Adult Stem Cells vs. Embryonic Stem Cells
The human body is made of some 100 trillion cells, be they blood cells, nerve cells, muscle cells or organ cells. Stem cells are the building blocks that eventually becomethose blood cells and organ cells. Their unique characteristics hold the promise of repairing tissue and curing disease. But the means of acquiring stem cells has been the subject of controversy.
Embryonic stem cells are more adaptable than adult stem cells.
Embryonic stem cells are essentially blank; that is, they have no identifying information that makes them any particular type of cell. They have the potential to make all tissues of the body. Researchers are learning to “program” embryonic stem cells to become specialized cell types, such as nerve cells or brain cells. Adult stem cells, by contrast, are already stamped with that information.
Think of an embryonic stem cell like a blank compact disc, which has the capability to receive information that turns it into music CD. Adult stem cells are like store-bought music CDs, and cannot be reverse engineered.
All stem cells have the remarkable ability to multiply and become tissue.
Stem cells can replicate themselves and grow indefinitely on their own. Dr. Leonard Zon, professor of pediatrics at the Children’s Hospital of Harvard Medical School and founding president of the International Society for Stem Cell Research, helps define stem cell properties:
“A stem cell has two characteristics,” he explains. “It can remake itself—we call that self-renewal. And it can differentiate, which means it can become a tissue. Many cells can become a specialized type of tissue but they don’t all have that ability of self-renewal.”
With the capability to grow the tissue for, say, a healthy heart valve, we may be able to replace and repair the tissue in a diseased heart.
Adult stem cells have been in clinical use for a quarter century.
“We know adult stem cell therapy works because we have 25 years of bone-marrow transplantation that’s been done,” says Dr. Zon. Using the example of a cancer patient, he explains how stem cell therapy can repair an immune system that’s been destroyed by chemotherapy. “I could give good blood stem cells back [to that patient]—good adult stem cells—and if they’re a match they’ll go into his blood-forming space, the bone marrow, and start making blood.
“Another place where stem cells have been used has been skin grafts. It’s known that you can take small populations of cells from the skin and grow them into sheets of tissue. Those have been invaluable for burn victims.”
A criticism leveled against embryonic stem cell research, however, is that they have not yet been put to effective use. To date, no one has been cured by embryonic stem cells. Dr. Zon argues that this is a poor reason to block the research: “Twenty years ago, no one had done a liver transplant, either. But now thousands of people are walking around thanks to liver transplantation.”
There is no federal law against stem cell research—but no federal dollars, either.
President Bush did not outlaw stem cell research. Rather, he prohibited the funding of embryonic stem cell research by the National Institutes of Health (outside of continued work on about 20 pre-existing stem cell lines). As Dr. Zon points out, this is an important issue because most scientists depend on federal tax dollars to fund their research.
That’s the feds. A number of states—including Arkansas, North Dakota, South Dakota, Iowa and Michigan—have prohibited or restricted research on live embryos.
Cord blood contains adult stem cells, not embryonic stem cells.
Some new parents are having the blood from their newborn’s umbilical cord cryogenically stored. The child or a sibling might be able to use the cord’s blood cells later in life for a marrow transplant. “Since it comes from the cord people often think the cells are embryonic, but the cells are adult stem cells,” says Dr. Zon.
Embryonic stem cells do not come from aborted fetuses.
Many opponents have a misperception of where embryonic stem cells come from. An egg is fertilized in a laboratory, constituting an embryo. The embryo can then be implanted in a woman, where it may impregnate her and later become a fetus; or the stem cells within the egg can be extracted and transferred to a Petri dish, where they can multiply indefinitely and be used to research diseases and cures.
The current ethical debate pivots on what constitutes a human life. Scientifically informed opponents of embryonic stem cell research believe that tinkering with fertilized eggs, even at a cellular stage preceding pregnancy, is unethical. No one has taken issue with the use of adult stem cells. One goal of researchers is to reprogram adult stem cells to have the “blank” characteristic of embryonic stem cells. Since no embryo would be involved, this achievement would overcome the ethical hurdles.
Adult Stem Cells vs. Embryonic Stem Cells has been reviewed for accuracy by Dr. Leonard Zon, professor of pediatrics at Harvard Medical School, Children’s Hospital, and founding president of the International Society for Stem Cell Research.
Confused by health myths and misinformation? Each week, Rich Maloof talks to leading health experts to bring you the straight facts on a broad range of health topics.
Read More on MSN Health & Fitness:
- New Life for Stem-Cell Research
- Stem Cell Transplant Shows Promise Against ALS
- Stem-Cell Therapy May Benefit Heart-Attack Patients
- Stem Cells Improve Child Brain Cancer Outcomes
be well, feel better
It's easy to rationalize a food binge (I worked out! I have PMS!). But it's just as simple to talk yourself out of inhaling unwanted calories.
Celebrate Independence Day without risking your health.
Some completely treatable health ailments can put a damper on your sexual allure. Here are 12 turn-offs to treat so that your partner stays turned on.
When do personality quirks cross the line into obsessive-compulsive disorder?
Are spray sunscreens safe? Is 30 SPF enough? Our skin expert has the answers.
Which are just gross, and which are truly dangerous?
Are these habits putting you at risk for illness or injury down the road?
Kitchen staples that soothe sunburns, boost your mood, and more.