Stem Cell Information

What are stem cells?

Stem cells are special kind of cells that have the ability to renew themselves through mitotic cell division and differentating into a diverse range of specialized cell types in the body such as heart muscle cells, nerves cells, and skin cells.

How many kinds of stem cells are there for human and where do they come from?

There are two kinds of stem cells.

Embryonic Stem Cells - derived from the inner cell mass of an early stage embryo (less than 2 weeks from post fertilization) known as blastocyst..

Adult Stem Cells - are found in the human body and in umbilical cord blood. The most well known source of adult stem cells in the body is bone marrow but they are also found in many organs and tissues; even in the blood.

What are the differences between embryonic stem cells and adult stem cells?

All stem cells possess two main properties. 1. Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state. 2. Potency - the capacity to differentiate into specialized cell types.

Embroynic Stem Cells
Adult Stem Cells
Embryonic stem cells have unlimited capacity for self renewal and potential to become any type of cell and are commonly considered to hold the most promise for regenerative medicine and tissue replacement after injury or disease Even though Adult Stem Cells have unlimited capacity for self renewal, it only have potential to become only cells of a closely related family of cells
Large numbers can be easily grown in laboratory. Present in the body in very small number and difficult to multiply in laboratory
To date, no successful medical treatments have been derived from Embryonic Stem Cell. medically treating human as well as animals for over 30 years
Can differentiate into unintended type of cells (Tumors, etc.). Can differentiate into a closely related family of cells.
Still can't control on what type of cells it should differentiate into. will always know what type of cells it will differentiate into.
Immune system rejection problem. No immune system rejection
controversy over ethical issues No significant ethical issues

Adult Stem Cells are found throughout the body after embroynic development and they can be found in children, as well as adults..

Normally, adult stem cells are more specialized, since they are assigned to a specific cell family, in humans and other mammals. These developmental events are irreversible.

However, "reassignment" has been observed in embryonic cells. For example, an embryonic stem cell that has already been assigned to become a brain cell somehow becomes a blood cell instead.

There is some evidence suggesting that adult stem cells also have this ability. An adult stem cell that has been assigned to become a vascular system cell may, in fact, reassign to become a kind of nerve cell under the right conditions. This has not yet been proven conclusively.