Heterochronic parabiosis is the process of linking together the circulatory systems of an old and a young individual. This is done in mice to try to isolate the roles of various signaling proteins in age-related alterations to metabolism, stem cell activity, and so forth. The older mice tend to show improvements in various short-term measures that otherwise decline with age.
While the full details of what is going on under the hood are not yet understood, why not trial a human therapy based on regular blood transplants from a young donor to an old recipient? This would be a stopgap on the way to figuring out the laundry list of signals that need to be altered and then altering them directly - which is in turn a stopgap on the way to repairing the underlying damage of aging that causes these signaling and metabolic changes, as well as many other forms of harm.
My guess is that in the present regulatory environment such a therapy would be unlikely to emerge. There is a very strong bias against progressing without a full explanation of the underlying molecular biology these days - therapies of the past are grandfathered in, but would never be admitted to clinical trials in today's risk averse world. As and when a comprehensive explanation emerges, researchers will focus on direct manipulation of the signals in question rather than developing a blood transfusion methodology to carry them over.
The population of baby boomers (age 60-65) is rapidly increasing globally. The aging of the human body is associated with the decline of cellular function which leads to the development of a variety of diseases. The increased demand for health care for the aging population creates significant financial burden to any healthcare system. Developing strategies and health intervention methods to ameliorate this situation is paramount.
Experiments utilizing heterochronic parabiosis in mice have demonstrated that replacing the aging cellular milieu with the plasma of a young experimental animal leads to reversal of cellular senescence. This article describes a hypothetical model of intermittent heterochronic plasma exchange in humans as a modality for heterochronic parabiosis in an attempt to delay cellular senescence.