Biocompatibility of Mn0.4Zn0.6Fe2O4 Magnetic Nanoparticles and Their Thermotherapy on VX2-Carcinoma-Induced Liver Tumors

Actively Targeted Magnetothermally Responsive Nanocarriers/Doxorubicin for Thermochemotherapy of Hepatoma

Nanodrug-delivery systems modified with targeting molecules allow antitumor drugs to localize to tumor sites efficiently. CD147 protein is expressed highly on hepatoma cells. Firstly, we synthesized magnetothermally responsive nanocarriers/doxorubicin (MTRN/DOX) which was composed of manganese zinc (Mn-Zn) ferrite magnetic nanoparticles, amphiphilic and thermosensitivity copolymer drug carriers together with DOX. Then CD147-MTRN/DOX was formed with MTRN/DOX and monoclonal antibody that specifically binds to CD147 protein. It could target hepatoma cells actively and improve the DOX concentration in the tumor sites. Subsequently, an external alternating magnetic field elevated the temperature of the thermomagnetic particles, resulting in structural changes in the thermosensitive copolymer drug carriers, thereby releasing DOX. Hence, CD147-MTRN/DOX could enhance the responsiveness of hepatoma cells to the pre-existing chemotherapy drugs owing to active targeting combined synergistically with thermotherapy and chemotherapy, which has more significant anticancer effects than MTRN/DOX.

Enhanced Synergism of Thermo-chemotherapy For Liver Cancer with Magnetothermally Responsive Nanocarriers

A combination of magnetic hyperthermia and magnetothermally-facilitated drug release system was developed as a promising strategy for liver cancer therapy. The thermosensitive copolymer, 6sPCL-b-P(MEO2MA-co-OEGMA) shows a good temperature-controlled drug release response. Mn-Zn ferrite magnetic nanoparticles (MZF-MNPs) exhibit a strong magnetic thermal effect with an alternating magnetic field (AMF). Owing to its high magnetic sensitivity, the magnetothermally-responsive nanocarrier/doxorubicin (MTRN/DOX) can be concentrated in the tumor site efficiently through magnetic targeting. Given this information, we synthesized MTRN/DOX which was composed of MZF-MNPs, thermosensitive copolymer drug carriers, and the chemotherapeutic drug---DOX, to study its anticancer effects both in vitro and in vivo.METHODS: MTRN/DOX was designed and prepared. Firstly, we investigated the accumulation effects of MTRN/DOX by Prussian blue staining, transmission electron microscopy (TEM), laser scanning confocal microscopy (LSCM) and conducted 7.0 T MRI. Following this, the magnetothermal effects of MTRN/DOX were studied using an infrared thermal camera. DOX uptake, distribution, and retention in tumor cells and the distribution of MTRN/DOX in vivo were then analyzed via LSCM, flow cytometry and live fluorescence imaging. Lastly, its anticancer effects were evaluated by MTT, AM/PI staining, Annexin-VFITC/PI staining and comparison of relative tumor volume. RESULTS: We found that MTRN/DOX can be efficiently concentrated in the tumor site through magnetic targeting, increasing the uptake of DOX by tumor cells, and prolonging the retention time of the drug within the tumors. MTRN/DOX showed good magnetothermal effects both in vitro and in vivo. Based on the above results, MTRN/DOX had significant anticancer effects. CONCLUSIONS: MTRN/DOX causes temporal-spatial synchronism of thermo-chemotherapy and together with chemotherapeutic drugs, produces a synergistic effect, which enhances the sensitivity of tumor cells to DOX and reduces their side effects.

An arsenal of magnetic nanoparticles; perspectives in the treatment of cancer

Nanomedicine is an emerging field, which constitutes a new direction in the treatment of cancer. Magnetic nanoparticles (MNPs) can circumvent vascular tissue to concentrate at the site of the tumor. Under the influence of an external, alternating magnetic field, MNPs generate high temperatures within the tumor and ablate malignant cells while inflicting minimal damage to healthy host tissue. Due to their theranostic properties, they constitute a promising candidate for the treatment of cancer. A critical review of the type, size and therapeutic effect of different MNPs is presented, following an appraisal of the literature in the last 5 years. This is a multibillion dollar industry, with a few studies moving to clinical trials within the next 5 years.

Combination of PEI-Mn0.5Zn0.5Fe2O4 nanoparticles and pHsp 70-HSV-TK/GCV with magnet-induced heating for treatment of hepatoma

Background

To explore a new combination of thermal treatment and gene therapy for hepatoma, a heat-inducible herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy system was developed in which thermal energy generated by Mn_0.5Zn_0.5Fe₂O₄ nanoparticles (MZF-NPs) under an alternating magnetic field was used to activate gene expression.

Methods

First, a recombinant eukaryotic plasmid, pHsp 70-HSV-TK, was constructed as a target gene for therapy. This recombinant plasmid was used to transfect SMMC-7721 hepatoma cells and the gene expression was evaluated. Magnet-induced heating was then applied to cells to assess the antihepatoma effects of the polyethylenimine (PEI)-MZF-NPs/pHsp 70-HSV-TK/GCV complex, in vitro and in vivo.

Results

The results showed that cells were successfully transfected with pHsp 70-HSV-TK and that expression levels of HSV-TK remained stable. Both in vitro and in vivo results indicated that the combination of gene therapy and heat treatment resulted in better therapeutic effects than heating-alone group. The rates of apoptosis and necrosis in the combined treatment group were 49.0% and 7.21%, respectively. The rate of inhibition of cell proliferation in the combined treatment group was significantly higher (87.5%) than that in the heating-alone group (65.8%; P<0.01). The tumor volume and mass inhibition rates of the combined treatment group were 91.3% and 87.91%, respectively, and were significantly higher than the corresponding rates of the heating-alone group (70.41% and 57.14%; P<0.01). The expression levels of Stat3 and Bcl-xL messenger RNA and p-Stat3 and Bcl-xL protein in the combined treatment group were significantly lower than those in the other groups (P<0.01). The expression levels of Bax messenger RNA and protein in the recombinant plasmid group were significantly higher than those in the other groups (P<0.01).

Conclusion

It can therefore be concluded that the combined application of heat treatment and gene therapy has a synergistic and complementary effect and that PEI-MZF-NPs can simultaneously act both as a nonviral gene vector and a magnet-induced source of heat, thereby representing a viable approach for the treatment of cancer.