 Heterocronic parabiosis is a well-known aging intervention in mouse studies, and it works. You stitch two mice together so they share blood, and like Highlander, the old mouse absorbs the life force of the younger mouse. It just happens to be one of the more, shall we say, unrealistic procedures for humans. I don't see a doctor prescribing you stitch a toddler to your back for a few months to smooth out those wrinkles. Plus that can't be good for your back. Welcome to Lifespan News, I'm Emmett Short. Today we're talking about the most problematic, yet perhaps one of the most promising cures for aging, young blood. New research published in Nature Aging has shown that factors in young blood can improve brain health this time. Studies also showed that factors in old blood, you guessed it, caused harm to young brains. That makes sense. I don't think anyone's surprised that old blood is not the cure for aging. In this study they joined some three to four month old mice with some 20 to 22 month old mice. Mice of the same age were joined as well for a control group. The goal of this research was to analyze what effects heterocronic parabiosis has on multiple types of brain cells. See other studies focus mainly on proteins or the proteome, but these researchers were looking at exosomes, lipids, and a bunch of other non-protein factors. Over 100,000 cells that consisted of 75 different types were analyzed. Similar to previous papers they found multiple beneficial and rejuvenative, rejuvenative, yeah rejuvenative effects on gene expression. The researchers found that 700 of the over 20,000 genes they analyzed had their expression changed. 442 gene expressions were changed in old animals by youthful blood. 155 gene expressions were changed in young animals by old blood. We don't know all the effects and impacts of these gene expressions and alterations, but based on what the study measured the overall impact seems to be positive. So in my view that means young blood, good old blood, bad. Some of the benefits were better gene expression, less senescence, improved intercellular communication that encouraged neurogenesis, the formation of new brain cells. One of the main things this paper highlights is the strong youth promoting effects of parabiosis on the blood brain barriers endothelial cells. Endothelial cells have such direct and constant contact with blood, which may be why youthful blood has such a strong effect on those cells specifically. While not all the effects are known including potential negative ones, here were three main takeaways from this paper. Youthful blood has a positive effect on blood vessels. Parabiosis could make the body process nutrients better, break down proteins more efficiently, and reduce age-related cell death. There may be new ways to slow brain aging and promote regeneration without targeting specific diseases or factors in the blood. I'd like to point out again all these benefits are to the older mouse. I'm sure the younger mouse benefited from wisdom passed down from the older mouse during their time as conjoined twins, but medical benefits were not apparent. But what if it's possible to use a combination of youthful systemic factors along with blood scrubbing known as plasmaparesis to restore vasculature and function to the aging brain? These studies are helping us figure out some less ethically challenging and technically feasible ways to reverse aging, and more experimentation and eventual human trials will be needed to figure out if they work and when those happen and when we have more to share. We'll have it for you right here, so make sure you subscribe to stay up to date. I'm Emma Short and we'll see you next time on Lifespan News.