How Do Brain Stem Cells Age? Their Damage Filter Breaks Down

Credit: Penn State

Could discovering how neural stem cells protect themselves from damage lead to treatment that helps combat aging? 

We now know that stem cells in the brain do in fact divide, and that this regenerative capacity begins to falter with age. The majority of our cells don't divide, and the bulk of division falls to stem cell niches dotted across our body. Stem cell populations do age, but they're more resistant than 'normal' cells are, and they produce higher levels of telomerase - enabling them to divide for years. 

How do brain stem cells remain free of damage?

Neural stem cells aren't perfectly protected from aging, but they're generally a hardier bunch. Scientists from the University of Zurich have now discovered that part of this aging resistance in neural stem cells is due to a 'diffusion barrier'. When they divide, these cells produce a barrier which filters out damaged proteins to one side, allowing the new cell to be damage-free. 

                                    Here you can see the asymmetric sorting of damaged proteins Credit: UZH

This diffusion barrier arises in the endoplasmic reticulum, where proteins are normally created and modified. It then prevents damage from travelling into the new daughter cell - confining it to the mother. This protects offspring from inheriting any damage accumulation.

This barrier weakens with age

This tactic remains effective for a while, but with age it starts to fray and allows some damage leak through into progeny. The overall stem cell population then begins to age as a whole, as damaged proteins are spread around. 

"This is an exciting new mechanism involved in stem cell division and aging. But as of now we are only just beginning to understand the molecular constituents and the true meaning of the barrier for stem cell division in the brain."

Does this mechanism happen in other stem cells? 

The heavy burden of division requires that stem cells take extra precautions, and analysing stem cells from other parts of the body could reveal that they also use similar protection. Rejuvenating this diffusion barrier could refresh a stem cell population, once again preventing damage from accumulating to toxic levels. 

Read more at Neuroscientist News