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Stem Cells

Stem Cells: An Introduction

Last updated date: 24th Mar 2023
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Cells in the body serve specific functions, but stem cells are cells that do not yet have a specific function and can become almost any cell needed. Stem cells are undifferentiated cells that can differentiate into specific cells as needed by the body. These cells also hold promise for treating diseases for which there is currently no cure.

Stem Cells

Stem cells are the raw materials of the body, the cells that give rise to all other cells with specialised functions. Under the right conditions, stem cells divide to form more cells known as daughter cells in the body or a laboratory. Stem cells are mostly found in bone marrow (the spongy centre of certain bones). This is where they divide to produce new blood cells. Once mature, blood cells leave the bone marrow and enter the bloodstream.

Stem cells generate new cells for the body as it grows and replaces damaged or lost specialised cells. They can do this due to two distinct properties: they can divide repeatedly to produce new cells. They can change into the other types of cells that make up the body as they divide. Scientists and doctors are interested in stem cells because they help to explain how certain bodily functions work and why they sometimes fail.

Types of Stem Cells

  • Totipotent Stem Cell: Totipotent stem cells have the capacity to divide and give rise to all types of cells in an organism. Totipotency, which enables cells to create both extra-embryonic and embryonic structures, has the highest differentiation potential. A zygote, which is created after a sperm fertilises an egg, is an illustration of a totipotent cell.

These cells have the potential to either develop into one of the three germ layers of a placenta in the future. The inner cell mass of the blastocyst develops pluripotency after around 4 days.

  • Pluripotent Stem Cell: Unlike extraembryonic structures like the placenta, pluripotent stem cells (PSCs) can create cells from all germ layers. One illustration is embryonic stem cells (ESCs). The inner cell mass of preimplantation embryos is where ESCs are derived. Induced pluripotent stem cells (iPSCs), which are produced from the epiblast layer of implanted embryos are another illustration.

From fully pluripotent cells like ESCs and iPSCs to representatives with less potency: multi-, oligo- or unipotent cells—, their pluripotency is a continuum. The teratoma development assay is one approach to evaluate their activity and spectrum. iPSCs are produced synthetically from somatic cells and have similar properties to PSCs. Their cultivation and use hold great promise for both the present and the future of regenerative medicine.

  • Multipotent Stem Cell: PSCs have a wider range of differentiation than multipotent stem cells, yet multipotent stem cells can specialise in discrete cells from particular cell lineages. A haematopoietic stem cell, which may give rise to various blood cell types, is one illustration. A haematopoietic stem cell differentiates into an oligopotent cell. The cells in its lineage are then the only cells that can differentiate. The ability of some multipotent cells to differentiate into unrelated cell types, however, makes them more appropriately referred to as pluripotent cells.

  • Oligopotent Stem Cell: Multiple cell types can be created by differentiating oligopotent stem cells. One type of stem cell can divide into white blood cells but not red blood cells in the myeloid stem cell.

  • Unipotent Stem Cell: These are solely capable of producing cells of the same kind. They can regenerate themselves, which means they still stem cells. Adult muscle stem cells are one example of that.

Sources of Stem Cells

  • Adult Stem Cells (ASCs): ASCs are undifferentiated cells that can regenerate or produce new cells that can replace injured or dead tissue. They are found in some differentiated tissues of our body. Adult stem cells may alternatively be referred to as "somatic stem cells." Non-reproductive cells in the body are referred to as "somatic" cells (eggs or sperm). ASCs are often insufficient in native tissues, making it challenging to investigate and remove them for research.

  • Embryonic Stem Cells (ESCs): The embryo (at this stage known as a blastocyst) comprises an inner cell mass that is capable of producing all the specialised tissues that make up the human body during days 3-5 after fertilisation and before implantation. ESCs are produced from the inner cell mass of an in vitro fertilised embryo, that has been given for study after receiving informed consent. ESCs are not made from eggs that have been fertilised inside of a woman.

Only found in the early stages of development, pluripotent stem cells are capable of developing into practically any form of cell. The goal of the research is to comprehend how these cells differentiate during development.

  • Mesenchymal Stem Cells (MSCs): MSCs are derived from the stroma, or connective tissue, that covers the body's organs and other tissues. MSCs have been employed by researchers to produce new bone, cartilage and fat cells as well as other bodily tissues. They might one day assist in resolving a variety of medical issues.

  • Induced Pluripotent Stem Cells (iPSC): These are produced in a lab by scientists utilising skin cells and other tissue-specific cells. These cells exhibit behaviours resembling those of embryonic stem cells, making them potentially valuable for creating a variety of treatments. However, additional investigation and development are required. Scientists first take samples from adult tissue or an embryo to produce stem cells. These cells are then placed in a controlled culture, where they will divide and procreate but not further specialise.

A stem-cell line is a collection of stem cells that are actively dividing and replicating in a controlled environment. There are a variety of uses for stem cell researchers sharing and managing stem cell lines. They can encourage stem cells to become more specialised in a specific way. Directed differentiation is the name of this procedure.

Stem Cell Therapy

Stem cell therapy commonly referred to as regenerative medicine uses stem cells or their byproducts to encourage the repair response of sick, malfunctioning or wounded tissue. It is the next step in the transplantation of organs, replacing donor organs which are scarce with cells.

In a lab, scientists cultivate stem cells. Through manipulation, these stem cells can be made to specialise in particular cell types, such as heart muscle cells, blood cells or nerve cells. The person can then receive the implanted specialist cells. The cells might be injected into the heart muscle, for instance, if the patient has cardiac problems. The healthy heart muscle cells that were transplanted could then aid in healing the damaged heart muscle.


Throughout a person's life, stem cells exist in their body. The body can use these stem cells whenever they are required. Adult stem cells, also known as tissue-specific or somatic stem cells, exist throughout the body from the time an embryo develops. Although the cells are non-specific, they are more specialised than embryonic stem cells. They remain in this state until the body requires them for another function, such as skin or muscle cells.

Everyday life requires the body to constantly renew its tissues. Stem cells divide regularly into some parts of the body, such as the gut and bone marrow, to produce new body tissues for maintenance and repair.

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FAQs on Stem Cells

1. What are the risks associated with stem cell therapy?

Stem cell therapy, like any other treatment, carries with it the possibility that the patient's immune system will reject the cells that are employed in the treatment. The enormous promise that stem cells have is that they are able to divide an infinite number of times and differentiate into a wide variety of cell types. Despite these remarkable capabilities, stem cells paradoxically have the capacity to give rise to malignant tumours. Due to the existence of these possible dangers, both patients and medical professionals must proceed with extreme caution. 

2. Which type of stem cells are most useful and why?

“Embryonic stem cells” because they are pluripotent, which means they can develop into all of the body's cell types apart from the placenta and umbilical cord. As they offer a reusable resource for researching healthy growth and disease, as well as testing medications and other treatments, these cells are highly significant. The cells are versatile and have great potential for use in regenerative medicine to cure a range of diseases that burden the human race, such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis (MS).

3. From where can we obtain stem cells?

We can receive stem cells from our bodies, from foetal amniotic fluid, from pluripotent cells, and the stem cells of other people. The bone marrow, brain, blood vessels, skin, teeth, and several other tissues all contain stem cells. There are some mesenchymal stem cells in the foetus' amniotic fluid as well. The function of the induced pluripotent cells is comparable to that of embryonic stem cells. As a result, these cells can be employed to create an individual's adult stem cells. Adult stem cells can change or develop into various unrelated cell types.

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