Mass.
General/Harvard study shows Sox2 expression is a widespread marker of adult
stem cells
Friday, 07 October 2011
Investigators at the Massachusetts General Hospital (MGH) Center for Regenerative Medicine and the Harvard Stem Cell Institute (HSCI) have found that Sox2 – one of the transcription factors used in the conversion of adult stem cells into induced pluripotent stem cells (iPSCs) – is expressed in many adult tissues where it had not been previously observed. They also confirmed that Sox2-expressing cells found in the stomach, testes, cervix and other structures are true adult stem cells that can give rise to all mature cell types in those tissues. The study appears in the October issue of Cell Stem Cell.
"We
have known that Sox2 is essential for maintaining pluripotency in embryonic
stem cells and neural stem cells and, with three other embryonic genes, is
sufficient to convert adult cells into iPSCs," says Konrad
Hochedlinger, PhD, of the MGH Center for Regenerative Medicine and HSCI,
who led the study.
"Our
study shows that Sox2 is a much more widespread marker of adult stem cells and
suggests these cells may share common genetic programs to maintain stem cell
fate, findings that could be exploited to amplify or modify these cells for
applications in regenerative medicine."
Hochedlinger's team set out to
investigate whether genes known to be important to pluripotent stem cells –
cells that can give rise to several different types of tissue – also play a
role in adult stem cells, which maintain populations of particular types of
tissue. Sox2 is one of four embryonic genes that are required to be expressed
for the generation of iPSCs – which have many of the characteristics of
embryonic stem cells – but the other three genes are not expressed in adult
stem cells. Sox2 is known to be expressed at the very earliest stages of
embryonic development and to play a role in development of several types of
fetal tissue. But prior to this study, its expression had been observed in only
a few types of adult tissues.
In a series of experiments with mice,
the researchers first showed that Sox2 continues to be expressed in specific
populations of adult cells of the stomach, esophagus, testes, cervix, anus and
the lens of the eye. These Sox2-expressing cells were proven to be able both to
replenish their population and to give rise to the fully differentiated cells
found within the particular tissue, confirming their status as adult stem
cells.
Additional findings revealed that fetal
tissues expressing Sox2, which are at a stage before the appearance of true
stem cells, will develop into tissues that include Sox2-expressing adult stem
cells and that Sox2 appears to be the only transcription factor expressed in
stem cells at all stages of development – embryonic, fetal and adult. However,
Sox2 expression has never been found in muscle or connective tissue, blood
cells, or in organs such as the heart or kidney, indicating that other factors
must play a similar role in those tissues.
"Adult
stem cells are difficult to isolate and manipulate, so the fact that Sox2
appears to be a marker for many adult stem cells may allow researchers to
isolate them more easily and study them in more detail," Hochedlinger explains.
"Manipulation
of Sox2 expression could help us push embryonic stem cells into particular
types of adult stem cells and, when combined with certain growth factors,
induce differentiation into desired types of tissue. All of these possibilities
need to be investigated."
Hochedlinger is an associate professor
of Medicine at Harvard Medical School and a Howard Hughes Medical Institute
Early Career Scientist.
Source:
Massachusetts General Hospital
Contact:
Sue McGreevey
Reference:
Sox2+ Adult Stem and Progenitor Cells
Are Important for Tissue Regeneration and Survival of Mice Katrin Arnold, Abby Sarkar, Mary Anna Yram, Jose M. Polo, Rod Bronson, Sumitra Sengupta, Marco Seandel, Niels Geijsen, Konrad Hochedlinger
Cell Stem Cell, Volume 9, Issue 4, 317-329, 4 October 2011, 10.1016/j.stem.2011.09.001
.........
For more on stem cells and cloning, go to CellNEWS at
http://cellnews-blog.blogspot.com/
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