Main Difference – Adult vs Embryonic Stem Cells
Adult stem cells and embryonic stem cells both give rise to differentiated cells in the body. Stem cells are capable of self-renewing and differentiating into specialized cells in the body. Adult stem cells are localized in several parts of the differentiated cells in the adult body while the inner cell mass of the blastocyst gives rise to embryonic stem cells. A variety of adult stem cells can be found, but embryonic stem cells are derived from the three germ layers. The main difference between adult and embryonic stem cells is that adult stem cells are multipotent whereas embryonic stem cells are pluripotent.
This article looks at,
1. What are Adult Stem Cells
– Characteristics, Location, Examples
2. What are Embryonic Stem Cells
– Characteristics, Location, Examples
3. What is the difference between Adult and Embryonic Stem Cells
What are Adult Stem Cells
Adult stem cells are found in differentiated tissues like bone marrow and brain and remain undifferentiated but continuously self-renew in the tissue, producing identical copies of cells throughout the lifetime of the organism. When needed, adult stem cells are differentiated into specialized cells of the tissue of origin. Adult stem cells are localized in some body parts. They are found in skeletal muscle, liver, pancreas, brain, eye, dental pulp, skin, bone marrow, blood and the lining of the gastrointestinal tract. Hematopoietic stem cells are found in the bone marrow, giving rise to the various type of cells found in the blood. They are considered as multipotent stem cells since they give rise to multiple types of blood cells from a single type of cells. This variation of differentiated cells is achieved by the regulated gene expression, which is controlled by the involvement of distinct types of transcription factors. Stem cells in the brain are also multipotent, giving rise to both blood cells and muscle tissues. Adult stem cell differentiation is shown in figure 1.
Figure 1: Adult stem cell differentiation
Since adult stem cells are rare and difficult to identify, it is difficult to purify them or grow them in cultures. Stem cells in the bone marrow are the most studied stem cell type.
What are Embryonic Stem Cells
Stem cells that are found in the early stages of the embryo are referred to as embryonic stem cells (ESCs). As a result of fertilization, zygote, which is considered as the earliest stage of the embryo, is formed. The zygote is divided by mitosis, forming the morula. Blastocyte is formed from morula 5-6 days after fertilization. The blastocyte is composed of trophoblast, which is the outer cell layer and inner cell mass. The inner cell mass is composed of pluripotent stem cells, which give rise to three germ layers: ectoderm, mesoderm, and endoderm. In the laboratory, this multipotent stem cells can be removed from the blastocyte in order to maintain their unspecialized stages as cell culture lines. These cell lines are used in medical therapies. Embryonic stem cells are shown in figure 2.
Figure 2: Embryonic Stem Cells
Difference Between Adult and Embryonic Stem Cells
Definition
Adult Stem Cells: Adult stem cells are found in differentiated tissues, but they remain undifferentiated.
Embryonic Stem Cells: Embryonic stem cells are found in the three germ layers of the embryo.
Safety of the Therapy
Adult Stem Cells: Adult stem cell-based therapies (ACT) have more advantages compared to embryonic stem cell- based therapies.
Embryonic Stem Cells: Embryonic stem cell-based therapies are not as safe as ACT since embryonic stem cells are more prone to develop into cancerous cells.
Description
Adult Stem Cells: Adult stem cells are well known.
Embryonic Stem Cells: Embryonic stem cells are relatively new and less known.
Potency
Adult Stem Cells: Adult stem cells cannot be differentiated into any kind of a specialized cell. Hence, they are multipotent.
Embryonic Stem Cells: Embryonic stem cells have the potential of differentiation into various cell types. Hence, they are pluripotent and considered as more powerful than adult stem cells.
Stem Cell Studies
Adult Stem Cells: The most studied type of adult stem cells is the stem cells in bone marrow.
Embryonic Stem Cells: Various types of stem cells are studied in the embryo.
Examples
Adult Stem Cells: Adult stem cells can be found in skeletal muscle, liver, pancreas, brain, eye, dental pulp, skin, bone marrow, blood and the lining of the gastrointestinal tract in humans.
Embryonic Stem Cells: Inner cell mass of the embryo contains embryonic stem cells, which give rise to the three germ layers.
Conclusion
Three types of stem cells can be identified during various development stages of organisms: embryonic stem cells, fetal stem cells, and adult stem cells. Each and every stem cell is capable of self-renewing and differentiating into specialized cell types. Embryonic stem cells have the potential to give rise to every type of body cells. The three germ layers are differentiated into various organs and tissues of the body. Hence, they are called pluripotent. Adult stem cells are found in diffrentiated organs. They are capable of differentiating into specific cells with the origin of that particular tissue. That means, adult stem cells are incapable of differentiating into any type of the specialized cells found in the body. But, adult stem cells may give rise to a limited variety of cell types. Hence, adult stem cells are multipotent. Therefore, the main difference between adult and embryonic stem cells is observed in their potency.
Reference:
1. National Research Council (US) and Institute of Medicine (US) Committee on the Biological and Biomedical Applications of Stem Cell Research. “Project Overview and Definitions.” Stem Cells and the Future of Regenerative Medicine. U.S. National Library of Medicine, 01 Jan. 1970. Web. 28 Mar. 2017.
2. National Research Council (US) and Institute of Medicine (US) Committee on the Biological and Biomedical Applications of Stem Cell Research. “Adult Stem Cells.” Stem Cells and the Future of Regenerative Medicine. U.S. National Library of Medicine, 01 Jan. 1970. Web. 29 Mar. 2017.
Image Courtesy:
1. “Stemcelldifferentiaion” (Public Domain) via Commons Wikimedia
2.”Human embryonic stem cells only A” By Human_embryonic_stem_cells.png: (Images: Nissim Benvenisty)derivative work: Vojtech.dostal (talk) – Human_embryonic_stem_cells.png (CC BY 2.5) via Commons Wikimedia
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