STEM CELLS

What are stem cells?

Stem cells are unique/unspecialized/undifferentiated body cells.

They have the ability to:-

• Divide and renew themselves for a long period of time.

• Remain undifferentiated in form.

• Develop into different and specialized cells.

 

Under the right condition, Stem cells divide into two daughter cells.

These daughter cells either become new stem cells or become specialized cells (differentiation) with a more specific function, such as blood cells, brain cells, heart muscle or bone. No other cell in the body has the natural ability to generate new cell types.

 

 

 

 

 

 

 

Where do stem cells come from?

 

By origin:-

• Embryonic stem cells:

These stem cells come from embryos that are three to five days old. At this stage, an embryo is called a blastocyst and has about 150 cells.These are pluripotent stem cells, meaning they can divide into more stem cells or can become any type of cell in the body. This versatility allows embryonic stem cells to be used to regenerate or repair diseased tissue and organs.

• Adult stem cells:

These stem cells are found in small numbers in most adult tissues, such as bone marrow, skin or fat. Compared with embryonic stem cells, adult stem cells have a more limited ability to give rise to various cells of the body. Until recently, researchers thought adult stem cells could create only similar types of cells. For instance, researchers thought that stem cells residing in the bone marrow could give rise only to blood cells. However, emerging evidence suggests that adult stem cells may be able to create unrelated types of cells. For instance, bone marrow stem cells may be able to create bone or heart muscle cells. This research has led to early-stage clinical trials to test usefulness and safety in people. For example, adult stem cells are currently being tested in people with neurological or heart disease.

 

By ability and potential:-

• Totipotent stem cells:

They can grow into any type of cells; they are the fertilized egg and the cells produced by the first divisions.

• Pluripotent stem cells:

They can grow into any type of stem cells, except the totipotent stem cells.

• Multipotent stem cells:

They can grow only into closely related cells.

Other stem cells:-

• Adult cells altered to have properties of embryonic stem cells (induced pluripotent stem cells):

Scientists have successfully transformed regular adult cells into stem cells using genetic reprogramming. By altering the genes in the adult cells.

Perinatal stem cells:

Researchers have discovered stem cells in amniotic fluid in addition to umbilical cord blood stem cells. These stem cells also have the ability to change into specialized cells.