Neurogenesis on video
Biologists have seen for the first time how new brain cells are born
Swiss and British biologists saw for the first time how new cells are formed inside the adult brain by learning to follow the movement of single stem cells in the memory center of mice, according to an article published in the journal Science (Pilz et al., Live imaging of neurogenesis in the adult mouse hippocampus).
"We hope that in the future we will learn how to use these stem cells to repair the brain and rid patients of problems such as Alzheimer's disease, Parkinson's, senile dementia or the most serious forms of depression," says Sebastian Jessberger from the University of Zurich (in a press release Stem cell divisions in the adult brain seen for the first time – VM).
Until the 1960s, it was believed that no new neurons appeared in adult mammals, and the death of nerve cells was compensated by the redistribution of functions among the remaining ones. In 1962, Joseph Altman from the USA in experiments on rats for the first time showed that the process of neurogenesis is going on in adult rodents, and 30 years later, in 1998, Peter Ericsson's group discovered that new cells are formed in the brains of adults.
Recent observations of the work of the human brain and other mammals show that some brain cells, for example, the olfactory center, are updated almost continuously, and in its other regions, including the hippocampus, the memory center, there are quite large colonies of stem cells that are presumably involved in neurogenesis.
According to Jessberger, many scientists doubt this, since no one has documented or seen the process of converting stem cells into full-fledged neurons before, which gave food for skeptics who believe that these cells do not participate in the renewal of nervous tissue, but only replace dead astrocytes, glia and other auxiliary brain cells.
To test these theories, scientists from Switzerland and Britain conducted a series of months-long observations of single stem cells living in the hippocampus, the memory center, in several experimental mice.
Such observations, according to Jessberger, were made possible thanks to two things – modification of mouse DNA, which automatically marked brain stem cells using glowing protein molecules, and a special system for analyzing images from a laser microscope, which removed almost all noise from images.
These observations were conducted as follows: biologists cut out a small "window" in the part of the skull under which the hippocampus was located, and then fired two infrared laser beams at the brain. These rays penetrated deep into the nervous tissue, interacted with protein molecules and caused them to glow at a different frequency, which makes it possible to separate the signal generated by stem cells from background noise.
Such observations helped scientists to trace the reproduction of stem cells, their spread through the hippocampus of mice and changes in their shape. After about two months of observations, some of these cells stopped multiplying and turned into full-fledged neurons that became part of the hippocampus and began to participate in the formation of new memories.
Scientists hope that the data they have collected and new experiments with brain stem cells will help us understand what principles and genes control their growth, migration and transformation into adult cells. This information, in turn, can become the basis for the first methods of treating Alzheimer's disease, epilepsy, strokes and other diseases accompanied by the loss of a large number of neurons.
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