Dr. Tony Wyss-Coray

For the first time, we could take an old brain and we could give factors from a young organism and ask, is that going to change the age of the brain?

And that's indeed what it did.

So we saw that there are stem cells in the brain of these mice that they got reactivated.

There was less inflammation, more activity that we can measure in the brain.

And then most importantly, we actually saw that their memory function improved.

Yeah, so we were actually not the first ones, but we collaborated with the person who in more modern times used this model again.

It's called parabiosis, where you have a surgical model where an old and a young mouse are paired, and their circulation allows for exchange of blood from the young to the old animal.

And my colleague who recruited me actually to Stanford, Tom Randall, used this model to study aging of stem cells in the muscle.

So he discovered that with old age, the muscle sort of deteriorates and doesn't regenerate.

And when he used the mouse, an old mouse, and paired it with a young mouse, and now this young circulation infusing, if you will, the old muscle, he regenerated that muscle.

And it looked almost like a young muscle.

And at the same time, he also observed effects in other tissues, including in the brain.

And that's when we started to collaborate and explored what could the effects of the brain, of young factors on the brain be.

And in part, we were also intrigued by that because we had separate studies in humans where we tried to find blood signatures of Alzheimer's disease.

And what we noticed is that we could see proteins that were correlated or even predictive of Alzheimer's disease

But the most striking difference was between younger and older people.

So we saw that the concentration of their proteins was very different in young people and old people.

And when you see something like that in biology, you always ask, is this cause or effect?

So do the proteins in our body change because they respond to the aging of the brain, for example, or do they actually drive the aging of the brain?

And here Tom had this model that allowed him to ask that question or that allowed us together to ask that question.