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 (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.
Stem cells can also be taken from umbilical cord blood just after birth. Of all stem cell types, autologous harvesting involves the least risk. By definition, autologous cells are obtained from one's own body, just as one may bank his or her own blood for elective surgical procedures.
Highly plastic adult stem cells are routinely used in medical therapies, for example in bone marrow transplantation. Stem cells can now be artificially grown and transformed (differentiated) into specialized cell types with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture. Embryonic cell lines and autologous embryonic stem cells generated through therapeutic cloning have also been proposed as promising candidates for future therapies. Research into stem cells grew out of findings by Ernest A. McCulloch and James E. Till at the University of Toronto in the 1960s.
Other articles related to "stem cell, stem cells, cell, cells":
... Stem cell markers are genes and their protein products used by scientists to isolate and identify stem cells ... Stem cells can also be identified by functional assays ... Below is a list of genes/protein products that can be used to identify various types of stem cells, or functional assays that do the same ...
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... The Stem Cell Center of the Texas Heart Institute was first in the United States to receive FDA approval for an adult stem cell clinical trial to treat patients with advanced heart failure ... by the National Institutes of Health to study stem cell treatments for patients with cardiovascular disease ... national consortium called the Cardiovascular Cell Therapy Research Network ...
... 1908 The term "stem cell" was proposed for scientific use by the Russian histologist Alexander Maksimov (1874–1928) at congress of hematologic society in Berlin ... It postulated existence of haematopoietic stem cells. 1963 McCulloch and Till illustrate the presence of self-renewing cells in mouse bone marrow ...
Famous quotes containing the words cell and/or stem:
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