The news services were abuzz last week with separate reports from Stanford and Harvard that researchers had discovered chemicals in the blood of young animals that when it was transfused into older animals caused an improvement in a host of different functions and structures. Such technique goes by the name of parabiosis. This term comes from the Greek "next to life." It implies two animals surgically joined so that they share the same circulatory system. The idea is simple having been used by researchers interested in aging for over a century, creating a crossmatch between a young and old body surgically so that the young and old blood mixes freely by these grafting techniques. Some of these experiments were burdened by critique by the animal rights groups, but historically little of interest has evolved.
That is until possibly last week, when the above noted workers reported in top journals, "young blood reverses effects of aging in mice." (1) Professor Tony Wyss-Corny, Stanford University School of Medicine, and his group write: "Our data indicate that the decline in neurogenesis and cognitive impairments observed during aging can be in part attributed to changes in blood born factors." (2)
It has been known for some time that young animals have higher levels of growth hormones. Professor Lee Rubin, director of the Harvard center of stem cell and regenerative biology, suggests that the decline in cognitive ability with age may be due to lessened blood supply. Injection of young blood thereby stimulates increased blood flow and more neural stem cells and brain plasticity. Besides these salutary findings the injected animals also improved strength and endurance. Even memory was improved.
The Stanford group sought to identify a possible mediator in the young blood. After screening for hundreds of candidate protein molecules they identified the chemokine CCL11 as one that appeared to fulfill expectations. The also found corresponding levels in the plasma and spinal fluid of aging humans.
All of the effort is exerted in the hope that some molecule may emerge that may serve as the long sought elixir of youth. The hub-bub recalled the time 30 years ago when I was president of The American Geriatrics Society and thereby served as commentator for the press in its enthusiasm of the work from the University of Wisconsin, reported in NEJM, about how human growth hormone reverses aging. (3)
I was conservative in my response. I reasoned that growth hormone levels are low in old people not because they are old but because they were physically inactive. I advised that we oldsters don't need to take a rejuvenating shot we need to take a walk.
Subsequently, several groups showed that growth hormone shots are dangerous and have effectively been abandoned.
So, beware of the new sizzle. Get off the couch. Ponce's Fountain is exercise.
1) Morin,M. Young Blood Reverses Effects of Aging in Mice Science Now May, 4, 2014
2) Wyss-Coray, T et al The Aging Systemic Milieu Regulates Neurogenesis and Cognitive Function Nature August31, 2011; 477: 90-94.
3) Rudman D. et al Human Growth Hormone Reverses Aging In Humans NEJM 1990 323;1.