The eve of Thanksgiving brought a truce to the stem cell wars. When two scientists, Shinya Yamanaka of Kyoto University and James A. Thomson of the University of Wisconsin, announced in separate papers that they had succeeded in creating embryonic stem cells from ordinary human cells, they laid claim to the holy grail of stem cell research -- a limitless supply of embryonic stem cells generated without destroying human embryos. This surprising success has set off a worldwide scramble among scientists to duplicate their results. If the results are successfully verified, scientific progress stands a chance of moving into the 21st century without the opposition of that nutty minority that thinks destroying a tiny clump of cells is too high a price to pay to save the human race.
Personally, I am encouraged, not in the least part because I have always been one of those nuts who opposed embryonic stem-cell research. But before we pop the corks and reserve Thomson and Yamanka tickets to Stockholm, let's take a breath. There are yet a few problems to overcome. Most importantly, the new technique uses a retrovirus to infect normal cells with four genes that convert them to stem cells. This technique could be dangerous, because these four genes sometimes insert themselves into regions of the host DNA that, when activated, trigger the infected cells to spontaneously convert to cancer cells. The good news is that most researchers are optimistic that this problem can be worked out. The bad: It may take a few years to do so. In the mean time, we are stuck like parents of a child who won't move out after graduation -- eventually we know the problem will end, but we can't say exactly when.
In my medical practice, I take care of many patients afflicted with illnesses that stem cell research may eventually help cure. Unfortunately, while all of them want a cure now, I have to tell them that they need to be patient. This is difficult advice to give because the proponents of stem cell research are proclaiming the opposite. Listening to them, one would conclude that the cure for every known disease is weeks away if only the power of the stem cell is unleashed. Not only is this untrue, but it tempts people to blur ethical issues that need not be blurred, and may encourage short-term moral compromises that we may not be happy with in the end.
But first a few facts. Embryonic stem cells are primitive cells that emerge very early after an egg is fertilized. An embryonic stem cell is completely undifferentiated, meaning that it has the ability to develop into any cell type found in the adult, be it brain, bone, or bowel. As biologists put it, an embryonic stem cell is a totipotential cell. (To keep our terminology clear, there is another common class of stem cell, the adult stem cell, which can differentiate into a few related tissue types but not every tissue type. Adult humans have adult stem cells throughout their bodies, but only embryos have the embryonic type.)
Embryonic stem cells have been the subject of intense interest since scientists successfully cloned a sheep in 1996. That event prompted speculation that scientists could use similar technology to manufacture large numbers of embryonic stem cells for medical purposes. These stem cells, the thinking went, could then be induced to differentiate into a cell type of interest, which then would be infused into a patient to replace cells damaged in a disease process. For example, in type 1 diabetes, when the beta islet cells of the pancreas fail, causing a drop in insulin and resultant high blood sugar levels, stem cells could replace the lost cells and hopefully cure the disease.
In a turn of events rather rare in public life, this arcane line of biological thinking has become a hot political topic. If stem cells can cure diseases, laypersons wondered, what are we waiting for? Let's spend all available scientific resources in this field! This vigorous response short-circuited the customary forums for medical discussion, and quotidian public events like elections, charity fund raisers, and even movie award shows have been expropriated by celebrities and politicians urging unabated stem cell research. And, as often happens when public figures try to summarize and espouse scientific theory, misconceptions abounded.
I will make room for two errors here. First, embryonic stem cells are not used in the treatment of any known human illness, and as of now are not proposed for any. This field is still in its infancy and its applications are not at all clear. Taking again the example of diabetes, scientists think it may eventually be possible to replace destroyed islet cells. What they don't know how to do is stop the disease process from destroying the replacements, too. Diseases are processes, and curing a disease is not often simply a matter of replacing damaged parts. Since we do not know what causes Parkinson's disease, or diabetes, or Alzheimer's disease in the first place, it is overreaching to say that embryonic stem cells are the cure. The usual medical pattern is: Find the cause of a disease, then treat it. The inverse -- treat the disease with stem cells, then discover the cause -- sounds rather absurd.
The second problem is, once we have an embryonic stem cell, what do we do with it? First we have to induce it to become the needed cell, and then, once we have managed this feat, we have to get it to the necessary location. Stem cells differentiate in the embryo via very complex and poorly understood processes. Just because we know that ectodermal cells differentiate into brain cells does not mean we can make that happen in a patient with Alzheimer's in the exact place we need a neuron replaced. This is an extremely complicated problem, and we are talking about decades of research before scientists pull this off -- if they ever do.
Aside from its huge technical challenges, stem cell research has been beset from the beginning with ethical objections. Until now, the only way to obtain embryonic stem cells has been to harvest them from fertilized human embryos, a process that kills the embryo. Many people, especially religious ethicists, object to the practice of intentionally fertilizing a human egg, potentially creating a human being, and then destroying it for research. A second ethical problem is that, if stem cells are ever to be used in human beings, the cells must come from a clone of the patient. Just as a person who gets an organ transplant must be tissue-matched to the transplant organ to prevent rejection, therapeutic stem cells must also be a match or the recipient's immune system will destroy the cells. Prior to the recent breakthrough, the only proposed method to generate large numbers of perfectly matched stem cells has been to clone the patient and harvest the stem cells from the clone. To put this ethical dilemma in perspective, consider that there are possibly a half a billion people in the world with diabetes. Imagine an enormous factory that clones human embryos by the tens of millions, one (or possibly several) for every person with diabetes. Destroying one embryo in a petri dish may seem unimportant, but the prospect of industrial-scale clone production should give most people at least momentary pause.
Defenders of stem cell research usually argue that the embryos used are "excess" embryos created in fertility clinics. These embryos, which cannot be used by anyone other than the parents, would have been destroyed anyway. As for the cloning issue, proponents generally ignore the issue altogether, often out of ignorance, but occasionally by saying that large scale stem cell therapy is many years away and we will cross that bridge when we come to it.
Neither one of these arguments convinces me. Though I have some sympathy for the argument that embryos are little more than a clump of cells, I fail to see how this excludes them from being human. In medical school I looked at many slides of mouse and chicken embryos, and no one ever called them pre-chicken or pre-mouse. A mouse embryo is mouse because it will one day grow into a mouse. It may not be recognizable as a mouse, but mouse embryos do not become dogs, or roosters, or humpback whales. In the same way, it is misleading to say that a human embryo is not a human yet. That is true if you define a human as having arms and legs and a beating four-chambered heart, but that is an arbitrary definition. If a human embryo is not human, what is it? It is certainly alive in the biological sense -- if a bacterium meets the biological definition of life than a four-celled embryo does also -- and if it is neither chicken, nor mouse, nor fish, nor bird, nor any other living creature on earth, it must, by process of elimination, be human. Maybe it does not feel pain or think, but it is certainly not ridiculous to call it alive and within the human category.
Which is why a significant number of people, myself included, have had qualms about stem cell research. As a medical doctor I have always thought one of principal ethics of life sciences should be respect for human life. (Remember First, do no harm?) I can understand that some people look upon a wad of cells about the size of a pixel on a flatscreen and wonder what the big deal is, but my view is that a foundational ethic has to be taken very seriously, or we will quickly get into a great deal of trouble. We become uneasy when our political leaders start quibbling about the definition of torture; perhaps we should be a little more thoughtful when scientists want to let the definition of human life slip a bit. I worry about the direction of science if it is willing to reclassify early-stage embryonic cells as pre-human not because good science supports such an observation, but because it allows us to continue our research with a clear conscience.
Is this a semantic argument? Are we simply applying words to an insignificant cell, and worrying ourselves unnecessarily? I think not. Labels may be a human convention, but they also allow us to think with greater clarity and precision. When we blur what we mean by life and human, we begin to siphon away any ability we have to place limits on what researchers do in the lab of the future.
Does this sound a little like the abortion debate? Yes, but with a major difference. While an abortion has a direct impact on the life of the mother and the fetus, stem cell research has no direct impact on an adult human life. Remember, the benefits of stem cell research are wholly theoretical, and could be decades away. The remoteness of the benefit only strengthens the argument that we should minimize the harm now.
Many of the people who take the full-speed-ahead approach argue that religious beliefs should be taken out of the discussion. If we are to do this, we still have to have ethical ground rules. I propose "Killing is wrong" as a reasonable starting point. I concede that this starting point does not solve the problem of embryonic research, but at least it allows us to escape the groundless "you're imposing your religion" complaint. Though religions do regard an embryo as human, science also recognizes the embryo as alive in a biological sense and human in the sense that it is not chicken or mouse. If we can agree to this much, the issue becomes how do we apply this knowledge -- a much more useful proposition than asking why we should even bother.
Proponents of stem cell research argue that their adversaries are nothing more than fundamentalist zealots who would rather see children die than give an inch in a debate. They often go on to roll up the stem cell nuts with those who believe evolution is an error and that criminal cases should be decided in deference to the Ten Commandments.
Yet this need not be the case. I believe fully in the validity of evolutionary theory, and support the separation of church and state. But embryonic stem cell research blithely glosses the reality that we are coming closer and closer to creating human life in the laboratory. Few seem to be concerned about that, as long as we benefit from the progress. This is tantamount to saying there should be no limit to how we tamper with human life as long as there is a payoff.
I frequently tell my patients that there are cures for many diseases, but there is no cure for mortality. Cure a person of diabetes and they will die of something else eventually. We cannot even be sure that the extra years gained will be happy ones. Of course we should try to relieve suffering (I would not be a doctor if I thought otherwise), but if there is any chance that scientific advances could cheapen our appreciation for life by ingraining the idea that it is acceptable to create life and destroy it for our own benefit, we need to approach the issue with much more seriousness than we have done so far.
Nor is this concern for the sanctity of life unique to conservatives. Strict vegans often believe that we should not eat animal flesh because we humans do not have the right to kill other animals for food. Though I am not personally a vegan, I can understand and respect the desire not to kill, even if such a change, carried out to its limit, would cause significant social upheaval (think of the many people, from cattle farmers to sausage makers to waiters at Outback Steakhouse, who would be out of work if no one ate meat). I find it difficult to understand how someone could admire the morality of a vegan, and then sneer at someone else who opposes stem cell research.
This long discussion seems moot with the new scientific discovery. Except that it is not. Yes, the particular problem of embryonic stem cell production may eventually be circumvented, but until the new techniques are perfected for laboratory use, the old methods will still predominate. More importantly, even if this conflict does go away, it goes away without resolution, or even fair discussion, of the underlying issues. If similar or related matters arise in medical research in the future (and I am certain that they will), we will go right back to the name calling.
No matter how the future plays out, we anti-stem cell nuts were right about one thing. We argued from the beginning that the embryo-destroying techniques need not be the only option, that there had to be a way to secure medical progress without killing embryos. Not only did there turn out to be a way, there turned out to be a way that avoided the embryo problem and also the human cloning issue we faced down the road. It was in part the obstinacy of the nuts that spurred scientists to find a new and better way. A new example of a very old maxim: Moral strictures drive people to find better ways. That is why I find the reaction some people have had to the new discovery -- thank God we don't have to deal with the nuts any more -- so disappointing. Even when moral thinking works people still find reasons to dismiss it.
At the very least, I hope for a faith in scientific progress. A realization that there are ways around problems if we try hard enough, and that there may be technological solutions for at least some of the moral dilemmas we will face in medicine over the coming decades. At the most, I dream that those not sensitive to moral issues in science will come to understand that very soon we may be capable of doing astonishing, even shocking, things in medicine, and that we might serve ourselves better if we started asking more serious questions about the meaning of human life.