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Stem Cells Then, Now, and Later
The History, Progression, and Future of Stem Cell Research
What is Cell Differentiation?
Definition:
"The process by which a cell becomes specialized in order to perform a specific function"
Red Blood
Bone
Muscle
Small Intestine
Liver
Neuron
Gene expression:
The specific combination of genes that are turned on or off that is responsible for cell specialization
Expressed - the process by which information from a gene is used in the synthesis of a functional gene product
Repressed - the deactivation of an active gene that causes the inhibition of transcription
Signaling molecules - molecules that bring messages to cells that help the cell know which activities and processes to perform
Stem Cell Classification
Totipotent
When a sperm cell and an egg cell unite, they form a one-celled fertilized egg. This cell is totipotent, meaning it has the potential to give rise to any and all human cells, such as brain, liver, blood or heart cells. Totipotent cells may also reculture as an entirely new organism.
Pluripotent
Pluripotent cells can give rise to all tissue types. These particular types of stem cells cannot give rise to an entire organism. After the fourth day of embryo development, totipotent cells become pluripotent stem cells.
Multipotent
Multipotent cells give rise to a limited range of cells within a tissue type. These are products of pluripotent cell specialization that contribute the the rise of certain cell lines (blood cells, skin cells and nerve cells). This means that they can become one of several types of cells within a given organ.
Adult
An adult stem cell is a multipotent stem cell that has the potential to replace cells that have died or sustained damage in the body - "an undifferentiated cell present in differentiated tissue. It renews itself and can specialize to yield all cell types present in the tissue from which it originated."
Somatic (Adult) Stem Cells
Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues. This is the primary role of adult stem cells: to maintain and repair the tissue in which they are found. Unlike embryonic stem cells, which are defined by their origin, the origin of adult stem cells in some mature tissues is still under investigation. If the differentiation of adult stem cells can be controlled in the laboratory, these cells may become the basis of genetic-based therapies.
Cell type: Multipotent
Adult Stem Cells In Action: Jim's Story
C.9
transplantation for the treatment of a broad spectrum of diseases. The isolation of human ES cells in 1998 spiked a general fascination around cell therapy, making human application of stem cell therapy a nearer and more plausible occurance.
Cell type: Pluripotent
The discovery of mouse embryonic stem cells enabled the manipulation of the mouse genome. The initial discovery of embryonic stem cells opened the door to pure populations of undifferentiated cells with indefinite, untapped potential for human manipulation and intervention. In this way, embryonic stem cell differentiation is considered to be a potentially unlimited source of cells and tissues for
Embryonic Stem Cells
Induced Pluripotent Stem Cells
Cell type: Pluripotent
"iPS cells are adult cells that have been genetically reprogrammed to an embryonic stem cell–like state by being forced to express genes and factors important for maintaining the defining properties of embryonic stem cells. Although additional research is needed, iPSCs are already useful tools for drug development and modeling of diseases, and scientists hope to use them in transplantation medicine."
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