Polyethylene glycol and cryonics
The blog Al Fin reports on polyethylene glycol (PEG) as an acute treatment for traumatic brain and spinal cord injury. PEG is hypothesized to confer cytoprotection by sealing damaged cell membranes. As such, PEG would also seem a promising candidate for the treatment of acute neural insults in which progressive cell permeability / damage plays a part such as stroke and cardiac arrest. Unfortunately, the inability of high molecular weight polymers to cross an intact blood brain barrier (BBB) may limit the use of PEG as a treatment for cerebral ischemia. One study that investigated PEG in a model of middle cerebral artery occlusion (MCAo) did not find any benefits for PEG. In cryonics, membrane sealing polymers like PEG may still be useful because they can cross the compromised BBB and prevent cell lysis when transport of the patient is delayed. Its membrane sealing properties may also be useful for extending the time cryonics patients can be perfused without causing edema.
As a high molecular weight polymer, PEG has also been investigated as a component for cold organ preservation solutions. A number of studies have found that PEG can be substituted for hydroxyethyl starch (HES) as the oncotic agent in University of Wisconsin solution (commercial name: Viaspan). Replacing HES with PEG in UW solution also decreases red blood cell aggregation and viscoscity.
PEG is also briefly discussed by Mike Perry as an embedding medium in his article about low-cost alternatives to cryonics.