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Line 1: − + + + + + + + + + + + − Current methods of generating iPSCs are not without limitations. While the process of inducing de-differentiation does yield pluripotent cells, these cells retain some [[epigenetics|epigenitic]] imprinting of the cell type from which they were derived. As such, iPSCs do not perfectly recapitulate the behavior of embryonic stem cells. Additionally, cell transplantation studies have demonstrated that iPSCs are significantly (~3-4 times, depending on the source tissue and method of induction) more tumorigenic in-vivo than embryonic stem cells, limiting their current therapeutic potential.
Induced pluripotent stem cells (view source)
Revision as of 01:52, October 10, 2012
, 01:52, October 10, 2012saving progress again, still expanding article
'''Induced pluripotent stem cells''', also known as '''iPSCs''', are pluripotent [[stem cells]] derived from [[cell differentiation|fully-differentiated]] ("adult") somatic cells. While they are often mistakenly referred to as "[[adult stem cells]]", this is not the proper term for them because biologists more commonly use the phrase "adult stem cells" to refer to the partially-differentiated stem cells residing in somatic tissues.
'''Induced pluripotent stem cells''', also known as '''iPSCs''', are pluripotent [[stem cells]] derived from [[cell differentiation|fully-differentiated]] ("adult") somatic cells. While they are often mistakenly referred to as "[[adult stem cells]]", this is not the proper term for them because biologists more commonly use the phrase "adult stem cells" to refer to the partially-differentiated stem cells residing in somatic tissues.
iPSCs are generated by [[transfection|transfecting]] fully differentiated cells with a combination of [[transcription factors]] that cause the cells to de-differentiate into a pluripotent state, mimicking the pluripotency of [[embryonic stem cells]]. As pluripotent cells, iPSCs can generate cells of any type; they can even be used to generate "organoids" (structures mimicking the organization of complex tissues) in-vitro (in [[cell culture|culture]]).
iPSCs are generated by [[transfection|transfecting]] fully differentiated cells with a combination of [[transcription factors]] that cause the cells to de-differentiate into a pluripotent state, mimicking the pluripotency of [[embryonic stem cells]] (ES cells). As pluripotent cells, iPSCs can generate cells of any type; they can even be used to generate "organoids" (structures mimicking the organization of complex tissues) in-vitro (in [[cell culture|culture]]).
Current methods of generating iPSCs are not without limitations. While the process of inducing de-differentiation does yield pluripotent cells, these cells retain some [[epigenetics|epigenitic]] imprinting of the cell type from which they were derived. As such, iPSCs do not perfectly recapitulate the behavior of ES cells. Additionally, cell transplantation studies have demonstrated that iPSCs are significantly (~3-4 times, depending on the source tissue and method of induction) more tumorigenic in-vivo than embryonic stem cells, limiting their current therapeutic potential.
==History==
The first iPSCs were produced in 2006 in the lab of Shinya Yamanaka at Kyoto University in Japan. Yamanaka and colleagues transfected mouse [[fibroblasts]] (in this case, skin cells) with a combination of four transcription factors (Oct3/4, Sox2, c-Myc, and Klf4) to generate cells with similar morphology, gene expression, and "growth properties" to ES cells<ref>http://www.cell.com/retrieve/pii/S0092867406009767</ref>. A year later, a team led by James Thomson at the University of Wisonsin generated the first human iPSCs by applying the same technique to human fibroblasts<ref>http://www.sciencemag.org/content/318/5858/1917.long</ref>.
Since then, researchers have been focused on addressing the shortcomings of the original technique, notably its low efficiency and the tumorigenicity of the resulting iPSCs, and many novel variations of the original method have been published. No current protocol for generating iPSCs is capable of producing cells that perfectly (and reliably) mimic the behavior of ES cells; accordingly, techniques for generating iPSCs will remain an area of intense research for the forseeable future.
==References==
==References==