Photo courtesy University of Wisconsin-Madison
Microscopic view of a colony of undifferentiated human embryonic stem cells being studied in developmental biologist James Thomson's research lab at the University of Wisconsin-Madison.
Many diseases kill cells within organs, claiming lives or impairing a person's ability to live a normal life. For example, about 5.8 million Americans have heartfailure and 670,000 people are diagnosed with it each year [source: Centers for Disease Control]. In heart failure, much of the heart muscle itself dies, so the heart cannot sufficiently pump blood.
Similarly, about 23.6 million Americans have diabetes [source: NIDDK, NIH]. Five to 10 percent of these people have Type Idiabetes in which the insulin-producingcells of the pancreas are dead. Finally, about 1 million Americans live with Parkinson's disease [source: Parkinson's Disease Foundation]. In this disease, cells that make the neurotransmitter dopamine, which helps control movement, die. Patients with Parkinson's disease have tremors and uncontrollable movements. But what if these dead cells could be replaced with fresh cells? Could the patients be treated and live normal lives? That's the goal of stem cell research.
There are several types of stem cells, including:A stem cell is essentially the building block of the human body. Stem cells are capable of dividing for long periods of time, are unspecialized, but can develop into specialized cells. The earliest stem cells in the human body are those found in the human embryo. The stem cells inside an embryo will eventually give rise to every cell, tissue and organ in the fetus's body. Unlike a regular cell, which can only replicate to create more of its own kind of cell, a stem cell ispluripotent. When it divides, it can make any one of the 220 different cells in the human body. Stem cells also have the capability to self-renew -- they can reproduce themselves many times over.
Stem Cell Basics
There are several types of stem cells, including:A stem cell is essentially the building block of the human body. Stem cells are capable of dividing for long periods of time, are unspecialized, but can develop into specialized cells. The earliest stem cells in the human body are those found in the human embryo. The stem cells inside an embryo will eventually give rise to every cell, tissue and organ in the fetus's body. Unlike a regular cell, which can only replicate to create more of its own kind of cell, a stem cell ispluripotent. When it divides, it can make any one of the 220 different cells in the human body. Stem cells also have the capability to self-renew -- they can reproduce themselves many times over.
- Embryonic stem cells - Embryonic stem cells include those found within the embryo, the fetus or the umbilical cord blood. Depending upon when they are harvested, embryonic stem cells can give rise to just about any cell in the human body.
- Adult stem cells - Adult stem cells can be found in infants, children and adults. They reside in already developed tissues such as those of the heart, brain and kidney. They usually give rise to cells within their resident organs.
- Induced pluripotent stem cells (IPSC)- These stem cells are adult, differentiated cells that have been experimentally "reprogrammed" into a stem cell-like state
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