Research at the Universities of Toronto, Canada, and Edinburgh, Scotland, hold the promise that doctors will be able to obtain stem cells from skin cells to cure disease. This would eliminate the need for the use of embryonic stem cells, which introduce health risks and have ethical problems.
Embryonic Stem Cells
When human cells are produced at conception and begin to divide, they contain all the genes necessary for any cell in the body: hence, they are stem cells. As they further divide, some of the genes are shut down or disabled, so that the cells eventually develop into cells that perform only the functions of different parts of the body. This process is called differentiation.
Embryonic cells from the excess embryos after in-vitro fertilization are at the early stages of differentiation, so can be made to grow into any type of cell. However, there are problems with embryonic cells:
- The ethical objection is that human embryos are killed to obtain cells.
- The body of a person injected with embryonic cells would automatically reject them so the person would need anti-rejection drugs for the rest of their life.
- Embryonic cells can cause cancer. Dr. Mick Bhatia of McMaster University, Hamilton, Ontario, is researching how to distinguish between cancer-causing and non-cancer-causing embryonic cells.
Adult Stem Cells From Skin
Dr Keisuke Kaji from the Medical Research Council (MRC) Centre for Regenerative Medicine, University of Edinburgh, and Dr Andras Nagy from the University of Toronto, have devised a new way of taking cells from a person's skin and converting them to stem cells. In effect, this reverses the process of differentiation by turning genes back on.
Previously, scientists did this by inserting viruses into the cells, but the viruses can activate cancer-causing genes.
Drs Kaji and Nagy have developed way to insert genetic material instead of viruses into a cell and to remove it once the cell has been converted to a stem cell.
Dr Nagy, Senior Investigator at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital and Canada Research Chair in Stem Cells and Regeneration, said: "We have found a highly efficient and safe way to create new cells for the human body which avoids the challenge of immune rejection."
The technique has not yet been used in a therapy.
Adult Stem Cells Used to Treat Diseases
What have been used in therapies, however, are adult stem cells from bone marrow.
The nose is another source of adult cells. The National Institute for Medical Research (NIMR), London, uses them to study repair of nerve fibres in the brain and spinal cord damaged by accidents or strokes.
NIMR's Dr. Geoff Raisman, head of the spinal repair unit at the University College London, has written on the institute's website: "By transplanting specialised pathway cells from the olfactory system, we have shown that severed connections in the spinal cord can be induced to regenerate and important functions restored.
"These findings provide a basis for future development of surgical treatments to reverse the devastating effects of human spinal cord injuries."
Real Therapies
Adult stem cells are providing real therapies. Research is making them more accessible, without the ethical problems and health risks associated with embryonic stem cells that have yet to be used in actual therapies.
References:
PiggyBac transposition reprograms fibroblasts to induced pluripotent stem cells, by Dr. Andras Nagy, University of Toronto, and Samuel Lunenfeld Research Institute of Mount Sinai Hospital published in Nature Online, March 1, 2009.
Virus free induction of pluripotency and subsequent excision of reprogramming factors, by Dr Keisuke Kaji, Centre for Regenerative Medicine, University of Edinburgh, et al,published in Nature Online, March 1, 2009.
Paper by Dr. Geoff Raisman, University College London, and National Institute for Medical Research, London, presented to Fifth Meeting of the Irish Network of Neural Stem-cell Investigators, National University of Ireland, Galway, Ireland, April 2006.
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