I think it’s a complicated issue and that the benefits of parabiosis may be partially explained by removal of some harmful factors in the blood but also by addition of youthful factors. Fresh albumin may have some benefits. Here is something I wrote about it elsewhere a while back:
The study below is interesting and suggests that injection of recombinant mouse serum albumin increases median lifespan of mice of both genders. Importantly the injected albumin was fresher and less damaged than endogenous albumin and this may be important.
I haven’t read the study in detail but going through it very quickly it appears that they didn’t measure albumin levels in the blood of the mice so it is not certain whether the injections led to a significant rise in blood albumin levels or if the blood levels remained relatively constant due to downregulation of endogenous production. Whichever is the case is important to know since it matters with respect to knowing whether the benefits in this study were caused merely by elevated albumin levels or by the infused albumin being “younger” and less damaged than the endogenous albumin or some combination of the two.
My immediate thoughts when I saw this study were that the results obviously have potential implications for interpreting the plasmapheresis experiments where saline with albumin was infused into rodents (anyone know how pure and undamaged that albumin was relative to that used in this study?). I also thought it has implications for the value of plasma albumin specifically as part of a blood biomarker for assessing biological age (albumin is if I recall the strongest predictor in the aging.ai formula) and whether higher plasma albumin is a causal factor in any health benefits or merely a marker.
If the benefits in this study were caused by the mice having higher proportion of less damaged albumin not by higher levels of albumin in the blood per se then one cannot expect to gain these benefits by raising albumin levels by any means but would require infusions of fresh albumin to get the benefits. Another thing one can do is to attempt to minimize the damages to the albumin (glycation, homocysteinylation etc.) that one already produces and is found normally in the blood.
If on the other hand the benefits in this study were caused by higher albumin per se and the freshness of that albumin relative to the endogenous one is not of much importance then one might be able to get the same benefits by attempting to raise blood levels of albumin.
These are my quick thoughts on this. Perhaps someone can look into the study in more detail.
Young and Undamaged rMSA Improves the Longevity of Mice
Jiaze Tang, Anji Ju, Boya Li, Shaosen Zhang, Yuanchao Gong, Boyuan Ma, Yi Jiang, Hongyi Liu, Yan Fu, Yongzhang Luo
doi: Young and Undamaged rMSA Improves the Longevity of Mice | bioRxiv
Improvement of longevity is an eternal dream of human beings. Here we report that a single protein recombinant mouse serum albumin (rMSA) improved the lifespan and healthspan of C57BL/6N mice. The median lifespan extensions were 17.6% for female and 20.3% for male, respectively. The grip strength of rMSA-treated female and male mice increased by 29.6% and 17.4%, respectively. Meanwhile, the percentage of successful escape increased 23.0% in rMSA-treated male mice using the Barnes Maze test. The rMSA used in this study is young and almost undamaged. We define the concept “young and undamaged” to any protein without any unnecessary modifications by four parameters: intact free thiol (if any), no advanced glycation end-product, no carbonylation, and no homocysteinylation. Here “young and undamaged” rMSA is much younger and less damaged than the endogenous serum albumin from young mice at 1.5 months of age. We predict that young and undamaged proteins altogether can further improve the longevity.
Quote from the full text:
“rMSA used in this study is not only “young” but also almost “undamaged”, which endows rMSA to offer more protection against unnecessary modifications and damages, and suggest that the four parameters could monitor the aging process. Here, “young” means that the rMSA is much fresher than the endogenous albumin from young mice at the age of only 1.5 months analyzed by the 4 parameters (free thiol, carbonyl, AGE, and Hcy).”