Heterochronic Parabiosis in Mice Fails to Extend Lifespan in the Older Animal
As practiced in the laboratory, heterochronic parabiosis is the surgical joining of the circulatory systems of an old and young mouse. The older mouse shows signs of rejuvenation, the younger mouse shows signs of accelerated aging. This has led to a great deal of debate and further research into mechanisms; the present weight of evidence favors the improvements in the old mouse to result from a dilution of harmful factors, such as damaged albumin, in the aged bloodstream, rather than by any provision of pro-regenerative factors carried in your blood but not in old blood. Researchers here show that heterochronic parabiosis actually fails to extend life span in the older mice, an interesting addition to the present body of evidence.
A new study in which young and old mice were surgically joined such that they shared blood circulation for three months showed that the old mice did not significantly benefit in terms of lifespan. In contrast, the young mice that were exposed to blood from old animals had significantly decreased lifespan compared to mice that shared blood with other young mice. Heterochronic parabiosis is a research tool used to assess the effect of organs and of blood-borne factors on young and old animals. Less controlled than direct blood exchange, parabiosis is a model of blood sharing between two surgically connected animals.
Researchers used heterochronic parabiosis between young and old mice and the isochronic controls for three months. They then disconnected the animals and studied the effects of being joined on the blood plasma and animal lifespan. "The most robust and interesting result of this study is the fact of a significant decrease in the lifespan of young mice from heterochronic parabiotic pairs. This data supports our assumption that old blood contains factors capable of inducing aging in young animals. Finding and selective suppression of aging factor production in the organism could be the key research field for life extension."
Link: https://home.liebertpub.com/news/can-exposure-to-young-blood-increase-lifespan/4941