Stem cells are the backbone for all types of cells and tissue in our body. They are undifferentiated cells which have the ability to form different types of cells of our body. The embryonic stem cell have the ability to to form whole body whereas, other stem cells have their limitations.
All the stem cells can renew and differentiate. The Stem cells make their own copies and increase their populations by multiplying. And when required they differentiate to refill the population of differentiated cells.
Characteristics of Stem Cells-
- They can renew.
- They are undifferentiated and un-specialized cells.
- They have potential to differentiate into specialized cells like blood, muscle, brain etc.
Types of Stem cells –
Based on the limitation of ability to differentiate, the stem cells have been divided into following types –
- Totipotent Stem cells –
When Egg (from Woman) and sperm (from male) fuses they form zygotic cell. The zygotic cell has the ability to form whole body. Because of such amazing potential, the zygotic cell is called as totipotent stem cell.
2. Pluripotent Stem cells –
In Embryo and fetus development process, the zygote develops to form blastocyst which gets implant to mother’s womb/uterus. The blastocyst comprises of Inner mass (ICM) and trophoblast. The inner mass is made from embryonic stem cells and they are called as pluripotent stem cells because they have ability to form a fetus (with tissues and organs). Whereas the trophoblast stem cells forms extra embryonic tissue like placenta and they are also pluripotent in nature. The placenta stem cells are called as adult stem cells (ACS).
Totipotent and Pluripotent Stem cells are called as Embryonic Stem Cells.
3. Multipotent Stem cells –
These cells have the ability to form only specialized cells of tissue and organs. They have ability to differentiate and forms more than one type of cells. The examples are as follows-
Hematopoietic Stem Cells (Blood Stem Cells) – Lymphoid and Myeloid cells. Lymphoid cells include T Cells, B cells and Natural killer cells. Whereas, Myeloid cells include monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, and megakaryocytes to platelets.
Mesenchymal Stem Cells – It can form Bone cells, Cartilage, Muscle cells, Neural cells, Skin cells, and Corneal cells
Neural Stem Cells – It differentiate into neurons, astrocytes and oligodendrocytes
Epithelial Stem Cells – epidermis and corneal epithelium) and linings (such as the digestive, respiratory, and uro-genital epithelia.
The placental, multipotent and unipotent stem cells are called as Somatic or Adult stem cells.
4. Unipotent Stem Cells-
These cells have the ability to differentiate into only one type of cell. The example of unipotent is dermatocytes.
Applications of Stem Cells –
- To grow them in artificial media/ invitro conditions and allowing us to learn more about cells and life.
- They can grown to replace the damaged and malfunctioning tissue or organs.
- To observe and study the mutations causing genetic diseases.
- They are also employed in conducting research on carcinogenesis.
- They are used for testing drugs and toxic molecules.
- To induce pluripotency by inserting embryonic genes and devolving cell from mature to embryonic state. Induced pluripotent cell can further be differentiated into required cells and can be used for replacing the damaged cells of the donor.