Where are they located?
Embryonic stem cells (ESCs) are found in embryos inside of the blastocyst. A blastocyst is an early embryo around three to five days old, it is also where we see the first stem cells in the body. Human embryonic stem cells (hESCs) are not fertilized inside of the human body, unlike what many believe, rather with the consent of both donors the egg is fertilized in an "in vitro fertilization clinic". (4)
What are their capabilities?
Human embryonic stem cells have great potential, being pluripotent cells. Pluripotent cells are undifferentiated, meaning that they are not a specific cell type. Being undifferentiated, human embryonic stem cells can become any cell type inside of the body. These prolific cells may be utilized multiple times. Science is based on replication, if the DNA was different then the results may vary. (5)
Embryonic Stem Cells
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How do we obtain them?
The first step in growing ESCs could start in an "in vitro fertialization clinc" where they fertiliaze an egg cell with some sperm cells with consent from both donors. After allowing the embryo to grow for a few days it becomes a blastocyst, and is removed leaving behind a few hundred cells (stem cells) not visibile by the naked eye. (17) The stem cells are then carefully grown in a controlled envirornment, or a cell culture. This is performed by transferring the preimplantation-stage embryo into a culture dish containing a culture medium. The culture medium is there to provide nutrients that the cells may need. Commonly, they are layered with a feeder layer, which provides a sticky surface allowing the cells to attatch.
This process does possess potential barriers. A common practice of making the feeder layers out of mouse embryonic skin cells creates the possibility of viruses or other macromolecules to contaminate the human cells. Recently, scientists have formulated new ways of giving the the nutrients required to feed the human embryonic stem cells and a sticky surface to catch the cells, eliminating the need for mouse embryonic skin cells.
Another difficulty in harvesting ESCs is when creating the embryonic stem cell line. When first being plated they might not always survive but if they do they are gently moved to more and more "fresh culture dishes". This subculturing could be repeated many times creating the very important embryonic stem cell line. (4)
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