Simon has recently done a substantial SoPD blog post on this (and related) research:
From Simon's SoPD blog post, here is my understanding of the current state-of-play regarding "young plasma for PD".
The "young plasma for PD" trial that NanCyclist took part in (NCT02968433), conducted at the Stanford Movement Disorders Clinic, is now coming to an end.
Independently of this, researchers (from Stanford University and Alkahest) who conducted the earlier "young plasma for AD" trial (NCT02256306), have "distilled" young plasma into an injectable "drug" (GRF6021) that is now being tested in a Phase 2 trial involving 90 volunteers with either PD or PD with mild cognitive impairment (NCT03713957).
An earlier version of the drug (GRF6019), consisting of about 400 proteins, is currently being tested on volunteers with either mild-to-moderate (NCT03520998 ) or severe (NCT03765762) Alzheimer's disease.
For anyone who might be interested, the new PD trial is currently recruiting PwPs.