Heterochronic Plasma Transfer: Experimental Design, Considerations, and Technical Challenges.

Experimental approaches such as Heterochronic Plasma Transfer (HPT) provide insights into the aging process and help identify the factors that impact aging, with the aim of developing anti-aging therapies. HPT involves the transfer of plasma from an animal of one age to an animal of a different age and highlights the effects of the systemic environment on aging. Despite its importance as an aging research tool, HPT is not without limitations and HPT experiments across various studies differ in key experimental designs considerations, presenting a challenge in obtaining comparable outcomes. In this review, we examine the caveats and experimental design considerations of HPT as a research tool. We provide insights into plasma preparation procedures, route of administration, dosing regimen, and appropriate controls to assist investigators in achieving their experimental goals.

Three Month Heterochronic Parabiosis Has a Deleterious Effect on the Lifespan of Young Animals, Without a Positive Effect for Old Animals.

Our previous study showed that an exchange of blood between heterochronic parabionts for 3 months did not rejuvenate the immune system of the old partners. Moreover, the young immune system became more aged and began to function according to the "old" principle. Does this forced aging affect all systems of the organism in this model? We checked the levels of corticosterone, testosterone, insulin-like growth factor 1 (IGF-1), insulin, and thyroxine in the blood of heterochronic parabionts, but did not find significant changes compared with age-related controls. Since numerous data support the possibility of rejuvenation of the brain, muscles, and other tissues using the model of heterochronic parabiosis, as well as opposite data, we planned to assess the overall effect of this long-term blood exchange on the rate of organism aging. We measured the life span of animals whose blood was exchanged for 3 months and then were disconnected. Median and maximum life expectancy decreased in young heterochronic parabionts compared with the isochronic control. Old heterochronic parabionts showed only a small trend toward an increase in the median life span, but it was not statistically significant, and the maximum life span did not change compared with the isochronic parabionts. These data support our assumption that old blood contains factors capable of inducing aging in young animals. The mechanism of selective suppression of aging factor production in the organism could be a key research field for life extension.