It is a cell with a unique capacity to produce unaltered daughter cell (self – renewal) and to generate specialized cell type (potency).
1.] Stem cells are the primitive cells which has two main functions :
- They have the capacity of self renewal
- They can be coaxed into differentiation.
SELF RENEWAL :-
1.] Self renewal can be achieved in two ways :
- Asymmetric cell division : Produces one daughter cell that is identical to the parental cell and one daughter cell that is different from the rental cell and is a progenitor or differentiated cell.
- Symmetric cell division : Produces two identical daughter cells.
1.] It is used to indicate a cell’s ability to differentiate into specialized cell type.
2.] Potency is classified as :
- Totipotent cells : These cells can form an entire organism autonomously.
- Multipotent cells : These cells can form multiple cell lineage but cannot form all of the body’s cell lineage.
- Oligopotent cells : These cells can form more than one cell lineage but are more restricted than multipotent cells.
- Unipotent or Monopotent cells : These cells can form a single differentiated cell lineage.
3.] Embryonic cells are pleuripotent, that is, they are capable of forming all the tissues of the body.
4.] Adult stem cells are usually only able to differentiate into a particular tissue.
TYPES OF STEM CELLS :-
1.] Stem cells are located in special sites called niches.
2.] Some stem cells are as follows :
- Oval cells are found in canals of Herrings of the liver.
- Satellite cells found in basal lamina of myotubules.
- Limbus cells found in canals of schlemm.
- Ito cells found in subendothelial space of Disse.
- Paneth cells found in the bottom of crypts.
STEM CELL STUDIES :-
Researchers and doctors hope stem cell studies can help to:
- Increase understanding of how diseases occur. By watching stem cells mature into cells in bones, heart muscle, nerves, and other organs and tissue, researchers and doctors may better understand how diseases and conditions develop.
- Generate healthy cells to replace diseased cells (regenerative medicine). Stem cells can be guided into becoming specific cells that can be used to regenerate and repair diseased or damaged tissues in people.People who might benefit from stem cell therapies include those with spinal cord injuries, type 1 diabetes, Parkinson’s disease, amyotrophic lateral sclerosis, Alzheimer’s disease, heart disease, stroke, burns, cancer and osteoarthritis.Stem cells may have the potential to be grown to become new tissue for use in transplant and regenerative medicine. Researchers continue to advance the knowledge on stem cells and their applications in transplant and regenerative medicine.
- Test new drugs for safety and effectiveness. Before using investigational drugs in people, researchers can use some types of stem cells to test the drugs for safety and quality. This type of testing will most likely first have a direct impact on drug development first for cardiac toxicity testing.New areas of study include the effectiveness of using human stem cells that have been programmed into tissue-specific cells to test new drugs. For the testing of new drugs to be accurate, the cells must be programmed to acquire properties of the type of cells targeted by the drug. Techniques to program cells into specific cells continue to be studied.For instance, nerve cells could be generated to test a new drug for a nerve disease. Tests could show whether the new drug had any effect on the cells and whether the cells were harmed.
STEM CELL THERAPY :-
Stem cell therapy, also known as regenerative medicine, promotes the repair response of diseased, dysfunctional or injured tissue using stem cells or their derivatives. It is the next chapter in organ transplantation and uses cells instead of donor organs, which are limited in supply.
Researchers grow stem cells in a lab. These stem cells are manipulated to specialize into specific types of cells, such as heart muscle cells, blood cells or nerve cells.
The specialized cells can then be implanted into a person. For example, if the person has heart disease, the cells could be injected into the heart muscle. The healthy transplanted heart muscle cells could then contribute to repairing defective heart muscle.
Researchers have already shown that adult bone marrow cells guided to become heart-like cells can repair heart tissue in people, and more research is ongoing.
Above Figure is taken from article written by Chinedu Cletus Ude et al 2018 (DOI: 10.1186/s40779-018-0154-9). Figure is used only for educational purpose
MULTIPLE CHOICE QUESTIONS [MCQs] :-
1.] “Oval cells” are seen in the stem cells of which of the following tissues ?
2.] Which of the following is the source of hepatic stem cells ?
a. Limbus cells
b. Ito cells
c. Oval cells
d. Paneth cell
3.] What is the process of cell specialization called ?
d. All of the above
4.] Adult stem cells are described as ?
5.] Name two sources of “ethical” stem cell ?
a. Cord blood
b. Bone marrow
c. Peripheral blood
d. All of the above
6.] Which of the statement is incorrect regarding stem cells ?
a. Developmental elasticity
b. Trans differentiation
c. Can be harvested from embryo
d. All of the above
7.] Cells or tissues donated by a related or unrelated individuals are called ?
8.] Stem cell treatment are risk free if they come from your own body ?
9.] Where can scientist obtain stem cell ?
a. Only from an embryo
b. Only from tissue in the body
c. Only from the brain
d. From an embryo or tissue in the body
10.] What is the least invasive source of stem cells from the human body ?
a. Cord blood
b. Adipose tissue
c. Bone marrow
1.] (c) Liver
2.] (c) Oval cell
3.] (b) Differentiation
4.] (a) Somatic
6.] (a) Development elasticity
7.] (c) Allogenic
9.] (d) From an embryo or tissue in the body
10.] (a) cord blood
1.] Textbook Of Pathology By Harsh Mohan; 7th edition; Page no. 163 – 164.
2.] Robbin’s Basic Pathology; 5th edition; Page no. 583 – 584.