FAQ's

1. What are stem cells?

Stem cells are special cells with a unique growth characteristic. They can make identical copies of themselves, as well as grow into more specialised cell types. For example, blood stem cells found in the bone marrow can generate both red blood cells that can carry oxygen and white blood cells that can fight infection. Blood stem cells in the body continue the supply of blood cells for the life of a person.

2. Are there different types of stem cells?

There are many different types of stem cells. Stem cells can be broadly divided into different types depending on where they are found. For example, tissue stem cells are present in many tissues, such as skin and liver. Tissue stem cells isolated from adult tissue are technically known as somatic stem cells, but can broadly be considered as tissue or adult stem cells. In contrast, stem cells isolated from embryos are called embryonic stem cells.

3. Do all adult tissues have stem cells?

Stem cells are not found in all tissues. Tissues that can repair themselves such as skin have tissue-specific stem cells. However, some tissues such as heart muscle cannot undergo self repair and do not have stem cells.

4. What is so special about embryonic stem cells?

Embryonic stem cells are different to adult or tissue-specific stem cells. Embryonic stem cells are the only stem cell that can be grown in large numbers in the laboratory and retain the ability to grow into any type of cells including nerve, heart muscle, bone and insulin-producing cells. Embryonic stem cells are often referred to as the ‘master' stem cell. Tissue-specific adult stem cells are few in number, hard to isolate and are difficult to grow outside the body. Adult stem cells, such as skin and bone marrow stem cells, can usually only grow into a limited number of cell types. For instance, skin stem cells can be grown in the laboratory to make more skin, but cannot make new heart muscle or other cell types.

There is recent scientific evidence to suggest that some adult stem cells such as nerve and blood stem cells may also have the ability to grow into other cell types. While this exciting prospect may provide an alternate source of some cell types, this option is currently still limited by the growth and availability of the starting stem cell.

5. Where do embryonic stem cells come from?

Embryonic stem cells can be isolated from seven day old embryos. Embryos at this stage are microscopic in size (smaller than the full-stop at the end of this sentence) and consist of a ball of approximately one hundred cells. At this stage the embryo has only two types of cells, those which make the animal or person, and those which will make the tissues which connect the foetus to the mother. Human embryonic stem cells have been isolated from IVF embryos that have been donated by patients at the end of their treatment (so called ‘spare' IVF embryos), or created from donated eggs and sperm specifically for embryonic stem cell isolation.

6. What are cord stem cells?

Cord stem cells are a type of blood stem cell that can be isolated in significant numbers from the placenta and umbilical cord of a newborn baby. Cord stem cells have been successfully collected and stored as frozen cells, and then some years later used as a source of the baby's own blood stem cells for transplantation.

7. What are foetal stem cells?

Foetal stem cells are isolated from foetuses aborted during early pregnancy. Many different types of tissue-specific stem cells can be isolated from foetal tissue including some tissue stem cells which cannot be found in the adult, such as nerve stem cells. Stem cells very similar to embryonic stem cells, called embryonic germ cells, have also been collected from foetal mouse tissue, though the ability to establish equivalent human cell lines has not been proven.

8. Why are stem cells of such importance in medicine?

Many researchers believe that stem cells may revolutionise human medicine through their ability to make new cells to replace a patient's diseased or damaged cells. The most promising use of stem cells may be to treat patients where the disease condition results from a loss of cells, and the patient is unable to repair or replace the poorly functioning cells on its own. Currently incurable diseases such as diabetes, Parkinson's disease, spinal cord injury, heart attack, stroke and traumatic brain injury could all be treated by transferring new cells, generated from stem cells, to the patient.

A very important benefit of stem cell therapy is that it is expected to provide a cure. For example, transplanted insulin-producing cells will continue to produce insulin for the life of a diabetic.

9. Are stem cells currently being used to treat patients?

The best example of stem cell-based therapy is the transplantation of bone marrow stem cells for patients with leukaemia and other blood disorders. Another example of stem cell-based therapy is the use of skin biopsies that are expanded in the laboratory to treat patients with severe burns.

For technical reasons, by far the majority, if not all, cell therapies require or will dramatically benefit from growing stem cells in the laboratory before use. The full promise of stem cell-based therapy is yet to be realised, as tissue stem cells cannot yet be grown well in the laboratory and the options available with human embryonic stem cells will need a great deal of further research and development.

10. Which stem cells are most promising and why?

To be useful in patient treatment, stem cells need to be grown in the laboratory into specific cell types. While stem cells isolated from foetal tissue, umbilical cord blood and adult tissue may be used for cell therapy, only embryonic stem cells can be grown in significant quantities in the laboratory and retain the ability to develop into any cell in the body. Other types of stem cells are restricted in the types of cells they can produce, and are difficult to grow in the laboratory. It is only through extensive research that the most effective means of providing cells for treatment will be identified. At present, many consider embryonic stem cells as the most likely therapeutic option.

11. What are the limitations of using embryonic stem cells?

Several obstacles need to be overcome before embryonic stem cell-based therapy is a realistic treatment option for patients. As embryonic stem cells have the potential to grow into any cell type in the body, it must be ensured that the purified populations of specialized cells for patient therapy no longer contain any non-specialised embryonic stem cells. Non-specialised embryonic stem cells carry the risk of tumour formation following transplantation, as they may continue to grow when implanted into the body.

The possibility of tissue rejection must also be addressed. Like all transplantation procedures, cells generated from embryonic stem cells will need to be tissue-matched so that the patient will not reject the transplanted cells. Transplant recipients would most likely also require long-term anti-rejection treatments that contribute undesirable side effects.

One alternative might be to establish banks of embryonic stem cells. However, the number of embryonic stem cell lines required in order to provide meaningful benefit would be very large.

Another possibility is to use cloning techniques to create an embryo from a patient's own cell and use this embryo to isolate embryonic stem cells. Embryonic stem cells isolated this way would share the same genetic make-up as the patient, and therefore avoid problems of donor matching and rejection.

Further research will be required to address these limitations and to identify which option will provide the best clinical outcome.

12. What are some of the ethical issues related to embryonic stem cells and human embryo research?

 

The principle objection to the use of embryonic stem cells is that a human embryo must be destroyed. Despite the possibility that stem cells isolated from embryos could offer enormous potential for improving the quality of life for people suffering from incurable diseases, opponents of human embryo research claim no benefit can justify the destruction of an embryo. While most people would agree that embryos are potential human beings, and therefore entitled to be treated with respect, many also believe that human embryos are not entitled to the full rights normally bestowed upon an actual person. One example of this difference is evident in law in Australia and other countries where abortion is legal. While it is true that all embryos have the potential to develop into a new person, reproductive biology is very inefficient and not every embryo that is created will develop into an actual person.

To date most human embryonic stem cell lines have been generated from donated IVF embryos. In order to treat infertility, more embryos than may be required are often created. At the completion of their treatment, IVF patients can either donate the ‘surplus' embryos to another couple, donate the embryos to research, or discard the embryos.

Every year around the world, hundreds of IVF embryos, no longer required by the patients, are discarded. Most view destruction of these ‘surplus' embryos negatively and many would rather see some form of beneficial outcome. The use of embryos for embryonic stem cell isolation and the potential treatment of patients with incurable diseases is one potential use.

A second objection revolves around the issue of creation of embryos for research. Recently, human embryos have been created from donated eggs and sperm specifically for the isolation of embryonic stem cells. This strategy is widely considered as ethically questionable as it involves the generation of a new, genetically individual embryo purely for potential benefit to others. It has also been suggested that cloning techniques could be used to create embryos for embryonic stem cell isolation.

This so called therapeutic cloning approach, does not require the creation of a new genetically distinct embryo by egg-sperm fusion, but rather produces embryonic cells which are copies of the patient. This would ensure that the patient will not reject cells following transplantation.

Yet another possibility is that animal eggs, instead of human eggs, could be used in therapeutic cloning. This option is now regarded by most researchers as being technically unsound and a possible risk to the patient.

Opponents view research as equivalent to destruction or death of the embryo, even though cells isolated from such an embryo may have life-saving potential for a patient. The ethical issues surrounding the use of human embryos are of significant concern and interest in modern society. These issues need to be thoroughly and openly reviewed with wide community participation before defining legislation is enacted.

13. How are different countries regulating human embryo research?

Human embryo research is viewed and regulated differently in different countries and even differently between states and territories within a country. This ranges from progressive, well-regulated legislation in the United Kingdom, to approved guidelines in Japan, and complete prohibition in Germany.