INTRODUCTION: Enter Stem Cells...!!

Stem cells are the primal cells found in all multicellular organisms. They retain the ability to renew themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types.


Stem Cell Properties:
1. Self-renewal: The ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
2. Unlimited potency: The capacity to differentiate into any mature cell type. In a strict sense, this requires stem cells to be either totipotent, although some multipotent or unipotent progenitor cells are sometime referred to as stem cells.

Potency definitions:

1. Totipotent stem cells: These are produced from the fusion of an egg and sperm cells. Cells produced by the first few divisions of the fertilized egg are also totipotent.These cells can differentiate into embryonic and extraembryonic cell types.
2. Pluripotent stem cells: These are the descendants of totipotent cells and can differentiate into cells derived from any of the three germ layers.
3. Multipotent stem cells: These cells can produce only cells of a closely related family of cells (e.g.-Hematopoietic stem cells differentiate into R.B.C, W.B.C, platelets etc.)
4. Unipotent stem cells: These cells can produce only one cell type, but have the property of self-renewal which distinguishes them from non-stem cells

Types of stem cells:

1. Embryonic stem cells: The stem cells obtained from the early developing stages of an embryo are called Embryonic stem cells. Stem cells obtained from this newly developed bundle of cells have the full potential to differentiate into absolutely, positively anything in the human body.Embryonic stem cells are pluripotent and give rise during development of all derivatives of three primary germ layers.
Embryonic stem cell lines are cultures of cells derived from the epiblast tissue of the inner cell mass of a blastocyst or earlier morula stage embryos.
2. Adult stem cells: Stem cells obtained from full grown adults are Adult stem cells. Stem cells have to be found in special parts of the body where they have been saved and undifferentiated, like in bone marrow or early stages of tissue development. They have been used for various applications such as cloning, trying to cure diabetis, and artificial blood.It is said that adult stem cells are clonogenic and unilineal.
The major function of adult stem cells is to maintain homeostasis in the body in terms of replacing dead or injured cells with new ones that function correctly.
3. Umbilical Cord stem cells: Stem cells obtained from the umbilical cord of a new born baby are the Umbilical cord stem cells. Millions of multipotent stem cells lie in the umbilical cord and the blood in it.These stem cells can be saved in a Stem Cell Bank and later used for bone marrow, anemia, and cancer treatments etc.


Stem cell culture:
Stem cells are cultured in laboratory and these cultured stem cells has their own research and clinical application. Major applications are: Functional genomic studies, Study of biological processes, Drug discovery and development, Cell-based therapy, Therapeutic cloning etc.