This prospective, non-interventional, within-subject paired biomarker study will evaluate whether circulating microplastic and nanoplastic-associated particle concentrations in peripheral blood change after clinically prescribed double-filtration plasmapheresis (DFPP). Twenty adult volunteers already undergoing DFPP independent of research participation will provide paired pre- and post-treatment blood samples. The primary endpoint is within-participant change in microplastic and nanoplastic-associated particle concentration measured by nano-flow cytometry with Nile Red staining. An exploratory subset of five participants will undergo Py-GC-MS analysis of paired blood samples and DFPP eluate to evaluate polymer-specific mass changes and the presence of plastic polymers in eluate. DFPP treatment decisions and procedural parameters are determined solely by the treating physician as part of routine care.

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.

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.

Procedures:

Each participant provides written informed consent, then undergoes blood sampling shortly before the DFPP treatment session and again within 10 minutes after 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 are present in the material removed during treatment.

Analytical Methods:

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.

Exploratory: Py-GC-MS for polymer-specific mass quantification in blood and eluate in a five-participant subset.

Statistical Analysis:

The primary analysis will evaluate within-subject change in circulating MNP particle concentration using a paired pre/post design. The primary hypothesis test 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. 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. Quality-control procedures include procedural blank review; values at or below the laboratory limit of quantification will be treated conservatively.

Inclusion Criteria:

• Age 18 to 80 years
• Body weight greater than 40 kg (approximately 88 lb)
• Already independently prescribed DFPP treatment by a qualified treating clinic
• Able to understand the study and provide voluntary informed consent
• Willing and able to provide blood samples before and after DFPP treatment
• Cleared for DFPP by the prescribing clinic
• Has not had plasmapheresis treatment within the past 7 days

Exclusion Criteria:

• Not yet prescribed DFPP by a treating clinic
• Major heart or circulatory problems, such as recent myocardial infarction or hypertensive crisis
• Serious kidney or liver impairment
• Blood-clotting disorders or significantly impaired coagulation
• Active infection, inflammation, or fever
• Severe frailty or very poor medical condition
• Anemia with hemoglobin below 8 g/dL
• Body weight under 40 kg
• Pregnancy or breastfeeding
• Determined by the treating clinic to be medically or mentally inappropriate for DFPP

Adults aged 18 to 80 who have already been independently prescribed and medically cleared for DFPP by a qualified treating clinic and who are willing and able to provide paired pre- and post-treatment blood samples.

Individual-level results will be returned directly to participants. Aggregate and de-identified findings will be published or otherwise made publicly available after study completion. No formal plan is currently established to share individual participant data with external researchers for this pilot study.