What Are Stem Cells
They are in a sense, the cells from which all else “Stems”. Bioethicist Alexander Capron of the World Health Organization described a stem cell as, “the foundation of organisms, the stalk from which everything buds and branches.”
Stem cells may be either embryonic or adult (Somatic). As a fertilized egg divides, the multiplying embryonic stem cells differentiate into or become all of the diverse tissues of the body, such as lungs, liver, brain, hair, heart.
Stem Cells are special cells with the amazing power to transform into any tissue or organ in your body. It is due to these special powers that they have the potential to treat over 80 life threatening diseases and disorders.
Although, there are various types of stem cells that exist in the human body, stem cell therapy makes use of two main types, namely Hematopoietic Stem Cells (HSC) and Mesenchymal Stem Cells (MSC).
The great thing about stem cells is that they can be extracted from a number of sources, like embryo, umbilical cord, cord blood, placenta, bone marrow, teeth, etc. The most abundant source of stem cells is the placenta (Chorion & Decidua), amniotic sac and amniotic fluid. For other sources.
Types of Stem Cells
There are various types of stem cells that exist in the human body. Depending on the disorder required to be treated, the following three types that may be used:
Hematopoietic Stem Cells (HSC):
These are found mostly in the bone marrow but also in peripheral blood, cord blood etc. These cells are hematopoietic or blood forming by nature. Thus, they generally give rise to blood forming cells eg. Red blood cells, white blood cells etc.
Hematopoietic stem cells (HSCs) are multipotent, self-renewing progenitor cells that develop from mesodermal hemangioblast cells. All differentiated blood cells from the lymphoid and myeloid lineages arise from HSCs. HSCs can be found in adult bone marrow, peripheral blood, and umbilical cord blood.
Mesenchymal Stem Cells (MSC):
These are bone marrow populating cells (different from HSC) that are present in the stroma. They possess the ability to differentiate into various cell types including, osteocytes (Bone), adipocytes (Fat), chondrocytes (Cartilage), myocytes (Muscle), cardiomyocytes (Cardiac Muscle) and neurons (Nerves) and blood vessels, and thus play a vital role in their regeneration as and when required.
Mesenchymal stem cells: the 'other' bone marrow stem cells. Mesenchymal stem cells (MSCs) can make several types of cells belonging to our skeletal tissues, such as cartilage, bone and fat. Scientists are investigating how MSCs might be used to treat bone and cartilage diseases.
Pluripotent Stem Cells (PSC):
These are stem cells that have the characteristics of both Hematopoietic & Mesenchymal cells. Thus, they are capable of differentiating into all types tissues in the body.
Image result for Pluripotent Stem Cellsen.wikipedia.org
Pluripotent stem cells are master cells. They're able to make cells from all three basic body layers, so they can potentially produce any cell or tissue the body needs to repair itself. This “master” property is called pluripotency.
The three primary germ layers (called the ectoderm, mesoderm, and endoderm) are the primary layers of cells in the embryo from which all tissues and organs develop. Human pluripotent stem cells are also known as human embryonic stem cells.
Autologous Stem Cells Transplant:
Autologous is when the donor and the receiver are the same person. Much like umbilical cord blood banking, tissue banking, stem cells are obtained from a person, processed and Cryo-stored for transplantation in future. This has gained tremendous precedence in major Indian cities in the past decade.
Role do Stem Cells Play in Human Biology?
Stem cells regenerate lost or damaged cells. For example, when a person gives or loses blood, stem cells will replenish the supply. If the skin is damaged, it generates new skin cells as it heals. Since stem cells have the ability to generate new tissue specific cells, this area of medicine is often called “Regenerative Medicine”.
All animals, including humans, start from one cell, which results from fertilization of an egg by a sperm. The resulting one cell contains all of the animal's genetic material or DNA and is capable of developing into a complete organism.
As the cell divides, the resulting cells or daughter cells will still contain all of DNA, while at the same time becoming specialized and more restricted in their ability to become all types of organs and tissues.
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