Difference between revisions of "Adult stem cells"

From Conservapedia
Jump to: navigation, search
(top: Spelling, grammar, and general fixes)
 
(32 intermediate revisions by 11 users not shown)
Line 1: Line 1:
Adult stem cells are undifferentiated cells that exist throughout the human body.  They can divide to replenish dying cells, and also regenerate to repair damaged tissuesAn example are olfactory cells in the nasal passages, which replenish to restore the sense of smell after suffering a cold.
+
'''Adult stem cells''' are multipotent, semi-differentiated, [[cell]]s that exist in all tissues.  "Adult stem cell", however, is not the preferred term used in the field to refer to them&#8212;developmental biologists will usually refer to them as "tissue resident stem cells" or as a specific cell type (often referencing the genes they express).  They function to maintain tissue homeostasis by dividing to replace damaged or senescent somatic cellsThe two most well-studied examples of adult stem cells are the hematopoietic stem cells, which give rise to blood cells, and the intestinal crypt stem cells, which give rise to the intestinal epithelium.<ref>http://9e.devbio.com/</ref>
  
Researchers have shown that adult stem cells from one germ layer can be converted into those of another, making adult stem cells at least as useful for cures as [[embryonic stem cells]] might beFor example, adult stems have been able to turn marrow cells into heart muscle and blood vessels in humans.
+
As multipotent cells, most adult stem cell types can generate cells of several different typesHowever, because they are already epigenetically programmed to favor a particular fate, they generally cannot generate cell types outside of their lineage without genetic manipulation.
  
While the United States has the largest medical research budget in the world, it also has the most politically powerful [[abortion]] industry.  The industry favors embryonic stem cell research over adult stem cell research in order to legitimize abortionHence relatively little research is done on adult stem cells in the United States, and most of the advances are made in mostly pro-life countriesFor example, in the case of a recently successful adult stem cell project for diabetics, "the research was done in Brazil because U.S. doctors were not interested in the approach."<ref>http://www.cnn.com/2007/HEALTH/conditions/04/10/diabetes.experiment.ap/index.html</ref> Brazil is a pro-life country that generally prohibits abortion.<ref>http://www.abortionfacts.com/statistics/world_statistics_brazil.asp</ref>
+
Identifying and characterizing stem cells within all adult tissues is an area of much intense ongoing research.  Understanding the mechanisms underlying the regulation of these stem cells has led to many recent breakthroughs in the field of cancer biologyA recent paradigm-shift in cancer biology was the discovery that cancer is a disease resulting from dysregulation of adult stem cells. The clinical implications of this concept are still being exploredObviously, there is still much in this field that remains unknown.
  
Portugal, a traditionally pro-life country that bans abortion,<ref>Only in April 2007 did Portugal legalize early abortions.[http://www.lifesite.net/ldn/2007/apr/07041001.html]</ref> is the leader in helping paralyzed victims with adult stem cell trials.<ref>http://www.webmd.com/alzheimers/news/20040624/paralysis-patients-tout-adult-stem-cells</ref> here]In contrast New Zealand, a pro-abortion country that has legalized abortion,<ref>http://www.abortion.gen.nz/legal/index.html</ref> recently banned adult stem cell trials for paralyzed victims, despite pleas by victims to have access to these treatments.<ref>http://www.nzherald.co.nz/search/story.cfm?storyid=0004FB3D-2994-15E5-9B1E83027AF1010F</ref>
+
Functionally, adult stem cells are very different from embryonic stem cells.  Whereas embryonic stem cells are omnipotent, and may be coaxed with growth factors into producing any known cell type, adult stem cells are already partially committed to a particular fate and, without genetic manipulation, will only generate a limited number of cell types.  As stated above, this is currently an intensive area of research, but at the present the two are not practically equivalent.
  
== References ==
+
[[Induced pluripotent stem cells]] are fully differentiated somatic cells that have been manipulated, either genetically or with growth factors (often a combination of the two), to become pluripotent stem cells.  These cells still retain some [[epigenetics|epigenetic]] imprinting of their original type—even with the most current techniques.  Mouse models have demonstrated that these cells have a significantly higher tumorigenic potential than transplanted embryonic stem cells.  As such, therapies involving induced pluripotent stem cells are primarily being studied only as options of last resort.  As scientists in the field devise better ways to generate these cells (new techniques are a current area of much research—there have been at least 40 published since 2009), they may become more clinically useful.  Until that happens, induced pluripotent cells cannot substitute for adult or embryonic stem cells in clinical medicine or research.
  
 +
 +
== References ==
 
<references/>
 
<references/>
 +
 +
[[Category:Genetics]]
 +
[[Category:Medicine]]

Latest revision as of 14:07, June 24, 2016

Adult stem cells are multipotent, semi-differentiated, cells that exist in all tissues. "Adult stem cell", however, is not the preferred term used in the field to refer to them—developmental biologists will usually refer to them as "tissue resident stem cells" or as a specific cell type (often referencing the genes they express). They function to maintain tissue homeostasis by dividing to replace damaged or senescent somatic cells. The two most well-studied examples of adult stem cells are the hematopoietic stem cells, which give rise to blood cells, and the intestinal crypt stem cells, which give rise to the intestinal epithelium.[1]

As multipotent cells, most adult stem cell types can generate cells of several different types. However, because they are already epigenetically programmed to favor a particular fate, they generally cannot generate cell types outside of their lineage without genetic manipulation.

Identifying and characterizing stem cells within all adult tissues is an area of much intense ongoing research. Understanding the mechanisms underlying the regulation of these stem cells has led to many recent breakthroughs in the field of cancer biology. A recent paradigm-shift in cancer biology was the discovery that cancer is a disease resulting from dysregulation of adult stem cells. The clinical implications of this concept are still being explored. Obviously, there is still much in this field that remains unknown.

Functionally, adult stem cells are very different from embryonic stem cells. Whereas embryonic stem cells are omnipotent, and may be coaxed with growth factors into producing any known cell type, adult stem cells are already partially committed to a particular fate and, without genetic manipulation, will only generate a limited number of cell types. As stated above, this is currently an intensive area of research, but at the present the two are not practically equivalent.

Induced pluripotent stem cells are fully differentiated somatic cells that have been manipulated, either genetically or with growth factors (often a combination of the two), to become pluripotent stem cells. These cells still retain some epigenetic imprinting of their original type—even with the most current techniques. Mouse models have demonstrated that these cells have a significantly higher tumorigenic potential than transplanted embryonic stem cells. As such, therapies involving induced pluripotent stem cells are primarily being studied only as options of last resort. As scientists in the field devise better ways to generate these cells (new techniques are a current area of much research—there have been at least 40 published since 2009), they may become more clinically useful. Until that happens, induced pluripotent cells cannot substitute for adult or embryonic stem cells in clinical medicine or research.


References

  1. http://9e.devbio.com/