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Stem cell research: The debate over embryonic and adult …

Back to lesson plans archive September 10, 2004

By Lisa Prososki, a former middle and high school teacher

Biology, General Science, Ethics

Two to three 50-minute class periods plus additional time for presentations and extension activities

Students will:

Stem cells are universal cells that have the ability to develop into specialized types of tissues that can then be used throughout the body to treat diseases or injuries. Stem Cell Research is a topic embroiled in much controversy. Scientists are hopeful that one day stem cells will be used to grow new organs such as kidneys or spinal cords as well as different types of tissues such as nerves, muscles, and blood vessels. The controversy sparked by the use of stem cells and research in this area comes from the fact that many people support the use of embryonic stem cells. These cells are taken from embryos that are just days old. As a result of this, the embryo, which is a developing human life, is destroyed. Many people feel it is immoral and unethical to destroy embryos for the sake of science. To further the debate, while these cells are easily cultured, replicate quickly, and have a relatively long life, embryonic stem cells have not yet been successfully used to provide any kind of therapy for humans and pose risks such as tumor growth and rejection by the body.

On the other side of the issue is the use of adult stem cells for research. Adult stem cells are available from a variety of sources including blood from the umbilical cord, the placenta, bone marrow, and even human fat. However, they are relatively hard to find and extract from some of these sources and do not always thrive well when cultured. In addition, they may have some limitations in the type of tissues they are able to form. For many years, adult stem cells have been used to provide a number of different therapies to people with a relatively high rate of success. Recent research has shown that adult stem cells taken from one area of the body are able to regenerate and form tissues of a different kind. In addition to the proven therapies and research, the use of adult stem cells from a patients own body decreases the risk of rejection because the cells are not seen as foreign invaders.

All in all, many scientists believe that the use of adult stem cells should be the primary focus of stem cell research based on past success, lower chances of patient rejection, and the idea that adult stem cell research does not spark the moral, ethical, and political debate seen so frequently when the use of embryonic stem cells is considered.

Imagine you live in a time and place where people no longer suffer from diseases like Parkinsons, diabetes, heart disease, cancer, organ failure, or Alzheimers. Imagine that spinal cords can be replaced and that most forms of paralysis have been eliminated. Imagine that nerves, muscles, and even badly burned skin can be regenerated and replaced. Now imagine that the source of this technology comes from something that cant be seen with the human eye. While it might sound like space-age technology that we see in science fiction books and movies, imagine that it could actually be a reality.

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Stem cell research: The debate over embryonic and adult ...

What are embryonic stem cells? [Stem Cell Information]

Introduction: What are stem cells, and why are they important? What are the unique properties of all stem cells? What are embryonic stem cells? What are adult stem cells? What are the similarities and differences between embryonic and adult stem cells? What are induced pluripotent stem cells? What are the potential uses of human stem cells and the obstacles that must be overcome before these potential uses will be realized? Where can I get more information? A. What stages of early embryonic development are important for generating embryonic stem cells?

Embryonic stem cells, as their name suggests, are derived from embryos. Most embryonic stem cells are derived from embryos that develop from eggs that have been fertilized in vitroin an in vitro fertilization clinicand then donated for research purposes with informed consent of the donors. They are not derived from eggs fertilized in a woman's body.

Growing cells in the laboratory is known as cell culture. Human embryonic stem cells (hESCs) aregenerated by transferringcells from a preimplantation-stage embryointo a plastic laboratory culture dish that contains a nutrient broth known as culture medium. The cells divide and spread over the surface of the dish. In the original protocol, the inner surface of the culture dish was coated with mouse embryonic skin cellsspecially treated so they will not divide. This coating layer of cells is called a feeder layer. The mouse cells in the bottom of the culture dish provide the cells a sticky surface to which they can attach. Also, the feeder cells release nutrients into the culture medium. Researchers have nowdevised ways to grow embryonic stem cells without mouse feeder cells. This is a significant scientific advance because of the risk that viruses or other macromolecules in the mouse cells may be transmitted to the human cells.

The process of generating an embryonic stem cell line is somewhat inefficient, so lines are not produced each time cells from the preimplantation-stage embryo are placed into a culture dish. However, if the plated cells survive, divide and multiply enough to crowd the dish, they are removed gently and plated into several fresh culture dishes. The process of re-plating or subculturing the cells is repeated many times and for many months. Each cycle of subculturing the cells is referred to as a passage. Once the cell line is established, the original cells yield millions of embryonic stem cells. Embryonic stem cells that have proliferated in cell culture for for a prolonged period of time without differentiating, and are pluripotentare referred to as an embryonic stem cell line. At any stage in the process, batches of cells can be frozen and shipped to other laboratories for further culture and experimentation.

At various points during the process of generating embryonic stem cell lines, scientists test the cells to see whether they exhibit the fundamental properties that make them embryonic stem cells. This process is called characterization.

Scientists who study human embryonic stem cells have not yet agreed on a standard battery of tests that measure the cells' fundamental properties. However, laboratories that grow human embryonic stem cell lines use several kinds of tests, including:

As long as the embryonic stem cells in culture are grown under appropriate conditions, they can remain undifferentiated (unspecialized). But if cells are allowed to clump together to form embryoid bodies, they begin to differentiate spontaneously. They can form muscle cells, nerve cells, and many other cell types. Although spontaneous differentiation is a good indication that a culture of embryonic stem cells is healthy, it is not an efficient way to produce cultures of specific cell types.

So, to generate cultures of specific types of differentiated cellsheart muscle cells, blood cells, or nerve cells, for examplescientists try to control the differentiation of embryonic stem cells. They change the chemical composition of the culture medium, alter the surface of the culture dish, or modify the cells by inserting specific genes. Through years of experimentation, scientists have established some basic protocols or "recipes" for the directed differentiation of embryonic stem cells into some specific cell types (Figure 1). (For additional examples of directed differentiation of embryonic stem cells, refer to the NIH stem cell report available at http://stemcells.nih.gov/info/scireport/pages/2006report.aspx.)

Figure 1. Directed differentiation of mouse embryonic stem cells. Click here for larger image. ( 2008 Terese Winslow)

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What are embryonic stem cells? [Stem Cell Information]

Practical Problems with Embryonic Stem Cells

While some researchers still claim that embryonic stem cells (ESCs) offer the best hope for treating many debilitating diseases, there is now a great deal of evidence contrary to that theory. Use of stem cells obtained by destroying human embryos is not only unethical but presents many practical obstacles as well.

"Major roadblocks remain before human embryonic stem cells could be transplanted into humans to cure diseases or replace injured body parts, a research pioneer said Thursday night. University of Wisconsin scientist James Thomson said obstacles include learning how to grow the cells into all types of organs and tissue and then making sure cancer and other defects are not introduced during the transplantation. 'I don't want to sound too pessimistic because this is all doable, but it's going to be very hard,' Thomson told the Wisconsin Newspaper Association's annual convention at the Kalahari Resort in this Wisconsin Dells town. 'Ultimately, those transplation therapies should work but it's likely to take a long time.'....Thomson cautioned such breakthroughs are likely decades away."

-Associated Press reporter Ryan J. Foley "Stem cell pioneer warns of roadblocks before cures," San Jose Mercury News Online, posted on Feb. 8, 2007, http://www.mercurynews.com/mld/mercurynews/16656570.htm

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"Although embryonic stem cells have the broadest differentiation potential, their use for cellular therapeutics is excluded for several reasons: the uncontrollable development of teratomas in a syngeneic transplantation model, imprinting-related developmental abnormalities, and ethical issues."

-Gesine Kgler et al., "A New Human Somatic Stem Cell from Placental Cord Blood with Intrinsic Pluripotent Differentiation Potential," Journal of Experimental Medicine, Vol. 200, No. 2 (July 19, 2004), p. 123.

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From a major foundation promoting research in pancreatic islet cells and other avenues for curing juvenile diabetes:

"Is the use of embryonic stem cells close to being used to provide a supply of islet cells for transplantation into humans?

"No. The field of embryonic stem cells faces enormous hurtles to overcome before these cells can be used in humans. The two key challenges to overcome are making the stem cells differentiate into specific viable cells consistently, and controlling against unchecked cell division once transplanted. Solid data of stable, functioning islet cells from embryonic stems cells in animals has not been seen."

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Practical Problems with Embryonic Stem Cells

Stem Cell Research Article, Embryonic Cells Information …

In the beginning, one cell becomes two, and two become four. Being fruitful, they multiply into a ball of many cells, a shimmering sphere of human potential. Scientists have long dreamed of plucking those naive cells from a young human embryo and coaxing them to perform, in sterile isolation, the everyday miracle they perform in wombs: transforming into all the 200 or so kinds of cells that constitute a human body. Liver cells. Brain cells. Skin, bone, and nerve.

The dream is to launch a medical revolution in which ailing organs and tissues might be repairednot with crude mechanical devices like insulin pumps and titanium joints but with living, homegrown replacements. It would be the dawn of a new era of regenerative medicine, one of the holy grails of modern biology.

Revolutions, alas, are almost always messy. So when James Thomson, a soft-spoken scientist at the University of Wisconsin in Madison, reported in November 1998 that he had succeeded in removing cells from spare embryos at fertility clinics and establishing the world's first human embryonic stem cell line, he and other scientists got a lot more than they bargained for. It was the kind of discovery that under most circumstances would have blossomed into a major federal research enterprise. Instead the discovery was quickly engulfed in the turbulent waters of religion and politics. In church pews, congressional hearing rooms, and finally the Oval Office, people wanted to know: Where were the needed embryos going to come from, and how many would have to be destroyed to treat the millions of patients who might be helped? Before long, countries around the world were embroiled in the debate.

Most alarmed have been people who see embryos as fully vested, vulnerable members of society, and who decry the harvesting of cells from embryos as akin to cannibalism. They warn of a brave new world of "embryo farms" and "cloning mills" for the cultivation of human spare parts. And they argue that scientists can achieve the same results using adult stem cells immature cells found in bone marrow and other organs in adult human beings, as well as in umbilical cords normally discarded at birth.

Advocates counter that adult stem cells, useful as they may be for some diseases, have thus far proved incapable of producing the full range of cell types that embryonic stem cells can. They point out that fertility clinic freezers worldwide are bulging with thousands of unwanted embryos slated for disposal. Those embryos are each smaller than the period at the end of this sentence. They have no identifying features or hints of a nervous system. If parents agree to donate them, supporters say, it would be unethical not to do so in the quest to cure people of disease.

Few question the medical promise of embryonic stem cells. Consider the biggest United States killer of all: heart disease. Embryonic stem cells can be trained to grow into heart muscle cells that, even in a laboratory dish, clump together and pulse in spooky unison. And when those heart cells have been injected into mice and pigs with heart disease, they've filled in for injured or dead cells and sped recovery. Similar studies have suggested stem cells' potential for conditions such as diabetes and spinal cord injury.

Critics point to worrisome animal research showing that embryonic stem cells sometimes grow into tumors or morph into unwanted kinds of tissuespossibly forming, for example, dangerous bits of bone in those hearts they are supposedly repairing. But supporters respond that such problems are rare and a lot has recently been learned about how to prevent them.

The arguments go back and forth, but policymakers and governments aren't waiting for answers. Some countries, such as Germany, worried about a slippery slope toward unethical human experimentation, have already prohibited some types of stem cell research. Others, like the U.S., have imposed severe limits on government funding but have left the private sector to do what it wants. Still others, such as the U.K., China, Korea, and Singapore, have set out to become the epicenters of stem cell research, providing money as well as ethical oversight to encourage the field within carefully drawn bounds.

In such varied political climates, scientists around the globe are racing to see which techniques will produce treatments soonest. Their approaches vary, but on one point, all seem to agree: How humanity handles its control over the mysteries of embryo development will say a lot about who we are and what we're becoming.

For more than halfof his seven years, Cedric Seldon has been fighting leukemia. Now having run out of options, he is about to become a biomedical pioneerone of about 600 Americans last year to be treated with an umbilical cord blood transplant.

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Stem Cell Research Article, Embryonic Cells Information ...

Stem Cell Therapy in Mexico

Stem Cell MX is dedicated to providing COPD and heart disease patients with information about stem cell therapy at Angeles Health International, Mexicos largest private hospital network.

Stem Cell Therapy is a fast growing area of medical research. Research into how stem cells can cure a number of conditions has been extensive over the past 3 decades and here at Stem Cell MX we are proud to be at the forefront of breakthrough discoveries and treatments. We dedicate ourselves to providing you with information about Stem Cells and what they can do for you.

At Stem Cell MX we can use Stem Cell therapy to treat 11 core treatable conditions including chronic obstructive pulmonary disease (COPD), heart conditions and joint conditions, such as osteoarthritis. We use two types of stem cell programs; autologous, meaning that we use your own stem cells, and allogeneic, where we use donated adult stem cells from one of the best labs in the world.

Stem cell research has had bad press over the years due to the misconception that Stem Cells can only come from embryos. This isnt true. Here at Stem Cell MX we only use Adult Stem Cells which have been harvested from either the donor or the patients themselves.

If you want to find out more about stem cell therapy with no obligation then contact us today. Our stem cell clinical trials are based on thirty years of research and clinical experience conducted by leading researchers and clinicians in Europe and the United States.

To find out the basics about stem cells read An Introduction to Stem Cells

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Stem Cell Therapy in Mexico