In the human body, there are more than 220 different cell types. All of those cell types are derived from a cluster of cells known as embryonic stem cells. These unique cells come from the inner cell mass of a blastocyst, a young embryo approximately four to five days old. What makes these cells so very unique is that they are pluripotent. This mean that they can be characterized to differentiate into any of the three germ layers which exist in the human body: endoderm, mesoderm, and ectoderm. The endoderm is comprised of the stomach, intestines, and the lungs. The mesoderm is mainly the muscle, blood, and bone. This leaves the ectoderm with your skin and nervous system. Another aspect of these cells is that they have the ability, under the right circumstances, to replicate themselves indefinitely. Since they have the ability to produce unlimited numbers of themselves, they can be used in medicine for regenerative therapy and medical research.
Regenerative therapy means exactly what it implies. Tissues which is lost or damaged due to disease or injury can be subsequently repaired or replaced by new tissue grown from administered embryonic stem cells. "After administration into the patient’s body, fetal stem cells migrate to the site of damage, engraft, [multiply], undergo specialization regulated by the new host, substitute lost or damaged cells, and restore the cell mass and impaired body functions." Some ailments which can possibly be treated with the use of embryonic stem cells are cancers, genetic diseases, Parkinson's, juvenile diabetes, spinal cord injuries, and blindness. So if major disabilities like the ones listed can be partially or fully treated, why don't we utilize them? What is the ethical issue regarding the harvest and use of these stem cells?
The main controversial issue of this type of research is the status of the human embryo. When the inner cell mass of the embryo is taken, the embryo dies. The reason for this, is because that inner cell mass is what forms the three germ layers of the human body, so without it the embryo will no longer develop. People who are against the harvesting, research, and use of these special cells are known to be "pro-life." They generally believe that the four day embryo as a potential human being has a soul and is plainly murdered when harvested. The pro-lifers are usually religious people who believe that the research of these stem cells "instrumentalizes and violates the sanctity of life." They see human life as starting the second the an egg becomes fertilized, though scientifically, an embryo is not human until it starts to perform human functions. At the time of harvest, it is only a cluster of cells, just like all of the other cells in the human body.
A popular philosopher by the name of Sam Harris makes a compelling argument for embryonic stem cell research in his article titled "The Case Against Faith." In this writing, he mentions how President Bush used his first veto to cut off federal funding to embryonic stem cell research. President Bush believes that human life begins at the moment of conception. Harris stated "[Bush] believes that there is a soul in every 3-day-old human embryo, and the interests of one soul—the soul of a little girl with burns over 75 percent of her body, for instance—cannot trump the interests of another soul, even if that soul happens to live inside a petri dish. Here, as ever, religious dogmatism impedes genuine wisdom and compassion." He goes on to make the comparison that the human embryo, when harvested, is a collection of a mere 150 cells, and there are more than 100,000 cells which exist in the brain of a fly.
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