Of Mice (but not) Men

I want to start transfusions today! Hook me up to a pint of that sweet, fresh blood, the good stuff, the primo plasma extracted from bursting-with-life 20-somethings. Because, as we now know, courtesy of The New York Times and The Washington Post and NPR, young blood transfused into old bodies can make those bodies – and minds — young again.

If you’re a mouse.

Believe me, I wanted to rejoice when I read earlier this week about a trio of new studies reporting that the blood of young mice reversed some significant signs of aging in older mice. Researchers in two of the studies (both the result of collaborations at the Harvard Stem Cell Institute) found dramatic improvements in the muscles and the circulatory systems of older mice that either shared a blood supply with young mice or were injected with a protein found abundantly in the blood of their younger lab-mates. The young-blood mice navigated mazes faster and ran longer on treadmills than their saline-injected peers.

The third study (also using mice), published in the estimable journal, Nature, concluded that “exposure of an aged animal to young blood can counteract and reverse pre-existing effects of brain aging at the molecular, structural, functional and cognitive level.” (Italics mine.) Researchers at Stanford and UCSF found structural changes in the hippocampus section of brains of the revitalized-by-blood mice that translated into – take a breath here — the “reversal of cognitive impairments.” The hippocampus plays a major role in the consolidation of both short- and long-term memory and is one of the first regions of the brain to suffer damage from Alzheimer’s. This finding could be the biggest – as in HUGE, amazing, millions-of-lives-altering — breakthrough in a century research on Alzheimer’s.

Or not.

This is not the platform to discuss the ethical issue of testing on animals. Here I’d just like to say that animal models are far from perfect. Or, to put it bluntly: What works in mice often does not work in humans. In a comprehensive comparison between the genes of mice and humans, scientists from institutions across America, Sweden and the UK found that there are more genetic differences between the two species than had been previously thought. In cancer research, according to the Journal of Nuclear Medicine, “The power of these models to predict clinical efficacy is a matter of dispute.”  Research on immunology using mice has also proven to be less-than-translatable.

Perhaps the biggest cautionary Of Mice and (Wo)man tale is resveratrol. You remember… the anti-aging “miracle”? Back in the early 2000s Harvard biologist David Sinclair used red wine-derived resveratrol to turn old mice into young mice. Resveratrol reversed heart disease and liver disease. It lowered cholesterol and blood pressure. It increased the elasticity of arteries. It significantly increased lifespan.

In mice.

Pharmaceutical giant GlaxoSmithKline bought Sinclair’s little start-up company for $720 million and started clinical trials. More than ten years later, the literature on resveratrol (in humans) remains contradictory and confusing. (GlaxoKlineSmith halted clinical trails in 2011.)

I hope – fervently – that these latest trio of mouse studies have meaning for us humans. But really, I lied: I am not ready to start transfusions today.