Stem cells located in the brain are able to produce neurons and are therefore seen as a hope for treatment. Now, a team of researchers from the Helmholtz Zentrum München and Ludwig-Maximilians-Universität München (LMU) has now discovered that the self-renewal rate of the stem cells is however limited, explaining why their number drops over the course of a lifetime.
This work lays the basis for further investigation of the signalling pathways that maintain the stem cells.
The generation of neurons, known as neurogenesis, in humans is mainly limited to development. In adults it takes place in only a few regions of the brain. These regions contain neuron stem cells that generate neurons in a process with various intermediary stages.
Stem Cell Renewal is Limited
Until now it was thought that maintaining the stem cell pool was based on the self-renewal of individual stem cells.
The team of scientists headed by Dr. Jovica Ninkovic and Professor Dr. Magdalena Götz were able to refute this. Both the self-renewal rate and the diversity of neurons formed from the stem cells are limited, and the number of stem cells decreases with age.
According to first author Dr. Filippo Calzolari:
“Our findings explain why neurogenesis declines in later years, as there are fewer and fewer neural stem cells. At the same time, we gained new knowledge on basic mechanisms of neurogenesis that until now were not understood."
Approaches to new therapies for brain diseases, such as stroke or dementia, for example, particularly concentrate on replacing lost neurons by stimulating the generation of new cells from stem cells.
Götz, Director of the Institute for Stem Cell Research at the Helmholtz Zentrum München and Chair of the Institute of Physiological Genomics at LMU, notes:
“In light of the fact that the stem cell supply is limited, we must now also look for ways to promote the self-renewal rate of the stem cells themselves and maintain the supply for a longer time."
Filippo Calzolari, Julia Michel, Emily Violette Baumgart, Fabian Theis, Magdalena Götz, Jovica Ninkovic.
Fast clonal expansion and limited neural stem cell self-renewal in the adult subependymal zone.
Nature Neuroscience, 2015; DOI: 10.1038/nn.3963