Theranostic Role of Iron Oxide Nanoparticle for Treating Renal Anemia: Evidence of Efficacy and Significance by MRI, Histology and Biomarkers

Abstract

(1) Background: Increasing attention has been given to applying nanosized iron oxide nanoparticles (IOPs) to treat iron deficiency anemia (IDA). Chronic kidney disease (CKD) patients who suffer from IDA often need long-term iron supplements. We aim to evaluate the safety and therapeutic effect of MPB-1523, a novel IOPs, in anemic CKD mice and to monitor iron storage by magnetic resonance (MR) imaging. (2) Methods: MPB-1523 was intraperitoneally delivered to the CKD and sham mice, and blood were collected for hematocrit, iron storage, cytokine assays, and MR imaging throughout the study. (3) Results: The hematocrit levels of CKD and sham mice dropped initially but increased gradually to reach a steady value 60 days after IOP injection. The body iron storage indicator, ferritin gradually rose and total iron-binding capacity stabilized 30 days after IOP injection. No significant inflammation or oxidative stress were observed in both groups. By T2-weighted MR imaging, the liver signal intensity gradually increased in both groups but was more pronounced in the CKD group, indicating aggressive utilization of MPB-1523. MR imaging, histology and electron microscopy showed MPB-1523 is liver-specific. (4) Conclusions: MPB-1523 can serve as a long-term iron supplement and is monitored by MR imaging. Our results have strong translatability to the clinic.

Keywords: chronic kidney disease; cytokines; iron deficiency anemia; iron oxide nanoparticles; magnetic resonance imaging; oxidative stress.

Figure 1

Study protocol of IOP injection in sham and SNx mice. Mice were divided into 2 groups including sham operation (Sham) treated with IOP, and subtotal nephrectomy (SNx) treated with IOP. N = 8 in sham group and N = 12 in SNx group IOP, iron oxide nanoparticle; SNx, subtotal nephrectomy; 2/3 Nx, 2/3 nephrectomy; UNx, uninephrectomy.

Figure 2

Effect of IOP injection on hematocrit in sham and SNx mice, (A) comparing its impact between the two groups and (B) assessing the time-dependent effect. * p < 0.05 compared with respective period of sham group. ^& p < 0.05 compared with its baseline level.

Figure 3

Effect of IOP injection on serum ferritin (A), TSAT (B), serum iron (C) and TIBC (D) in sham and SNx mice throughout the study. * p < 0.05 compared with respective period of sham group.

Figure 4

Effect of IOP injection on serum TNF-α (A), IL-6 (B), serum 8-OHdG (C) in sham and SNx mice throughout the study. ^& p < 0.05 compared with its baseline level.

Figure 5

Serial T2 weighted MRI study of the SNx mice (A) and sham control mice (B) before and after IOP administration. MR images of three organs including liver, spleen and kidneys were illustrated. There is no visible organ damage after IOP administration. Significant liver signal intensity drop is observed after IOP administration. Quantitative measurement of the liver and renal signal intensity was illustrated (C). After the single dose of IOP delivery, the signal intensity of the liver elevated gradually which is more pronounced in the SNx group. There is no significant signal intensity change of the spleen in both groups. (D) Quantification of MR signal intensity of liver before and after single dose IOP injection in sham and SNx mice. ^& p < 0.05 compared with its baseline level before IOP injection. Data are expressed as mean ± SEMs.

Figure 6

Histological observation of organs including skeletal muscle, lung, liver, kidney, spleen and residual kidney of SNx group for the existence of IOP by Pearl Stain with counter stained with Acid Fast (A–J) and Electron microscopy of liver of sham control (K) and SNx group (L). The pearl stain showed blue staining at the trabecula region of spleen and inside the vasculature of the liver in both sham control and SNx group. The residual kidney of the SNx group (I) had significant pearl staining. EM of the liver in both sham control and SNx group showed presence of small amount of IOP inside the vesicle organelle of the hepatocyte.

Figure 7

Representative images (A) and quantification (B) of immunohistochemistry of liver tissues from control, SNx and sham groups 60 days after IOPs delivery. Ferritin expression could be observed in both SNx and sham groups and there is stronger ferritin expression in sham group as compared to SNx group. Moreover, the transferrin expression was similar as the expression of ferritin in these three groups. * p < 0.05 compared with control group. ^& p < 0.05 compared with its sham group. Data are expressed as mean ± SEMs.