Myths and Misconceptions About Stem Cell Research

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Myths and misconceptions about stem cell research

There are a lot of myths about stem cell research, the origin of the stem cells themselves, and the type of work that takes place. Learn what really takes place in stem cell research.

If you have additional questions about stem cell research that aren't addressed here, you might find answers in our Stem Cell Basics. If you don't find the answers there, please email us at

How does CIRM ensure that the stem cell research it funds is carried out ethically?

Stem cell research, like any biomedical research, poses social and ethical concerns that CIRM, and the broader research community, takes very seriously. The research community has a history of addressing ethical challenges, and dealing with them in ways that allow research to move forward responsibly.

State and national funding bodies, such as CIRM and the NIH, have comprehensive policies to govern research. For example, CIRM-funded researchers must comply with a comprehensive set of regulations that have been carefully developed and are in accordance with national and international standards. These regulations were among the first formal policies governing the conduct of stem cell research and are in accordance with recommendations from the National Academies and from the International Society for Stem Cell Research. CIRM’s Standards Working Group meets regularly to consider new ethical challenges as the science progresses and to revise standards to reflect the current state of the research.

See a video about ethics training that all CIRM grantees undergo (4:03)

Where do the embryos come from to create stem cell lines?

All the human embryonic stem cell lines currently in use come from four to five day old embryos left over from in vitro fertilization (IVF). In in vitro fertilization, researchers mix a man's sperm and a woman's eggs together in a lab dish. Some of those eggs become fertilized and begin developing. At about five days the egg has divided to become a hollow ball of roughly 100 cells called a blastocyst which is smaller than the size of the dot over an “i”. It is these very early embryos that are implanted into the woman in the hopes that she becomes pregnant.

Each cycle of IVF can produce many blastocysts, some of which are implanted into the woman and the rest are stored in the IVF clinic freezer. After a couple has completed their family, they must decide what to do with any remaining embryos. They can continue paying to store the embryos or they can defrost the embryos, which destroys them. Some couples may choose to donate the embryos for adoption, though that option is not commonly taken. In some states, couples can also choose to donate the frozen embryos for research. These donated embryos are the source of human embryonic stem cell lines.

Some embryonic stem cell lines also come from embryos that a couple has chosen not to implant because they carry genetic mutations like the ones that cause cystic fibrosis or Tay Sachs disease. These are discovered through routine genetic testing prior to implantation. Still other embryos might be malformed in some way that causes them to be rejected for implantation into the mother. These embryos with genetic defects of malformations would have been discarded if the couple had not choosen to donate them to stem cell research.

See a video about creating stem cell lines from left over IVF embryos (4:11)

I'm opposed to abortion. Do embryonic stem cell lines come from aborted fetuses?

No. Emybronic stem cells only come from four to five day old blastocysts or younger embryos.

I've heard that creating embryonic stem cell lines destroys the embryo

This is true in most cases. The hollow blastocyst contains a cluster of roughly 20-30 cells called the inner cell mass. These are the cells that become embryonic stem cells in a lab dish. The process of extracting these cells destroys the embryo. Remember that the embryos were donated from in vitro fertilization clinics. They had either been rejected for implantation and were going to be destroyed, or the couple had decided to stop storing the embryos for future use. The embryos used to create embryonic stem cell lines were already destined to be destroyed.

A second method for creating embryonic stem cell lines does not destroy the embryo. Instead, scientists take a single cell from a very early stage IVF embryo and can use that one cell to develop a new line. The process of removing one cell from an early stage embryo has been done for many years as a way of testing the embryo for genetic predisposition to diseases such as Tay Sachs. This process is called preimplantation genetic testing.

What other options do people have for unused embryos from fertility treatments?

People who undergo IVF and have stored embryos have several options regarding what to do with the excess embryos once they have completed their family.

  • They can simply discard the embryos
  • They can store the embryos indefinitely at their own expense
  • They can give the embryos to other infertile couples. (More information about that option is available through the RESOLVE: The National Infertility Association)
  • They can donate the embryos to general research or stem cell research

People who donate their left over embryos for research go through an extensive consenting process to ensure that they understand embryonic stem cell research. Under California state, national, or international regulations, no human embryonic stem cell lines should be created without explicit consent from the donor.

Where do human eggs come from for creating stem cell lines through SCNT?

The process of SCNT requires human eggs from living donors. There are a wide range of national and international policies regarding human egg donation. All policies require voluntary and informed consent from the women so they understand the risks and benefits of egg donation.

  See a video about creating stem cell lines through SCNT (3:15)

Policies vary as to whether women may be paid or otherwise compensated to donate eggs.  Most jurisdictions allow donors to be reimbursed for direct costs such as travel to the clinic or lodging.  Some also allow payments or IVF services to be provided to egg donors.

I've heard that adult stem cells are as good or better than embryonic stem cells

Adult stem cells are extremely valuable and have great potential for future therapies. However, these cells are very restricted in what they can do. Blood forming stem cells can treat some blood diseases, and brain stem cells may be able to treat some neural diseases, but those cells can’t turn into other tissues types. What’s more, adult stem cells don’t grow indefinitely in the lab, unlike embryonic stem cells, and they aren’t as flexible in the types of diseases they can treat.

It's true that the news is full of stories about people who had great results from adult stem cell therapies. Few of these therapies are part of big trials that can test to be sure that a potential therapy is safe and effective. Until some of these large trials take place with both adult and embyonic stem cells we won't know which cells are the most effective for different diseases. In fact, even researchers who study adult stem cells advocate working with embryonic cells as well.

CIRM encourages work with adult stem cells and is excited about their potential for treating some diseases. However, the goal of CIRM is to accelerate new treatments for incurable diseases and at this time the most effective way of doing that is by exploring all types of stem cells: adult, embryonic, iPS and cancer. That's why CIRM has funded researchers pursuing a wide range of approaches to finding cures for diseases.

See a video about the differences between adult and embryonic stem cells (3:29)

See a video about the dangers of stem cell tourism (3:38)

Don't iPS cells eliminate the need to use embryos in stem cell research?

iPS cells are also called reprogrammed cells. They are adult cells – usually skin cells – that scientists can genetically reprogram to appear like embryonic stem cells. They are a very exciting advance, which is why CIRM has funded many grants exploring new ways of creating and using these cells to study or treat disease. However, the technology to create iPS cells is very new and it is still not known whether those cells have the same potential as human embryonic stem cells or whether the cells are safe for transplantation.

Many CIRM-funded researchers are working to find better ways of creating iPS cells that are safe and avoid dangerous virus or mutation so the cells can be used therapeutically. In the mean time, waiting for iPS cells to become therapeutically safe – which will likely take many years – would slow the search for disease treatments. Cures can’t wait, which is why CIRM funds all types of stem cell research.

Experts agree that research on all types of stem cells is critical.  In September 2008, a panel of experts convened by the U.S. National Academy of Sciences agreed that the use of human embryonic stem cells is still necessary.  As the expert panel, chaired by Richard Hynes of the Massachusetts Institute of Technology stated “It is far from clear at this point which types of cell types will prove to be the most useful for regenerative medicine, and it is likely that each will have some utility.

See a video about creating iPS cells (3:40)

Can't stem cell research lead to human cloning?

No. Every significant regulatory and advisory body has restrictions on reproductive cloning. The National Academy of Sciences has issued guidelines banning the technique as has the International Society for Stem Cell Research. The California constitution and CIRM regulations specifically prohibit reproductive cloning with its funding.


Updated 1/11

© 2013 California Institute for Regenerative Medicine