Blastocyst Brouhaha.

• Author: Bailey, Ronald
• Position: Morality of use of human embryonic stem cells in research - Brief Article

Which human cells count as people?

Are 5-day-old human embryos people? That's the fundamental question at issue in the ongoing and heated discussion regarding embryonic stem cell research. The debate was sparked when privately funded researchers announced their discovery nearly three years ago. They found that stem cells, which have the potential to develop into any of the body's 220 different types of specialized cells, hold great therapeutic promise. The hope is that stem cells will someday be able to help physicians fix spinal cord injuries, cure diseases such as Parkinson's, Alzheimer's, and diabetes, and regenerate malfunctioning organs such as livers and hearts.

Embryonic stem cells are derived from 5-day-old human embryos, technically called blastocysts at that stage of development. These consist of about 150 cells. While they are not the only source of usable stem cells, embryonic stem cells are regarded as the best source for possible therapeutic applications. They are also the most controversial: Opponents claim that the destruction of human embryos, a byproduct of extracting the stem cells from the blastocysts, is equivalent to destroying a human being.

So, are the embryos from which stem cells are derived people? The answer: Only if every cell in your body is also a person.

Why? Because it is logically (if not quite logistically) possible for each of your body's cells to become your twin. Each skin cell, each neuron, each liver cell is potentially a person. All that's lacking is the will and the application of the appropriate technology. Cloning technology at this point in time is clunky. In the future, though, researchers will likely be able to skip cloning, and simply flip a few genetic switches to regress any of your cells to earlier stages of development, says Harold Varmus, former director of the National Institutes of Health. Ultimately, researchers could take your cells all the way back to the embryonic stage, then implant them into a womb where they could eventually develop into complete human beings.

"What happens when a skin cell turns into a totipotent stem cell [a cell capable of developing into a complete organism] is that a few of its genetic switches are turned on and others turned off," writes bioethicist Julian Savulescu in the April 1999 issue of the Journal of Medical Ethics. "To say it doesn't have the potential to be a human being until its nucleus is placed in the egg cytoplasm [i.e., cloning] is like...