On this episode of X10, we talk about a plasma transfusion experiment that studied what happens when young plasma is injected into older animals.
Is the blood of the young really an elixir of youth? Can it keep us healthy as we age, and, if so, what hidden components give it this great power? These aren’t questions from a conspiracy theory or horror story; they’re legitimate, if dramatically worded, research questions. Join us as we find out more.
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We should start by saying that there is no clear evidence that blood transfusion is an effective rejuvenation therapy. The FDA warns against companies that are selling plasma infusions as unproven treatments for age-related conditions and other problems. That said, there is serious research being done on the topic, though it’s hard to know what to make of the findings so far.
The research goes back to experiments in the 1950s with a process known as parabiosis, which means combining two organisms into a single physiological system. In heterochronic parabiosis experiments, the circulatory systems of young and old mice were connected so that they shared their blood. This rejuvenated the old mice, but that could be because they had access to the younger organs.
To get around that, researchers injected older animals with blood – in particular, plasma – from younger animals. It worked! In various experiments over the past few decades, blood plasma infusions from young animals improved the health of organs from the skin to the brain. The converse also seems to be true – serum from older animals inhibited the growth of cell cultures, and old-to-young plasma transfusions led to age-related neurological changes.
The reason we’re talking about this now is a manuscript that was released on bioRxiv in May 2020, which you’ll find linked in the description below. It caused a bit of a splash – and rightly so, because the findings are pretty striking! The work was done by a team of researchers at several universities around the world as well as a couple from a company called Nugenics. The paper basically reports two major results.
First, they developed a set of six epigenetic clocks for rat tissues, two of which can also be used in human tissues. Epigenetic clocks will be the topic of another video, but the basic idea is that they estimate age by measuring epigenetic changes. If you don’t know what epigenetics is, we’ve got a series of videos that can teach you about it.
The point is that the researchers developed tools to accurately estimate the biological age of various rat tissues. They used them to measure the effect of treating rats with a blood plasma fraction developed by Nugenics, which they don’t describe in detail.
The rats were injected four times over eight days, and the process was repeated 95 days later. Sixty days after that, the rats were sacrificed and epigenetic clock estimates were made from their organs. Overall, the epigenetic clocks reported that the treated rats were 54% younger on average, with specific organs ranging from 19% to 75% younger. That’s pretty amazing.
Epigenetic clocks generally correlate well with other markers of aging, but the researchers didn’t just rely on them. They also measured things like fat accumulation, memory, oxidative stress, and cellular senescence, and in each case, there was improvement. Basically, they found that the plasma treatment rejuvenated the rats both when measured with epigenetic clocks and with other age-related biomarkers.
It’s an exciting study, but, of course, there are caveats. First of all, this is just a preprint and hasn’t been peer reviewed — at least when we wrote this script. Second, the research will be difficult to replicate since they don’t describe what the treatment actually was – though presumably that will change once patents are filed. Third, the sample size is really small. Six rats got the treatment, and six served as a control. That doesn’t invalidate the results, but it’s worth noting.
And speaking of controls, the treatment for the control rats was just a saline solution. As David Sinclair and others have pointed out, it would have been better to use plasma fractions from old blood as a control. Time will tell how well these findings hold up. Even if this particular study doesn’t pan out, it does seem like there are some rejuvenating factors in young blood. We just have to figure out what they are and hope that they’re easy to synthesize.
There’s also one more question to resolve: can these treatments extend lifespan? Despite the evidence for rejuvenation, it might be that plasma treatments don’t actually lead to longer life. A 2014 study in mice found that repeated injections of young blood plasma didn’t extend the lifespan of mice, nor did it improve the health of their organs. That might be a consequence of the strain they used, the experimental protocol, or maybe some other factors. The only way we’ll find out is to keep chipping away at these problems with experiment after experiment.
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