We have been told that brains do not regenerate, and don’t even make new cells after adulthood in mammals.
Apparently both of these long held “truths” are wrong…?
In a 2024 paper, Yamanaka Factors were used in a typical on-off manner (so called partially reprogramming) to rejuvenate cells in the brain of aged mice. While this is an often repeated experiment to show the reversal of age-related pathologies, the process can also make cells forget their epigenetically encoded fate. But in this experiment, the process did not dedifferentiate the cells, as one might fear. That is, unlike many mitotic cells tested in the past, these postmitotic brain cells did not forget their cellular fate - they stayed brain cells.[1]
And in a 2025 paper, the idea that old brains can not generate new neurons has also been challenged. [2]
The take-away? Brains can indeed regenerate. And it might be safer than rejuvenation of other organs, due to being mostly post-mitotic. And we are just beginning to understand this.
Note: For those who are noted that this might be a help for Alzheimer’s and other brain diseases of old age, there is some research beginning on that angle. [3]
So interesting!