Brain stem cells can be awakened, say Schepens scientists
Study findings promise to help in treatment of brain diseases
Boston, MA-Scientists at Schepens Eye Research Institute have
identified specific molecules in the brain that are responsible for
awakening and putting to sleep brain stem cells, which, when
activated, can transform into neurons (nerve cells) and repair
damaged brain tissue. Their findings are published online this week
in the Proceedings of the National Academy of Science (PNAS).
An earlier paper (published in the May issue of Stem Cells) by the
same scientists laid the foundation for the PNAS study findings by
demonstrating that neural stem cells exist in every part of the
brain, but are mostly kept silent by chemical signals from support
cells known as astrocytes.
³The findings from both papers should have a far-reaching impact,²
says principal investigator, Dr. Dong Feng Chen, who is an associate
scientist at Schepens Eye Research Institute and an assistant
professor of ophthalmology at Harvard Medical School. Chen believes
that tapping the brain¹s dormant, but intrinsic, ability to
regenerate itself is the best hope for people suffering from brain-
ravaging diseases such as Parkinson¹s or Alzheimer¹s disease or
traumatic brain or spinal cord injuries.
Until these studies, which were conducted in the adult brains of
mice, scientists assumed that only two parts of the brain contained
neural stem cells and could turn them on to regenerate brain tissue--
the subgranular zone (SGZ) of the hippocampus and the subventricular
zone (SVZ). The hippocampus is responsible for learning and memory,
while the SVZ is a brain structure situated throughout the walls of
lateral ventricles (part of the ventricular system in the brain) and
is responsible for generating neurons reponsible for smell. So
scientists believed that when neurons died in other areas of the
brain, they were lost forever along with their functions.
In the first study, Chen¹s team learned that stem cells existed
everywhere in the brain by testing tissue from different parts of
adult mice brains in cultures containing support cells (known as
astrocytes) from the hippocampus, where stem cells do regenerate.
In the cultures the stem cells from other brain regions came to life
and turned into neurons.
When they compared the chemical makeup of the areas known to generate
new neurons in the hippocampus with other parts of the brain, the
team discovered that astrocytes in the hippocampus were sending one
signal to the stem cells and that those from the rest of the brain
were sending a different signal to stem cells.
In the second (PNAS) study, the team went on to discover the exact
nature of those different chemical signals. They learned that in the
areas where stem cells were sleeping, astrocytes were producing high
levels of two related molecules--ephrin-
found that removing these molecules (with a genetic tool) activated
the sleeping stem cells.
The team also found that astrocytes in the hippocampus produce not
only much lower levels of ephrin-A2 and ephrin-A3, but also release a
protein named sonic hedghoc that, when added in culture or injected
into the brain, stimulates neural stem cells to divide and become new
neurons.
³These findings identify a key pathway that controls neural stem cell
growth in the adult brain and suggest that it may be possible to
reactivate the dormant regenerative potential by adding sonic
hedgehoc, or blocking ephrin-A2 or ephrin-A3,² says Dr. Jianwei Jiao,
the first author of the two papers.
The next step for the team will be to stimulate the sleeping stem
cells in animals who are models of neurodegenerative disorders, such
as Parkinson's disease, to see if the brains can repair themselves
and restore their damaged functions.
###
Schepens Eye Research Institute is an affiliate of Harvard Medical
School and the largest independent eye research institute in the
country.
Public release date: 6-Jun-2008
Contact: Patti Jacobs
pjacobs12@comcast.
617-864-2712
Schepens Eye Research Institute
http://www.eurekale
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»«¤»¥«¤»§«¤»¥«¤»§«¤»¥«
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
____________________________________________
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»«¤»¥«¤»§«¤»¥«¤»§«¤»¥«
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch format to Traditional
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___
No comments:
Post a Comment