More Data on Plasma Dilution in Humans
Diluting blood plasma in old individuals reduces circulating levels of harmful signals, such as pro-inflammatory proteins and debris, for long enough to allow improvement in tissue function. Significant dilution requires the introduction of new albumin, and there is presently some question over how much of the benefits result from the dilution of circulating factors versus delivery of albumin which is typically sourced from blood donations from (on average) younger individuals, and is thus less damaged. Researchers here report on the effects of repeated plasma dilution treatments in three human patients, showing an improvement in circulating protein levels known to change with age, some inflammation-linked, some more generally associated with processes of aging. It is an interesting addition to present understanding, and suggests the need for clinical trials of plasma dilution: it is a cheap intervention, and thus even modest benefit makes it worth the effort.
For people, plasma dilution is known as plasmapheresis or therapeutic plasma exchange (TPE); it replaces a patient's plasma with saline and purified albumin. The blood cells are returned to the patient so that while the cell profile does not change, the circulating blood proteins are diluted, including cytokines, autoreactive antibodies or toxins, and such pathogenic determinants of specific disorders. Although its full therapeutic benefits are still being discovered, TPE is one of the treatments for autoimmune and neurological diseases.
Here, we followed the effects of a miniaturized TPE in mice and of pilot studies of TPE with 3 human patients by studying the longitudinal effects of rounds of TPE on hallmarks of systemic aging. The results demonstrate significant and lasting rejuvenation of both humoral and cellular blood compartments in people who underwent repeated plasmapheresis. The rejuvenative changes are not limited to a reduction of inflammaging but encompass diminished circulatory protein markers of neurodegeneration and cancer, as well as reduced senescence, lower DNA damage, and improved myeloid/lymphoid homeostasis.