Q. What are stem cells?

A. Stem cells are the very early cells that can develop into almost all other types of cell and tissue. They occur in the five-day embryo and also in the developing foetus and in the umbilical cord at birth. They can also be found in adult tissues, such as bone marrow.

Q. What makes stem cells unique?

A. They are unspecialized. Specialized cells such as blood and muscle do not normally replicate themselves. When they are seriously damaged by disease or injury, they cannot replace themselves. Stem cells can divide and produce identical copies of themselves over and over again.

Q. What are the different kinds of stem cells?

A. Stem cells are divided into two groups: embryonic stem cells and adult stem cells. Human embryonic stem cells are obtained from embryos that are five to six days old. Adult stem cells are derived from a fetal or adult tissue and can usually only give rise to the cells of that tissue.

Q. What is the source of embryonic stem cells?

A. They are derived from embryos that develop from eggs that are fertilized in vitro (outside the womb) in fertility clinics and subsequently donated for research with the consent of the couples.

Q. Why is the use of stem cells often seen as controversial?

There is no opposition to the use of adult stem cells - the kind the new clinic will research. Controversy revolves around the use of embryos that are fertilized in vitro. The embryos are surplus and would never have been implanted in the womb of the woman seeking to get pregnant, but many religious groups believe that an embryo is a person and should not be destroyed under any circumstances, even to aid the cause of medical research.

Q. What are the advantages and limitations of the two different stem cell types?

A. Embryonic stem cells can generate all the cell types in the body. They can multiply indefinitely in the laboratory, offering exciting possibilities to reduce reliance on donor cells and organs and resolve problems of supply.

Adult stem cells are rare in mature tissues and methods for expanding their numbers in cell cultures in a lab have not been worked out. A potential advantage of using adult stem cells is that they could be reintroduced into a patient's own body and not be rejected by the patient's immune system. Embryonic stem cells from a donor could lead to transplant rejection.

Q. How is stem cell research being used to treat diseases?

A. Stems cells are used in the treatment of extensive burns and to restore the blood system in patients with leukaemia and other blood disorders.

Q. What about the treatment of other diseases?

A Stem cells offer the possibility for treatment of diseases such as Parkinson's, strokes, heart disease and diabetes, but significant technical hurdles remain that will only be overcome through years of intensive research.

Q. How is stem cell research relevant to spinal cord injuries?

A. Thanks to the findings of a large number of animal studies, scientists are working on ways that stem cells may contribute to repair of the spinal cord. Scientists in the U.S. are hoping to start a clinical trial to investigate the safety and benefits of using a type of nerve cell to treat spinal cord injuries- if granted a licence by the FDA.

Q. What about Alzheimer's?

A. A recent clinical trial that introduces genetically modified stem cells to the Alzheimer brain to stop cells from dying has shown this approach to be of some benefit to patients with Alzheimer's disease.

Q. Explain the different approaches various countries take to stem cell research.

The U.S. is considered the leader in stem cell research, but there is concern that it is slipping behind countries such as the U.K., Korea, Singapore, Sweden, Israel, Australia and China.

Private funding for stem cell research in the U.S. outstrips funding from the federal Government, which bans funding for research on new embryonic stem cells other than the 61 stem cells lines already in existence. U.S. President George Bush vetoed a bill last year would have lifted the ban last year.

Individual states have moved to fill the void, including Massachusetts, Illinois and California. California has provided $10 billion over the next 10 years to fund embryonic and adult stem cell research.

The U.S. federal government does not ban embryonic cell research, it just doesn't fund it. Top U.S. scientists acknowledge there are ethical issues involved, but say public discussion in the US on the issue is based on misinformation and emotionally charged discussions, especially from religious groups.

In the U.K., studies in embryonic stem cell research are subject to the oversight of the Human Fertilisation and Embryology Authority. Clinical studies in adult stem research are subject to review from an independent body as well.

In Canada, stem cell research is funded by various institutions, including government and health charities, but the largest source of funding is the Canadian Institutes of Health Research.

Canada has around 70 senior scientists working in stem cell research. One third are at the University of Toronto and its associated hospitals.

Research in Canada has historically been on adult stem cells, but with the recent passing of new legislation, a small amount of human embryonic research is now under way. A Stem Cell Oversight Committee has also been established to conduct ethical review of embryonic research proposals. n

Research: Meredith Ebbin. Sources: Institute for Stem Cell Research, a division of the University of Edinburgh, the U.K. Stem Cell Initiative and the U.S. National Institutes of Health websites.