Evaluating DFPP for Microplastic and PFAS Reduction (DFPP-MNP)

Background and Rationale:

Microplastics and nanoplastics (MNPs) have been detected in human blood and every major organ. Increasingly, studies associate MNP exposure with a range of health conditions, including cardiovascular disease, metabolic disease, gastrointestinal disease, neurodegenerative disease, and cancer. There has been very little study of clinical approaches to remove MNPs from the human body. Such efforts have been limited in part by challenges in measuring MNPs in human blood, especially nanoplastics, which are too small to be detected by most equipment.

Double-filtration plasmapheresis (DFPP) is an established treatment for dozens of health conditions mediated by substances circulating in plasma. In DFPP, a first filter separates blood cells from plasma, and a second filter removes molecules from plasma according to the filter characteristics. The filtered plasma and blood cells are then recombined and returned to the patient. In 2025, a study showed that the material removed from plasma by a specialized type of DFPP called Inuspheresis with the CE-marked IN300 device includes microplastic molecules.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental chemicals that can also be measured in human blood and have been associated with a range of health conditions. This study will additionally evaluate whether circulating PFAS concentrations change after DFPP.

Study Design:

This is a single-group, open-label, prospective, within-subject observational pilot study. Approximately 20 adult participants who have already been independently prescribed DFPP by their treating clinic will be enrolled. Study samples and research data will be anonymized before research analysis.

Procedures:

Each participant provides written informed consent, then undergoes blood sampling shortly before the DFPP treatment session and again within 10 minutes of the end of the treatment session, after approximately 0.75 plasma volumes have been treated. Adverse events and tolerability observations are recorded throughout the treatment encounter. For a randomly selected subset of five participants, additional exploratory analyses will be performed on paired blood samples using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), and a sample of DFPP eluate will be collected to assess whether plastic polymers and PFAS are present in the material removed during treatment.

Analytical Methods:

Co-Primary: Nano-flow cytometry with Nile Red staining, which has been shown in multiple studies to provide detection and counting of microplastic and nanoplastic particles down to approximately 50 nanometers in human blood.

Co-primary: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measurement of total quantified PFAS concentration in paired pre- and post-treatment blood samples from all participants.

Exploratory: Py-GC-MS for polymer-specific mass quantification in blood and eluate in a five-participant subset. PFAS analytes in eluate will also be evaluated in the same subset.

Statistical Analysis:

The primary analyses will evaluate within-subject change in circulating MNP particle concentration and total quantified PFAS concentration using a paired pre/post design. The primary hypothesis tests will be the Wilcoxon matched-pairs signed-rank test. Effect size will be summarized using the median within-participant percent change and geometric mean post/pre ratio with a 95% confidence interval. Based on an approximate paired-analysis power calculation, a sample size of 20 participants provides approximately 80% power to detect a large within-participant reduction on the order of 50%, assuming a two-sided alpha of 0.05 and variability of paired log post/pre ratios not materially exceeding approximately 1.0. The same paired sample size will be used to characterize the PFAS co-primary endpoint. Because this is an early paired biomarker study with two co-primary endpoints, no formal multiplicity adjustment is planned, and the co-primary p-values will be interpreted descriptively. Exploratory Py-GC-MS analyses in the five-participant subset are not powered for definitive hypothesis testing; results will be summarized using absolute and percent change. Exploratory PFAS eluate results will be summarized descriptively. Quality-control procedures include procedural blank review; values at or below the laboratory limit of quantification will be treated conservatively.