While each cell in the body serves a specific purpose, stem cells are cells that do not yet have defined functions and can differentiate into almost any cell required.
Stem cells are undifferentiated cells that can differentiate into any type of cell the body requires.
Essentially, stem cells are the body’s raw materials — the cells that serve as the building blocks from which all other cells with specialized roles are formed.
Cells known as daughter cells are formed when stem cells divide properly in either the body or a laboratory setting, according to the circumstances.
These daughter cells either differentiate into new stem cells (self-renewal) or into specialized cells (differentiation) that perform a more specific job, such as blood cells, brain cells, heart muscle cells, or bone cells, depending on their parent cell type.
No other cell in the body has the intrinsic potential to generate new cell types, except for the one that is responsible for cell division.
Sources of Stem Cells and their markers
Embryonic stem cells
Embryonic stem cells are a type of stem cell that originates from an embryonic cell.
The stem cells used in this study were harvested from embryos that were three to five days old.
At this stage, an embryo is referred to as a blastocyst, and it contains approximately 150 cells.
These are pluripotent stem cells, which means that they have the ability to proliferate and differentiate into any type of cell in the body.
Because of their adaptability, embryonic stem cells can be employed to regenerate or repair damaged tissue in a variety of signaling pathways are also known to play a role in cell fate determination.
Lectins and other related peptides have been discovered to bind to ESCs specifically.
For the optimal utilization of ESCs and the explication of the mechanisms driving pluripotency and self-renewal of ESCs, more knowledge of these markers is crucial.
Types of Stem Cell Markers
1. Cell Surface Markers
- Stage Specific Embryonic Antigens (SSEA)
Three (Hematopoietic Stem Cell Marker) monoclonal antibodies recognized specific carbohydrate epitopes associated with the lacto-series and globo-series glycolipids SSEA-1, SSEA-3, and SSEA-4, which led to the discovery of SSEAs. During development, these carbohydrate-associated molecules are crucial in modulating cell surface contacts. SSEA-1 (CD15/Lewis x) is expressed on the pre-implantation surface of murine embryos, as well as in mouse and human germ cells and teratocarcinoma stem cells, but it is lacking in human ESC and human embryonic carcinoma cells.
- A cluster of Differentiation (CD) Antigens
CD antigens are surface proteins that include integrins, adhesion molecules, glycoproteins, and receptors, among other groups. CD antigens differ depending on the cell type. Antibodies that recognize CD antigens are frequently utilized in cell sorting, as well as in identifying and characterizing different cell types. ESC from mice and humans is linked to several CD antigens. CD9, CD24, and CD133 are CD antigens linked with pluripotent hES cells.
- Integrins
Integrins collaborate with other proteins to facilitate cell-cell and cell-matrix interaction and communication, including cadherins, immunoglobulin superfamily cell adhesion molecules, selectins, and syndecans. They bind to fibronectin, vitronectin, collagen, and laminin on the cell surface and in the ECM. Integrins not only do outside-in signaling, but they also perform inside-out signaling. Outside-in signaling through one integrin can stimulate inside-out signaling through another integrin. As a result, they both transmit information from the ECM to the cell and disclose the cell’s condition to the outside, allowing for quick and flexible responses to environmental changes. Integrins are found on a variety of cell surfaces and play a crucial role in the formation of ESC niches.
2. Transcription Factors
Important activities are always performed by genes that function in the nucleus. Transcription factors play an important role in gene regulation. Under normal circumstances, several of these transcription factors are dormant and only bind to their corresponding recognition sequences when a specific signal transduction event occurs. The appearance of unique genes in the nucleus that perform activities indicates that the cell has responded to a particular situation.
3. Signal Pathway related markers
The best-characterized markers are usually found on the cell surface. To transmit messages, an external signal that could not pass easily through the cellular membrane must interact with cell surface molecules. When a specific intracellular signal pathway is engaged, it sets in motion a series of molecular events that cause specific gene expressions to be regulated in response to the signal. Several intracellular signal pathways play essential roles in ESC self-renewal and pluripotency, hence many signal pathway-related proteins that are necessary for these functions can be considered ESC markers.