What is stem cell. Stem cells are
biological cells found in all multicellular
organisms, that can
divide (through
mitosis) and
differentiate into diverse specialized cell types and can self-renew to produce more stem cells. In
mammals, there are two broad types of stem cells:
embryonic stem cells, which are isolated from the
inner cell mass of
blastocysts, and
adult stem cells, which are found in various tissues. In
adult organisms, stem cells and
progenitor cells
act as a repair system for the body, replenishing adult tissues. In a
developing embryo, stem cells can differentiate into all the specialized
cells[ectoderm,endoderm and mesoderm-see induced pluripotent stem
cells] (these are called pluripotent cells), but also maintain the
normal turnover of regenerative organs, such as blood, skin, or
intestinal tissues.
There are three accessible sources of
autologous adult stem cells in humans:
- Bone marrow, which requires extraction by harvesting, that is, drilling into bone (typically the femur or iliac crest),
- Adipose tissue (lipid cells), which requires extraction by liposuction, and
- Blood, which requires extraction through pheresis,
wherein blood is drawn from the donor (similar to a blood donation),
passed through a machine that extracts the stem cells and returns other
portions of the blood to the donor.
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