Stem cells are the body's master cells from which all cells and tissues are formed. Because some types of stem cells in theory can develop into any type of tissue, some people believe they hold the promise to cure diseases and other ailments.
Stem cells are found (1) throughout the human body, such as in skin cells, and (2) in embryos. Stem cells found in the human body are referred to as "adult stem cells," while stem cells in the second category are known as "embryonic stem cells." Adult stem cell research is harmless and is not controversial. Embryonic stem cell research, though, requires the destruction of embryos and is very controversial.
Before one can arrive at an informed conclusion about the ethics of stem cell research, it is very important to first understand the difference between adult stem cells and embryonic stem cells.
Adult stem cells are undifferentiated cells, found inside the tissues and organs of the body, that are capable of regenerating damaged tissue or self-renewing indefinitely. They are also called somatic stem cells (from the Greek word soma meaning body). Adult stem cells are found in all tissues of a human being, and give rise to all the specialized cell types of the tissue from which it originated. For instance, bone marrow contains two types of stem cells - one which forms all the types of blood cells in the body, and one which forms bone, cartilage, fat and connective tissue. These stem cells cannot form other types of cells, such as brain cells.[1] Since they are limited to what type of cells they can become, they are called non-pluripotent cells.
Induced pluripotent stem cells (iPS cells or iPSCs) are derived in the laboratory from adult somatic cells. While research is still ongoing, they are believed to be identical to natural pluripotent stem cells, such as embryonic stem cells. (Pluripotent cells have the ability to become any cell in the body.) They were first produced in 2006 from mouse cells and in November 2007 from human cells.[2]
Embryonic stem cells, as the name suggests, are derived from embryos. This process requires the harvesting and destruction of live human embryos that have been fertilized in vitro and then destroyed at the blastocyst stage, about four to five days into development. Embryonic stem cells are pluripotent.[3]
Experiments using adult stem cells raises no moral issues since no embryo is destroyed. Research using embryonic stem cells is unethical, since it requires the creation and destruction of living human embryos. Nearly half of all Americans oppose it, many scientists and doctors have gone on the record to express their deep misgivings about the procedure, and religious leaders condemn it.
The Catholic Church (1.1 billion members world-wide), the Baptist churches (38 million believers), and the Orthodox Church (225 million faithful) condemn all forms of embryonic stem cell research. In December 2008, the Vatican issued a document titled "Dignitas Personae," or "The Dignity of the Person," outlining the Church's official positions on issues relating to biomedical technology. Among the topics addressed are stem cell research, in vitro fertilization, genetic testing and human cloning, all of which the Church opposes. According to the Vatican, such techniques undermine the sacredness of every human life .
In June of 2008, the US Conference of Catholic Bishops (USCCB), in a statement devoted exclusively to the issue of embryonic stem cell research, reiterated the Church's long-standing belief that human life is a precious gift from God and deserves protection and the greatest respect. The bishops condemned the direct killing of innocent "embryonic human beings" in the interest of research and opposed the use of taxpayer funds to support such policies. The USCCB statement made it very clear that harvesting embryonic cells is a deliberate act that kills human life, a "gravely immoral act."[4]
In October 2001, the Synod of Bishops of the Orthodox Church in America (OCA), in a statement titled "Embryonic Stem Cell Research in the Perspective of Orthodox Christianity", also affirmed the sanctity of all human life, created in the image of God, which begins at the moment of conception. The Orthodox bishops denounced any research based on the destruction of embryonic cells, regardless of its potential benefits.[5] The Church's position is clear that a live embryo is human life and not just a "clump of cells." Destroying them to extract stem cells for research purposes is "morally and ethically wrong in every instance."[6]
From a moral standpoint, adult stem cells clearly provide the least controversial solution. But what about the science? Which approach has shown the most promise and provided the better medical results?
Adult Stem Cell Research: The Proven Medical Alternative In 2007, the Coalition of Americans for Research Ethics compiled and published a paper showing the impressive success of adult stem cell therapies. Titled "Peer-Reviewed References List Showing Applications of Adult Stem Cells that Produce Therapeutic Benefit to Human Patients." The report documented over 70 treatments and 1,300 human clinical trials for adult stem cell research.[7]
As of April 2007, adult stem cells had produced treatments for approximately 26 types of cancers, 19 auto-immune diseases, 2 cardiovascular and 1 ocular problems, 3 immunodeficiencies, 3 neural degenerative diseases and injuries, 10 anemias and other blood conditions, 4 wounds and injuries, 5 different metabolic disorders, 2 types of liver disease, and 1 bladder disease. On the other hand, no embryonic stem cells research had made it past the animal testing phase.
There have been numerous advances since April 2007. In just the four-month period from November 2008 to March 2009, adult stem cell breakthroughs have included potential treatments for muscular dystrophy[8], the ability to create iPSCs without using a carrier virus[9], treatment for Parkinson's Disease[10], treatment for Multiple Sclerosis[11], and engineering tissue using stem cells to create a trachea for transplant[12]. Adult stem cell treatments have already helped patients with more than 100 different types of diseases and conditions.
By contrast, no therapies have been developed using embryonic stem cells. There are currently no ongoing clinical trials using embryonic stem cells. On January 23, 2009, the FDA gave approval to the Geron Corporation to conduct a clinical trial using human embryonic stem cells on spinal cord injured patients. However, this is NOT a trial to test whether or not they can treat the injury or restore function, it is a test of the safety of injecting human embryonic stem cells into human beings.[13]
The suitability of adult stem cells for potential cures and the many medical successes have attracted significant financial support from private companies, universities, and venture capitalists. Adult stem cells have yielded proven therapies.
The same cannot be said about embryonic stem cells experimentation. Embryonic stem cells have many drawbacks in addition to ethical ones. They cause tumors, and the adult cells derived from them may be rejected by the patient's immune system. Furthermore, whatever disease process caused the patients' tissue cells to die is likely to kill introduced cells as well. Any treatments from embryonic stem cells are decades away.[14] In addition, the number of eggs needed to develop, let alone test potential therapies is enormous, which could very easily lead to the exploitation of women and cause very real medical risks associated with hyperovulation.[15] While all these problems may be solvable, so far none of them have been.
As Dr. Mehmet Oz, a cardiovascular surgeon at Columbia University and a regular on Oprah's television show, pointed out on the March 27, 2009 show with actor Michael J. Fox who suffers from Parkinson's Disease,
"I think, Oprah, the stem cell debate is dead."
The problem with embryonic stem cells is that embryonic stem cells come from embryos, like all of us are made from embryos, and those cells can become any cell in the body, but it's very hard to control them and so they can become cancer."
"I can take a little bit of your skin, take those cells, get them to go back in time so they are like they were when you were first made, and then they will start to make that dopamine and I think those cells, because they won't be as prone to cancer and because they're your genes will be the ones that are ultimately used to cure Parkinsons."
"I think we are single digit years away from making a big impact in the lives of Parkinson's disease but also diabetics, heart disease, people who have had a lot of problems."[16]
Notes:
1 Stem Cell Information from the National Institutes of Health. Website: http://stemcells.nih.gov/info/glossary.asp
2 Okita K, Nakagawa M, Hyenjong H, Ichisaka T, Yamanaka S. Generation of Mouse Induced Pluripotent Stem Cells Without Viral Vectors. Science. 2008 Oct 9.
3 Stem Cell Information from the National Institutes of Health. Website: http://stemcells.nih.gov/info/glossary.asp
4 US Conference of Catholic Bishops, On Embryonic Stem Cell Research, website: http://www.usccb.org/prolife/issues/bioethic/bishopsESCRstmt.pdf
5 OCA, Embryonic Stem Cell Research in the Perspective of Orthodox Christianity, website: http://www.oca.org/news/160
6 OCA, Orthodox Church and Stem Cells Research, website: http://www.oca.org/QA.asp?ID=68&SID=3
7 "Peer-Reviewed References Showing Applications Of Adult Stem Cells That Produce Therapeutic Benefit For Human Patients", website: http://www.stemcellresearch.org/facts/asc-refs.pdf
8 "Stem cell breakthrough gives new hope to sufferers of muscle-wasting diseases", March 5, 2009; website: http://www.eurekalert.org/pub_releases/2009-03/uons-scb030509.php
9 "Stem cell breakthrough could solve ethical dilemmas", Times Online, March 2, 2009, website: http://www.timesonline.co.uk/tol/news/uk/science/article5830251.ece
10 "Adult Stem Cell Research Reverses Effects of Parkinson's Disease in Human Trial", Medical News Today, Feb. 16, 2009. Website: http://www.medicalnewstoday.com/articles/139199.php
11 Stem cells 'reset' immune system in MS patients, Jan. 29, 2009. Website: http://www.breitbart.com/article.php?id=CNG.e67f6ceac8d2d7ee544d913d28fedcc9.1231&show_article=1
12 Adult Stem Cell Breakthrough: First Tissue-engineered Trachea Successfully Transplanted, Science Daily, Nov. 18, 2008. Website: http://www.sciencedaily.com/releases/2008/11/081119092939.htm
13 For more information on the Geron testing: http://www.stemcellresearch.org/facts/geronq&a09.pdf
14 "Stem cell pioneer warns of roadblocks before cures," San Jose Mercury News Online, posted on Feb. 8, 2007. Website: http://www.mercurynews.com/mld/mercurynews/16656570.htm
15 "As Demand for Donor Eggs Soars, High Prices Stir Ethical Concernts," The New York Times, May 15, 2007 Website: http://www.nytimes.com/2007/05/15/health/15cons.html?_r=2&oref=slogin&pagewanted=print)
16 Video segment from the Oprah Winfrey show, http://www.oprah.com/media/20090319-tows-dr-oz-brain
