is continues to occur throughout life but dramatically decreases with increasing age. This decrease is mostly related to a decline in proliferative activity as a result of an impoverishment of the microenvironment of the aged brain, including a reduction in trophic factors and increased inflammation.

Results

We determined that human umbilical cord blood mononuclear cells (UCBMC) given peripherally, by an intravenous injection, could rejuvenate the proliferative activity of the aged neural stem/progenitor cells. This increase in proliferation lasted for at least 15 days after the delivery of the UCBMC. Along with the increase in proliferation following UCBMC treatment, an increase in neurogenesis was also found in the aged animals. The increase in neurogenesis as a result of UCBMC treatment seemed to be due to a decrease in inflammation, as a decrease in the number of activated microglia was found and this decrease correlated with the increase in neurogenesis.

Conclusion

The results demonstrate that a single intravenous injection of UCBMC in aged rats can significantly improve the microenvironment of the aged hippocampus and rejuvenate the aged neural stem/progenitor cells. Our results raise the possibility of a peripherally administered cell therapy as an effective approach to improve the microenvironment of the aged brain

With a little help, our brains can be trained to heal themselves. After a traumatic brain injury, some of your brain cells go into reset mode, reverting to a stem cell-like state. Using these "reset cells," a group of German researchers were able to coax the brains of injured mice to regrow neurons to replace damaged tissue (the images above are micrographs of the cells regrowing over time).

Though their methods are far from perfect, this breakthrough could help replace dead or damaged brain cells in people suffering from Alzheimer's as well as any type of injury. It's just a matter of extending the brain's natural self-healing powers.

According to an article in the Proceedings of the National Academies of Science today:

Magdalena Götz and colleagues found that cells called astrocytes expand and multiply after brain injury. The authors induced brain injury in mice, then observed as quiescent astrocytes activated themselves and became reactive, causing reactive gliosis, which is the universal cellular reaction to brain injury. The researchers found that the reactive astrocytes remained astrocytes in the cerebral cortex, whereas in a cell culture they could be coaxed to switch to different brain cell types, including neurons. These results identify astrocytes as a source of stem cells in the injury site and show that other types of brain cells do not have this potential. The authors conclude that the cells provide a promising cell type to initiate repair in humans after brain injury.