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Stem cell transplants can be used to treat various types of cancer, such as leukemia, myeloma, and some types of lymphoma. Bone marrow is extracted and used to replicate healthy cells.

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A stem cell transplant is a treatment for some types of cancer. For example, you might have one if you have leukemia, multiple myeloma, or some types of lymphoma. Doctors also treat some blood diseases with stem cell transplants.

In the past, patients who needed a stem cell transplant received a "bone marrow transplant" because the stem cells were collected from the bone marrow. Today, stem cells are usually collected from the blood, instead of the bone marrow. For this reason, they are now more commonly called stem cell transplants.

Why are bone marrow and stem cells important?

A part of your bones called "bone marrow" makes blood cells. Marrow is the soft, spongy tissue inside bones. It contains cells called "hematopoietic" stem cells (pronounced he-mah-tuh-poy-ET-ick). These cells can turn into several other types of cells. They can turn into more bone marrow cells. Or they can turn into any type of blood cell.

Certain cancers and other diseases keep hematopoietic stem cells from developing normally. If they are not normal, neither are the blood cells that they make. A stem cell transplant gives you new stem cells. The new stem cells can make new, healthy blood cells.

Types of stem cell transplant

The main types of stem cell transplants and other options are discussed below.

Autologous transplant. Doctors call this an AUTO transplant. This type of stem cell transplant may also be called high-dose chemotherapy with autologous stem cell rescue.

In an AUTO transplant, you get your own stem cells after doctors treat the cancer. First, your health care team collects stem cells from your blood and freezes them. Next, you have powerful chemotherapy, and rarely, radiation therapy. Then, your health care team thaws your frozen stem cells. They put them back in your blood through a tube placed in a vein (IV).

It takes about 24 hours for your stem cells to reach the bone marrow. Then they start to grow, multiply, and help the marrow make healthy blood cells again.

Allogeneic transplantation. Doctors call this an ALLO transplant.

In an ALLO transplant, you get another person's stem cells. It is important to find someone whose bone marrow matches yours. This is because you have certain proteins on your white blood cells called human leukocyte antigens (HLA). The best donor has HLA proteins as much like yours as possible.

Matching proteins make a serious condition called graft-versus-host disease (GVHD) less likely. In GVHD, healthy cells from the transplant attack your cells. A brother or sister may be the best match. But another family member or volunteer might work.

Once you find a donor, you receive chemotherapy with or without radiation therapy. Next, you get the other person's stem cells through a tube placed in a vein (IV). The cells in an ALLO transplant are not typically frozen. So, doctors can give you the cells as soon after chemotherapy or radiation therapy as possible.

There are 2 types of ALLO transplants. The best type for each patient depends his or her age and health and the type of disease being treated.

Ablative, which uses high-dose chemotherapy

Reduced intensity, which uses milder doses of chemotherapy

If your health care team cannot find a matched adult donor, there are other options. Research is ongoing to determine which type of transplant will work best for different patients.

Umbilical cord blood transplant. This may be an option if you cannot find a donor match. Cancer centers around the world use cord blood.

Parent-child transplant and haplotype mismatched transplant. These types of transplants are being used more commonly. The match is 50%, instead of near 100%. Your donor might be a parent, child, brother, or sister.

Choosing a transplant

Your doctor will recommend an AUTO or ALLO transplant based mostly on the disease you have. Other factors include the health of your bone marrow and your age and general health. For example, if you have cancer or other disease in your bone marrow, you will probably have an ALLO transplant. In this situation, doctors do not recommend using your own stem cells.

Choosing a transplant is complicated. You will need help from a doctor who specializes in transplants. So you might need to travel to a center that does many stem cell transplants. Your donor might need to go, too. At the center, you talk with a transplant specialist and have an examination and tests. Before a transplant, you should also think about non-medical factors. These include:

Who can care for you during treatment

How long you will be away from work and family responsibilities

If your insurance pays for the transplant

Who can take you to transplant appointments

Your health care team can help you find answers to these questions.

How a transplant works

The information below tells you the main parts of AUTO and ALLO transplants. Your health care team usually does the steps in order. But sometimes certain steps happen in advance, such as collecting stem cells. Ask your doctor what to expect before, during, and after a transplant.

AUTO transplant timeline

Part 1: Collecting your stem cells

A doctor puts a thin tube called a "transplant catheter" in a large vein. The tube stays in until after the transplant. Your health care team will collect stem cells through this tube and give chemotherapy and other medications through the tube.

You get injections of a medication to raise your number of white blood cells. White blood cells help your body fight infections.

Your health care team collects stem cells, usually from your blood.

Time: 1 to 2 weeks

Where it's done: Clinic or hospital building. You do not need to stay in the hospital overnight.

Part 2: Transplant treatment

Time: 5 to 10 days

Where it's done: Clinic or hospital. At many transplant centers, patients need to stay in the hospital for the duration of the transplant, usually about 3 weeks. At some centers, patients receive treatment in the clinic and can come in every day.

Part 3: Getting your stem cells back

Time: Each infusion usually takes less than 30 minutes. You may receive more than 1 infusion.

Where it's done: Clinic or hospital.

Part 4: Recovery

Time: approximately 2 weeks

Where it's done: Clinic or hospital. You might be staying in the hospital or you might not.

ALLO transplant timeline

Part 1: Collecting stem cells from your donor

The health care team gives your donor injections of a medication to increase white cells in the blood, if the cells are collected from blood. Some donors will donate bone marrow in the operating room during a procedure which takes several hours.

Time: Varies based on how the stem cells are collected

Where it's done: Clinic or hospital

Part 2: Transplant treatment

Time: 5 to 7 days

Where it's done: Many ALLO transplants are done in the hospital.

Part 3: Getting the donor cells

Time: 1 day

Where it's done: Clinic or hospital.

Part 4: Recovery

You take antibiotics and other drugs. This includes medications to prevent graft-versus-host disease. You get blood transfusions through your catheter if needed. Your health care team takes care of any side effects from the transplant.

After the transplant, patients visit the clinic frequently at first and less often over time.

Time: Varies

For an ablative transplant, patients are usually in the hospital for about 4 weeks in total.

For a reduced intensity transplant, patients are in the hospital or visit the clinic daily for about 1 week.

Milestones of successful transplant

The words "successful transplant" might mean different things to you, your family, and your doctor. Below are 2 ways to measure transplant success.

Your blood counts are back to safe levels. A "blood count" is the number of red cells, white cells, and platelets in your blood. A transplant makes these numbers very low for 1 to 2 weeks. This causes risks of:

Infection from low numbers of white cells, which fight infections

Bleeding from low numbers of platelets, which stop bleeding

Tiredness from low numbers of red cells, which carry oxygen

Doctors lower these risks by giving blood and platelet transfusions after a transplant. You also take antibiotics to help prevent infections. When the new stem cells multiply, they make more blood cells. Then your blood counts improve. This is one way to know if a transplant is a success.

It controls your cancer. Doctors do stem cell transplants with the goal of curing disease. A cure may be possible for some cancers, such as some types of leukemia and lymphoma. For other patients, remission is the best result. Remission is having no signs or symptoms of cancer. After a transplant, you need to see your doctor and have tests to watch for any signs of cancer or complications from the transplant.

Questions to ask the doctor

Talking often with the doctor is important. It gives you information to make health care decisions. The questions below may help you learn more about stem cell transplant. You can also ask other questions that are important to you.

Which type of stem cell transplant would you recommend? Why?

If I will have an ALLO transplant, how will we find a donor? What is the chance of a good match?

What type of treatment will I have before the transplant? Will radiation therapy be used?

How long will my treatment take? How long will I stay in the hospital?

How will a transplant affect my life? Can I work? Can I exercise and do regular activities?

How will we know if the transplant works?

What if the transplant doesn't work? What if the cancer comes back?

What are the side effects? This includes short-term, such as during treatment and shortly after. It also includes long-term, such as years later.

What tests will I need later? How often will I need them?

If I am worried about managing the costs of treatment, who can help me with these concerns?

More Information
Bone Marrow Aspiration and Biopsy Making Decisions About Cancer Treatment Donating Blood and Platelets Donating Umbilical Cord Blood
Additional Resources
Explore BMT Be the Match: National Marrow Donor Program Blood & Marrow Transplant Information Network
U.S. Department of Health and Human Services: Understanding Transplantation as a Treatment Option

National Bone Marrow Transplant Link

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What is a Stem Cell Transplant (Bone Marrow Transplant)?

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A stem cell transplant is a treatment for some types of cancer. For example, you might have one if you have leukemia, multiple myeloma, or some types of lymphoma. Doctors also treat some blood diseases with stem cell transplants.In the past, patients who needed a stem cell transplant received a "bone marrow transplant" because the stem cells were collected from the bone marrow.

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Disadvantages
-high uncertainties
-unknown side effects
-playing god
-perpetuates cloning of humans

Advantages
-immune medical benefits
-better knowledge of human growth
-key to reversing aging
-cure development defects before they happen

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Stem cell research is the use of either adult or embryonic cells to treat and cure diseases. Stem cells are immature and not fully developed cells of the human body that have the potential to be manipulated into different types of cells. There is a large debate surrounding stem cell research, which is mostly a moral one. Let's take a look at the good and bad that could come from the use of stem cells in our society.

The Advantages of Stem Cell Research

1. Immense Medical Benefits
The main purpose of researching stem cells is to asses their use in the medical field. It has been shown that they can be extremely beneficial in therapeutic cloning to treat chronic illnesses. They have also been a wonderful stepping stone into the advancement of regenerative medicines.

2. A Better Knowledge of Human Growth
By studying the very foundation of human growth, stem cells, in depth, scientists have been able to gain a much better understanding of how our bodies work. This is vital for advancing medicine, medical processes, and even cures for degenerative illnesses.

3. The Key To Reversing Aging
Stem cells are the key to regenerative processes, which could possibly be age reversal. By reviving organs in our body that have become old or worn out, you could essentially live forever or at least greatly prolong the lives of humans.

4. Cure Development Defects Before They Happen
Stem cell research doesn't just benefit the people walking around the earth, but also the ones that haven't been born yet. The effects of these cells on embryos could change the way that birth defects are treated. They could possibly be corrected before the child is even born, greatly improving their quality of life and chance of survival.

The Disadvantages of Stem Cell Research

1. High Uncertainties
One of the largest issues that people have with stem cell research is just how risky and unknown it truly is. Major advancements still need to be made and new technology must be developed before it can be used in an efficient and safe way.

2. Unknown Side Effects
Since stem cells are still in their research phase, the true long term effects of their use is not known or understood. Using them could cause new illnesses and disease to develop, or even interfere with the natural functions of the body.

3. Playing God
The moral argument is another big one when it comes to this topic. Many people believe that altering the basic structure of a human's genes is putting hands somewhere they should not be. The moral issue is the most frequently argued.

4. Perpetuates Cloning of Humans
Cloning is the process of making an exact genetic copy of a living organism. Stem cell research also aids the research into human cloning. Human cloning has been widely reviewed as a detriment to society with many negative benefits.

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Important Facts About Stem Cell Research

Parkinson's disease, spinal cord injuries, birth defects, damaged organs, and cancer could all be possibly treated with the use of stem cells.

Bone marrow transplantation is the only form of stem cell research that has been proven to be effective and safe.

Manipulating cells and their functions in a clinical setting or laboratory can hinder their normal functions and render them dangerous for use.

Stem cells can copy themselves for an unlimited period of time.

The reason that they have gained so much attention, is because stem cells are "blank" cells that can be turned into almost anything that the body needs.

Therapeutic cloning is a type of stem cell research.

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Advantages and Disadvantages of Stem Cell Research

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Stem cell research is the use of either adult or embryonic cells to treat and cure diseases. Stem cells are immature and not fully developed cells of the human body that have the potential to be manipulated into different types of cells. There is a large debate surrounding stem cell research, which is mostly a moral one.

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Cell can be collected by bone marrow, circulating blood or umbilical cord blood.

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The Canadian Cancer Society is a national community-based organization of volunteers whose mission is the eradication of cancer and the enhancement of the quality of life of people living with cancer.

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Up until recently, scientists could only extract stem cells via babies' inner cell masses. This process stirred up a lot of moral and ethical debate about whether or not stem cell research should be funded by the government.

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Regulations and policies change frequently to keep up with the pace of research, as well as to reflect the views of different political parties. Here President Obama signs an executive order on stem cells, reversing some limits on federal research funding. (White House photo by Chuck Kennedy)

Governments around the globe have passed legislation to regulate stem cell research. In the United States, laws prohibit the creation of embryos for research purposes. Scientists instead receive "leftover" embryos from fertility clinics with consent from donors. Most people agree that these guidelines are appropriate.

Disagreements surface, however, when political parties debate about how to fund stem cell research. The federal government allocates billions of dollars each year to biomedical research. But should taxpayer dollars be used to fund embryo and stem cell research when some believe it to be unethical? Legislators have had the unique challenge of encouraging advances in science and medicine while preserving a respect for life.

U.S. President Bush, for example, limited federal funding to a study of 70 or so hES cell lines back in 2001. While this did slow the destruction of human embryos, many believe the restrictions set back the progress of stem cell research.

President Obama overturned Bush's stem cell policy in 2009 to expand the number of stem cell lines available to researchers. Policy-makers are now grappling with a new question: Should the laws that govern other types of pluripotent stem cells differ from those for hES cells? If so, what new legislation is needed?

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Governments around the globe have passed legislation to regulate stem cell research. In the United States, laws prohibit the creation of embryos for research purposes. Scientists instead receive "leftover" embryos from fertility clinics with consent from donors. Most people agree that these guidelines are appropriate.

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In order to obtain the stem cells the researchers must fertilize an egg in a laboratory then destroy it to separate out the cells.
In order to make a stem cell the researcher must take a skin sample from an adult patient and grow it on a petri dish in a laboratory

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What makes a stem cell so much more valuable, from a scientific perspective, than any other cell in the body? Stem cells are the chameleons of the cell world, meaning they can transform into any other cell type. A heart cell, for example, is just that: a cell that's part of the heart. The same goes for skin cells, hair cells, brain cells and nearly every other cell in the human body.

But, a stem cell, on the other hand, can make a lot more choices about what it can do and become. Just like any cell that actively grows and divides, a stem cell can divide and just form an exact copy of itself: another stem cell. But, more miraculously, a stem cell can grow and instead form a completely different type of cell.

However, a stem cells ability to transform fades with age. By adulthood, the stem cells present in the body have already received directions for what type of cell they need to produce. For instance, a blood stem cell can produce fresh blood cells, but not any other cell type.

Only embryonic stem cells, those taken from an embryo, have the capacity to form all the cells in the body. These stem cells, when placed in the right environment, can become a blood cell, kidney cell, brain cell, or any other cell type imaginable. From a therapeutic perspective, it makes sense that scientists and medical professionals would want to work with embryonic stem cells, since the possibilities for their use are endless.

But, in the past, acquiring these valuable stem cells in an acceptable manner proved difficult. In order to obtain these stem cells, scientists needed to fertilize a human egg in the laboratory and then ultimately destroy it to separate out the stem cells. As a result, federal funding for stem cell research that led to harm of a human embryo was banned, and public opinion branded stem cell research unethical.

But, over the past decade, scientists have worked tirelessly to prove the importance of stem cell research and show just how revolutionary it can be to modern medicine. And, after overcoming seemingly insurmountable difficulties, scientists have made a stem cell that's just like an embryonic stem cell, except it doesn't actually come from an embryo.

These ground-breaking stem cells are called Induced Pluripotent Stem cells, or iPS cells. iPS cells are skin cells that have been turned into stem cells. They behave and function like typical stem cells, even though they started out as just regular body cells. Just as the name alludes to, these cells are induced to become stem cells in a laboratory, as this transformation is not known to occur naturally in humans.

How are scientists making these stem cells? It starts by taking a skin cell sample from an adult patient and growing them in a petri dish in the laboratory. Next, these cells must be reprogrammed to think they are stem cells and not skin cells. To do this, scientists take advantage of normal biology and the fact that all cells in the body contain all the same genetic material, or genes.

The only thing different between a stem cell and skin cell is which genes are turned on and which genes aren't important and kept off. A gene acts as the blueprint for a protein, and it's these proteins that control what a cell will become. Genes in the on position can produce proteins needed to turn a cell into a stem cell or skin cell, for instance. What scientists can do is add a group of proteins normally found in stem cells, called the Yamanaka factors, to the skin cells growing in the petri dish in order to turn back the clock and turn these skin cells into stem cells again. Hence, the skin cells have been induced to become pluripotent stem cells (iPS cell).

With this new, ethical source of iPS cells, scientists can now explore how they can be used to treat disease. As mentioned earlier, stem cells can produce other cell types when placed in the right environment. This is because stem cells receive information from their environment, or their niche, in order to know exactly how to behave. So, if a scientist wants to form heart cells, they can recreate the heart environment in the petri dish containing the stem cells. In this case, the scientists are fooling the stem cells into thinking they are in the heart. The stem cells, wanting to "fit in," will slowly begin to turn into heart cells as they grow. Scientists can use this method with iPS cells to create new treatments for disease.

For a patient suffering from Alzheimer's disease, this could mean making new, healthy brain cells from the iPS cells. Scientists could also create new blood cells for patients suffering from Sickle Cell disease, or replace heart cells damaged after a heart attack.

The best part about this type of treatment is that the transplanted cells originate from the patient who needs the transplant, so there is minimal risk that the cells will be recognized by the body as foreign and destroyed. This is a major problem with current transplant procedures, since they use organs and tissues from anonymous donors and our bodies can detect cells that aren't our own and destroy them.

Ultimately, this newfound ability to generate stem cells puts scientists one step closer toward their end goal, but there's still a lot of work to be done. For example, figuring out how to re-create a specific environment, such as the heart or liver, is not easy. Also, even if scientists are able to form the cell type they want, finding a way to transplant these back into the patient and have the cells survive is another obstacle that must be overcome. Much success has been achieved thus far directing cells to become eye cells, which has proved just how promising iPS cells are for the treatment of disease.

The first human trial using iPS cell technology was this past September in Japan. Scientists and ophthalmologists believe iPS cells hold great potential in the treatment of macular degeneration, or breakdown of the retina in the eye, which eventually leads to blindness. Current technologies for treatment of this disease aim to slow down disease progression, but it's ultimately untreatable.

During this trial, scientists turned iPS cells into retinal cells and transplanted them into the damaged retina. The hope was that these new cells could replace the damaged cells and help to regenerate a healthy retina. Only time will tell how successful this treatment will be, but even so, the discovery and existence of iPS cells has already transformed the future of modern science. There are high hopes for where iPS technology will go from here, with thoughts that one day, stem cells like these can be used to recreate entire organs, like the liver, to be used in organ transplants.

With an ever-aging population and debilitating diseases plaguing our society, there will always be a need for better treatments and more advanced technologies. Rarely there arises such a technology that can revolutionize how we treat a single disease, let alone multiple diseases that affect all different parts of the body. Induced Pluripotent Stem cells hold that potential, and could stand amongst the greatest and most impactful scientific advances for the treatment of disease.

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Induced Pluripotent Stem Cells: Taking Control Into Our Own Hands

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What makes a stem cell so much more valuable, from a scientific perspective, than any other cell in the body? Stem cells are the chameleons of the cell world, meaning they can transform into any other cell type. A heart cell, for example, is just that: a cell that's part of the heart.

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Multipotent stem cells can create other types of cells, but is limited in terms of being able to differentiate.

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Q. I'm in doubt regarding myelodysplasia - is it multipotent or pluripotent?

A. That's a great question because it lets us talk about hematopathology (yay!) and also stem cells (which can be confusing unless someone explains some simple stuff).

What is a stem cell?
First, let's talk about stem cells. The thing that makes a stem cell a stem cell, at least in my mind, is the ability to self-renew. This means that the stem cell can either divide into two daughter cells which will mature into grown up cells, or (and more commonly) it can give rise to two cells: one that will become a mature cell, and another which retains the capacity to divide again. It's called asymmetric division: instead of giving rise to two of the same cells, you get one regular cell and another stem cell (which can continue this cycle of replication for a long long time).

(Virtually) limitless replication
Most cells have a limited number of times that they can divide. This is because the telomeres (little protective DNA sequences) on the end of the chromosomes get a little shorter every time the DNA replicates - and eventually they are so short that they can't protect the DNA and the cell is unable to divide. Stem cells and cancer cells have an enzyme called telomerase that replenishes the telomeres, keeping them nice and long so the cell can keep on dividing. Stem cells do eventually die - so technically, there are a limited number of cell divisions...but it's a really, really big number. Cancer cells, on the other hand, are often totally immortal - they can just keep on dividing and dividing.

Totipotent
Another cool thing about stem cells is that they can give rise to many different kinds of cells. Here's where things can get murky. There are stem cells in an embryo which are able to give rise to any of the cell types in the body: hepatocytes, epithelial cells, neurons, cardiac muscle cells...everything. This makes sense: if you're going to grow into a human, you have to have cells that give rise to all the necessary cell types. These stem cells are called totipotent or pluripotent stem cells. There's a slight difference between the two words: totipotent means that the stem cell can give rise to any and all human tissue cells - and it can even give rise to an entire functional human. The only totipotent cells in human development are the fertilized egg and the cells in the next few cell divisions.

Pluripotent
After those few cell divisions, the cells become pluripotent. Pluripotent cells are similar to totipotent cells in that they can give rise to any and all human tissue cells. They're different, though, because they are not capable of giving rise to an entire organism. On day four of development, the tiny little embryo forms two layers: one that will become the placenta and the other that will become the baby. The cells that will become the baby can give rise to any human tissue type (obviously) - but those cells alone can't give rise to the entire organism (because you can't form the baby without the placenta). Slight difference - but enough to make a separate term.

Multipotent
Another term you should know is multipotent. Multipotent stem cells cannot give rise to any old cell in the body - they are restricted to a limited range of cell types. For example, there are multipotent stem cells in the bone marrow that can give rise to red cells, white cells and platelets. They can't give rise to hepatocytes, or any other cell type, though - so they are not totipotent or pluripotent.

There are lots of multipotent stem cells in the adult human body. They reside in the bone marrow, skin, muscle, GI tract, endothelium, and mesenchymal tissues. This means that there is a nice source for replacing cells that have died or been sloughed away.

What about myelodsyplasia?
So back to your question. Myelodysplasia is a hematopoietic disorder in which cells in the bone marrow grow funny ("dysplasia") - they might be binucleate, or not have the normal number of granules, or whatever. In addition, some cases have an increase in blasts in the bone marrow - but not over 20%, or you'd call it an acute leukemia. Some cases transform, eventually, into an acute myeloid leukemia; others just stay the way they are and don't become nasty.

Check out the image above, from a case of myelodysplasia. There is a bizarre, multinucleated erythroblast at 11 o'clock (this is called "dyserythropoiesis", or disordered red cell growth). There are also two messed-up neutrophils ("dysgranulopoiesis") at 4 o'clock and 10 o'clock - the one at 4 o'clock has only two nuclear lobes, and both are hypogranular (not enough specific granulation). There's also an increase in blasts, if this field is representative: there's one in the middle and (probably) one at 5 o'clock.

This disorder (actually, it's a group of disorders) involves stem cells in the bone marrow. Sometimes only one cell line is involved (red cells, say); other times all three cell lines are involved (red cells, white cells and platelets). Either way, the disorder involves a stem cell, and since the stem cells in the bone marrow are multipotent, it would be correct to say that myelodysplasia is a disorder of multipotent stem cells in the bone marrow. It's kind of redundant, though, because as far as we know, there aren't any other kind of stem cells in the bone marrow! But at least you know the answer to your question now.

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Q. I'm in doubt regarding myelodysplasia - is it multipotent or pluripotent? A. That's a great question because it lets us talk about hematopathology (yay!) and also stem cells (which can be confusing unless someone explains some simple stuff). What is a stem cell? First, let's talk about stem cells.

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One of the most important types of stem cells because they can develop into any cell found in the human body.

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Totipotent stem cells have the potential to create an entire organism and are often considered the 'master' cells. Their harvesting from foetal tissue does, however, raise ethical concerns.

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Embryonic stem cells are pluripotent cells that can divide indefinitely into exact copies of itself. Eventually they will differentiate into different cells that make up the body.

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They're on the cutting edge of science and the sharp tongues of politicians.

They are the builders of life. And they are one of the most divisive topics of discussion in the United States: stem cells.

They're on the cutting edge of science and the sharp tongues of politicians.

They are the builders of life. And they are one of the most divisive topics of discussion in the United States: stem cells.

An embryonic stem cell is a non-specialized cell that can divide indefinitely into identical copies of itself.

"The only other cell in the body that has the same trait is a cancer cell," said Kessler, who spoke at the symposium. "More recently it's been recognized that many, if not most, cancers seem to arise in stem cells that are present in the body."

So how should teachers approach the topic of stem cells in the classroom?

Scientists and educators tackled that question at the Chicagoland Stem Cell Symposium hosted by Northwestern University in February.

The symposium kicked off the first of four that the Biotechnology Institute of Arlington, Va., plans to hold in academic institutions across the country this year.

The Biotechnology Center at Northwestern University's Kellogg School of Management partnered with the Biotechnology Institute, the national biotechnology education organization, to organize the Chicagoland Stem Cell Education Symposium. The goal of the symposium was to give teachers the tools to offer the next generation of students abroad-based education so they can make informed decisions about the use of new technologies. Most biology textbooks provide little or no coverage of stem cell biology, making it difficult for science teachers to prepare students for understanding the fundamental science and ethical landscape critical for developing future medical innovations in this complex area.

Kessler and other speakers covered the ethics of stem cell research, its medical potential and its alternatives in order to give science teachers the background to approach the topic in their classes.
Embryonic stem cells
Researchers collect embryonic stem cells during the blastocyst stage, when a fertilized egg has developed after a few days into a mass of cells that will become the placenta and the embryo.

Embryonic stem cells eventually differentiate into all the different types of cells that make up the body. That's how a cluster of indistinct cells can develop into a baby.

But even when the body is fully formed, some stem cells are still at work. They continue to grow hair, to repair skin, to form new blood cells and even to form new brain cells.

Researchers are now trying to use different types of stem cells to aid patients with anything from multiple sclerosis to heart disease.

Types of stem cells

There are three different types of stem cells: totipotent cells, pluripotent cells and multipotent cells.

More powerful than the embryonic stem cell is the fertilized egg. It is a totipotent cell that can develop into an entire embryo.

Embryonic stem cells are pluripotent cells, which can give rise to all the cell types in the body but cannot create the substance in which embryonic cells must live.

Multipotent cells have the potential to differentiate into different types of cells, but they are much more limited.

For example, multipotent cells regenerate our skin cells, Kessler said.

"If you think about my skin, I would've eroded it away a long time ago if I didn't have stem cells constantly replacing it," he said.

Multipotent stem cells are often called "adult" stem cells, which, according to Dr. Kessler, "is a bit of a misnomer" because embryos have them as well.

One of the best known examples of this type of cell is found in the bone marrow. This cell creates the family of blood cells: red blood cells, white blood cells and platelets.

One can also find adult stem cells in the nervous system, heart and many, if not all, organs of the body.

Embryonic stem cell lines

Anatomy professor James Thomson created the first embryonic stem cell line in 1998 at the University of Wisconsin in Madison.

To develop an embryonic stem cell line, a researcher must use the inner cell mass of a blastocyst. The researcher separates these cells, puts them in a culture dish and tries to keep them growing without differentiating into specific types of cells.

"It sounds easy," Kessler said. "It's not."

Researchers obtain the blastocysts used in creating embryonic stem cell lines mainly from fertility clinics that conduct in vitro fertilization for women who have trouble becoming pregnant.

The in vitro fertilization procedure involves removing the eggs from a woman's ovaries and fertilizing them outside of the womb.

The fertilized eggs are then allowed to develop in a Petri dish, usually for three to five days. Doctors check the development of the embryos and transfer one or more to the uterus.

Not every embryo is used in the procedure. Doctors often choose only the best-developed embryos and transfer as few as possible to avoid the risk of a more dangerous multiple-birth pregnancy.

Embryos that aren't used are either discarded or stored. The stored embryos are cryopreserved, or frozen.

In 2002, about 400,000 embryos were frozen in storage in the United States, according to a study by the Society for Artificial Reproductive Technology.

Of the embryos in the 2002 study, about 11,000 - 3 percent - were set aside for research.

But unused embryos are often of poorer quality and some lose viability in the freeze-thaw process. Researchers estimated that in the unlikely event they were all dedicated to stem cell research, those 11,000 embryos could create at most 275 stem cell lines.

Stem cell lines cannot develop by themselves at the bottom of a Petri dish. They need to be cultured in something.

The first embryonic stem cell lines created in the United States were cultured on a layer of feeder cells. Back then, researchers typically used skin cells from mice for this.

Today scientists have discovered how to develop stem cell lines without the use of mouse cells.

But researchers used animal feeder cells in all the embryonic stem cell lines created before Aug. 9, 2001 - the only embryonic lines that may be used for federally funded research.

Scientists continue to create new stem cell lines in the United States, but they are prohibited from using federal funding to pay for the research.

Designer cells

The stem cells lines being used for research now cannot be used to treat patients, Kessler said.

Embryonic stem cells can become any type of cell in the body, but no one can change their genetic makeup.

New cells created by these lines would be like donated organs. They would not match the DNA of the recipient and would be rejected by the immune system.

One way to get around this problem is to create cells that perfectly match the recipient's DNA.

This can be done through somatic cell nuclear transfer, also known as therapeutic cloning.

It's called "cloning" because the process involves taking DNA from an adult cell and creating exact copies of it.

To create embryonic stem cells that match a patient's DNA, a scientist must take the nucleus, the part of the cell that contains all of its genetic information, from one of that patient's cells.

In recent experiments, researchers have used the nuclei of adult skin cells.

The scientist then places that nucleus into an egg cell. The egg cell begins to divide and eventually forms a blastocyst with DNA identical to that of the patient.

That blastocyst contains embryonic stem cells that can recreate any cell in the patient's body.

Using adult cells

Investigators in Japan have discovered a way to use adult cells to create cells that act like embryonic stem cells.

Researchers used a virus to insert four genes into a skin cell. With that bit of manipulation, they can convert the adult cell into one that can be differentiated into other types of cells. This is called an induced pluripotent stem cell.

"A lot of people are hopeful that this technique will get around a lot of the ethical issues having to do with somatic cell nuclear transfer," Kessler said.

But the technology of creating these cells is not perfect, Kessler said.

"There's a concept of plasticity," Kessler said. "For example, you could take a fat stem cell and use that to create cells for the brain. I wish that were true because we'd have no trouble getting donors for it."

Until alternatives become as versatile as embryonic stem cell lines, scientists should not limit their research to only one type of stem cell, Kessler said.

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They're on the cutting edge of science and the sharp tongues of politicians. They are the builders of life. And they are one of the most divisive topics of discussion in the United States: stem cells.They're on the cutting edge of science and the sharp tongues of politicians.

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Somatic, or adult stem cells, are undifferentiated cells that can renew itself. Once a stem cell reaches adulthood, it can only produce a specific type of cell.

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1. Introduction: What are stem cells, and why are they important?

2. What are the unique properties of all stem cells?

3. What are embryonic stem cells?

4. What are adult stem cells?

5. What are the similarities and differences between embryonic and adult stem cells?

6. What are induced pluripotent stem cells?

7. What are the potential uses of human stem cells and the obstacles that must be overcome before these potential uses will be realized?

8. Where can I get more information?

IV. What are adult stem cells?

An adult stem cell is thought to be an undifferentiated cell, found among differentiated cells in a tissue or organ. The adult stem cell can renew itself and can differentiate to yield some or all of the major specialized cell types of the tissue or organ. The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found. Scientists also use the term somatic stem cell instead of adult stem cell, where somatic refers to cells of the body (not the germ cells, sperm or eggs). Unlike embryonic stem cells, which are defined by their origin (cells from the preimplantation-stage embryo), the origin of adult stem cells in some mature tissues is still under investigation.

Research on adult stem cells has generated a great deal of excitement. Scientists have found adult stem cells in many more tissues than they once thought possible. This finding has led researchers and clinicians to ask whether adult stem cells could be used for transplants. In fact, adult hematopoietic, or blood-forming, stem cells from bone marrow have been used in transplants for more than 40 years. Scientists now have evidence that stem cells exist in the brain and the heart, two locations where adult stem cells were not at first expected to reside. If the differentiation of adult stem cells can be controlled in the laboratory, these cells may become the basis of transplantation-based therapies.

The history of research on adult stem cells began more than 60 years ago. In the 1950s, researchers discovered that the bone marrow contains at least two kinds of stem cells. One population, called hematopoietic stem cells, forms all the types of blood cells in the body. A second population, called bone marrow stromal stem cells (also called mesenchymal stem cells, or skeletal stem cells by some), were discovered a few years later. These non-hematopoietic stem cells make up a small proportion of the stromal cell population in the bone marrow and can generate bone, cartilage, and fat cells that support the formation of blood and fibrous connective tissue.

In the 1960s, scientists who were studying rats discovered two regions of the brain that contained dividing cells that ultimately become nerve cells. Despite these reports, most scientists believed that the adult brain could not generate new nerve cells. It was not until the 1990s that scientists agreed that the adult brain does contain stem cells that are able to generate the brain's three major cell types- astrocytes and oligodendrocytes, which are non-neuronal cells, and neurons, or nerve cells.

A. Where are adult stem cells found, and what do they normally do?

Adult stem cells have been identified in many organs and tissues, including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, gut, liver, ovarian epithelium, and testis. They are thought to reside in a specific area of each tissue (called a "stem cell niche"). In many tissues, current evidence suggests that some types of stem cells are pericytes, cells that compose the outermost layer of small blood vessels. Stem cells may remain quiescent (non-dividing) for long periods of time until they are activated by a normal need for more cells to maintain tissues, or by disease or tissue injury.

Typically, there is a very small number of stem cells in each tissue and, once removed from the body, their capacity to divide is limited, making generation of large quantities of stem cells difficult. Scientists in many laboratories are trying to find better ways to grow large quantities of adult stem cells in cell culture and to manipulate them to generate specific cell types so they can be used to treat injury or disease. Some examples of potential treatments include regenerating bone using cells derived from bone marrow stroma, developing insulin-producing cells for type 1 diabetes, and repairing damaged heart muscle following a heart attack with cardiac muscle cells.

B. What tests are used to identify adult stem cells?

Scientists often use one or more of the following methods to identify adult stem cells: (1) label the cells in a living tissue with molecular markers and then determine the specialized cell types they generate; (2) remove the cells from a living animal, label them in cell culture, and transplant them back into another animal to determine whether the cells replace (or "repopulate") their tissue of origin.

Importantly, scientists must demonstrate that a single adult stem cell can generate a line of genetically identical cells that then gives rise to all the appropriate differentiated cell types of the tissue. To confirm experimentally that a putative adult stem cell is indeed a stem cell, scientists tend to show either that the cell can give rise to these genetically identical cells in culture, and/or that a purified population of these candidate stem cells can repopulate or reform the tissue after transplant into an animal.

C. What is known about adult stem cell differentiation?

As indicated above, scientists have reported that adult stem cells occur in many tissues and that they enter normal differentiation pathways to form the specialized cell types of the tissue in which they reside.

Normal differentiation pathways of adult stem cells. In a living animal, adult stem cells are available to divide for a long period, when needed, and can give rise to mature cell types that have characteristic shapes and specialized structures and functions of a particular tissue. The following are examples of differentiation pathways of adult stem cells ( Figure 2) that have been demonstrated in vitro or in vivo.

Figure 2. Hematopoietic and stromal stem cell differentiation. Click here for larger image. (© 2008 Terese Winslow)

Hematopoietic stem cells give rise to all the types of blood cells: red blood cells, B lymphocytes, T lymphocytes, natural killer cells, neutrophils, basophils, eosinophils, monocytes, and macrophages.

Mesenchymal stem cells have been reported to be present in many tissues. Those from bone marrow (bone marrow stromal stem cells, skeletal stem cells) give rise to a variety of cell types: bone cells (osteoblasts and osteocytes), cartilage cells (chondrocytes), fat cells (adipocytes), and stromal cells that support blood formation. However, it is not yet clear how similar or dissimilar mesenchymal cells derived from non-bone marrow sources are to those from bone marrow stroma.

Neural stem cells in the brain give rise to its three major cell types: nerve cells (neurons) and two categories of non-neuronal cells-astrocytes and oligodendrocytes.

Epithelial stem cells in the lining of the digestive tract occur in deep crypts and give rise to several cell types: absorptive cells, goblet cells, Paneth cells, and enteroendocrine cells.

Skin stem cells occur in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells give rise to keratinocytes, which migrate to the surface of the skin and form a protective layer. The follicular stem cells can give rise to both the hair follicle and to the epidermis.

Transdifferentiation. A number of experiments have reported that certain adult stem cell types can differentiate into cell types seen in organs or tissues other than those expected from the cells' predicted lineage (i.e., brain stem cells that differentiate into blood cells or blood-forming cells that differentiate into cardiac muscle cells, and so forth). This reported phenomenon is called transdifferentiation.

Although isolated instances of transdifferentiation have been observed in some vertebrate species, whether this phenomenon actually occurs in humans is under debate by the scientific community. Instead of transdifferentiation, the observed instances may involve fusion of a donor cell with a recipient cell. Another possibility is that transplanted stem cells are secreting factors that encourage the recipient's own stem cells to begin the repair process. Even when transdifferentiation has been detected, only a very small percentage of cells undergo the process.

In a variation of transdifferentiation experiments, scientists have recently demonstrated that certain adult cell types can be "reprogrammed" into other cell types in vivo using a well-controlled process of genetic modification (see Section VI for a discussion of the principles of reprogramming). This strategy may offer a way to reprogram available cells into other cell types that have been lost or damaged due to disease. For example, one recent experiment shows how pancreatic beta cells, the insulin-producing cells that are lost or damaged in diabetes, could possibly be created by reprogramming other pancreatic cells. By "re-starting" expression of three critical beta cell genes in differentiated adult pancreatic exocrine cells, researchers were able to create beta cell-like cells that can secrete insulin. The reprogrammed cells were similar to beta cells in appearance, size, and shape; expressed genes characteristic of beta cells; and were able to partially restore blood sugar regulation in mice whose own beta cells had been chemically destroyed. While not transdifferentiation by definition, this method for reprogramming adult cells may be used as a model for directly reprogramming other adult cell types.

In addition to reprogramming cells to become a specific cell type, it is now possible to reprogram adult somatic cells to become like embryonic stem cells ( induced pluripotent stem cells, iPSCs) through the introduction of embryonic genes. Thus, a source of cells can be generated that are specific to the donor, thereby increasing the chance of compatibility if such cells were to be used for tissue regeneration. However, like embryonic stem cells, determination of the methods by which iPSCs can be completely and reproducibly committed to appropriate cell lineages is still under investigation.

D. What are the key questions about adult stem cells?

Many important questions about adult stem cells remain to be answered. They include:

How many kinds of adult stem cells exist, and in which tissues do they exist?

How do adult stem cells evolve during development and how are they maintained in the adult? Are they "leftover" embryonic stem cells, or do they arise in some other way?

Why do stem cells remain in an undifferentiated state when all the cells around them have differentiated? What are the characteristics of their "niche" that controls their behavior?

Do adult stem cells have the capacity to transdifferentiate, and is it possible to control this process to improve its reliability and efficiency?

If the beneficial effect of adult stem cell transplantation is a trophic effect, what are the mechanisms? Is donor cell-recipient cell contact required, secretion of factors by the donor cell, or both?

What are the factors that control adult stem cell proliferation and differentiation?

What are the factors that stimulate stem cells to relocate to sites of injury or damage, and how can this process be enhanced for better healing?

Previous | IV. What are adult stem cells? | Next

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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?