Adult stem cells are undifferentiated cells , found throughout the body after development, that multiply by cell division to replenish dying cells and regenerate damaged tissues. Scientific interest in adult stem cells is centered on their ability 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. They have mainly been studied in humans and model organisms such as mice and rats. To ensure self-renewal, stem cells undergo two types of cell division see Stem cell division and differentiation diagram. Symmetric division gives rise to two identical daughter stem cells, whereas asymmetric division produces one stem cell and one progenitor cell with limited self-renewal potential. Progenitors can go through several rounds of cell division before finally differentiating into a mature cell. It is believed that the molecular distinction between symmetric and asymmetric divisions lies in differential segregation of cell membrane proteins such as receptors and their associated proteins between the daughter cells. Under normal conditions, tissue stem cells divide slowly and infrequently. They exhibit signs of quiescence , or reversible growth arrest. Infrequent cell divisions also help reduce the risk of acquiring DNA mutations that would be passed on to daughter cells.
California Institute for Regenerative Medicine
Stem cells and derived products offer great promise for new medical treatments. Learn about stem cell types, current and possible uses, ethical issues, and the state of research and practice. You've heard about stem cells in the news, and perhaps you've wondered if they might help you or a loved one with a serious disease. You may wonder what stem cells are, how they're being used to treat disease and injury, and why they're the subject of such vigorous debate. Stem cells are the body's master cells. All other cells arise from stem cells, including blood cells, nerve cells and others. Stem cells are the body's raw materials — cells from which all other cells with specialized functions are generated.
Nature Reviews Molecular Cell Biology
The primary role of adult stem cells in humans is to maintain and repair the tissue in which they are found. Stem cells are very flexible cells, sometimes considered immature, that have not developed to a final specialized cell type like skin, liver, heart, etc. Since they have not yet specialized, stem cells can respond to different signals and needs in the body by becoming any of the various cell types needed, e. In that sense they are a bit like a maintenance crew that keeps repairing and replacing damaged or worn out cells in the body. Microscopic in size, stem cells are big news in medical and science circles because they can be used to replace or even heal damaged tissues and cells in the body. They can serve as a built-in repair system for the human body, replenishing other cells as long as a person is still alive. They naturally exist in our bodies, and they provide a natural repair mechanism for many tissues of our bodies. They belong in the microenvironment of an adult body, while embryonic stem cells belong in the microenvironment of the early embryo, not in an adult body, where they tend to cause tumors and immune system reactions. New therapies using adult type stem cells, on the other hand, are being developed all the time. Stem Cells are being used today to help people suffering from dozens of diseases and conditions.
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. 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.