Neuron News

Still, only in California.

Researchers from the Salk Institute for Biological Studies are bringing the control of brain cell development from in vitro to in vivo.

Stems cells — in a petri dish — are currently being routinely genetically converted into specific types of cells by introducing certain growth factors. Here, an injected retrovirus into the brain of a mouse to deliver a specific gene into adult stems is used to control stem cell development in vivo. It was previously shown that particular gene, called the Ascl1, converted neuronal stems cells into oligodendrocytes, the critical neuron network supportive cell that forms fatty insulation layers around axons to speed up the propagation of electrical signals.

The extremely exciting prospect of this discovery is the potential ability to increase the production of certain types of brain cells in patients where they are deficient. In particular, multiple sclerosis (more) is caused by the immune system killing off oligodendrocytes, so that neuron communication throughout the body is severely degraded. But, if replacement cells can be controlled, then the effects of the disease might be minimized.

“Adult Stem Cells Reprogrammed In Their Natural Environment” :: ScienceDaily :: July 1, 2008 :: [ READ ]

“Directed differentiation of hippocampal stem/progenitor cells in the adult brain” :: Nature Neuroscience :: Published online: 29 June 2008 [ READ ABSTRACT ]

Learn more about the researchers involved in the project:

• Fred H. Gage, Ph.D.,Laboratory for Genetics and the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Diseases.
• Sebastian Jessberger, M.D., assistant professor at the Institute of Cell Biology at the Swiss Federal Institute of Technology in Zurich

Only in California. No, really.

With previous failures of converting embryonic stems cells only into supporting glial cells instead of general neurons, Stuart Lipton’s research group at the Burnham Institute for Medical Research in La Jolla, CA recently discovered how to convert mice stem cells into neurons. These cells were then transplanted into a mouse brain and they successfullyconnected and functioned within the existing neuron network.

The work is funded from a four-year, $75 million grant (pdf) from the California Institute for Regenerative Medicine.

Understanding how stems cells transform into any of the hundreds of types of cells in the human body is still a challenge, but Lipton’s team is focusing on the protein MEFC2 and how it links to the genes in the stem cell to tell it to turn into a neuron.

Although we’re still far far away from doing clinical trials to throw these neurons into human brains and “see what happens”, this research is critical just for further fundamental understanding of neuron cell development, growth, and function. How neurons grow and, in particular, how they interconnect with one another is a major factor in the overall resulting function of the brain. So, watching how a neuron is “born” (and understanding it so well that we can guide the process) and then interconnect will provide more insight into the function of a larger neuron network.

The research is published in The Journal of Neuroscience June 25, 2008 Issue [Read the abstract]

“Repairing damage to brain may be nearer” :: SignOnSanDiego.com :: June 25, 2008 :: [READ]

“Scientists repair brain using GM embryo cells” :: Telegraph.uk.co :: June 24, 2008 :: [READ]

Sophisticated brain imaging has never been able to directly image the activity of neurons (namely, fMRI and PET scans). Instead, the realization that active neurons caused increased blood flow to occur in the vicinity allowed researchers to develop the techniques that could more easily monitor the flow activity. As blood flow increased in a region of the brain, then the neurons in the area must also be screaming with increased activity.

But, neurons do not have a direct connection to blood vessels and blood flow in the brain.

The correlation between active neurons and the resulting blood flow changes has just now been directly realized by a team at MIT who used two-photon excitation microscopydeveloped by the lab of Watt Webb at Cornell University. They found that another very common cell that composes about 1/2 of all brain cells, called an astrocyte which directly affects blood flow and is electrically quite unlike the neuron, instead reacts to non-electrical stimuli from surrounding cells.

This is a rather significant discovery and further research will lead to a deeper understanding of how our complex neural networks function and how they stay alive in our heads.

…..

MIT unlocks mystery behind brain imaging :: PhysOrg.com June 19, 2008
[ read article ]

“Tuned Responses of Astrocytes and Their Influence on Hemodynamic Signals in the Visual Cortex”
James Schummers, Hongbo Yu, and Mriganka Sur
Science 20 June 2008: 1638-1643.
[ read abstract ]

Movies of visually evoked responses of neurons and astrocytes [ view ]

About Mriganka Sur at MIT

Picower Institute for Learning and Memory at Massachusetts Institute of Technology
[ visit ]