[tt] Neuro-regeneration breakthroughs

[Hughes, James J.]

http://www.sciencealert.com.au/news/20071705-15883.html

Brain regeneration breakthrough

Thursday, 17 May 2007
The University of Queensland

Neuroscientists at UQ's Queensland Brain Institute (QBI) have revealed
two major discoveries, edging them closer to harnessing the brain's
inherent powers of self-repair and regeneration.

In findings announced in the Journal of Neuroscience, QBI
neuroscientists have identified the stem cell population responsible for
production of neurons, and the mechanism which drives this process.

The research - published in two scientific papers - builds on the
pioneering 1992 discovery of the presence of precursors in the adult
brain which have the potential to produce neurons, a process also called
neurogenesis.

QBI Director Professor Perry Bartlett said the research offered a 'new
insight' into how this regulation might occur.

"For the first time, we've been able to identify a mechanism that's able
to regulate production of nerve cells, a step that's crucial to our
understanding of memory and learning," Professor Bartlett said.

"The same mechanism helps regulate growth of healthy brain tissue, so
identifying this process is essential for the development of
therapeutics to treat conditions such as dementia."

Neuroscientists at UQ have long been intrigued by the way nerve cells
are formed in the hippocampus - a part of the brain crucial to memory -
as this function is known to degenerate with age or disease.

"For more than 15 years, we've known that the brain contains stem cells,
but until now we have not been able to identify the mechanisms that
regulate production of these new nerve cells," Professor Bartlett said.

He said the latest research was more evidence the human central nervous
system had the potential capacity to respond to its outside environment
by generating new nerve cells.

Both the QBI studies confirmed that the naturally occurring protein -
brain-derived neurotrophic factor (BDNF) - is vital for neurons to
develop from precursor-stage cells.

In one of the QBI studies, a series of experiments demonstrated that the
chemical receptor (P75) plays an important role in enhancing nerve cell
production.

In the other study, a team of QBI neuroscientists found a way to
identify neurons at the intermediate stage of development, when the
cells are in the process of changing from stem cells to mature nerve
cells.

The discovery charts how this complex natural process occurs in a
healthy brain, using the protein Doublecortin (DCX) as a marker.

Using the DCX marker to identify intermediate cells advances
understanding of the hippocampus and provides researchers with a
powerful new way of visualising a mechanism which had until recently
been essentially theoretical.

QBI's Dr Tara Walker said the DCX findings meant scientists could now
isolate and study specific cells of interest in the hippocampus, a
region which has a high turnover of neural stem cells.

"Our immediate goal was to identify the genes important in promoting the
survival and differentiation of these immature nerve cells," she said.

"With this knowledge, we are well placed to further develop our
understanding of the basic mechanisms that regulate the generation of
healthy, new nerve cells in the brain."

"Our long-term goal is to develop new therapies whereby nerve cells can
be generated to replace those lost or damaged in disease or trauma," she
said.

The QBI research augments ongoing efforts to identify mechanisms that
can repair compromised brain tissue, and represents another milestone in
understanding the fundamental workings of the brain.

Significant advances in determining the molecular regulation of nerve
cell function and development will have a major impact on our
understanding of more complex areas such as behaviour, cognition,
ageing, neurological disease and mental illness.

Mental and neurological diseases account for about 45 per cent of the
burden of disease in Australia.