What are stem cells?
The human body contains 220 different types of cells such as blood, brain, heart tissue, nerve cells, bones, etc. In 1998, researchers at the University of Wisconsin and the Johns Hopkins University in Baltimore MD found a way of harvesting stem cells from embryos and maintaining their growth in the lab. Stem cells are a type of primitive cell. Scientists have found ways of coaxing these stem cells to develop into most types of human cells, Researchers are confident that they will lead to treatments to many diseases: bone loss, broken bones, brain damage due to oxygen starvation, severe burns, cancer (some forms), diabetes, Lou Gehrig's disease, heart disease, hepatitis, incomplete bladder control, Huntington's, leukemia, lupus, muscular dystrophy, multiple sclerosis, osteoarthritis, Parkinson's, spinal cord injuries, and stroke! The Coalition for the Advancement of Medical Research estimates stem cell research shows promise to develop cures and/or new treatments for 100 million Americans who currently suffer from a wide variety of diseases and disorders.
Research is opposed by many pro-lifers, mainly Roman Catholics and conservative Protestants. They feel that the embryos from which the stem cells are often extracted are human persons. Many believe that the embryos have a soul. Since the embryos are killed when the stem cells are removed, pro-lifers view the extraction procedure as murder and a type of Nazi-like medical experimentation on human beings. They generally have no objection to adult stem cells that are extracted from an umbilical cord, a child's body or an adult's body, if the appropriate consent is obtained.
There are two main ethical problems associated with embryonic stem cells. Both remain very hot political matters:
These concerns have resulted in severe limitations on embryonic stem cell research in the U.S. However, research elsewhere in the world has led to techniques by which ordinary cells -- e.g. skin cells -- can be modified to produce Induced Pluripotent Stem Cells (iPS cells) that have many of the properties of embryonic stem cells without the ethical concerns. 6 More details
Embryos as a source of stem cells:
Embryonic stem cells are commonly extracted from unwanted, surplus embryos. These are typically embryos that are created during medical procedures in fertility clinics which help infertile couples conceive. When a woman undergoes in-vitro fertilization, she is given medication that causes her to produce perhaps two dozen mature ova. These are then fertilized, usually with sperm provided by her husband. About three days later, each embryo is at the blastocyst stage -- a collection of 4 to 10 cells.This photograph shows a seven-cell embryo which is fixed in position between two pipettes. Portions of six cells can be seen; the seventh is out of view behind the remaining cells. Two to five days after fertilization, two to four embryos are implanted in the woman's womb, in the hope that one or two will develop into a single newborn or twins. The rest are usually quickly deep frozen in liquid nitrogen for potential future use by the couple. Some are simply discarded.
These are sometimes called "pre-embryos." They have no brain, central nervous system, mouth, heart, lungs, or other internal organs. They have no organs to see, hear, touch, taste; they lack a body, head, arms, legs; they have no self awareness, memory, thought processes, or consciousness. They are smaller than a pin-prick. They consist of a number of identical, undifferentiated cells containing human DNA. They do have the potential to grow into fetuses and become newborn babies. Many, probably most, pro-lifers believe that they are human persons with souls. Skeptics feel that souls do not exist -- in embryos, fetuses, newborns, children or adults.
There is no simple way to dispose of the excess embryos. Occasionally, a couple will to go back for a second try at achieving a pregnancy. Two to four additional embryos are removed from storage, thawed out, and implanted. But even when that happens, perhaps 16 of the couple's ova will remain in storage. There is currently no simple way of handling the unneeded embryos:
The surplus embryos will almost all be eventually be destroyed, even if it happens accidentally, decades in the future, due to equipment malfunction or human error.
Research on surplus embryos in government labs is currently suspended. But if it were to be re-authorized, then researchers could remove some of these embryos from liquid nitrogen storage, thaw them out, and allow them to grow to the blastocyst stage. This consists of a collection of 100 to 300 undifferentiated cells, still lacking a brain, central nervous system, mouth, and other components as described above. The stem cells would then be extracted, killing the embryo in the process.
If an artificial womb were developed, frozen embryos could be thawed out and allowed to develop into newborns. There are many more North American couples willing to adopt babies than there are embryos in the medical freezers. However, development of an artificial womb has its own unique ethical concerns.
Some scientists reason that the unneeded surplus embryos should be used to benefit humanity rather than be simply discarded. Many pro-lifers regard these surplus frozen embryos as actual human persons with souls, deserving of protection, even if there is no practical way to have them develop into a fetus and later become a newborn.
As of mid-2001, there were over 110,000 frozen, stored surplus embryos in the U.S. alone. 1 Some estimates in 2005 run as high as 400,000.
Is it practical to create embryo stem cells for therapeutic use?:
The answer, as of early 2009 is no.
In order to make embryo stem cells practical for therapeutic use, it would be necessary to create a new stem cell line for each patient that needs treatment. This is illegal in any government-funded laboratory in the U.S. It is being done in places like England and Korea, where researchers are now world leaders in this technology.
At the current state of knowledge, creating a new stem cell line for mammals is difficult; for primates -- including humans -- it is particularly difficult.
However, iPS cells will probably be the wave of the future. They have many of the same properties as embryonic stem cells without the serious deficiencies of adult stem cells. 6
References used in the above essay:
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