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Stem Cells FAQs & Information
What are stem cells?
Stem cells are cells that can 1) self-replicate and 2) give rise to more differentiated cells.
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What is an adult stem cell?
An adult stem cell is a stem cell that gives rise to limited types of cells. For example, a hematopoietic (blood) stem cell found in the bone marrow is an adult stem cell that gives rise to red blood cells, white blood cells and platelets. top
What are umbilical cord stem cells?
These are hematopoietic (blood) stem cells that are found in the placental and cord blood. These can be harvested after the delivery of a neonate. Of note, cord stem cells are NOT embryonic stem cells. top
What classes of stem cells exist?
There are three classes of stem cells totipotent, pluripotent, and multipoten:
- A totipotent stem cell has total potential to develop into an organism. A fertilized egg is a totipotent stem cell.
- Pluripotent stem cells can give rise to all cell types in the body, but do not give rise to the supporting structures (placenta, amnion, chorion) required for develpoment of an organism.
- Multipotent stem cells give rise to a small number of different cell types.
What are human embryonic stem cells?
Human embryonic stem cells are pluripotent stem cells. They can give rise to all the cell types in the human body, but because they do not give rise to the amnion and chorion they do not have the potential to develop into an organism.
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Where do human embryonic stem cells come from?
Pluripotent stem cells are isolated from 3-5 day old human embryos at the blastocyst stage. A second less commonly used source is primordial gonadal tissue obtained from a fetus in the first trimester.
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What is a human embryonic stem cell line?
This is a culture of hESCs derived from a single embryo. Because stem cells can self-replicate, just a few hESCs can give rise to a whole population of identical hESCs, or a cell line. top
Why do scientists want to use stem cell lines?
Once established, a cell line can be grown in the laboratory indefinitely and cells may be frozen for later use or distributed to other researchers. Because each cell line has its own distinct genetic footprint, researchers are often interested in using the same cell line for a number of related experiments. top
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.
- Studying stem cells will help us to understand how stem cells transform into the array of specialized cells that make up the human body. Some of the most serious medical conditions, such as cancer and birth defects, may result from problems that occur in this process of differentiation. A better understanding of normal cell development will allow us to understand and perhaps correct the errors that cause these medical conditions.
- Stem cells will provide a tool for pharmacologic development. Stem cell research should allow the development of cell populations with a specific 'disease' – these cell populations can them be used for initial testing with candidate drugs.
- Finally, and perhaps the most exciting potential application of stem cells is cell therapy. Pluripotent stem cells offer the possibility of a renewable source of replacement cells and possibly tissues to treat a myriad of diseases, conditions, and disabilities including Parkinson's disease, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis and rheumatoid arthritis. top
Have human embryonic stem cells been used successfully to treat any human diseases yet?
No. This area of research is very young. Human embryonic stem cell (hESC) research only began in 1998, when a group led by Dr. James Thomson at the University of Wisconsin developed a technique to isolate and grow the cells. In addition, federal funds to support hESC research have only been available since August 9, 2001, and there are significant limitations to the types of hESC research that can be funded. At this point, the promise is huge, but hESC research is in its early stages. In contrast, research with adult stem cells such as blood-forming stem cells in bone marrow (called hematopoietic stem cells, or HSCs) has been active for over decades. And this research has resulted in treatment of patients; for example, bone marrow (stem cell) transplants have been conducted for over 40 years. top
What is Somatic Cell Nuclear Transfer?
Somatic cell nuclear transfer (SCNT), is a technique in which the nucleus of a somatic cell (any cell of the body except sperm and egg cells) is injected, or transplanted, into an egg, that has had its nucleus removed. The product of SCNT has the same genetic material as the somatic cell donor. top
Is Somatic Cell Nuclear Transfer the same as Cloning?
Yes. SCNT is a technique of cloning. The product of SCNT is nearly genetically identical to the somatic cell used in the process. (Of note, the product of SCNT is not technically100% identical in that the cytoplasm of the oocyte includes mitochondrial DNA.) While SCNT is considered cloning – it is important to differentiate between therapeutic and reproductive cloning. The following FAQ addresses these differences. top
What is the difference between therapeutic cloning and reproductive cloning?
Reproductive cloning includes the placement of the product of SCNT into a uterus for the purpose of a live birth. The resulting organism would, in theory, be the genetic copy of the somatic cell donor. Reproductive cloning has been performed in animals for many years and is burdened by many technical and biological problems. Only about 1 percent of all the eggs that receive donor DNA can develop into normal surviving clones. Therapeutic cloning uses SCNT for the sole purpose of deriving cells for research, and potentially in the future for therapy. In therapeutic cloning, the product of SCNT is not placed into a uterus and hence a live birth is never a possibility. Therapeutic cloning provides two potential benefits.
- The first is for studying specific diseases. If the somatic cell donor has a genetic disease, such as muscular dystrophy, the product of SCNT would also have muscular dystrophy genes. Cells derived from this SCNT product could then be used to study the biology of muscular dystrophy with the goal of finding new ways to prevent, treat or even cure the disease.
- The second is to create 'designer cells' for transplantation. Whenever cells, tissue or entire organs are transplanted from one person to another, the recipient's immune system sees the new material as foreign and tries to reject the transplant. In order to avoid this, transplant recipients are given drugs that modulate the recipient's immune system to avoid rejection. Therapeutic cloning offers a possible solution. If Ms. Jones needs a transplant, a somatic cell from Ms. Jones could be used for SCNT. The resultant product would have the same genetics as Ms. Jones. The cells derived and grown for transplant would be accepted by Ms. Jones' immune system as one of their own. top
Why not use adult stem cells instead of using human embryonic stem cells in research?
Human embryonic stem cells are pluripotent and hence have much greater developmental potential than adult stem cells which can only give rise to a few specific types of cells. Adult stem cells are thought to exist in every type of tissue in the body. But, to date, the isolation of many types of adult stem cells has been limited. Hematopoietic stem cells are readily available via bone marrow aspiration. But, stem cells for solid organs such as liver or brain have proven more difficult to identify and derive. The hope is that hESCs can be used to derive every type of adult stem cell in the body and allow research that is currently not possible. top
Does Massachusetts state law permit human embryonic stem cell research?
Yes. Massachusetts state law that was enacted in May 2005 allows hESC research and it allows the derivation of hESCs from embryos that were created for reproductive purposes and are no longer needed for reproduction and from somatic cell nuclear transfer. top
What are the NAS guidelines?
The National Academy of Science (NAS) issued guidelines for hESC research in April 2005. The guidelines contain detailed recommendations with regard to many aspects of hESC research, including:
- donor recruitment and informed consent
- how stem cells should be characterized, handled, transferred, and stored
- the establishment of local Embryonic Stem Cell Research Oversight (ESCRO) Committees
- guidance on what kinds of research should be considered for approval and what kinds should be prohibited at this time top
Is IRB review and approval required for all hESC research?
No. IRB approval is required for:
- the derivation of hESCs from existing embryos or SCNT
- research using hESCs if the identity of the gamate and/or somatic cell donors is known to the researcher. No IRB approval is required for the use of de-identified exising hESCs. top
How many hESC lines are available to researchers?
It is easiest to think of two categories of hESC lines:
- First, the federal government has limited the use of federal funds to those hESCs that were already derived as of August 9, 2001. These cell lines are listed on a registry maintained by the NIH. Initially, 60 cell lines were thought to be available, but in fact, only 22 lines are viable for research. 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. Much has changed in the derivation and maintenance of hESCs since 2001, as a result the hESCs listed by the NIH may not be optimal for all research.
- The second category is those hESCs that have been derived after August 9, 2001. These cell lines are not listed by the NIH. Research using these cells cannot be supported with federal funds. top
Does federal government fund embryonic stem cell research?
The federal government limits its funding to specific hESCs derived before August 9th 2001. Specifically, federal funds are only allowed for research on hESCs listed on NIH Registry, and on derivative products from hESCs on NIH Registry. top
What is the source of the Center for Regenerative Medicine’s human embryonic stem cell research funding?
Human embryonic stem cell research at the Center for Regenerative Medicine is supported primarily by private philanthropic donations. These donations allow us to support a wide range of research activities that could not be supported from other sources such as NIH funding. In future, we also expect to apply to NIH and other funding agencies for support of eligible activities. top
How can I donate money to the Center for Regenerative Medicine?
Since many of our research activities are not eligible to receive federal funding, the Center for Regenerative Medicine depends upon philanthropic support. To learn more about how to support our programs, please visit our Ways to Give section by clicking here. top
What’s unique about the Center for Regenerative Medicine?
The Center for Regenerative Medicine is dedicated to understanding how tissues are formed and may be repaired in settings of injury. Its primary goal is to develop novel therapies to regenerate damaged tissues and thereby overcome debilitating chronic disease. The success of this effort requires a cohesive team of scientists and clinicians with diverse areas of expertise, but with a shared mission and dedication to the larger goal.
The Center for Regenerative Medicine has extensive interactions with other investigators at MGH and in the broader Harvard-MIT community. The Center helped galvanize the establishment of the Harvard Stem Cell Institute (HSCI), which is co-directed by Dr. Scadden and Dr. Douglas Melton of Harvard Faculty of Arts and Sciences and the Howard Hughes Medical Institute. As an important confederated partner of HSCI, the Center brings specific features that augment other elements of HSCI, including unique stem cell clinical investigation expertise and ongoing collaborative clinical trials using stem cell transplantation. The Center emphasizes technologies that will ultimately be critical for the success of stem cell based medicine, including bioengineering, biomaterials expertise, close links to in vivo imaging capability and its GMP facility for sophisticated cell manipulation. top
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