Effects of charge, concentration, exposure duration, and size of polymethyl methacrylate micro/nanoplastics on human liver cells

Authors: Shelver, Weilin; Billey, Lloyd; McGarvey, Amy; HOSELTON, SCOTT - North Dakota State University; BANERJEE, AMRITA - Fount Bio

Submitted to: Society of Environmental Toxicology and Chemistry (SETAC)
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2024
Publication Date: 10/22/2024
Citation: Shelver, W.L., Billey, L.O., Mcgarvey, A.M., Hoselton, S.A., Banerjee, A. 2024. Effects of charge, concentration, exposure duration, and size of polymethyl methacrylate micro/nanoplastics on human liver cells. Society of Environmental Toxicology and Chemistry (SETAC). 25149.

Interpretive Summary:

Technical Abstract: Micro/nanoplastics (MNP) are ubiquitous environmental contaminants that are detected in urban and remote airs, waters, soils, and seas. Human exposure to MNP has been demonstrated by the presence of MNP in blood, feces, milk, urine, and placenta amongst other tissues. Polymethyl methacrylate (PMMA) MNP have frequently been isolated from biota, food, environmental matrices, and humans, possibly due to large quantities of historical production and broad arrays of use. However, information about the cellular effects of PMMA MNP is scant. To this end, the effects of size, surface function (aminated, carboxyl or non-functionalized), concentration, and exposure duration of PMMA particles on HepG2 human liver cells were studied. Aminated and carboxylated PMMA MNP ranging from 50 - 5000 nm were not toxic at concentrations of 0.1 - 100 µg/mL for up to 24 h. The majority of non-functionalized PMMA MNP size-concentration-duration combinations were not cytotoxic, with the exception of the following: 50 nm, 10 µg/mL, at 1hr duration; 1000 nm, 10 µg/mL, at 6 h duration; and 1000 nm, 0.1 µg/mL, at 24 h duration. Production of the pro-inflammatory interleukin-8 (IL-8) increased > 2x with an increase in exposure from 4 to 24 h regardless of particle size (50 - 5000 nm) or surface function studied. Confocal microscopy images revealed that PMMA MNP 50, 100, and 1000 nm particles were taken up by HepG2 cells irrespective of surface function. Less than 10% of cells underwent apoptosis at 24 and 48 h for 50 nm and 1000 nm beads at 100 µg/mL. From 72 - 120 h, apoptosis increased in a time dependent manner for cells treated 50 nm beads of all surface functions, with amine beads causing highest apoptosis at 120 h (36 %). While the percentage apoptosis was similar between 50 and 1000 nm for amine beads, the percentage apoptosis increase was less uniform for cells treated with 1000 nm carboxyl or 1000 nm non-functionalized beads. Collectively, PMMA MNP were able to translocate into HepG2 cells, elicit an IL-8 response, and induce apoptosis, but were not cytotoxic at the concentrations tested.