Human life begins with a single fertilized cell, also called a zygote. Slowly, the zygote divides into multiple cells leading to the formation of the human body.

As the cell grows, they become differentiated, which means they take on a specific function. This differentiation of cells helps the body in growing tissues and organs.

Stem cells are those cells that are not differentiated yet. They do not have any specific function. However, they are the foundation of every organ and tissue in the human body.

Stem cells can self-renew, which means they can produce more stem cells. Also, they can transform into other types of cells and take on specific functions in the body.

These properties of stem cells make them a powerful aid in treating various diseases. Stem cells banks can help in replacing damaged cells with new and healthy cells. Hence, when the cells in the body get damaged due to injury or diseases, stem cells can help in speedy recovery.

Stem cells can be bifurcated into three different types based on when and where they are formed. Let us discuss the different types of stem cells in detail.

1) Embryonic stem cells.

These cells are derived from the human embryos 3 to 5 days after the fertilization process called In-Vitro Fertilization (IVF). The cells are fertilized in a lab and not inside the human body. They are donated for research purposes with the informed consent of donors.

The inner cell mass of the blastocyst gives rise to specialized cells of all the tissues and organs in the body. The blastocyst is a very tiny hollow ball of cells formed a few days after the sperm fertilizes the egg.

The cells inside the blastocyst become specialized and form the different parts of the human body. The scientist extracts the inner cell mass and grows them in specific conditions to retain the properties of embryonic stem cells.

These cells are pluripotent, which means they have the potential to become any kind of cell type in the body. This unique property makes them ideal for research and discovery.

2) Adult stem cells

Adult stem cells, also known as somatic stem cells, are undifferentiated stem cells that are found in differentiated tissues in our body. Somatic cells are found in bone marrow, placenta, umbilical cord, brain, fat tissue, skin, gut, etc.

In comparison to embryonic stem cells, these cells are more specialized. These cells can generate different cells for their origin tissues and organs. Hence, they can help in replacing damaged cells.

However, some studies show that adult stem cells can also help in growing other cells than those tissues they reside in. These cells remain inactive until they are called upon by the body to morph into different cell types.

There are generally very few adult stem cells in native tissues. Hence, they are less likely to be used for research purposes.

Adult stem cells can also be bifurcated into different types, such as:

• Hematopoietic Stem Cells (Blood Stem Cells)

• Neural Stem Cells

• Mesenchymal Stem Cells

• Epithelial Stem Cells

• Skin Stem Cells

3) Induced pluripotent stem cells

Induced pluripotent cells are produced in the laboratory by transforming adult stem cells to have the characteristic of embryonic stem cells. Embryonic genes are introduced into the somatic cells that enable them to behave like pluripotent cells.

This means that induced pluripotent cells can form different cell types in the body. The method of genetic reprogramming provides a great opportunity for medical advancements, the study of body development, disease progression, etc. However, more research is required before the cells can be used for clinical trials.

These are the three different types of stem cells that can be used for medical purposes.