According to the National Institutes of Health (NIH), stem cells are 1 "Cells with the ability to divide for indefinite periods in culture and to give rise to specialized cells." Stem cells are basically unspecialized cells that can, with proper physiologic or experimental conditions, become specialized cells. Specialized cells are usually called differentiated cells. These differentiated cells can then be used to repair damaged cells and eventually cure many diseases and disorders in humans. This could revolutionize the way society treats health issues. Instead of trying to destroy and sure a disease or disorder, doctors could simply grow new cells that would be able to repair or replace the damaged cells and tissue.
Adult Stem Cells
There are two major types of stem cells, embryonic and adult stem cells. Adult stem cells are the undifferentiated cells that are found in tissue and organs in adults. These cells are usually found mixed in with differentiated cells. These cells are used to repair and maintain the tissue in which they are found. Research of adult stem cells began in the 1960?s when scientists discovered them in bone marrow. Stem cells from bone marrow have been used in transplants for the past 30 years. Currently, scientists are unsure as to how adult stem cells develop. A major advantage to using adult stem cells is that each patient?s stem cells can be extracted, grown, and then reinserted into their body. This would ensure that the immune system would not reject the new cells. One of the problems with adult stem cells is that there are a very few number of stem cells in a sample of tissue. Another problem is that scientists are unsure about the flexibility of adult stem cells. Since they are found only in certain tissues, it is uncertain is stem cells found in one type of tissue can be used to grow cells for another type. Recently, however, there has been some evidence that indicates that adult stem cells may be able to develop into more than one type of specialized cell, but nothing is entirely conclusive. Because of these problems, adult stem cells are difficult to use for extensive research.
Embryonic Stem Cells
Embryonic stem cell research is the more controversial of the two major types of stem cells. These types of stem cells are taken from embryos that were produced through in vitro fertilization. Most embryos used for stem cell research are taken from those donated after in vitro fertilization. Once the embryo that is to inserted back into the woman?s body is chosen, scientists use the left over embryos to extract stem cells. After about four or five days after fertilization, the egg becomes a group of cells called a blastocyst. The inner cell mass of the blastocyst contains about thirty cells that can be extracted. Once extracted, the cells are put into a culture dish which contains a nutrient broth or culture medium. The culture dish has been coated with mouse skin cells in the past. This gives the stem...