The Future of Treatment for Brain Injuries – New Brain Tissue From Special Cells
Research on synthesis and regeneration of brain tissue is advancing rapidly. Here are four recent news reports on current research (1, 2, 3, 4) that predict that the near future of medicine will seem like science fiction.
Why is there so much excitement? Neuroscientists have found that the answer to regenerating brain tissue lies in the enormous potential of “stem cells.” Each of your organs, including the brain, has a reservoir of special cells (“stem cells”) that can regenerate the tissue of that organ. Since all cells of the body have exactly the same DNA (or blueprint for the cell), the cells of different tissues are formed by activating different subsets of the DNA. (Think of the cells of different tissues as running different programs.) The reports discuss ways to make neural stem cells, how stem cells reproduce, and how implanting neural stem cells into the brain is already controlling or curing diseases of the brains of animals. When neural stem cells are implanted into the brain (a relatively simple surgical procedure), they become whichever cells are needed to replace old, missing, or damaged brain cells. In this way, the brain essentially heals itself. The additional (i.e., implanted) stem cells help a natural process. Some of the experiments have been done in mice (see my previous explanation of why the mouse is a good first model for humans), but soon the experiments will be done in humans. The current research predicts that repair of brain injury is not only possible, but is also likely to be done in the near future.
In paper #1, neuroscientists from the Medical College of Georgia at Georgia Regents University identified a molecule of neural stem cells (ganglioside GD3). GD3 is crucial for the ability of neural stem cells to reproduce and maintain a pool of healthy stem cells that can be used to replace old or damaged cells in the brain. Normally organ formation means that the cells are finished reproducing. They’re at a kind of “dead end” for cells. The ability to continuously reproduce is one of the amazing properties of stem cells. They’re part of the organ, yet they can reproduce and they can become any cell, so there is always a reservoir of stem cells ready to become any needed cell. In a major advance, the research team at the Medical College of Georgia showed in mice that the pool of neural stem cells in the part of the brain they examined was greatly reduced when the cells lacked ganglioside GD3, and the pool was restored when GD3 was present. The scientists want to figure out how to keep neural stem cells making abundant GD3. That way, there will always be plenty of neural stem cells to replace brain cells as needed.
Paper #2 describes groundbreaking research by neuroscientists at the Whitehead Institute of MIT. They were able to take the cells of fully developed tissue (cells that can no longer form new tissue and don’t reproduce) and turn them into neural stem cells that can reproduce and form new brain tissue. There are two exciting aspects of this research. First, the team was able to form “pluripotent” stem cells (i.e., cells able to form new tissue of any kind) directly from “mature” cells (i.e., cells of any fully developed organ) without requiring them to go through an undeveloped state normally seen only in the cells of early embryos before their development into our various tissues. Second, the necessary factors were introduced and turned on by a chemical. Once neural stem cells were formed, the chemical was removed, and the cells retained the properties of neural stem cells. This was the first time such a feat had been accomplished. It guarantees an abundance of neural stem cells that will be needed for transplantation therapy.
Paper #3 describes the research done at Lund University in Sweden. Parkinson’s Disease is a disease of the brain that causes movement problems. Millions of people worldwide have this affliction. It’s known that the Parkinson’s brain is deficient in the production of a chemical (dopamine) that is needed for proper movement. Neuroscientists derived dopamine-producing neurons from human stem cells. The dopamine-producing neurons were implanted into the brains of rats with a Parkinson’s-like disease. The synthetic neurons were specifically implanted into the region of the rat brain that controls movement. The implanted dopamine-producing neurons colonized the brain and led to normal levels of dopamine in the brain. As a result, the diseased rats had normal motor function.
Sixty-five million people worldwide are afflicted with epileptic seizures. About 1/3 are not helped by any medication. One highly regarded hypothesis is that the cause of seizures is due to a low number of seizure-inhibiting neurons (interneurons). Paper #4 tells of the research of neuroscientists at McLean Hospital in Massachusetts and the Harvard Stem Cell Institute. They implanted seizure-inhibiting neurons into the brains of mice bred to have epileptic-like seizures. The seizure-inhibiting neurons were human cells derived from human stem cells. Fifty percent of the mice with the implanted cells no longer had seizures. The other 50% had a severely reduced number of seizures. The scientists showed that the human neurons integrated into the mouse brains and dampened the signals from the highly excited mouse neurons that lead to epileptic seizures. The next step is to find a way to purify the interneurons, so only seizure-inhibiting neurons would be implanted.
(Clip Art compliments of Bing.)