Wednesday, May 19, 2010

Brain Cell Regeneration Using Reprogrammed Astroglia

The brain consists of two major cell types: neurons, which transmit information, and glial cells, which support and protect neurons. Interestingly, evidence suggests that some glial cells, including astroglia, can be directly converted into neurons by specific proteins, a transformation that may aid in the functional repair of damaged brain tissue. However, in order for the repaired brain areas to function properly, it is important that astroglia be directed into appropriate neuronal subclasses. In this study, we show that non-neurogenic astroglia from the cerebral cortex can be reprogrammed in vitro using just a single transcription factor to yield fully functional excitatory or inhibitory neurons. We achieved this result through forced expression of the same transcription factors that instruct the genesis of these distinct neuronal subtypes during embryonic forebrain development. Moreover we demonstrate that reactive astroglia isolated from the adult cortex after local injury can be reprogrammed into synapse-forming excitatory or inhibitory neurons following a similar strategy. Our findings provide evidence that endogenous glial cells may prove a promising strategy for replacing neurons that have degenerated due to trauma or disease. _PLOS
Scientists from the Helmholtz Center and Ludwig-Maximilians University in Munich, have used a virus to reprogram brain helper cells -- astroglia -- into actual neurons. They were able to convert astroglia from early post-natal and adult mouse brains into either excitatory or inhibitory neurons, depending upon the transcription factors which were introduced.
The study adds to growing evidence that certain cell types can be transformed directly into other cell types without first being converted into stem cells. Researchers have previously transformed skin cells into neurons, and one type of pancreatic cell into another. Marius Wernig, a coauthor of the skin cell study and a stem cell biologist at Stanford University, says there's a growing awareness that it may not be necessary to erase a cell's existing identity before giving it a new one.

...this latest study "means that these astroglial cells could be converted in the brain" without the need for a transplant. Berninger says that one of the next challenges is to determine whether these reprogrammed neurons can survive and function in a living brain.

Fortunately, the brain seems to have a ready source of astroglia. When the brain is injured, these cells proliferate, similar to the way the skin repairs itself after a wound. The researchers found they could also derive neurons from injury-induced astroglia taken from the brains of adult mice. _TechnologyReview
we first aimed at a more potent neuronal reprogramming by inducing higher and more persistent expression of neurogenic fate determinants in astroglial cells. This allowed us not only to obtain fully functional neurons that also establish synapses from astroglial cells in vitro but also to demonstrate that distinct neurogenic transcription factors, such as on the one hand Neurog2 and on the other Dlx2 alone or in combination with Mash1, can indeed instruct the selective generation of different neuronal subtypes, such as glutamatergic and GABAergic neurons, respectively. Moreover, we found that the reprogramming efficiency of postnatal cortical astroglia towards GABAergic neurons by Dlx2 could be enhanced by first expanding the astroglial cells under neurosphere conditions prior to forced expression of Dlx2. Given that following brain injury reactive astroglia from the adult cerebral cortex de-differentiate, resume proliferation, and can give rise to self-renewing neurospheres in vitro [16], we finally show that neuronal reprogramming and subtype specification are not restricted to postnatal stages but can also be achieved from adult cortical astroglia responding to injury. _PLOS
The findings are a striking reminder that nature offers us many more possibilities than we can presently conceive of. But perhaps we will grow in our conceptual capacity, over time.

The possibility of regenerating brain tissue in situ -- without the need for inserting new cells from elsewhere -- offers new hope for brain trauma, infection, infarct, atrophy, and senility. But it also offers a distinctly new possibility which most observors are not quite ready to think about -- much less discuss.

I am referring to the possibility of growing entirely new neural networks in situ, from astroglia. The possibility that humans can induce their own brains to create entirely new brain centers and pathways, using more advanced forms of such techniques, should not be overlooked.

There is currently a race between biological methods of repairing and enhancing human organs, and technological methods of compensating for organ damage or loss -- the cyborg approach. A cyborg may utilise nano-technological enhancement, and thus manifest no outward sign of distinction from standard normal humans. The same would be true for most biological enhancements or remediation.

This lack of overt differences between ordinary persons and enhanced persons is quite important to most military uses of enhanced individuals, and to virtually all covert uses by government and other organisations.

But these tools of transformation are not likely to remain limited to deep pocketed groups and individuals. Garage biohackers are not as uncommon as you might think, and are performing a similar service for bio-hacking as the garage techno-hackers performed for microcomputers in the early days. And it is also extremely likely that persons involved in expensive and large scale research into bio-transformation technologies will set off on their own as they discover the ability to profit from their technical knowledge and skills.

Cross-posted at Al Fin

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Tuesday, May 18, 2010

Tricks of Epigenetic Memory

It is common knowledge that a person's memory tends to get a bit foggy as he ages. A young person's memory tends to be crisper and quicker than that of a person in senescence. But it is possible that there is a means within our grasp by which we can turn back the clock in the aging brain -- back to a time of quicker and clearer recall, and a stronger grasp of new knowledge.
A new study published in Science sheds some light on how “memory disturbances” in an aging mouse brain are associated with altered “hippocampal chromatin plasticity” — the combination of DNA, histones, and other proteins that make up the chromosomes associated with the hippocampus. Specifically, the study describes an acetyl genetic switch that produces memory impairment in aging 16-month-old mice. Because the acetyl wasn’t present in young 3-month-old mice, the study concludes that it acts as a switch for a cluster of learning and memory genes.

...Dr. Fischer’s research shows that when young mice are learning, an acetyl group binds to a particular point on the histone protein. The cluster of learning and memory genes on the surrounding DNA ends up close to the acetyl group. This acetyl group was missing in the older mice that had been given the same tasks. By injecting an enzyme known to encourage acetyl groups to bind to any kind of histone molecule, Fischer’s team flipped the acetyl genetic switch to the “on” position in the older mice and their learning and memory performance became similar to that of 3-month-old mice. _hplus
Dr Fischer, of the European Neuroscience Institute in Goettingen, Germany, pinpointed a tiny protein called H4K12 that controls genes key to memory and learning in the mouse brain.

...In an accompanying article, Professor David Sweatt , a U.S. neurobiologist, said that turning on H4K12 was likely to help with both Alzheimer's and age-related memory loss.
He said the German results 'provide important proof of principle that this might be a viable approach to therapeutic interventions in ageing'.
'These studies will hopefully lead to more effective prevention strategies to improve quality of life in the aged, as well as contribute to a better understanding of memory function,' he added.
The treatment of other brain conditions, such as schizophrenia and Parkinson's disease, could be improved by finding other switches that act in a similar way.
Dr Marie Janson, of the Alzheimer's Research Trust, said: 'Although in mice, this research gives us clues about how memories are formed and function in the brain.
'We now need to find out if the same processes happen in the human brain.
'This understanding is vital if we are to develop ways to protect the ageing brain from cognitive decline.
'Alzheimer's and other dementias are complex, with many things happening in the brain, so it's likely that we'll need several drugs to treat them effectively._DailyMail

Brain function is inextricably tied to genetic function. The relationship is certainly of a circular nature. If we are to learn to live long and fulfilling lives, we will need to undertand ourselves better, at a much deeper level than we once thought possible.

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Saturday, May 15, 2010

Stem Cells to Restore Your Hearing, Your Heart, Your Teeth

Stanford University researchers have developed a way to grow replacement "hair cells" for the inner ear, in mice. The hair cells are responsible for hearing, and the cumulative loss of hair cells over a lifetime result in permanent hearing loss. If humans could learn to regenerate the hair cells in the inner ear, hearing loss could be reversed without the need for electronic devices such as cochlear implants or hearing aids. Source via Brian Wang

Geron scientists have demonstrated the safety of GRNCM1 (cardiomyocites or stem cells) for replacing damaged heart tissue. This treatment, once approved, is likely to be used to treat chronic heart failure -- a significant cause of death and disability worldwide.
Source 1 (via Brian Wang), Source 2

Columbia University researchers are developing a method for growing replacement teeth "in place", inside the actual socket of the lost tooth. The method utilises stem cells to re-grow the tooth along with accompanying soft tissue support. This approach will do away with the need to use hardware implants, or to grow teeth outside the body in culture media.
Source via Brian Wang

The re-growth of body organs in place -- using the original tissue matrix as a scaffolding -- is a safer approach than re-growing organs outside the body, then surgically implanting them. Both approaches will probably become common, but in circumstances where in situ stem cell replacement is effective, most persons will likely opt for that approach.


Friday, May 07, 2010

Stem Cells from Endometrial Tissue Reverse Parkinson's?

Scientists at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), have injected endometrial stem cells into the brains of mice with an induced form of Parkinson's Disease. The injected stem cells began producing dopamine -- the neurotransmitter that is deficient in Parkinson's.
The finding raises the possibility that women with Parkinson's disease could serve as their own stem cell donors. Similarly, because endometrial stem cells are readily available and easy to collect, banks of endometrial stem cells could be stored for men and women with Parkinson's disease.

"These early results are encouraging," said Alan E. Guttmacher, M.D., acting director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH Institute that funded the study. "Endometrial stem cells are widely available, easy to access and appear to take on the characteristics of nervous system tissue readily."

Parkinson's disease results from a loss of brain cells that produce the chemical messenger dopamine, which aids the transmission of brain signals that coordinate movement. This is the first time that researchers have successfully transplanted stem cells derived from the endometrium, or the lining of the uterus, into another kind of tissue (the brain) and shown that these cells can develop into cells with the properties of that tissue. The findings appear online in the Journal of Cellular and Molecular Medicine. _SD

An optimal form of brain regeneration would likely combine the use of exogenous growth factors and stem cells, along with the stimulation of endogenous stem cell and growth factor production. There is a lot to be learned about how the brain works normally, and what goes wrong in degenerative conditions, trauma, ischemia, and aging.

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Thursday, May 06, 2010

Even an Old Hippocampus Continues Making New Neurons

The brain maintains neuronal stem cells throughout life, according to scientists at Max Planck Institute who studied the phenomenon of lifelong neurogenesis in mouse brains.
The precise factors that influence the reactivation of dormant stem cells are not yet clear. The cells can, however, be stimulated to divide again. The scientists observed more newborn hippocampal neurons in physically active mice than in their inactive counterparts. "Consequently, running promotes the formation of new neurons," says Verdon Taylor. Pathological brain activity, for example that which occurs during epileptic seizures, also triggers the division of the neuronal stem cells.

...The presence of neurons that are formed over the course of life has also been demonstrated in the human hippocamus. Therefore, scientists suspect that different types of active and inactive stem cells also arise in the human brain. It is possible that inactive stem cells in humans can also be activated in a similar way to inactive stem cells in mice. _Physorg
If increased physical activity can stimulate new nerve cell generation, a strong argument could be made for encouraging a more active physical regimen throughout a person's lifetime. Such a finding argues for the importance of physical rehabilitation as a treatment for neurodegenerative diseases, and after a stroke or other necrotising brain injury.

Making new neurons is not the same thing as being sure the neurons are healthy and optimally functioning. Scientists are learning more about the micro-differences between healthy neurons and those that are not so healthy. The delicate micro-structures called dentritic trees or arbours, are important to good communication within the neuronal networks. And the health of these dendritic trees depends upon optimal quantities of certain cell proteins -- which are under genetic control.

And that genetic control is of course under the control of transcription factors which are influenced by a number of other things -- some under genetic control, and some influenced by the evironment.

Finding more ways that a person can optimise the generation of healthy new neurons -- and to maintain the health of those in existence -- will be worth all the time it will take.


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