First, the science: To understand "stem cells", and the debates about them, a simple analogy may be useful. Imagine that you have an 8 year old child who is a spectacular athlete, who can run, jump, swim, skate, play tennis, do acrobatics...she has the potential to be anything, but has not yet chosen.
Then, think of Sue Bird moving next door, and coaching her in basketball. Your daughter drops the other sports, plays only basketball, and thus is no longer as advanced in the others, but, while in high school, she plays all positions in basketball: center, forward and guard. Later, she moves on to college where the coach, already having a center, installs her as forward. That becomes her position, and she finally becomes a professional, playing only forward.
The human embryonic stem cell (hESC) is that 8 year old, having the potential to become any cell in the body (nerve, heart, lung, kidney, pancreas, liver, bone, blood, etc) depending on the environment (in this case, the "coach" is a chemical signal and the nature of cells nearby). The "adult" stem cell is that girl in high school---committed to baskbetball, but able to become a center, forward or guard depending, again, on the "coach" and the surrounding environment. Thus, a marrow stem cell can produce any of the blood cells, but not nerve cells, just as the high school girl basketball star is no longer going to be tennis champion.
[The word "adult" is actually misleading, because newborns have completely formed organs (otherwise they would not survive), and each organ has its own "adult" stem cell that is destined to being one of the cells of that organ. Better words are "pluripotential" for the embryonic stem cell (meaning it can become anything---pluri + potential), and "committed" for the adult stem cell (committed to being a nerve cell, a pancreas cell, etc., but not yet becoming a particular type of nerve or pancreatic cell) much like the high school girl is not yet a forward, guard or center. The final stage, college and pro--when she actually becomes a forward, and nothing else---is the "differentiated" cell that performs the function of a particular type of nerve, or the pancreas cell that secretes insulin, or the white blood cell that fights infections.
hESCs are cell lines derived from embryos that can, but only if implanted in a woman's womb, and that womb does not later reject it (i.e., statistically about a 25% chance), become a baby. If not implanted in the womb, or, if implanted and later rejected, it cannot and will not. There are 100s of thousands of such embryos in freezers from In Vitro Fertilization (IVF) clinics that will never be used to attempt implantation. They can either be used for research or be destroyed.
Because hESCs can be "coached" to become any cell in the body, they have the greatest potential to be used to replace cells in the body damaged by disease. For example, diseased nerve cells in the brain that cause Parkinson's disease may be replaced by hESCs that have been coaxed to be brain cells. Destruction of insulin-producing cells leads to diabetes; those destroyed cells may be replaced by hESCs coaxed to become insuling-producing cells. And, so on.
That, in a nutshell, is the science. [Abstracted from a talk I delivered for the Women's Bioethics Project.] Now, for the politics.
During the 2002 and 2003 sessions of Congress, the radical right Republicans enacted--not once, but twice--a law that outlawed all research on hESCs and that anyone who received hESC therapy outside the United States could be arrested at the border when they tried to return. Fortunately, that bill never passed the Senate because there is a strong possibility Bush would have signed it.
After the passage of hESC research funding in California, and the nationwide publicity that explained to people just what was being outlawed by Congress, the radical rightwing no longer prevailed. Both Houses, under Republican leadership, passed a law that funded hESC research, but was vetoed by Bush, and Congress did not have the votes to override. Even more interesting, the radical rightwing itself, led by Tom DeLay had retreated in defeat to the position that hESC research should not be outlawed, but that federal money should not be spent doing it. With Democrats in control, Congress can certainly pass the same bill, and may have the votes to override if Bush vetoes again.
I would, however, like to propose a different approach. One of the major problems progressives have faced, and one of the reasons their political support has eroded over the years, is that their beliefs in the "rationality" of their cause is reason to ride roughshod over peoples' deeply held sensibilities. The rightwing has done the same in spades: Terry Schiavo, the original hESC bills described above, Iraq, systemic corruption with a name "K-Street Project" and a website, suppressing the truth about global warming,,,,a record of utter contempt for the American people. [More on all this in another column].
The Democratic Congress should take the opportunity of acknowledging that hESC research is a deeply moral issue to some people, who would feel not only defeated but scorned if their tax dollars were spent on it. It can do this by passing the same bill that Bush vetoed last session, but with a wrinkle: allow people to check-off (as is currently done with federal funding for campaigns) a box that says that up to $X of their taxes may be spent on hESC research. "X" can be determined by Congress, and it can be a dollar figure or a percentage. It would not obligate Congress to all the money, but would make it available. No one's total taxes would increase.
This mechanism would provide active acknowledgement of peoples' deeply held views, without compromising hESC research and development. Obviously, it could be argued that this should apply to any program: the war, welfare payments, education initiatives, environmental regulations. I would suggest that, however, that those matters are conventionally political, while issues surrounding the embryo are not. Moreover, if such a measure would help build trust across philosophical divides, let us not allow the perfect to be the enemy of the good.
Perhaps, hESCs could not only be a major breakthrough in medical care, but also help to heal the body politic.
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