Determining the Tumor Suppressive Effects of a New Drug Delivery System Loaded with Iron Oxide Nanoparticles

Abstract

Background

Magnetic hyperthermia treatment (MHT) using magnetic nanoparticles (MNPs) has emerged as a novel strategy for cancer therapy. However, one concern of traditional hyperthermia is that it may affect both normal and tumor tissues. The current study therefore aimed to examine the antitumor effects of locally injecting magnetic nanoparticles encapsulated in super carbonate apatite (sCA), an efficient drug delivery system in combination with MHT. This study also investigated the effects of this combination on magnetic particle imaging (MPI).

Methods

First, the amount of iron encapsulated into the sCA was determined, after which a phantom experiment was performed to examine the pH sensitivity of MNPs encapsulated in the sCA (sCA-MNPs) or MNPs (pH 6.4–7.4) using an MPI scanner. Thereafter, an in vitro experiment involving the quantification of iron uptake in sCA-MNP-, MNP-, and sCA-treated Colon-26 cells and an in vivo experiment involving an MPI study after MNP or sCA-MNP injection were conducted. The antitumor effects of the following five groups were compared: Control, MNPs, MNPs + MHT, sCA-MNPs, and sCA-MNPs + MHT.

Results

Our findings showed that the maximum encapsulation efficiency of iron into the sCA was 29.5% ± 1.59%. The phantom experiment in the sCA-MNP group revealed that the MPI signal was highest during the low-pH condition and decreased during the high-pH condition. However, the MPI signal in the MNP group remained unaffected. Our results showed that sCA-MNPs were better incorporated into the cells compared to MNPs and sCA alone. The in vivo experiment showed that MPI values increased immediately after to 4 h after injection in the sCA-MNP group but did not increase in the MNPs group. The sCA-MNP + MHT group showed stronger antitumor effects compared to the MNP + MHT group 1 to 5 days after MHT.

Conclusions

Combination therapy with sCA-MNPs and MHT may be useful for cancer treatment, with sCA-MNPs being successfully imaged through MPI.