Stem Cell Culture

It is a fascinating commentary on our times that a political candidate’s position on a matter relating to cell biological research may be the determining factor in an election. By some counts, at least seven seats in the U.S. House of Representatives this fall hinge, in large measure, on the issue of human embryonic stem cell research.

With high-profile celebrities like Michael J. Fox, Nancy Reagan, Mary Tyler Moore, and the late Christopher Reeve having given their support to the cause, the scientific community is pushing hard to have current restrictions on human embryo research lifted.

In January, Nobel Laureate Paul Nurse, who is the president of Rockefeller University and a highly influential scientist, wrote an opinion piece entitled, “U.S. Biomedical Research under Siege,” in which he expressed the frustration of many in the scientific community. One of Nurse’s concerns is that “the present political leadership and certain influential parts of society appear to have little understanding of, or respect for, science” (Cell 124, 2006).

What is the evidence for this claim? According to Nurse, opposition to human embryonic stem cell research is a major indication that “certain influential parts of society” (aka Christians) do not respect or understand science.

Could this be true? Is the only reason a person would oppose research with human embryos because he or she is ignorant in matters of science? My contention is that resistance to research of this sort is the expected consequence of applying biblical ethics to a proper understanding of the science. The purpose of this article is to help Christians grasp the basics of the science of human stem cell research and then to evaluate the science from a biblical perspective. I will also discuss the current status of the political debate on the issue and suggest ways that Christians should respond to the current situation.

Stem Cell Biology

Your body is made up of trillions of cells that are specialized into over 200 distinct varieties. This incredible diversity of cell types originates with a single cell—the fertilized egg. During the process of development, this single cell divides into many other cells, which themselves multiply and become specialized into various organs and tissues. As cells become more specialized, they lose the potential to become other types of cells.

Scientists speak of certain types of cells within our bodies as stem cells because they remain in an unspecialized state, have the ability to divide indefinitely, and have the potential to become various specialized cells. For example, stem cells found in bone marrow can produce cells that specialize into red blood cells as well as numerous types of white blood cells.

The two qualities of stem cells that have made them attractive as potential therapeutic agents are (1) their ability to divide and replenish themselves indefinitely, and (2) their ability to mature into a variety of different specialized cell types. The hope of what is now called “regenerative medicine” is that stem cells can be used to replace cells that have been damaged by disease or injury in cases where the body is not normally able to repair itself.

In theory, doctors would isolate stem cells and then grow them in laboratory cultures to get massive quantities. These stem cells would be treated with growth factors that would induce them to specialize into heart muscle, for example. These heart muscle cells would be delivered to a patient’s heart in an effort to replace tissue damaged by a heart attack. The same concept could be used to treat patients with leukemia, diabetes, Parkinson’s disease, Alzheimer’s disease, ALS (Lou Gehrig’s disease), spinal cord injuries, and a host of other conditions.

While the goal of this type of treatment is laudable, the means of achieving it have sparked much controversy. The problem lies in the source of the stem cells used for treatment. There are several sources of stem cells in the human body in its stages of development. During embryonic development, the few cells from which the entire body will form have tremendous potential to become other cell types. Stem cells taken from embryos are referred to as embryonic stem cells (ESCs). ESCs are considered “totipotent,” meaning that they have the potential to become all of the other cell types in the body.

The other major sources of stem cells do not involve the embryo and so are called adult stem cells (ASCs). ASCs can be found in many tissues within the body including bone marrow, peripheral blood, liver, nerve, fat, intestine, skin, muscle, eye, and others. Umbilical cord blood and placenta are also sources of stem cells that do not derive directly from the embryo and so can be classified as ASCs. ASCs are considered to be “pluripotent” or “multipotent,” which means that they can be induced to become most of the different cell types in the body (pluripotent) or a few of the cell types (multipotent). Using ASCs in research has not been contentious because these cells can be collected without destroying an embryo. ESCs, on the other hand, cannot be retrieved without destroying an embryo and are thus highly controversial.

Embryonic Stem Cells

In 1998, researchers at the University of Wisconsin first reported that they had successfully isolated human ESCs and grown them in laboratory culture. To isolate and grow ESCs, researchers take a human embryo that is five to seven days old and break it open. An embryo at this stage is called a blastocyst. It is essentially a hollow ball of approximately 100 cells. The cells forming the ball are called the trophoblast and are designed to become the connections between the mother and developing baby. Inside the ball there are a few dozen cells that will actually develop into the baby. This inner cell mass contains the totipotent ESCs.

To get to these cells, researchers have to break apart the outer ball of cells and tease out the ESCs, thus destroying the embryo. The ESCs are then transferred to culture dishes where they grow into thousands of cells. If the scientists can get the ESCs to continue growing indefinitely in the culture dishes, they have created a new ESC line. Theoretically then, these cells could be grown up and induced to become various specialized cells that would be used to treat disease (see Figure 1).

The hypothetical advantages of ESCs are their ability to transform into any cell type (totipotency) and the ease of maintaining and expanding them in culture. The reality has been far different. In addition to the serious ethical problems of creating ESC lines, researchers have had trouble from a technical side. It turns out that ESCs are finicky growers and have been difficult to maintain as pure cultures. ESCs may also suffer from having too much unguided potential, since they often form tumors by growing out of control when implanted in a host. Immune system rejection has also been a problem with ESCs, creating a situation where immunosuppressing drugs are required for the recipient to tolerate the cells.

The technical hurdles with ESCs have been so great, in fact, that not a single medical success or even a clinical trial has been reported. At this point, ESCs are used in mice and other animal systems but not in humans.

Adult Stem Cells

In contrast, research with ASCs has been much more successful to date. Despite the drum beat of the celebrities, the media, and some segments of the scientific community arguing that ASCs are incapable of doing what ESCs can do, the reality has been that ASCs are fairly easy to obtain and capable of transforming into a wide range of specialized cells. In fact, ASCs have been used in actual treatments of over 60 different human diseases. These include more than 15 different cancers as well as multiple sclerosis, arthritis, lupus, anemia, osteoporosis, heart damage, stroke, Parkinson’s disease, and spinal cord injury.

Let me be quick to add that these treatments are all experimental in nature and are a long way from becoming standard treatments. But the fact remains that work with ASCs to date has shown much more promise than anything done with ESCs (see http://www.stemcellresearch.org/ for an extensive list of references).

The advantages of working with ASCs are significant. These cells can be harvested from the patient, grown up, specialized, and then put back into the same patient, thus eliminating the issue of tissue rejection. Certain types of ASCs, like umbilical cord blood cells, are adaptable to the immune system of the host and are less prone to rejection even when used in treating people other than the donor. The tremendous success of cord blood stem cells in treatment has recently led to the establishment of a national registry of donated cord blood. In addition to the technical advantages of using ASCs in treatment, they can be used without the highly controversial moral concerns that surround the use of ESCs.

What About Cloning?

Partly out of a desire to find alternatives to procuring ESC lines from unwanted embryos frozen in fertility clinics, and partly out of a desire to solve the problem of tissue rejection when using ESCs to treat disease, some scientists are interested in developing a technique called somatic cell nuclear transfer (SCNT) to generate new ESC lines. SCNT differs from normal fertilization in that all of the genetic material in the embryo comes from only one parent. A somatic cell is any cell in the body that has a full set of 23 pairs of chromosomes (this is essentially all the cells except sperm and eggs).

To create an embryo by SCNT, a somatic cell (usually a skin cell) is taken from one individual and fused with a donated egg that has had its genetic material removed. The egg has the resources needed to support the development of the new embryo but no DNA of its own. The somatic cell contributes all the genetic material. When this egg, which now contains the somatic cell genetic material, is pulsed with an electrical current, it starts to divide like a normal embryo. This embryo is a genetic clone of the person who donated the somatic cell.

What would happen if we put this embryo into a surrogate mother, who had been prepared with hormone treatment to carry a baby? Potentially, the embryo would develop into a human clone of the original somatic cell donor. If the somatic cell donor was a man, the clone would be a man. If the donor was a woman, the clone would be a woman.

This process, which is sometimes referred to as “reproductive cloning” has not been done with human beings and is, in fact, illegal in much of the developed world. This process has been successfully done in a number of different mammals, beginning with Dolly the sheep in 1997 and including mice, pigs, cows, dogs, and horses. The scientific community in the U.S. is largely opposed to cloning to create babies, because it is too dangerous to the clone. Based on the work already done in animals, only 1 to 3 percent of cloned embryos actually survive to be born, and once they are born they have many abnormalities. Ian Wilmut, the scientist who cloned Dolly the sheep, has said, “There are no normal clones.”

But what if we use the process of SCNT to create an embryo clone of our somatic cell donor and, instead of putting that embryo into a surrogate mother, we break the embryo apart and isolate the ESCs within? This would, theoretically, allow us to use the resultant ESC line to treat a disease in the somatic cell donor without the problem of tissue rejection. This process, which scientists are careful to distinguish from reproductive cloning, is called, “therapeutic cloning” (see Figure 2).

Therapeutic cloning of human embryos is legal in most places but has not yet been successfully done in humans. South Korean researcher Hwang Woo-Suk claimed to have been the first to successfully create ESC lines by SCNT, but his data have recently been shown to be fabricated. The scientific community finds itself in the inconsistent position of opposing reproductive cloning because it is too dangerous to the clone while at the same time supporting therapeutic cloning which always results in the complete destruction of the clone. There is a clear connection between cloning to produce a child and cloning to produce new ESC lines: They both involve using SCNT to create embryos that are clones of the somatic cell donor. The only difference in the techniques is whether the cloned embryo is broken apart and its cells harvested or is implanted in a surrogate mother in the hopes that a child will result.

Stem Cell Politics

To understand the current stem cell debate, one needs to know a little about the current law regulating this type of research. In 1996, an amendment to the bill that reauthorized National Institutes of Health (NIH) funding stipulated that no federal funding could be used to support research in which embryos were created or destroyed (this includes reproductive and therapeutic cloning). During the Clinton administration, NIH-funded researchers were allowed to circumvent the spirit of the amendment by using private or state funds to create new embryonic cell lines (a process that destroyed embryos) and then using the federal money to work on the resultant ESCs. In August 2001, President Bush, acting as the chief executive, changed the way the NIH bill was being enforced. He decided to allow federal funds to be used only on ESC lines that were already in existence at the time of his decision but not on any cell lines created after August 2001. Since NIH is the major source of funding for basic research in this country, spending upwards of $20 billion a year, the president’s decision effectively shut off the federal incentive for creating new ESC lines.

The current NIH policy has been very effective at funneling research efforts more into ASC research as well as ESC research that does not require additional embryo destruction. Congress has not outlawed destructive embryo research; it has merely decided that federal taxes will not fund it. As a result, several state governments (Calif., Conn., Md., and N.J.) have established ESC research initiatives, hoping to spark private, biotech investments in their states.

In May 2005, the U.S. House of Representatives passed a bill that would lift the restrictions on federal funding for creating new ESC lines. Early indications were that influential Republicans in the U.S. Senate would also support the bill. After a full year, the Senate has yet to debate the bill. With the threat of a presidential veto looming and the high political stakes involved, Senate Majority Leader Frist has been reluctant to bring the bill to the floor.

Proponents of ESC research have been turning up the pressure on Sen. Frist to allow the bill to come for a vote. There are several groups pushing for removing the restrictions on ESC funding. In addition to some well-meaning people who genuinely believe ESCs hold the greater promise for advances in human health, there are some groups with motives that are less pure. The pro-abortion crowd is committed to fighting any legislation that would recognize the embryo as having rights. Certain Democratic politicians have identified the stem cell issue as a potential “wedge” over which they may be able to split the Republican Party. Some segments of the scientific community are resistant to any legislation that slows down their research agendas. There is no question that the pressure to expand destructive embryo research is going to intensify.

A Christian Perspective

Hopefully you have been repulsed by much of what is going on in this field of research. The Scripture is clear that human beings are made in the image of God and, therefore, have dignity and value based inherently on who they are (Gen. 1:26-27; 9:6). The Bible treats human beings as human beings regardless of whether they are young or old, in the womb or out, perfectly formed or handicapped. For example, David writes that God formed him and knew him while he was still in his mother’s womb (Ps. 139:13-16). The idea that God is relationally involved with His people even while they are developing in the womb has strong support in Scripture (see Jer. 1:5; Ps. 71:6; Rom. 9:10-13; and Luke 1:41-44).

God says that it is wrong to take innocent human life (Ex. 20:13). There is no scriptural warrant for the idea that at some stages of its development human life is expendable or to be treated like a commodity to be used for the benefit of others. In the absence of compelling scriptural data to the contrary, we must infer that human life begins at conception (or activation of the embryo, in the case of cloning) when a unique human being has started to grow and divide.

It is very important that Christians understand that an embryo is human life in its earliest and most vulnerable form. An embryo is not a “prehuman.” Nor does it have value only because it has the potential to grow up to be an adult. One of the recent proposals for an “ethical” way to do ESC research is to use SCNT to create embryos that have fatal flaws in them (this is called altered nuclear transfer or ANT). Since the resultant embryos would never live to become babies, the logic goes, we could destroy them without the ethical concerns we might otherwise have. If Christians have made the mistake of saying the embryo has dignity and value only because of what it will become and not because of what it is, we will have trouble fighting against such defective logic. Our human dignity does not come from our potential or from our level of cognition but from being what God has made us.

Christians should be squarely against any research that requires the creation and destruction of human embryos, no matter how laudable the motives of those doing the research are. We are not to participate in evil that good may result. Our culture needs us to speak out against such evils. We must realize that science is designed to tell us what can be done. It has no mechanism for telling us what should be done. Science itself is not equipped to address the morality of destructive embryo research. An ethical system that stands outside of science must be used.

As Christians we have the only truly consistent ethical system that exists in the world. Society needs to hear our voice on this issue. We should be encouraging Congress to keep the current NIH funding restrictions in place, as well as pushing for a ban on all forms of research that create and destroy embryos. Even if there were no good alternatives to ESC research, we would be obligated to speak and work against it, but, in the present situation, our job is made easier because the encouraging results with ASCs give us a legitimate alternative to support while we express our opposition to the destruction of embryos for research purposes.

Christians also need to oppose research efforts to create man in our own image. Although most mainstream scientists do not support reproductive cloning, there is a growing subculture of people in our society who are very interested in manipulating the human genome in order to “improve” our species. Others view cloning as a means of achieving immortality. For people who do not know Christ, why not do everything possible to keep one’s DNA alive? We must be faithful to point out that our ultimate home is in heaven and that the only way to get eternal life is by the grace of God in Jesus Christ.

Conclusion

There is a great deal of confusion about the issue of stem cell research. My research has led me to believe that in some cases those interested in promoting destructive embryo research have intentionally tried to confuse the public in order to pursue their agendas. The use of terms like SCNT instead of cloning is just one of many such examples.

Now more than ever, Christians need to stay educated and active on these issues. Pay close attention to the news and respond when it is appropriate. Pray fervently that God would be pleased to have mercy on us and change our hearts. Try to persuade and educate those in your sphere of influence.

Ultimately only Christ can change our culture, but what will He say to us if we remain on the sidelines during the battle? “If you faint in the day of adversity, your strength is small” (Prov. 24:10).