What are Stem Cells Simplified

Understanding the Basics of Stem Cells

Stem Cells: divide and supply the cells that construct the bodies of all animals and plants.

Stem Cells: are biological cells found in all multicellular organisms, that can divide (through mitosis) and differentiate into various specialized cell types and can self-renew to produce more stem cells.

 

 

Two Common Characteristics

1. They have the capacity to divide.
2. Their daughter cells can differentiate into one or more specialized cell types.

The two daughter cells that are produced from the division of a stem cell may have different fates.

One of the cells may remain an undifferentiated stem cell, while the other daughter cell can differentiate into a specialized cell type.

In mammals, Stem Cells are categorized to their developmental stage and their ability to differentiate

 

 

Asymmetric Division/Differentiation Pattern

The population of stem cells remains constant, yet stem cells provide a population of specialized cells.

For Example: In mammals, this mechanism is needed to replenish cells that have a finite life span such as skin cells and red blood cells.

 

POTENCY

The ultimate stem cell is the fertilized egg, in which multiple cellular divisions can give rise to an entire organism.

A fertilized egg is considered to be totipotent because it can produce all of the cell types in the adult organism.

 

In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.

 

The blastocyst stage of embryonic development occurs prior to uterine implantation. Embryonic stem cells are pluripotent, which means they can also differentiate into almost every cell type of the body.

 

A single embryonic stem cell has lost the ability to produce an entire, intact individual.

 

Embryonic & Fetal Stages of Development

At the early fetal stage of development,, the cells that later give rise to sperm or eggs cells, known as the embryonic germ cell (EG cells) also are pluripotent.

 

During the embryonic and fetal stages of development, multipotent and unipotent stem cells are produced that give rise to the differentiated cells within the tissues and organs of an animal’s body.

 

A multipotent stem cell can differentiate into several cell types, but far fewer than an embryonic stem cell can differentiate into.

For Example: stem cells found in the bone marrow can supply cells that populate two different tissues, the blood and lymphoid tissues.

 

Other stem cells found in the adult seem to be unipotent, or only able to produce daughter cells that differentiate into one cell type.

For Example: stem cells in the testis produce daughter cells that only differentiate into sperm.

 

Some Potential Uses of Stem Cell to Treat Diseases

 

Cell/Tissue Type	Disease Treatment
Nerve	Implantation of cells into the brain to treat Parkinson disease
Skin	Treatment of burns and skin disorders
Cardiac	Repair of joints damaged by injury or arthritis
Bone	Repair of damaged bone or replacement with new bone
Liver	Repair or replacement of liver tissue damaged by injury or disease
Skeletal Muscle	Repair or replacement of damaged muscle