exact replica of a man’s thumb bone. By contrast, embryonic stem cell therapies could be rejected for the same reason that an organ transplant is rejected; the cells come from someone else’s body.
Even though induced pluripotent stem cells now constitute a realistic alternative to embryonic pluripotent cells, scientists must make them safe for a patient’s body. Early attempts to produce induced pluripotent stem cells used viruses to activate the process of de-differentiation to a pluripotent state, but that method created an unacceptable number of tumors. It is important to note that all pluripotent stem cells, whether induced or embryonic, can cause tumors. In and of itself, the fact is not an argument against induced pluripotent stem cells. In practice, the risk of tumor growth may be greater with induced pluripotent cells because a patient’s immune system sees induced pluripotent stem cells as “self” and does not reject them. Scientists then discovered they could use plasmids, which do not affect the patient’s DNA, and hence cannot produce tumors. But there is another problem. The process begins with an “old” cell and involves many intermediate steps, which increases the likelihood of genetic abnormalities. To address this problem, scientists developed tests to distinguish defective stem cells from healthy ones.
To summarize, induced pluripotent stem cells constitute an ethical alternative because they provide scientists with the functional equivalent of embryonic stem cells without destroying embryos. Moreover, unlike embryonic stem cells, they provide therapies that avoid the dangers of immune rejection. Finally all pluripotent cells, whether induced or harvested from embryos, form tumors when injected into a body. These last two issues, rejection and tumor formation, constitute serious technical obstacles to the use of embryonic stem cells for therapy. Adult stem cell research, on the other hand, is not only free of such obstacles, but by 2009 had already produced therapies for over 60 diseases. We have heard that a lack of federal funding has delayed embryonic stem cell therapy, but it seems quite reasonable to ask whether technical obstacles explain the disparity better than stem cell politics.
The tendency of pluripotent cells to form tumors is quite instructive because it underscores an obvious fact: The human body converts stem cells to body cells more effectively than any scientific technique. The press often refers to embryonic stem cells as the “gold standard” of stem cells because they can differentiate into any cell in the body. Unfortunately, they are also more likely to form tumors than adult stem cells, so if the regeneration of human tissue is the primary social benefit of stem cell research, adult stem cells appear to come closer to the “gold standard.”
However, there are at least two technical difficulties that have been associated with adult stem cells. First, any single adult stem cell can be coaxed into becoming one of several different tissues, but it does not possess the biological capacity to become any cell in the body. Science may provide a solution to this problem by, for example, compiling a ’library’ of the different types of adult stem cells in the body, which could then be used to generate all of the body’s tissue cells. Scientists are already discovering that adult stem cells are more pliable than previously thought and even exhibit pluripotency. For example, one type of bone marrow stem cell can generate most tissue types and heart tissue; pancreatic stem cells can generate muscle cells or neurons. Second, adult stem cells are more difficult to locate than embryonic stem cells, and extraction can require invasive procedures. If extraction does prove difficult, however, induced pluripotent stem cells can be produced in abundance from a bit of the patient’s skin.
Sadly, President Obama’s executive order in March 2009 expands embryonic stem cell research while neglecting other types of stem cell research. First, this order permits funding of ESCR “to the extent permitted by law.” The Dickey Amendment currently prohibits federal funding for the creation or destruction of human embryos, but there is clearly a powerful lobby to eliminate that amendment. President Obama placed no limitations of his own on research using embryos, leaving the issue to Congress. Second, the President’s order also needlessly revokes George Bush’s order from 2007 encouraging ethical alternatives to ESCR and gives no reason why. Thus the Obama policy directs federal money away from ethical alternatives and toward ESCR, which is not only morally controversial but also at present less effective for regenerative therapies.
Although I am not a social scientist, allow me to suggest some possible consequences of President Obama’s policy. Now that our government has expanded its support for ESCR, there is increased pressure on that research to produce stem cell therapies. In order to produce those therapies, ESCR must overcome the immune rejection problem I explained earlier. That would be possible if the embryo destroyed to create the therapy was genetically identical to the patient. A method called therapeutic cloning, or somatic nuclear cell transfer (SCNT), creates an embryo that is identical to an existing person by inserting a nucleus from that person’s body cell into a human egg. Creating an embryo for research or therapy is called “therapeutic cloning,” and creating a child with the same genetic profile as a specific individual is called “reproductive cloning.” In his remarks presenting the new policy, President Obama allowed therapeutic cloning, but repudiated reproductive cloning, although both procedures create exactly the same thing: a human embryo. Our government is still developing its policy on therapeutic cloning, which would enable scientists to create a custom-made embryo from a specific individual, and then kill that embryo within a certain length of time, for example 14 days, in order to create regenerative therapies that would not be rejected by that patient’s immune system.
There is a more disturbing possibility. If stem cells differentiate better in the body, why not extend the 14-day life limit of a custom-made embryo to, say, two months. Plenty of scientific studies have shown, for example, that kidney cells from a fetus quickly form kidney cells in an adult. Does this proposal sound outlandish? The popular columnist William Saletan made this argument back in 2005. It is called “fetal farming.” Perhaps such a gruesome industry will never develop. Perhaps the source of embryos will be limited to IVF clinics, which may start producing 10 to 15 “spare” embryos to meet the increased demand, instead of just five to 10. Would the Obama Administration be able to regulate all that? What about the ethical alternatives?
Creating induced pluripotent stem cells from tissue cells goes a long way towards resolving the ethical problems of killing embryos in the name of research. But even if these ethical alternatives cannot be developed, ESCR would still not be justified. I know that many people do not agree. Perhaps they might say that I, as a theologian and not a scientist, should get out of the debate. As a theologian, a citizen, and most importantly, a human being, I am responsible for forming a moral judgment regarding the social practices of our time. I hope that you will eventually agree with me that embryo destructive research should be banned. But I will count this address as a success even if, by just helping you to understand the issues, I have contributed to the debate.