Embryonic stem cells, as their name suggests, are derived from embryos.
Specifically, embryonic stem cells are derived from embryos that develop from eggs that have been fertilized in vitro—in an in vitro fertilization clinic—and then donated for research purposes with informed consent of the donors.
They are not derived from eggs fertilized in a woman’s body. The embryos from which human embryonic stem cells are derived are typically four or five days old and are a hollow microscopic ball of cells called the blastocyst.
The blastocyst includes three structures
- Trophoblast, which is the layer of cells that surrounds the blastocyst
- Blastocoel, which is the hollow cavity inside the blastocyst
- Inner cell mass, which is a group of approximately 30 cells at one end of the blastocoel.
Embryonic Stem Cells They can develop into each of the more than 200 cell types of the adult body when given sufficient and necessary stimulation for a specific cell type.
Most of the research on embryonic stem cell has been done on mouse embryonic stem cells or human embryonic stem cells .
Both require very different environments in order to maintain an undifferentiated state. Without optimal culture conditions or genetic manipulation, embryonic stem cells will rapidly differentiate.
A human embryonic stem cell is also defined by the presence of several transcription factors and cell surface proteins. The transcription factors Oct-4, Nanog, and SOX2 form the core regulatory network that ensures the suppression of genes that lead to differentiation and the maintenance of pluripotency.
The cell surface antigens most commonly used to identify hES cells are
- Glycolipids SSEA3 and SSEA4
- Keratan sulfate antigens Tra-1-60 and Tra-1-81.
Embryonic stem cells, being pluripotent cells, require specific signals for correct differentiation. If injected directly into another body, ES cells will differentiate into many different types of cells, causing a teratoma. A teratoma is a tumor with tissue or organ components resembling normal derivatives of all three germ layers.
Differentiating ES cells into usable cells while avoiding transplant rejection are just a few of the hurdles that embryonic stem cell researchers still face. Because of their combined abilities of unlimited expansion and pluripotency, embryonic stem cells remain a theoretically potential source for regenerative medicine and tissue replacement after injury or disease.
About Arun Pal Singh