Can We Build a New Brain?
By Dr Jill Ammon-Wexler
Pioneer Brain/Mind Researcher
© 2006 All Rights Reserved

Many researchers today are looking at the possibility of using of human stem cells to repair of various organs in the human body. And more recently, this research has begun to look toward perhaps replacing missing and dying nerve cells in the brain and spinal cord.

Spinal Cord Repair
Researchers at Harvard Medical School and Massachusetts Institute of Technology recently used human stem cells to attempt to repair spinal cord injuries in rats. They bridged breaks in the cord with stem cells placed on scaffolds composed of a polymer similar to the dissolvable suture material used by surgeons to close wounds.

The implanted stem cells, which can develop into many other cell types, did manage to replace enough of the spinal cord cells needed for movement to allow the rats to regain some limited ability to walk

Brain Damage Repair
At Harvard medical School researchers implanted stem cells in mice with brain damage. According to neurologist Evan Snyder, the stem cells rescued the injured nerve cells of aged mice whose brains were compromised by the equivalent of Parkinson's disease and normal aging in humans.

"If the experiments had been done in humans, it is difficult to know if we would have gotten the same results," Snyder admits. "But I think there's a possibility that stem cells might help re-form some of the lost connections between cells sufficiently to promote restoration of function."

The researchers were surprised to see that stem cells not only replaced missing brain tissue, but also provided protection for cells disabled by age. "It's not unreasonable to think that in humans the early implantation of stem cells might forestall or even pre-empt degenerative diseases such as Parkinson's and Alzheimer's," Snyder says. "Perhaps, attacks by such diseases could be made less ferocious and mild enough for patients to adapt."

The researchers implanted a scaffold full of neural stem cells – stem cells that had already begun the process of developing into brain cells – near the damaged brain cells.

“We observed a rich complexity of 'cross talk' between the implanted cells and the injured brain," Snyder relates. "They exchanged signals and built nerve-fiber connections to each other. Each changed the fate of the other in such a way that lost brain tissue gave the appearance of being reconstituted. Blood vessels even grew and the new brain tissue became nourished by the animal's own brain."

The tissue replacement reportedly seemed spontaneous. The researchers did not add chemicals or genes to the stem cells or to the brain, and did not manipulate them in any way. The scaffolding degraded in about four-to-six weeks, and the mice had no seizures, no further brain damage, and went about normal behavior patterns.

"It's not unreasonable to think about doing this with humans someday," Snyder says. "However, before that happens we need to know immensely more about what the cells are doing. In the re-created parts of the brain, for example, are there undesirable as well as beneficial connections that could potentially make things worse?"

Can Senility be Slowed?
Another Snyder-led team reports on experiments to test whether neural stem cells might restore disabled cells in an aging brain.

Mice were treated with chemicals to trigger the slow loss of brain function typical of diseases such as Parkinson's and Alzheimer's. About 10 percent of the implanted cells spontaneously became new brain cells active in producing a chemical missing in people with afflictions like Parkinson's. But, surprisingly, most of the stem cells became “supporters” for endangered brain cells, preventing them from dying.

"We could see areas of the brain whose function would have been lost to disease but whose nerve cells were now alive and active," Snyder says.”We may be seeing a process even more powerful and effective than replacement - protection as a potent alternative or additional mechanism."

"We have obtained some compelling preliminary results," Snyder says. "If we are successful, we might consider beginning experiments with some ALS patients within five years. We might also consider trying stem cell therapy on Parkinson's patients within five years.”

Other Exciting Research
Dr John Yu, an expert in stem cell technology at the Cedars-Sinai Maxine Dunitz Neurosurgical Institute in Los Angeles , has shown that brain cells can be made in the laboratory from bone marrow cells.

"By making neural cells in a petri dish, we may provide bone marrow cell with the environment to be made into neurons more efficiently, thereby allowing us to treat diseases such as stroke, Alzheimer's and brain tumours.

Another team of scientists from the University of Wisconsin-Madison and the University of Bonn Medical Center have also shown that stem cells from early human embryos can, in a laboratory dish, become precursor brain cells.

Transplanted into the brains of baby mice, the precursor cells subsequently showed their ability to further differentiate into neurons and astrocytes – the types of cell that populate the different regions of the brain and spinal cord.

The Outlook?
At this point the research community does not agree about the potential for replacing neural elements lost to neurodegenerative diseases, stroke, or trauma using either embryonic or mature stem cells

But still – this early research is important for at least two reasons: One, it establishes the fact that both embryonic and adult stem cells can be guided down a developmental pathway to becoming brain cells. And two, it shows that they can be transplanted into animals to further develop into the more specific types of cells necessary for normal brain function.

But obviously, additional research is necessary to study the implications, and the possibility that such implants will lead to normal behavior and lasting positive effects.

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