Published on October 31, 2007 at 11:39 AM
Next, the scientists took a closer look at how the green-colored stem cells behaved in the mouse brain. They found that only about 4 percent of them turned into neurons, indicating the stem cells were not improving memory simply by replacing the dead brain cells. In the healthy mice, the stem cells migrated throughout the brain, but in the mice with neuronal loss, the cells congregated in the hippocampus, the area of the injury. Interestingly, mice that had been treated with stem cells had more neurons four months after the transplantation than mice that had not been treated.
“We know that very few of the cells are becoming neurons, so we think that the stem cells are instead enhancing the local brain microenvironment,” Blurton-Jones said. “We have evidence suggesting that the stem cells provide support to vulnerable and injured neurons, keeping them alive and functional by making beneficial proteins called neurotrophins.”
If supplemental neurotrophins are in fact at the root of memory enhancement, scientists could try to create a drug that enhances the release or production of these proteins. Scientists then could spend less time coaxing stem cells to turn into other types of cells, at least as it relates to memory research.
“Much of the focus in stem cell research has been how to turn them into different types of cells such as neurons, but maybe that is not always necessary,” Yamasaki said. “In this case, we did not have to make neurons to improve memory.”