Stem cells are specialized cells that can transform into almost any kind of cell in the body. This potential to turn into other cells holds the promise of repairing damage to organs caused by injury or disease. Embryos contain the most versatile stem cells, which have the potential to become almost any other cell in the body. Controversy over embryonic stem cell research has led to consideration of other types of stem cells, including adult stem cells and stem cells from the umbilical cord blood of newborn babies.
Types of Stem Cells
Scientists characterize stem cells on the basis of their ability to transform into other cells. The cells in embryos can become any other cell in the human body, and are known as totipotent, according to the Department of Genetics at the University of Utah. As cells mature, they become pluripotent, having the ability to transform into almost any kind of cell in the body. These are the kinds of stem cells found in placenta. Stems cells in umbilical cords are multipotent. They can transform into several different kinds of cells, but not every kind of cell. Adult stem cells, found in bone marrow, blood, skin, muscles and nerves, are also multipotent.
Umbilical Cord Blood
The umbilical cord connects the infant in the womb to the placenta, which provides the nutrients the fetus needs to grow. After the child's birth, doctors cut the umbilical cord, leaving the belly button in place. According to the Department of Genetics at the University of Utah, umbilical cord blood contains stem cells that are genetically identical to the baby they're from. Umbilical cords and the blood they contain are often discarded as medical waste, but these stem cells can be harvested for use in medical research. Some people also choose to harvest their child's stem cells and store them in medical storage facilities, in the event the child should need them some day.
Uses
Stem cells from newborn umbilical cord blood can be used to treat leukemia and other blood disorders, in place of the bone marrow often used. The stem cells transform into new, healthy bone marrow. Umbilical cord blood stem cells are less likely to be rejected than bone marrow cells, reports the Department of Genetics at the University of Utah. There is also a potentially greater supply of umbilical cord stem cells than other types of stem cells. Parents can donate their infant's cord blood and it can be stored until needed.
Transplants for Infants
While much of the news has focused on the idea of harvesting stem cells from umbilical cords, researchers at the Medical College of Georgia have studied using mature stem cells to treat brain damage in infants that occurs at birth. Dr. James Carroll, chief of the Section of Pediatric Neurology, has studied implanting stem cells from the bone marrow of adult mice into mice with brain damage. These stem cells migrate to the brain and appear to repair the damage. Carroll hopes that in the future stem cell transplants in newborns who show signs of brain damage such as cerebral palsy could repair the damage and allow the children to grow up without disability.
Misconceptions
Researchers obtain embryonic stem cells from frozen embryos from fertility clinics that were never implanted in humans. According to the University of Michigan, these embryos are donated and if not used for research, they would be destroyed. Some religious groups have objected to use of these embryos for research. On August 9, 2001, U.S. President George W. Bush initiated a policy that provided federal funds for embryonic stem cell research only if the cells were harvested prior to this date. This limited the number of cells and cell lines available for research. On March 9, 2009, President Barack Obama issued an executive order removing these limitations. Though neither of these policies affect research on cells from newborn cord blood, some people mistakenly associate all stem cell research with embryonic stem cells.
References
- The University of Utah: What Are Some Different Types of Stem Cells?
- Medical College of Georgia: Stem Cell Transplants Linked to Treatment of Cerebral Palsy
- University of Michigan: Stem Cell Research - Frequently Asked Questions
- National Institutes of Health: Stem Cell Information --- Federal Policy
- University of Utah: Stem Cell Therapies Today
