You also did fascinating research, you studied transplantation and blood transfusions as models to assess rejuvenation and aging. So how does it work? Yeah, well, I mean, we talk about stem cell therapy and gene therapy. People have been doing blood transfusions for a long time. 

It's really about the implanting hematopoietic stem cells, rejuvenating the hematopoietic system. 

That's been going on for a long time. So it's a good model to really study aging. So we got the idea. We wrote a review on this, we got the idea to think about it and work with Dr. James Kirkland at Mayo Clinic. And Stephane Julian is in our group, just to put together some concepts about what this means. And the challenge is, it is very hard to do transplants from older individuals. So once you get beyond a certain age, you can't be a donor for transplantation.  Dr. Brian Kennedy. Dr. Anton Titov, MD. 

This could be organ transplantation, not just blood transfusions. 

So we want to understand what is it that's changing about aging. Some of the questions that you might consider, for instance, when you put a tissue from an older person into a younger person, you know, that may not necessarily be a good thing. It could have systemic effects on the younger person that the the older tissues has been used to signaling that's adapted over time.  Dr. Brian Kennedy. Dr. Anton Titov, MD. And so we're thinking about age differences with transplantation and trying to figure out ways to rejuvenate older transplant tissues, so that it can be used. Because there is always a shortage of these materials for transplant. we can figure out ways to make even in vitro, take a tissue out, take blood out, take an organ out, make it younger, in vitro, and then put it in person. 

That could be a real achievement. It would save a lot of lives. So I think it's a good, there's not a lot that we know yet, but it's a good area to look at because it could have a really big impact. And it allows us to study host-recipient responses, and that'll be relevant as we think about stem cell transplantation and some of the other things that are coming down the road as well.  Dr. Brian Kennedy. Dr. Anton Titov, MD. 

What about blood transfusions? Is there actual data in humans, so maybe in experimental tissues, in vitro data that transfusing younger blood somehow rejuvenates the tissues of the older recipient? 

Well, I think there's very good evidence that there are factors in young blood that help protect adult stem cells in various tissues in the recipient. There are also factors in old blood that are driving, promoting inflammation. So they can have an adverse effect on a young recipient. I don't think that periodic blood transfusions is going to have much of an effect, because I just don't think you can, unless you're doing this every day, I don't think that you're likely to get enough of the factors to have a huge effect.  Dr. Brian Kennedy. Dr. Anton Titov, MD. 

That's just my speculation. But if we can identify what those factors are and deliver them directly, those protective factors, especially, then that's a huge opportunity. Because those are things that circulate and get to a whole range of different tissues. And if they can preserve your stem cells in those various tissues, it's likely to have a big impact on aging.  Dr. Brian Kennedy. Dr. Anton Titov, MD. So I really think the companies that are trying to tease out those specific factors are really exciting to watch.