Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues.
Research into adult stem cells has been fueled by their abilities to divide or self-renew indefinitely and generate all the cell types of the organ from which they originate — potentially regenerating the entire organ from a few cells.
Unlike embryonic stem cells, the use of adult stem cells in research and therapy is not controversial because the production of adult stem cells does not require the destruction of an embryo.
Adult stem cells can be isolated from a tissue sample obtained from an adult.
They have mainly been studied in humans and model organisms such as mice and rats.
The rigorous definition of a stem cell requires that it possesses two properties: Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
Multipotency or multidifferentiative potential - the ability to generate progeny of several distinct cell types, for example both glial cells and neurons, opposed to unipotency - restriction to a single-cell type.
Adult stem cells, similar to embryonic stem cells, have the ability to differentiate into more than one cell type, but unlike embryonic stem cells they are often restricted to certain lineages.
The ability of a stem cell of one lineage to become another lineage is called transdifferentiation.
