Stem Cells: Frequently asked questions (FAQS)
What are human embryonic stem cells?
Stem cells are cells that have the remarkable potential to develop into many
different cell types in the body. Serving as a sort of repair system for the
body, they can theoretically divide without limit to replenish other cells for
as long as the person or animal is still alive. When a stem cell divides, each "daughter" cell
has the potential to either remain a stem cell or become another type of cell
with a more specialized function, such as a muscle cell, a red blood cell, or
a brain cell.
A more detailed primer on stem cells can be found at http://stemcells.nih.gov/info/basics.
What classes of stem cells are there?
There are three classes of stem cells: totipotent, multipotent, and pluripotent.
- A fertilized egg is considered totipotent, meaning that its potential is total;
it gives rise to all the different types of cells in the body.
- Stem cells that can give rise to a small number of different cell types are
generally called multipotent.
- Pluripotent stem cells can give rise to any type of cell in the body except
those needed to develop a fetus.
Where do stem cells come from?
Pluripotent stem cells are isolated from human embryos that are a few days old.
Cells from these embryos can be used to create pluripotent stem cell "lines"
—cell cultures that can be grown indefinitely in the laboratory. Pluripotent stem
cell lines have also been developed from fetal tissue obtained from fetal
tissue (older than 8 weeks of development).
Why do scientists want to use stem cell lines?
Once a stem cell line is established from a cell in the body, it is essentially
immortal, no matter how it was derived. That is, the researcher using the line
will not have to go through the rigorous procedure necessary to isolate stem
cells again. Once established, a cell line can be grown in the laboratory indefinitely
and cells may be frozen for storage or distribution to other researchers.
Stem cell lines grown in the lab provide scientists with the opportunity to "engineer" them
for use in transplantation or treatment of diseases. For example, before scientists
can use any type of tissue, organ, or cell for transplantation, they must overcome
attempts by a patient's immune system to reject the transplant. In the future,
scientists may be able to modify human stem cell lines in the laboratory by using
gene therapy or other techniques to overcome this immune rejection. Scientists
might also be able to replace damaged genes or add new genes to stem cells in
order to give them characteristics that can ultimately treat diseases.
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Why are doctors and scientists so excited about human embryonic stem cells?
Stem cells have potential in many different areas of health and medical research.
To start with, studying stem cells will help us to understand how they transform
into the dazzling array of specialized cells that make us what we are. Some of
the most serious medical conditions, such as cancer and birth defects, are due
to problems that occur somewhere in this process. A better understanding of normal
cell development will allow us to understand and perhaps correct the errors that
cause these medical conditions.
Another potential application of stem cells is making cells and tissues for medical
therapies. Today, donated organs and tissues are often used to replace those
that are diseased or destroyed. Unfortunately, the number of people needing a
transplant far exceeds the number of organs available for transplantation. Pluripotent
stem cells offer the possibility of a renewable source of replacement cells and
tissues to treat a myriad of diseases, conditions, and disabilities including
Parkinson's and Alzheimer's diseases, spinal cord injury, stroke, burns, heart
disease, diabetes, osteoarthritis and rheumatoid arthritis.
Have human embryonic stem cells been used successfully to treat any human diseases
Scientists have only been able to do experiments with human embryonic stem cells
(hESC) since 1998, when a group led by Dr. James Thomson at the University of
Wisconsin developed a technique to isolate and grow the cells. Moreover, Federal
funds to support hESC research have only been available since August 9, 2001,
when President Bush announced his decision on Federal funding for hESC research.
Because many academic researchers rely on Federal funds to support their laboratories,
they are just beginning to learn how to grow and use the cells. Thus, although
hESC are thought to offer potential cures and therapies for many devastating
diseases, research using them is still in its early stages.
Adult stem cells such as blood-forming stem cells in bone marrow (called hematopoietic
stem cells, or HSCs) are currently the only type of stem cell commonly used to
treat human diseases. Doctors have been transferring HSCs in bone marrow transplants
for over 40 years. More advanced techniques of collecting, or "harvesting",
HSCs are now used in order to treat leukemia, lymphoma and several inherited
The clinical potential of adult stem cells has also been demonstrated in the
treatment of other human diseases that include diabetes and advanced kidney cancer.
However, these newer uses have involved studies with a very limited number of
What will be the best type of stem cell to use for therapy?
Pluripotent stem cells, while having great therapeutic potential, face formidable
technical challenges. First, scientists must learn how to control their development
into all the different types of cells in the body. Second, the cells now available
for research are likely to be rejected by a patient's immune system. Another
serious consideration is that the idea of using stem cells from human embryos
or human fetal tissue troubles many people on ethical grounds.
Until recently, there was little evidence that multipotent adult stem cells could
change course and provide the flexibility that researchers need in order to address
all the medical diseases and disorders they would like to. New findings in animals,
however, suggest that even after a stem cell has begun to specialize, it may
be more flexible than previously thought.
There are currently several limitations to using adult stem cells. Although many
different kinds of multipotent stem cells have been identified, adult stem cells
that could give rise to all cell and tissue types have not yet been found. Adult
stem cells are often present in only minute quantities and can therefore be difficult
to isolate and purify. There is also evidence that they may not have the same
capacity to multiply as embryonic stem cells do. Finally, adult stem cells may
contain more DNA abnormalities—caused by sunlight, toxins, and errors
in making more DNA copies during the course of a lifetime. These potential weaknesses
might limit the usefulness of adult stem cells.
I have Parkinson’s Disease. Is there a clinical trial that I can participate
in that uses stem cells as therapy?
The public may search a database of NIH-sponsored clinical trials at http://www.clinicaltrials.gov. Enter the search terms of interest (in this case, Parkinson's Disease and stem cells) to search for applicable clinical trials.
Where can I donate umbilical cord stem cells?
NIH cannot accept donated umbilical cord stem cells from the general public.
The American Red Cross maintains a Web page on donating cord blood at http://www.redcross.org/services/biomed/0,1082,0_108_,00.html, and the International Cord Blood Society has one at http://www.cordblood.org/public/insights.
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Research and Policy Questions
Which research is best to pursue?
The development of stem cell lines that can produce many tissues of the human
body is an important scientific breakthrough. This research has the potential
to revolutionize the practice of medicine and improve the quality and length
of life. Given the enormous promise of stem cells therapies for so many devastating
diseases, NIH believes that it is important to simultaneously pursue all lines
of research and search for the very best sources of these cells.
Why not use adult stem cells instead of using human embryonic stem cells in research?
Human embryonic stem cells are thought to have much greater developmental potential
than adult stem cells. This means that embryonic stem cells may be pluripotent –that
is, able to give rise to cells found in all tissues of the embryo except for
germ cells rather than being merely multipotent--restricted to specific subpopulations
of cell types, as adult stem cells are thought to be.
What are the NIH Guidelines on the utilization of stem cells derived from human fetal tissue (embryonic germ cells)?
The Federal Register Announcement National Institutes of Health Guidelines for Research Using Human Pluripotent Stem Cells (230k PDF; get Adobe Reader), published August 25, 2000, was "superceded as it pertains to embryonic stem cell research" on November 14, 2001). However, Section II. B, titled "Utilization of Human Pluripotent Stem Cells Derived from Human Fetal Tissue," still governs human embryonic germ cell research. In addition, Section III, titled "Areas of Research Involving Human Pluripotent Stem Cells That Are Ineligible for NIH Funding," governs both human embryonic stem cell and human embryonic germ cell research.
May individual states pass laws to permit human embryonic
stem cell research?
Individual states have the authority to pass laws to permit human embryonic stem cell research using state funds. Unless Congress passes a law that bans it, states may pay for research using human embryonic stem cell lines that are not eligible for Federal funding.
Where can I find information about patents obtained for stem cells?
Click this link to search the US Patent and Trademark Office for "stem cell."
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Cell Line Availability and the Registry
I am a scientist funded by the NIH. How many cell lines are available to me, and how do I get them?
In the third quarter of 2004, there are 22 human embryonic stem cell lines that federally supported
researchers can purchase. The cell lines can be purchased by contacting the cell line providers
directly. Information on the lines and how to contact providers can be found
on the NIH Stem Cell Registry.
In addition, this site provides researchers with a unique NIH identifier code
to apply for Federal funds to do research using human embryonic stem cells.
I'm interested in purchasing more than one cell line from the NIH Stem Cell Registry.
What is known about the status of the cell lines and their availability?
Many of the cell lines have been characterized as embryonic stem cells by detecting
expression of surface antigen markers specific to embryonic stem cells, determining
if the cells are pluripotent, and demonstrate that the cells are undifferentiated.
A number of scientific publications have described the characterization of human
embryonic stem cells. Although the characterization approaches may differ across
laboratories, an example of the strategies used can be found in Thomson et al.
(1998), Science, 282,1145–1147.
Providers of the federally eligible cells are working to make them available
to researchers. This includes developing quality control measures to grow and
reproduce the cell lines in sufficient numbers, having the administrative structure
to receive and process requests, and establishing material transfer agreements
with research purchasers. The providers of federally eligible cell lines have
the most up-to-date information on availability. A list of these sources and
contact information is available on the NIH Stem
Who owns the cells?
The stem cell lines remain the property of the individual stem cell providers,
as listed on the NIH Stem Cell Registry. Researchers
may negotiate a material transfer agreement (MTA) with the cell providers in
order to specify their rights and responsibilities concerning resulting data, publications,
and potential patents. Examples of MTAs negotiated between the Department of
Health and Human Services/NIH and various stem cell line providers are listed by provider http://stemcells.nih.gov/research/registry.
When does NIH anticipate that more stem cell lines will become available?
In the third quarter of 2004, there are 22 human embryonic stem cell lines that federally supported
researchers may purchase. This number is up from only one or two lines in Spring
2002. The increased availability of the lines is a direct consequence of NIH’s
funding of infrastructure awards to support cell providers to develop their eligible
lines into distribution-quality, well-characterized cell lines. Up-to-date information on available lines can be found on the NIH Stem Cell Registry.
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Does NIH fund embryonic stem cell research?
Research on human embryonic stem cell lines may receive NIH funding if the cell
line meets the following criteria: removal of cells from the embryo must have
been initiated before August 9, 2001, when the President outlined this policy;
and the embryo from which the stem cell line was derived must no longer have
had the possibility of developing further as a human being. The embryo must have
been created for reproductive purposes but no longer be needed for them. Informed
consent must have been obtained from the parent(s) for the donation of the embryo,
and no financial inducements for donation are allowed.
In order to ensure that federal funds are used to support only stem cell research
that is scientifically sound, legal, and ethical, NIH examines stem cell lines
and maintains a Stem Cell Registry of lines that satisfy the criteria.
Are there any areas of research involving human pluripotent stem cells that are ineligible for NIH funding?
The Federal Register Announcement National Institutes of Health Guidelines for Research Using Human Pluripotent Stem Cells (230k PDF; requires Adobe Reader), published August 25, 2000, was "superceded as it pertains to embryonic stem cell research" on November 14, 2001). However, Section II. B, titled "Utilization of Human Pluripotent Stem Cells Derived from Human Fetal Tissue," still governs human embryonic germ cell research. In addition, Section III, titled "Areas of Research Involving Human Pluripotent Stem Cells That Are Ineligible for NIH Funding," governs both human embryonic stem cell and human embryonic germ cell research.
Can a scientist supported by federal funds conduct research with stem cell lines that are not listed on the NIH Human Embryonic Stem Cell Registry?
No federal funds may be used, either directly or indirectly, to support research on human embryonic stem cell lines that do not meet the criteria established by President Bush on August 9, 2001. Cell lines not listed on the NIH Human Embryonic Stem Cell Registry do not meet these criteria. Thus, research on lines (or their derivatives) not listed on the NIH Human Embryonic Stem Cell Registry may not be supported by federal funds.
What if a scientist is conducting research with both federally fundable and non-federally fundable human embryonic stem cells?
Scientists who receive federal funds and study both federally fundable and non-federally fundable human embryonic stem cells must charge research costs for study of non-federal lines only to non-federal sources of funding. With respect to indirect costs, such as facilities and administrative (F&A) costs, scientists should adhere to the guidelines in OMB Circular A-21. This document describes how to keep budget records so as to prevent federal funds from indirectly supporting research on non-federally fundable human embryonic stem cells.
Technical guidance provided by the DHHS Division of Cost Allocation states that the cost principles and Cost Allocation Standards contained in OMB Circular A-21, particularly with regard to the treatment of activities sponsored by industry and foreign governments are equally applicable to unallowable stem cell research. The regulations strictly forbid the shifting of costs from these activities to Federally-sponsored activities. Strict adherence to the principles contained in the circular, requires the allocation of indirect costs, also known as facilities and administrative (F&A) costs, to both Federally sponsored and other activities, which would include unallowable stem cell research. Federal policy is clear that no Federal funding may be used, either directly or indirectly, to support human embryonic stem cell research outside the criteria established by the President on August 9, 2001, i.e., it is unallowable. Therefore, the direct costs of such activity must be charged only to non-Federal sources of funding. With respect to F&A costs, institutions engaged in unallowable stem cell work must strictly adhere to guidance contained in OMB Circular A-21. Strict compliance with cost allocation methodologies described in the circular, including the Cost Allocation Standards, will prevent the shifting of unallowable Stem Cell research costs to federally sponsored programs. The F&A costs which are allocated to Stem Cell research will not be charged to federally sponsored activities because the direct costs of the Stem Cell programs are only charged to non-Federal sources of funding. A properly documented F&A proposal utilized in the establishment of F&A rates, should demonstrate that none of the costs of unallowable stem cell research or other unallowable activities have been shifted to federally sponsored activities.
Who is responsible for setting the policy to allow Federal money to be used
for human embryonic stem cell research?
As the head of the Executive Branch of the Federal Government, which includes
the National Institutes of Health, the President of the United States has the
final responsibility and authority to set Federal government policy for funding
human embryonic stem cell research. But Congress has appropriations authority
and can possibly override the President's decision.
I am a university research administrator. One of our NIH-funded investigators
would like to use a cell line that was created after August 9th, 2001, and
it is not eligible for research using Federal funds. What should I tell the
investigator who wants to work with these cells in his laboratory?
Institutions need to provide clear instructions to investigators who conduct
research that is "unallowable" under Federal research funding policy.
In laboratories where there is both Federal and non-Federal funding, investigators
and their staffs must separate allowable and unallowable activities in such
a way that permits the costs incurred in the research to be allocated consistently
to the appropriate funding source. In your example, for instance, the time
and effort of laboratory personnel working on the stem cell line created after
August 9, 2001, may not be charged to any Federal grant. Acquisition of equipment,
use of cell and tissue culture supplies in the project, and travel to a conference
to discuss or present this work likewise may not be federally supported.
I am an investigator who receives NIH funding, and I am planning to derive
new human embryonic stem cell lines. Can I conduct the derivations in my laboratory,
or do I need to find a non-university funded laboratory to do this work?
You may do the derivation in your university supported laboratory as long as:
1) you carefully and consistently allocate all costs of doing the derivation
to a non-Federal funding source; and 2) your university or research center
has in place a method of separating the costs of supporting your laboratory
so that any of the facilities and administrative (F&A) costs allocable
to your new stem cell line work are excluded from the federal share of the
organized research cost base, per the provisions of OMB Circular A-21.
Can you explain what accounting principles are necessary to demonstrate that
unallowable charges are not being absorbed by NIH funded research, e.g., indirect
The cost principles contained in OMB Circular A-21, http://www.whitehouse.gov/omb/circulars/a076/trans21final.html
particularly with regard to treatment of allowable and unallowable costs, contain
the necessary guidance. Federal policy is explicitly clear that no Federal
funding may be used, either directly or indirectly, to support human embryonic
stem cell research outside the criteria established by the President on August
9, 2001, i.e., it is unallowable. Therefore, the direct costs of such work
must be charged only to non-Federal sources of funding. With respect to indirect
costs, also known as facilities and administrative (F&A) costs, institutions
engaged in unallowable stem cell work must be able to demonstrate that none
of the costs of supporting this work have been included in the rates established
and used to charge F&A costs to federally funded research.
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