Brain Development

Converting Adult Stems Cells in the Brain

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:

Embryonic Stem Cell Coaxed into Functioning Neuron

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]

Blood and the Brain

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 ]

Neurons Movies at a Billion Billion Frames Per Second

One way to figure out how your brain works … still an enormous realm of this universe that remains to be understood … is quite simple in principle: watch brain cells grow and connect and just do their thing, and try to learn something from it.

Of course, mounting a video camera into your skull isn’t a pleasant idea. So, there are techniques that allow brain cells, called neurons, to be grown in other environments like glass dishes or silicon wafers. Coaxing the cells to actually survive in this foreign way is something of a black art, but when done successfully scientists have a great way to directly watch neurons do their thing.

An astounding recent advancement in imaging technology has pushed these movie makers to the next level with incredibly high effective frame rates. Just like a strobe light at a party make the dance floor look like a slow flashing of images before your hazy eyes, advanced, high-speed lasers can be pulsed very quickly to illuminate a field of view.

Jeff Lichtman, at the Washington University School of Medicine in St. Louis, MO, has taken advantage of this new technology to watch neuron development with such a high resolution. Scientists in other fields, such as chemistry, biology, and physics are also exploring important applications.

Read more about this exciting technology…

Read the article from Small Times ]

What’s Connecting the Neurons?

Neurons communicate via electrical pulses that shimmy down long branches called axons and dendrites. It is the emergent communication from these vast networks that somehow bring about complicated, high-order function in our body’s nervous system.

But how are these branches formed in the first place? How do the axons and dendrites know where to go so that the “correct” function results? This is an enormous question and many researches are experimenting with how neuron networks actually develop (this will later be highlighted in our upcoming academic research topical category).

Understanding this developmental process is critical to fabricating functioning neuron devices in silicon. If the neurons are to grow and live happily on a computer chip, then the environment on that chip must be just right for the finicky brain cell.

Also, if the route to fabricating the device is to have baby neurons grow their branching networks on their own (which is a typical method used by researchers), and if we want the device to result in a specific function, then it might be very important to know how to guide the growing branches to the appropriate neighboring neuron (although this will be an important point of debate).

John Thomas, a professor at the Salk Institute, has recently reported on an important discovery on a certain protein interaction occurring in the neuron’s environment that signals to a growing branch to “go the other way!” Read more about this work, and consider how it could be a vital bit of biology that will aid in controlling how neurons may develop and live in a silicon world.

Read the article from ScienceDaily News ]

Channeling Nerve Growth

Don’t loose your nerves. You might not get them back.

It’s an well know “fact” that once a brain cell dies, it won’t grow back. Scientists are continuing to discover that this is not always the case, as has been previously discussed here in Neuron News. More developments from a United States government lab is continuing to show that damaged nerve cells might be coaxed into rejuvenation.

Surya Mallapragada, an Ames Laboratory associate in Materials Chemistry, has developed micro channels in degradable polymers that can guide growing axons to fill in gaps of important nervous system wiring caused by some sort of damage.

There has been some success with nerves in rats, but they are still learning about how this approach will work in the central nervous system comprised of the brain, spinal cord and optic nerve.

Read the article from the Ames Laboratory ]

Last updated October 26, 2021