A new technique of preparing neural stem cell grafts may be able to rejuvenate the aging brain
A team of scientists have tested a preparation of neural stem cells in mice, implanting these cells into the aging hippocampus - a region of the brain involved with memory maintenance and creation. The hippocampus is especially vulnerable to age-related decline, shrinking in volume and function and displaying signs of inflammation and oxidative stress. Finding ways to stimulate neurogenesis (the creation of new neurons) and regenerating this region is therefore a key therapeutic target when it comes to protecting and even restoring memory.
"We chose the hippocampus because it's so important in learning, memory and mood function. We're very excited to see that the aged hippocampus can accept grafted neural stem cells as superbly as the young hippocampus does and this has implications for treating age-related neurodegenerative disorders. It's interesting that even neural stem cell niches can be formed in the aged hippocampus"
When these cells were implanted, they proved able to sustain themselves for a time in older animals, dividing and producing a similar number of new cells in both young and old animals. A few cells were also able to establish a new 'niche', in which new neurons were continuously produced. 3 months after implantation these neurons were still being produced.
"What was really exciting is that in both old and young brains, a small percentage of the grafted cells retained their 'stemness' feature and continuously produced new neurons. They are still producing new neurons at least three months after implantation, and these neurons are capable of migrating to different parts of the brain"
An improvement on past techniques
This donor source of stem cells has advantages of previous efforts which have involved fetal neurons. Neural stem cells are better at tolerating low oxygen levels and grafting trauma than already differentiated cells. In order to produce this graft, the researchers obtained cells from the sub-ventricular region of the brain, which holds a population of neural stem cells which persist throughout life. These cells have shown promise in mitigating stroke damage and replenishing lost neurons as well.
While for this research, a sample of neural stem cells was taken from the animals in the study, in the future these cells could be obtained from induced pluripotent stem cells for example, produced from a donor's skin cells.
"Next, we want to test what impact, if any, the implanted cells have on behavior and determine if implanting neural stem cells can actually reverse age-related learning and memory deficits. That's an area that we'd like to study in the future. I'm always interested in ways to rejuvenate the aged brain to promote successful aging, which we see when elderly persons exhibit normal cognitive function and the ability to make memories"
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