Can one be an advocate for embryonic stem cell research while opposing human cloning experimentation? That's the question facing about 30 United States Senators who have not taken a final position on human cloning legislation to be brought before the Senate.
But we must first understand the similarities and distinctions between the two. It's important to understand that human "therapeutic" or "research" cloning is an experimental tool often confused with, but distinct from, embryonic stem cell research. Only then can we appropriately dissect a debate on the potential of the science versus the restraint defined by ethics and moral concerns.
Most agree that human reproductive cloning, or the cloning of human beings, should be banned. The contentious issue is whether this ban should extend to all human cloning, including human research cloning experimentation, a brand new field. Advocates point to its potential to develop tissues that will not be rejected by a patient's immune system. They also argue for human cloning as a source of genetically diverse stem cells for research. Moreover, they say such experimentation will further our basic understanding of biology and life's origins.
However, regardless of our religious background, most of us remain extremely uncomfortable with the idea of creating cloned human embryos to be destroyed in an experiment. As a physician and legislator who struggles with this inherent tension between scientific progress and ethical concerns, I focus on two fundamental questions: (1) Does the scientific potential of human research cloning experimentation justify the purposeful creation of human embryos, which must be destroyed in experiments? and (2) Does the promise of human embryonic stem cell research depend on experimental human research cloning?
At this point in the evolution of this new science, I cannot justify the purposeful creation and destruction of human embryos in order to experiment on them, especially when the promise and success of human embryonic stem cell research does not depend on experimental research cloning.
President Bush last August outlined a scientifically and ethically balanced policy that allows federal funding of embryonic stem cell research for nearly 80 stem cell lines. This has opened the door to a significant expansion of embryonic stem cell research. Further, there are no restrictions on private research using stem cells from the thousands of embryos left over after in vitro fertilization. This research, too, is underway. The promise and hope for new cures is being investigated. And the promise of this research does not - I repeat, does not - depend on human cloning.
Human cloning would indeed provide another source of stem cells - this time by asexual reproduction. But a human embryo still has to be created - then destroyed - to produce these stem cells. Moreover, there has been very little research cloning experimentation in animals - a prerequisite to any demands for such work in humans. Given the early state of this uncharted new science, the large number of federal cell lines and the unlimited number available for private research, I believe there is presently a sufficient number and range of cell lines.
As a heart transplant surgeon, I know intimately the challenges of transplant rejection. But I also know that there are multiple promising strategies to address this issue, such as the development of "tolerance strategies," improved pharmacologic immunosuppression, and the manipulation of cell surface structure to make cells "invisible" to the immune system, none of which carry the ethical burdens attached to human cloning.
No one can deny the potential human cloning holds for increased scientific understanding. But given the serious ethical concerns this research raises, the fact that promising embryonic stem cell research will continue even under a cloning ban, the lack of significant research in animal models, and the existence of promising alternatives, I am unable to find a compelling justification for allowing human cloning today.
The fact that we are even engaged in this debate testifies to the rapid and encouraging progress of science. As it moves forward, we will undoubtedly be forced to reexamine this issue. For now, the proper course is to stop short of allowing cloning research in humans, but to enthusiastically embrace the ongoing public and private stem cell research that holds such great hope for those who suffer from a wide range of diseases and conditions such as Alzheimer's disease, Parkinson's disease and diabetes.