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Stem cells are cells that are the “first” cells that all others types of cell are derived from, as they have the ability to divide many times, whilst maintaining an undifferentiated state. However they are of great interest to the medical profession, due to their remarkable ability to differentiate into any required specialised cell.
There are two types of stem cells in mammals; Embryonic Stem Cells (ESCs) and Adult Stem Cells (ASCs). ESCs are found in blastocysts five days after an egg has been fertilised and if the pregnancy continued would go on to develop into different embryonic tissues. ESCs are remarkable in that they have the ability to differentiate into any type of cell, and so are known as pluripotent. Adult Stem Cells (ASCs) are found in various pockets in adult mammalian tissues, such as the bone marrow and brain. They provide replacement cells to maintain the tissues. ASCs normally only differentiate into the tissues in which they are found, rather than any type of tissue like ESCs, and so are known as multipotent. Induced pluripotent stem cells are adult non-stem cells which are forced to express certain genes that allow them to mimic pluripotent ESCs.
There are many ethical dilemmas surrounding stem cell treatment. In order to obtain ESCs, a five day old embryo, which could potentially develop into new life, is destroyed . The main argument for using ESCs, are that the applications of these technologies have great potential to alleviate human suffering, and the blastocyst from which the stem cells are taken, is simply a group of cells with no physical or emotional senses. (For more details on ethical issues that surround ESCs, check out the Euro Stem Cell website .)
However there may be an alternative to ESCs; ‘New Scientist’ magazine recently reported that a type of multipotent stem cell can be taken from cadavers up to 5 days after death . Whilst these cells are not pluripotent, they can still be used in a wide range of treatments. Since many people already donate their organs after death, it may not be a great step to consent use of stem cells for medical treatments.
Another option being explored, is to awaken ASCs in the body from their dormant state by stimulating neighbouring cells, which has been successful in fruit flies. 
Due to stem cells ability to regenerate and differentiate into multiple tissues, many researchers believe that many types of disease and tissue damage will be able to be treated using them in the future. Current research is looking at repairing spinal cord injuries and nerve pathways of the eye and heart, as well as liver and bone replacements [4 . Elsewhere, researchers have shown that certain cancers can be treated with stem cell therapy, particularly leukemias, as the stem cells replace the cells lost by the patient during chemotherapy and radiation therapy. 
Recently, the BBC highlighted that scientists in the University College London Institute of Ophthalmology had successfully derived light sensitive cells from ESCs, which were transplanted into blind mice, and successfully improved their vision. They hope that if human trials are successful, conditions such as diabetes related blindness and age related macular degeneration will be able to be treated via this technique.
Stem cells research is already being used to treat various human degenerative conditions, however, finding a way to collect and culture stem cells cheaply, in a way that does not affront various factions, would make the treatments more accessible. Treating patients with their own stem cells to minimise rejection of the cells by the body is the next important step, and “personalised medicine” may offer many patients an alternative to a lifetime of medication, hospital visits and potentially increase their life span.
”Embryonic stem cell research: an ethical dilemma” from EuroStemCell, available from: http://www.eurostemcell.org/factsheet/embyronic-stem-cell-research-ethical-dilemma [accessed 25th January 2013]
 Jessica Hamzelou, (2012) “Cadaver stem cells offer new hope of life after death”, New Scientist online, available from: http://www.newscientist.com/article/dn23034-cadaver-stem-cells-offer-new-hope-of-life-after-death.html [accessed 25th January 2013]
 Chell JM, & Brand AH (2010). “Nutrition-responsive glia control exit of neural stem cells from quiescence.” Cell, 143, 1161-73, available from: http://wellcometrust.wordpress.com/2011/01/27/awakening-stem-cells-in-the-brain/ [accessed 26th January 2013]
 “Stem Cell Research”, UK Stem Cell Foundation, available from: http://www.ukscf.org/research/ourResearch.htm#spinalcord [accessed 25th January 2013]
 “Stem Cell Transplants”, American Cancer Society, available from: here [accessed 25th January 2013]
 Fergus Walsh, (2012) “’Blind’ mice eyesight treated with transplanted cells”, BBC News Health, available from: http://www.bbc.co.uk/news/health-17748165 [accessed 25th January 2013]
How can stem cells be used to treat diseases of old age?
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