Plasma proteins facilitates placental transfer of polystyrene particles

Abstract

Background: Nanoparticles, which are exposed to biological fluids are rapidly interacting with proteins and other biomolecules forming a corona. In addition to dimension, charge and material the distinct protein corona influences the interplay of nanoparticles with tissue barriers. In this study we were focused on the impact of in situ formed human plasma protein corona on the transfer of 80 nm polystyrene nanoparticles (PS-particles) across the human placenta. To study materno-to fetal PS transfer we used the human ex vivo placental perfusion approach, which represents an intact and physiological tissue barrier. To analyze the protein corona of PS particles we performed shotgun proteomics of isolated nanoparticles before and after tissue exposure.

Results: Human plasma incubated with PS-particles of 80 nm and subsequent formed protein corona enhanced the transfer across the human placenta compared to PS-corona formed by bovine serum albumin and dextran which served as a control. Quantitative and qualitative changes of plasma proteins determined the changes in PS transfer across the barrier. Based on the analysis of the PS-proteome two candidate proteins, namely human albumin and immunoglobulin G were tested if these proteins may account for the enhanced PS-transfer across the placenta. Interestingly, the protein corona formed by human albumin significantly induced the transfer of PS-particles across the tissue compared to the formed IgG-corona.

Conclusion: In total we demonstrate the PS corona dynamically and significantly evolves upon crossing the human placenta. Thus, the initial composition of PS particles in the maternal circulation is not predictive for their transfer characteristics and performance once beyond the barrier of the placenta. The precise mechanism of these effects remains to be elucidated but highlights the importance of using well designed biological models when testing nanoparticles for biomedical applications.

Keywords: Biocorona; Dual ex vivo placental perfusion; Human placenta; Nanoparticle; Plasma proteins; Polystyrene; Transfer.

Fig. 1

Scheme of the ex vivo placental perfusion setting. (with the use of BioRender.com)

Fig. 2

Time kinetics of PS-particles concentrations in maternal and fetal compartment using control- (continuous line, n = 5) or plasma medium (dashed line, n = 5). Each graph shows data obtained from different sampling ports: a maternal artery, b maternal vein, c fetal artery, and d fetal vein. Statistical analysis by using a linear mixed model was performed. Significant interaction effects (time, media) are displayed above distinct time points. Significant main effect (media) is indicated to the right of the graphs (b, d). Statistically significant differences are depicted as: *p < 0.05, **p < 0.01 and ***p < 0.001. Data are presented as mean ± SD

Fig. 3

Heatmap displaying normalized abundancy of proteins on PS particles. The color scale illustrates the relative level of each protein on particles in plasma and maternal media compared to the 40 most abundant ranked proteins on particles in the fetal circuit. The different colors indicate the level of protein abundancy. The highlighted proteins were selected for detailed analysis (albumin and IgG, framed boxes)

Fig. 4

Time kinetics of PS-particle concentrations in maternal and fetal compartment using HSA- (continuous line, n = 5), IgG medium (dashed line, n = 3) or control medium (dotted grey line, n = 5). Each graph shows data obtained from different sampling ports: a maternal artery, b maternal vein, c fetal artery, and d fetal vein. Statistical analysis was performed by a linear mixed model. Significant interaction effects (time, media) are displayed above distinct time points (c). Significant main effect (media) is indicated to the right of the graphs (d). (Statistically significant differences are depicted as: *p < 0.05, **p < 0.01 and ****p < 0.0001. Data are presented as mean ± SD

Fig. 5

Recovery of PS-particles as a function of applied media. Total PS-particle levels of maternal and fetal reservoirs are normalized to applied PS-particle concentration in the maternal reservoir (40 µg/ml). Data was analyzed with One-Way-ANOVA and Holm-Sidak´s multiple comparison test in Graph Pad Prism. Data are presented as mean ± SD

Fig. 6

Scheme illustrating changes of protein corona during placental perfusion experiments. The PS-particle protein corona changed significantly in the number and abundancy of proteins depending on the perspective. PS-particles isolated from the fetal circulation showed a decreased protein diversity after 6 h, but relative higher protein abundancy for some specific proteins e.g. albumin and IgG. Particles isolated from the maternal circulation showed a major increase in the total number of different corona proteins (with the use of BioRender)