Here is my understanding of the current state-of-play regarding "young plasma for PD" clinical trials.
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​The "young plasma for PD" trial that Nan_Cyclist took part in (NCT02968433), conducted at the Stanford Movement Disorders Clinic, is now overdue for completion.​
Status: Active, not recruiting
Estimated Study Completion Date: December 2019 (no results published AFAIK)
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​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).​
Status: Active, not recruiting
Estimated Study Completion Date: November 2020
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​An earlier version of the drug (GRF6019), consisting of about 400 proteins, was tested on volunteers with either mild-to-moderate (NCT03520998 ) or severe (NCT03765762) Alzheimer's disease.​
Status (of both): Completed
Results: In December 2019, Alkahest presented data from NCT03520998.

Alkahest Presents Data from Phase 2a Study in Mild-to-Moderate Alzheimer’s Disease:
Alkahest Presents Data from Phase 2a Study in Mild-to-Moderate Alzheimer’s Disease - Alkahest

In addition, Alkahest have recently started a trial "Assessing Efficacy and Safety of AKST4290 in Subjects With Parkinson's Disease on Stable Dopaminergic Treatment". AKST4290 (a non-plasma-derived product) is an orally-administered small molecule that acts as a modulator of inflammation. More information on AKST4290 (formerly called ALK4290) is available in this SoPD blog post from Simon (December 2018):
From Alchemy to Alkahest | The Science of Parkinson's

For anyone who might be interested, the new PD trial is currently recruiting PwPs.
Study Assessing Efficacy and Safety of AKST429 in Subjects With Parkinson's Disease on Stable Dopaminergic Treatment - Full Text View - ClinicalTrials.gov