Effects of multiple injections on the efficacy and cytotoxicity of folate-targeted magnetite nanoparticles as theranostic agents for MRI detection and magnetic hyperthermia therapy of tumor cells

Meysam Soleymani,Mohammad Reza Kalhori,Saeed Khodayari,Hamid Khodayari,Mahmoud Reza Hadjighassem,Zhila Shaterabadi,Ali Mohammad Alizadeh,Solmaz Khalighfard

doi:10.1038/s41598-020-58605-3

Abstract

Folate-targeted iron oxide nanoparticles (FA@Fe3O4 NPs) were prepared by a one-pot hydrothermal method and then used as cancer theranostic agents by combining magnetic resonance imaging (MRI) and magnetic hyperthermia therapy (MHT). Crystal structure, morphology, magnetic properties, surface functional group, and heating efficacy of the synthesized nanoparticles were characterized by XRD, TEM, VSM, FTIR, and hyperthermia analyses. The results indicated that the crystal structure, magnetic properties, and heating efficacy of the magnetite nanoparticles were improved by hydrothermal treatment. Toxicity of the prepared NPs was assessed in vitro and in vivo on the mammary cells and BALB/c mice, respectively. The results of the in vitro toxicity analysis showed that the FA@Fe3O4 NPs are relatively safe even at high concentrations of the NPs up to 1000 µg mL−1. Also, the targetability of the FA@Fe3O4 NPs for the detection of folate over-expressed cancer cells was evaluated in an animal model of breast tumor using MRI analysis. It was observed that T2-weighted magnetic resonance signal intensity was decreased with the three-time injection of the FA@Fe3O4 NPs with 24 h interval at a safe dose (50 mg kg−1), indicating the accumulation and retention of the NPs within the tumor tissues. Moreover, the therapeutic efficacy of the MHT using the FA@Fe3O4 NPs was evaluated in vivo in breast tumor-bearing mice. Hyperthermia treatment was carried out under a safe alternating magnetic field permissible for magnetic hyperthermia treatment (f = 150 kHz, H = 12.5 mT). The therapeutic effects of the MHT were evaluated by monitoring the tumor volume during the treatment period. The results showed that the mice in the control group experienced an almost 3.5-fold increase in the tumor volume during 15 days, while, the mice in the MHT group had a mild increase in the tumor volume (1.8-fold) within the same period (P < 0.05). These outcomes give promise that FA@Fe3O4 NPs can be used as theranostic agents for the MRI and MHT applications.

Highlights

Folate-targeted iron oxide nanoparticles (FA@Fe3O4 NPs) were prepared by a one-pot hydrothermal method and used as cancer theranostic agents by combining magnetic resonance imaging (MRI) and magnetic hyperthermia therapy (MHT)
In a similar manner to the MHT, the major obstacles limiting the clinical application of the magnetic nanoparticles (MNPs) as a T2-weighted contrast agent for MRI of tumors are the nonspecific accumulation and low concentration of the nanoparticles in the tumor tissue, causing no strong signal can be detected by the tumor tissue
It can be observed that the MRI signal of the tumor region was significantly decreased by repeating the IP injection of the folic acid (FA)@Fe3O4 NPs, so that after three injections, the lowest intensity in the tumor area was obtained, indicating the more accumulation and retention of the FA@Fe3O4 NPs in the tumor tissue. These results revealed that the FA@Fe3O4 NPs have a high potential to target the breast tumors in vivo and can be used as a targeted MRI contrast agent in the diagnostic research

Summary

Introduction

Folate-targeted iron oxide nanoparticles (FA@Fe3O4 NPs) were prepared by a one-pot hydrothermal method and used as cancer theranostic agents by combining magnetic resonance imaging (MRI) and magnetic hyperthermia therapy (MHT). Folate receptors are expressed at the relatively low levels in normal cells, but they are over-expressed in the surface of several cancer cells, including the ovary, breast, colon, lung, and brain[25] Another approach that increases the number of nanoparticles in the tumor region is the successive injections of the targeted-nanoparticles at a safe dose, which can help the accumulation of the nanoparticles in the tumor tissue due to the enhanced permeability and retention (EPR) effects. The potential of the FA@Fe3O4 NPs to target the folate receptor cancer cells, as well as the effect of multiple injections on the accumulation of nanoparticles in the tumor tissue, was investigated by the MRI technique. The output of this study could be especially useful for improving the active-targeted MNPs as a single theranostic agent for combining MRI and MHT for the detection and treatment of cancer

Methods

Results

Conclusion