http://www.eurekalert.org/pub_releases/2011-05/uow-hbm051711.php


Public release date: 22-May-2011
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Contact: Su-Chun Zhang
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 608-265-2543
 University of Wisconsin-Madison

Human brain's most ubiquitous cell cultivated in lab dish
 

MADISON - Pity the lowly astrocyte, the most common cell in the human
nervous system. 

Long considered to be little more than putty in the brain and spinal cord,
the star-shaped astrocyte has found new respect among neuroscientists who
have begun to recognize its many functions in the brain, not to mention its
role in a range of disorders of the central nervous system. 

Now, writing in the current (May 22) issue of the journal Nature
Biotechnology, a group led by University of Wisconsin-Madison stem cell
researcher Su-Chun Zhang reports it has been able to direct embryonic and
induced human stem cells to become astrocytes in the lab dish. 

The ability to make large, uniform batches of astrocytes, explains Zhang,
opens a new avenue to more fully understanding the functional roles of the
brain's most commonplace cell, as well as its involvement in a host of
central nervous system disorders ranging from headaches to dementia. What's
more, the ability to culture the cells gives researchers a powerful tool to
devise new therapies and drugs for neurological disorders. 

"Not a lot of attention has been paid to these cells because human
astrocytes have been hard to get," says Zhang, a researcher at UW-Madison's
Waisman Center and a professor of neuroscience in the UW-Madison School of
Medicine and Public Health. "But we can make billions or trillions of them
from a single stem cell." 

Although astrocytes have gotten short shrift from science compared to
neurons, the large filamentous cells that process and transmit information,
scientists are turning their attention to the more common cells as their
roles in the brain become better understood. There are a variety of
astrocyte cell types and they perform such basic housekeeping tasks as
helping to regulate blood flow, soaking up excess chemicals produced by
interacting neurons and controlling the blood-brain barrier, a protective
filter that keeps dangerous molecules from entering the brain.

 Astrocytes, some studies suggest, may even play a role in human
intelligence given that their volume is much greater in the human brain than
any other species of animal. 

"Without the astrocyte, neurons can't function," Zhang notes. "Astrocytes
wrap around nerve cells to protect them and keep them healthy. They
participate in virtually every function or disorder of the brain." 

The ability to forge astrocytes in the lab has several potential practical
outcomes, according to Zhang. They could be used as screens to identify new
drugs for treating diseases of the brain, they can be used to model disease
in the lab dish and, in the more distant future, it may be possible to
transplant the cells to treat a variety of neurological conditions,
including brain trauma, Parkinson's disease and spinal cord injury. It is
possible that astrocytes prepared for clinical use could be among the first
cells transplanted to intervene in a neurological condition as the motor
neurons affected by the fatal amyotrophic lateral sclerosis, also known as
Lou Gehrig's disease, are swathed in astrocytes. 

"With an injury or neurological condition, neurons in the brain have to work
harder, and doing so they make more neurotransmitters," chemicals that in
excess can be toxic to other cells in the brain, Zhang says. 

"One idea is that it may be possible to rescue motor neurons by putting
normal, healthy astrocytes in the brain," according to Zhang. "These cells
are really useful as a therapeutic target." 

The technology developed by the Wisconsin group lays a foundation to make
all the different species of astrocytes. What's more, it is possible to
genetically engineer them to mimic disease so that previously inaccessible
neurological conditions can be studied in the lab. 


###

In addition to Zhang, co-authors of the new Nature Biotechnology paper
include Robert Krencik, Jason Weick and Zhijian Zhang, all of UW-Madison,
and Yan Liu of Fudan University Shanghai Medical School. The work was
supported by the ALS Foundation, the National Institute of Neurological
Disorders and Stroke, the National Multiple Sclerosis Society, the Bleser
Family Foundation and the Busta Family Foundation.
 
An image is available for download at
http://www.news.wisc.edu/newsphotos/astrocytes.html 




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