Melanin-like nanoparticles alleviate ischemia-reperfusion injury in the kidney by scavenging reactive oxygen species and inhibiting ferroptosis

Abstract

Kidney transplantation is essential for patients with end-stage renal disease; however, ischemia-reperfusion injury (IRI) during transplantation can lead to acute kidney damage and compromise survival. Recent studies have reported that antiferroptotic agents may be a potential therapeutic strategy, by reducing production of reactive oxygen species (ROS). Therefore, we constructed rutin-loaded polydopamine nanoparticles (PEG-PDA@rutin NPs, referred to as PPR NPs) to eliminate ROS resulting from IRI. Physicochemical characterization showed that the PPR NPs were ∼100 nm spherical particles with good ROS scavenging ability. Notably, PPR NPs could effectively enter lipopolysaccharide (LPS)-treated renal tubular cells, then polydopamine (PDA) released rutin to eliminate ROS, repair mitochondria, and suppress ferroptosis. Furthermore, in vivo imaging revealed that PPR NPs efficiently accumulated in the kidneys after IRI and effectively protected against IRI damage. In conclusion, PPR NPs demonstrated an excellent ability to eliminate ROS, suppress ferroptosis, and protect kidneys from IRI.

Keywords: Biological sciences; Biomedical materials; Drug delivery system; Nanoparticles.

Graphical abstract

Figure 1

Characterization of PPR NPs (A) TEM images of PDA, PP, and PPR NPs. (B) DLS distribution of PDA, PP, and PPR NPs. (C) Zeta potentials of PDA, PP, and PPR NPs. (D) FI-IR analysis of PDA, PP, and PPR NPs. (E) UV-Vis analysis of PDA, PP, and PPR NPs. (F) The dose curve of rutin, detected by UV-Vis spectrophotometer at 350 nm. (G) UV-Vis analysis of rutin. (H) DPPH clearance of rutin, PP, and PPR NPs. (I) ABTS clearance of rutin, PP, and PPR NPs. n = 3. ∗∗∗p < 0.001. Data are represented as mean ± SEM.

Figure 2

In vitro cellular uptake and biocompatibility of PPR NPs (A and B) CLSM images of HK-2 cells, after being incubated with Rho labeled PRP NPs for 1–8 h (left) and their statistic intensities (right). Scar bar, 30 μm. (C) Cell viabilities of HK-2 cells, after being incubated with PDA, PP, and PPR NPs, using CCK-8 assay. (D) Cell viabilities of LPS-induced HK-2 cells, after being incubated with PP and PPR NPs, using CCK-8 assay. (E) LDH leakage of LPS-induced HK-2 cells, after being incubated with PP and PPR NPs, using Elisa assay. n = 3. ∗∗p < 0.01, ∗∗∗p < 0.001. Data are represented as mean ± SEM.

Figure 3

Intracellular antioxidant activity of PPR NPs (A and B) CLSM images of ROS inside LPS-stimulated HK-2 cells, after being incubated with PP and PPR NPs (left) and their statistic intensities (right). Scar bar, 200 μm. (C–E) CLSM images of oxidized and reduced proteins inside LPS-stimulated HK-2 cells, after being incubated with with PP and PPR NPs (left), and their statistic intensities (right). Scar bar, 100 μm. n = 3. ∗∗∗p < 0.001. Data are represented as mean ± SEM.

Figure 4

Effects of PPR NPs on mitochondrial repair (A) CLSM images of JC-1 inside LPS-stimulated HK-2 cells, after being incubated with PP and PPR NPs (left), and their statistic intensities (right). Scar bar, 200 μm. (B) CLSM images of mPTP inside LPS-stimulated HK-2 cells, after being incubated with PP and PPR NPs (left), and their statistic intensities (right). Scar bar, 200 μm. (C and D) Flow cytometry images of mitoROS inside LPS-stimulated HK-2 cells, after being incubated with = PP and PPR NPs (left), and their statistic intensities (right). (E–H) The expression mitochondrial complex I, III, IV, and V inside LPS-stimulated HK-2 cells, after being incubated with with PP and PPR NPs. n= 3. ∗p < 0.05. ∗∗p < 0.01. ∗∗∗p < 0.001. Data are represented as mean ± SEM.

Figure 5

In vivo enrichment and IRI alleviate the effect of PPR NPs (A) In vivo distribution of PPR NPs inside IRI mice. (B) Ex vivo distribution of PPR NPs inside the major organs of IRI mice. (C) The content of CRE in IRI mice’s blood. (D) The expression of collagen fraction of IRI mice, according to (G). (E) The expression of GPX4 of IRI mice, according to (H). (F–H) HE, Masson, and IHC staining of IRI mice’s kidneys. n = 3. ∗∗∗p < 0.001. Data are represented as mean ± SEM.