The master cells of all tissue types. Stem cells serve as an internal repair system, dividing without limit to replenish other cells for the life of the person. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another, more specialized cell, depending on the tissue where it lives. For instance, muscle stem cells generate new muscle cells to build or repair muscle damage; skin stem cells constantly generate new skin cells for renewal or damage repair.
Adult stem cells: All cells of the living human body. Stem cells found in amniotic fluid, placenta or cord blood represent the earliest stage of adult stem cells. They may be multipotent, capable of developing into most cells and tissues of the body, or tissue-specific.
Induced pluripotent stem cell (iPSC): An adult stem cell that has been programmed to revert back to a pluripotent state. Because they are collected directly from the patient, there is no risk of transplant rejection. They are in widespread use for research and clinical trials to treat catastrophic and degenerative diseases that have no other cure. Dr. Shinya Yamanaka and Sir John Gurden received the 2012 Nobel Prize in Medicine for their 2006 discovery.
Embryonic stem cells: Cells collected from in vitro fertilization clinics when donated to research with the informed consent of donor(s). Considered pluripotent, or capable of developing into all cells and tissues of the body.