In today’s New York Times there is a report on some new experiments on rejuvenation. Blood from young mice, it appears, can reverse signs of aging in old mice. The article cites experiments in the 1950s by Clive McCay (famous for his experiments showing that calorie restriction extends life)  that joined rats together by their skins so that in time, their circulatory systems became joined. The old rats became more youthful.(1) But so little was known about the molecular processes behind aging that the experiments reached a dead end. New experiments in the early 2000s, this time with mice, showed that a particular protein in young mouse blood activated dormant stem cells and reversed aspects of the aging process. Subsequent experiments involving injecting young blood into old mice rejuvenated brain, muscle, and skeletal cells.(2)

To those of us who live in the seventeenth century these experiments have a familiar ring. In the late 1660s, dozens of blood transfusion trials were performed across Europe, and rejuvenation was just one of the benefits that experimenters touted. In the Philosophical Transactions of the Royal Society of London in May 1667, appeared “An Account Of another Experiment of Transfusion viz. of Bleeding a Mangy into a Sound Dog” by  Thomas Coxe. Coxe estimated that 14 to 16 ounces of blood were exchanged by the dogs. “No alteration at all [was] to be observed in the Sound Dog,” But “for the Maingy Dog, he was in about 10 days or a fortnights space perfectly cured,” although Coxe attributed the cure more to the blood the dog had lost than to the blood it had received.

A decade later, the playwright Thomas Shadwell satirized the by now discredited transfusion craze in The Virtuoso. The title character, Sir Nicholas Gimcrack (said to be based on Robert Boyle) similarly exchanged blood between a “mangy spaniel” and a “sound bulldog.” The witness of the experiment, Sir Formal Trifle, declared “Indeed that which ensu’d upon the operation was miraculous, for the mangy spaniel became sound and the bulldog mangy.” “Not only so,” added Sir Nicholas, “but the spaniel became a bulldog and the bulldog a spaniel.”

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(1) Age Changes in the Bones, Blood Pressure, and Diseases of Rats in Parabiosis
Horrington E.M., Pope F., Lunsford W., McCay C.M.
Gerontologia 1960;4:21–31

(2) Rejuvenation of aged progenitor cells by exposure to a young systemic environment
Irina M. Conboy, Michael J. Conboy, Amy J. Wagers, Eric R. Girma, Irving L. Weissman, & Thomas A. Rando
Nature 433, 760-764 (17 February 2005)

Heterochronic parabiosis: historical perspective and methodological considerations for studies of aging and longevity.
Conboy, M. J., Conboy, I. M., Rando, T. A.
Aging cell 2013; 12 (3): 525-530