Stem Cells

Stem cells are primal cells common to all multi-cellular organisms that retain the ability to renew themselves through cell division and can differentiate into a wide range of specialized cell types. Research in the human stem cell field grew out of findings by Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s.



A stem cell is a primitive type of cell that can be coaxed into developing into most of the 220 types of cells found in the human body (e.g. blood cells, heart cells, brain cells, etc). Some researchers regard them as offering the greatest potential for the alleviation of human suffering since the development of antibiotics. Over 100 million Americans and two billion other humans worldwide suffer from diseases that may eventually be treated more effectively with stem cells or even cured. These include heart disease, diabetes, and certain types of cancer.



Stem cells can be extracted from very young human embryos -- typically from surplus frozen embryos left over from in-vitro fertilization (IVF) procedures at fertility clinics. A couple undergoing IVF is faced with four alternatives for their 16 or so surplus embryos:



There are very few parents willing to give their embryos to another couple for a variety of emotional reasons. There are very few couples willing to receive them for emotional reasons and because thawed embryos have such a low chance of starting a pregnancy. Preservation can be expensive.



Stem cell properties

These properties can be illustrated in vitro, using methods such as clonogenic assays, where the progeny of single cell is characterized. However, in vitro culture conditions can alter the behavior of cells, making it unclear whether the cells will behave in a similar manner in vivo. Considerable debate exists whether some proposed adult cell populations are truly stem cells.



• Totipotent stem cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent. These cells can differentiate into embryonic and extraembryonic cell types.

• Pluripotent stem cells are the descendants of totipotent cells and can differentiate into cells derived from the three germ layers.

• Multipotent stem cells can produce only cells of a closely related family of cells.

• Unipotent cells can produce only one cell type, but have the property of self-renewal which distinguishes them from non-stem cells.



Treatments

Medical researchers believe that stem cell therapy has the potential to radically change the treatment of human disease. A number of adult stem cell therapies already exist, particularly bone marrow transplants that are used to treat leukaemia. In the future, medical researchers anticipate being able to use technologies derived from stem cell research to treat a wider variety of diseases including cancer, parkinson's disease, spinal cord injuries, and muscle damage, amongst a number of other impairments and conditions. However, there still exists a great deal of social and scientific uncertainty surrounding stem cell research, which could possibly be overcome through public debate and future research.



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