Stem Cells and Their Application

Study Notes

Large numbers of embryonic stem cells can be grown in culture, while adult stem cells are rare in mature tissues and methods for expanding their numbers in cell culture have not yet been worked out.
The use of the patient's own adult stem cells would mean that the cells would not be rejected by the immune system.

Studies of human embryonic stem cells may yield information about the complex events that occur during human development.
Scientists can identify how undifferentiated stem cells become differentiated, which could lead to new strategies for therapy for diseases such as cancer and birth defects.
Human stem cells could be used to test new drugs, allowing for safety testing on differentiated cells generated from human pluripotent cell lines.
Stem cells offer the possibility of a renewable source of replacement cells and tissues to treat diseases including Parkinson's, Alzheimer's, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis.

Adult stem cells are found in many organs and tissues, including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, and liver.
The primary role of adult stem cells is to maintain and repair the tissue in which they are found.
Adult stem cells have the ability to differentiate into specialized cell types, known as normal differentiation, and may also exhibit trans-differentiation or plasticity.

Methods used to identify adult stem cells include labeling cells in a living tissue, removing cells from a living animal, and isolating cells in cell culture.
A single adult stem cell should be able to generate a line of genetically identical cells, known as a clone, which gives rise to all the appropriate differentiated cell types of the tissue.

Normal differentiation: adult stem cells give rise to specialized cell types of the tissue in which they reside, such as hematopoietic stem cells giving rise to all types of blood cells.
Trans-differentiation or plasticity: adult stem cells may exhibit the ability to form specialized cell types of tissues other than the place where they reside.

Embryonic stem cells are pluripotent, meaning they can differentiate into all cell types of the body.
Laboratory tests used to identify embryonic stem cells include growing and subculturing the stem cells for many months, inspecting the cultures through a microscope, and using specific techniques to determine the presence of surface markers and proteins such as Oct-4.