Stem cells

Stem cells are able to repair and replace damaged tissues and organs, and research on the use of these remarkable cells to treat many otherwise incurable conditions is ongoing. In this lesson, we'll learn what stem cells are and how they are being used in medicine.

Definition of a Stem Cell

Stem cells are the cells that are capable of forming the entire human body. They're amazing since the very beginning of life, a fertilized egg cell divides repeatedly to form a group of stem cells that will go on to eventually make all the organs and tissues in your body. Stem cells are also present in adults, where they play an important role in repairing and replacing damaged cells and tissues.The main feature of a stem cell is that it can divide to give rise to both more stem cells and also specialized cells like nerve cells or muscle cells. No other type of cell can do this! In this way, stem cells replenish themselves at the same time that they provide new specialized cells to create or repair organs and tissues.

Types of Stem Cells

There are several different types of stem cells, and they have different abilities and functions. Totipotent stem cells have the ability to differentiate into every type of cell in the body. These are only found in very early embryos and disappear later in fetal development. Pluripotent stem cells are also found only in embryos and are able to form almost all of the types of cells in the body. At later stages of fetal development, and even in adults, there are stem cells known as multipotent, which means that they are able to form several types of specialized cells that are in closely related families of cells. For example, mesenchymal stem cells can give rise to cells that make up all types of connective tissues, like muscle, bone, and cartilage. This is a type of multipotent stem cell, because it can divide to produce several types of related cells, but it could never produce a cell of a different type, such as a nerve cell or liver cell.Take a look at this image. This is a hematopoietic stem cell in the bone marrow, which can differentiate into all of the blood cells (red and white) in the body. Other types of stem cells in the bone marrow can differentiate into connective tissue, like muscle and bone, or to nervous tissue.