Sonodynamic therapy (SDT): a novel strategy for cancer nanotheranostics

Investigation of the tumoricidal effects of sonodynamic therapy in malignant glioblastoma brain tumors

OBJECTIVE

Glioblastoma is the most common primary brain tumor; survival is typically 12-18 months after diagnosis. We sought to study the effects of sonodynamic therapy (SDT) using 5-Aminolevulinic acid hydrochloride (5-ALA) and high frequency focused ultrasound (FUS) on 2 glioblastoma cell lines.

PROCEDURE

Rat C6 and human U87 glioblastoma cells were studied under the following conditions: 1 mM 5-ALA (5-ALA); focused ultrasound (FUS); 5-ALA and focused ultrasound (SDT); control. Studied responses included cell viability using an MTT assay, microscopic changes using phase contract microscopy, apoptotic induction through a caspase-3 assay, and apoptosis staining to quantify cell death.

RESULTS

SDT led to a marked decrease in cell extension and reduction in cell size. For C6, the MTT assay showed reductions in cell viability for 5-ALA, FUS, and SDT groups of 5%, 16%, and 47%, respectively compared to control (p < 0.05). Caspase 3 induction in C6 cells relative to control showed increases of 109%, 110%, and 278% for 5-ALA, FUS, and SDT groups, respectively (p < 0.05). For the C6 cells, caspase 3 staining positivity was 2.1%, 6.7%, 11.2%, and 39.8% for control, 5-ALA, FUS, and SDT groups, respectively. C6 Parp-1 staining positivity was 1.9%, 6.5%, 9.0%, and 37.8% for control, 5-ALA, FUS, and SDT groups, respectively. U87 cells showed similar responses to the treatments.

CONCLUSIONS

Sonodynamic therapy resulted in appreciable glioblastoma cell death as compared to 5-ALA or FUS alone. The approach couples two already FDA approved techniques in a novel way to treat the most aggressive and malignant of brain tumors. Further study of this promising technique is planned.

Oxygen-Sufficient Nanoplatform for Chemo-Sonodynamic Therapy of Hypoxic Tumors

Modulation of hypoxia is an essential factor for enhancing the effects of antitumor therapies, especially sonodynamic therapy and chemotherapy. To improve the efficacy of combination therapy by reversing the hypoxic tumor microenvironment, we developed shell-core structured PPID-NPs, which were designed with a polymer shell onto the sonosensitizer and a chemotherapeutic drug were loaded and a perfluorocarbon core loaded with oxygen. The perfluorocarbon core provides sufficient oxygen not only for causing the sonosensitizer to produce more singlet oxygen to induce cell apoptosis but also for reducing drug resistance to enhance therapeutic efficacy. Furthermore, the release of chemotherapeutic drugs at the tumor site can be controlled. Thus, PPID-NPs can efficiently inhibit the growth of breast cancer by synergistic therapy under ultrasound exposure. We believe that our oxygen-sufficient nanoplatform could be an ideal therapeutic system for hypoxic tumors.

Therapeutic Effect of Doxorubicin-Chlorin E6-Loaded Mesoporous Silica Nanoparticles Combined with Ultrasound on Triple-Negative Breast Cancer

Introduction

Sonodynamic Therapy (SDT) has good targeting and non-invasive advantages in solid cancers, but its antitumor effect is not sufficient to replace traditional treatments. Some studies that combined SDT with chemotherapy or nanoparticles have managed to enhance its efficiency and overcome the side effects of chemotherapy.

Materials and Methods

In this study, we synthesized and characterized mesoporous silica nanoparticles (MSN-DOX-Ce6) loaded with doxorubicin (DOX) and sonosensitizer, chlorin e6 (Ce6). Then, we conducted in vitro and in vivo experiments to explore the antitumor effect of MSN-DOX-Ce6 under ultrasound (US) treatment.

Results

The characterization tests showed that the nanoparticles are uniformly sized spheres with mesoporous structure, resulting in a high drug-loading efficiency. In the in vitro experiments, MSN-DOX-Ce6 could effectively inhibit cell proliferation under US but not more than other treatment groups. However, the in vivo studies showed that MSN-DOX-Ce6+US has better antitumor effect than DOX+Ce6+US or DOX alone on xenograft tumor-bearing mice.

Conclusion

In summary, MSNs showed a great potential for DOX and Ce6 delivery. We concluded that under US, MSN-DOX-Ce6 nanocomposites increase the antitumor effect of DOX and SDT and thereby are a potential treatment for solid tumors.

Photo- and Sono-Dynamic Therapy: A Review of Mechanisms and Considerations for Pharmacological Agents Used in Therapy Incorporating Light and Sound

As irreplaceable energy sources of minimally invasive treatment, light and sound have, separately, laid solid foundations in their clinic applications. Constrained by the relatively shallow penetration depth of light, photodynamic therapy (PDT) typically involves involves superficial targets such as shallow seated skin conditions, head and neck cancers, eye disorders, early-stage cancer of esophagus, etc. For ultrasound-driven sonodynamic therapy (SDT), however, to various organs is facilitated by the superior... transmission and focusing ability of ultrasound in biological tissues, enabling multiple therapeutic applications including treating glioma, breast cancer, hematologic tumor and opening blood-brain-barrier (BBB). Considering the emergence of theranostics and precision therapy, these two classic energy sources and corresponding sensitizers are worth reevaluating. In this review, three typical therapies using light and sound as a trigger, PDT, SDT, and combined PDT and SDT are introduced. The therapeutic dynamics and current designs of pharmacological sensitizers involved in these therapies are presented. By introducing both the history of the field and the most up-to-date design strategies, this review provides a systemic summary on the development of PDT and SDT and fosters inspiration for researchers working on 'multi-modal' therapies involving light and sound.

An Ultrasound Activated Vesicle of Janus Au-MnO Nanoparticles for Promoted Tumor Penetration and Sono-Chemodynamic Therapy of Orthotopic Liver Cancer

Sonodynamic therapy (SDT) has the advantages of high penetration, non-invasiveness, and controllability, and it is suitable for deep-seated tumors. However, there is still a lack of effective sonosensitizers with high sensitivity, safety, and penetration. Now, ultrasound (US) and glutathione (GSH) dual responsive vesicles of Janus Au-MnO nanoparticles (JNPs) were coated with PEG and a ROS-sensitive polymer. Upon US irradiation, the vesicles were disassembled into small Janus Au-MnO nanoparticles (NPs) with promoted penetration ability. Subsequently, GSH-triggered MnO degradation simultaneously released smaller Au NPs as numerous cavitation nucleation sites and Mn²⁺ for chemodynamic therapy (CDT), resulting in enhanced reactive oxygen species (ROS) generation. This also allowed dual-modality photoacoustic imaging in the second near-infrared (NIR) window and T₁ -MR imaging due to the released Mn²⁺ , and inhibited orthotopic liver tumor growth via synergistic SDT/CDT.

Preparation and Characterization of Magnetic Fe3O4/CdWO4 and Fe3O4/CdWO4/PrVO4 Nanoparticles and Investigation of Their Photocatalytic and Anticancer Properties on PANC1 Cells

Fe3O4/CdWO4 and Fe3O4/CdWO4/PrVO4 magnetic nanoparticles were prepared at different molar ratios of PrVO4 to previous layers (Fe3O4/CdWO4) via the co-precipitation method assisted by a sonochemical procedure, in order to investigate the photocatalytic performance of these systems and their cytotoxicity properties. The physico-chemical properties of these magnetic nanoparticles were determined via several experimental methods: X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transformation infrared spectroscopy and ultraviolet-visible diffuse reflection spectroscopy, using a vibrating sample magnetometer and a scanning electron microscope. The average sizes of these nanoparticles were found to be in the range of 60-100 nm. The photocatalytic efficiency of the prepared nanostructures was measured by methylene blue degradation under visible light (assisted by H2O2). The magnetic nanosystem with a 1:2:1 ratio of three oxide components showed the best performance by the degradation of ca. 70% after 120 min of exposure to visible light irradiation. Afterwards, this sample was used for the photodegradation of methyl orange, methyl violet, fenitrothion, and rhodamine-B pollutants. Finally, the mechanism of the photocatalytic reaction was examined by releasing ˙OH under UV light in a system including terephthalic acid, as well as O2-, OH, and hole scavengers. Additionally, the cytotoxicity of each synthesized sample was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against the human cell line PANC1 (cancer), and its IC50 was approximately 125 mg/L.

ROS-Responsive Blended Nanoparticles: Cascade-Amplifying Synergistic Effects of Sonochemotherapy with On-demand Boosted Drug Release During SDT Process

Sonodynamic therapy (SDT) not only has greater tissue-penetrating depth compared to photo-stimulated therapies, but also can also trigger rapid drug release to achieve synergistic sonochemotherapy. Here, reactive oxygen species (ROS)-responsive IR780/PTL- nanoparticles (NPs) are designed by self-assembly, which contain ROS-cleavable thioketal linkers (TL) to promote paclitaxel (PTX) release during SDT. Under ultrasound (US) stimulation, IR780/PTL-NPs produce high amounts of ROS, which not only induces apoptosis in human glioma (U87) cells but also boosts PTX released by decomposing the ROS-sensitive TL. In the U87 tumor-bearing mouse model, the IR780/PTL-NPs releases the drug at the target sites in a controlled manner upon US irradiation, which significantly inhibits tumor growth and induces apoptosis in the tumor tissues with no obvious toxicity. Taken together, the IR780/PTL-NPs are a novel platform for sonochemotherapy, and can control the spatio-temporal release of chemotherapeutic drugs during SDT.

Intelligent Hollow Pt-CuS Janus Architecture for Synergistic Catalysis-Enhanced Sonodynamic and Photothermal Cancer Therapy

As a noninvasive treatment modality, ultrasound (US)-triggered sonodynamic therapy (SDT) shows broad and promising applications to overcome the drawbacks of traditional photodynamic therapy (PDT) in combating cancer. However, the SDT efficacy is still not satisfactory without oxygen (O₂) assistance. In addition, there is also much space to explore the SDT-based synergistic therapeutic modalities. Herein, a novel Pt-CuS Janus composed of hollow semiconductor CuS and noble metallic Pt was rationally designed and successfully synthesized. The hollow CuS shows a large inner cavity for loading sonosensitizer molecules (tetra-(4-aminophenyl) porphyrin, TAPP) to implement SDT. Moreover, the deposition of Pt not only enhances photothermal performance compared with those of CuS nanoparticles (NPs) due to the effect of the local electric field enhancement but also possesses nanozyme activity for catalyzing decomposition of endogenous overexpressed hydrogen peroxide (H₂O₂) to produce O₂ that can overcome tumor hypoxia and augment the SDT-induced highly toxic reactive oxygen species (ROS) production for efficient cancer cell apoptosis. Importantly, the generated heat of Pt-CuS by 808 nm laser irradiation can accelerate the catalytic activity of Pt and elevate the O₂ level that further facilitates SDT efficacy. Interestingly, the thermally sensitive copolymer coated around the Janus can act as a smart switch to regulate the catalytic ability of Pt and control TAPP release that has a significant effect on modulating the therapeutic effect. The synergistic catalysis-enhanced SDT efficiency and highly photothermal effect almost realized complete tumor resection without obvious reoccurrence and simultaneously displayed a highly therapeutic biosafety. Furthermore, the high optical absorbance allows the as-synthesized Pt-CuS Janus for photoacoustic (PA) imaging and NIR thermal imaging. This work develops a versatile nanoplatform for a multifunctional theranostic strategy and broadens the biological applications by rationally designing their structure.

Photodynamic Therapy Enhanced the Antitumor Effects of Berberine on HeLa Cells

In this study we investigated the antineoplastic effects of Berberine (BBR)-mediated photodynamic therapy (PDT) on HeLa cells and its related mechanisms. The CCK-8 assay and flow cytometry were used to evaluate the proliferation and apoptosis of cells respectively. In addition, changes in protein expression levels were assessed using western blot. BBR at dose of 10 mg/kg was injected intraperitoneally to mice with tumors and PDT treatments were performed 24 hours later. In vivo imaging systems were used to evaluate the fluorescence of BBR. In vitro, PDT significantly enhanced the effects of BBR on inducing cell apoptosis and inhibiting proliferation. The in vivo results showed that the fluorescence intensity in the PDT group was decreased compared with that in the BBR group. Tumor weights and tumor size in the PDT group were less than those in the control group; however, when BBR was applied without PDT, no significant differences were observed between the BBR and control group. The results of western blot showed that PDT enhanced the inhibitory effects of BBR on the mammalian target of rapamycin (mTOR) signaling pathway, that may partly explain the potential underlying mechanisms.

Membrane-permeabilized sonodynamic therapy enhances drug delivery into macrophages

Macrophages play a pivotal role in the formation and development of atherosclerosis as a predominant inflammatory cell type present within atherosclerotic plaque. Promoting anti-atherosclerotic drug delivery into macrophages may provide a therapeutic potential on atherosclerotic plaque. In this study, we investigated whether membrane-permeabilized sonodynamic therapy (MP-SDT) enhances drug delivery into THP-1 macrophages. Images of confocal microscopy confirmed that the optimal plasma distribution of the sonosensitizer protoporphyrin IX (PpIX) was at 1 hour incubation. The non-lethal parameter of MP-SDT was determined by cell viability as measured by a CCK-8 assay. Bright field microscopy demonstrated plasma membrane deformation in response to MP-SDT. Using SYTOX Green, a model drug for cellular uptake, we found that MP-SDT significantly induced membrane permeabilization dependent on ultrasound intensity and exposure time. Using Fluo-3 AM, intracellular calcium elevation during MP-SDT was confirmed as a result of membrane permeabilization. Membrane perforation of MP-SDT-treated cells was observed by scanning electron microscopy and transmission electron microscopy. Moreover, MP-SDT-induced membrane permeabilization and perforation were remarkably prevented by scavenging reactive oxygen species (ROS) during MP-SDT. Furthermore, we assessed the therapeutic effect of MP-SDT in combination with anti-atherosclerotic drug atorvastatin. Our results showed that MP-SDT increased the therapeutic effect of atorvastatin on lipid-laden THP-1-derived foam cells, including decreasing lipid droplets, increasing the cholesterol efflux and the expression of PPARγ and ABCG1. In conclusion, MP-SDT might become a promising approach to facilitating the delivery of anti-atherosclerotic drugs into macrophages via membrane permeabilization.

Cavitation Induced by Janus-Like Mesoporous Silicon Nanoparticles Enhances Ultrasound Hyperthermia

The presence of nanoparticles lowers the levels of ultrasound (US) intensity needed to achieve the therapeutic effect and improves the contrast between healthy and pathological tissues. Here, we evaluate the role of two main mechanisms that contribute to the US-induced heating of aqueous suspensions of biodegradable nanoparticles (NPs) of mesoporous silicon prepared by electrochemical etching of heavily boron-doped crystalline silicon wafers in a hydrofluoric acid solution. The first mechanism is associated with an increase of the attenuation of US in the presence of NPs due to additional scattering and viscous dissipation, which was numerically simulated and compared to the experimental data. The second mechanism is caused by acoustic cavitation leading to intense bubble collapse and energy release in the vicinity of NPs. This effect is found to be pronounced for as-called Janus NPs produced via a nano-stopper technique, which allow us to prepare mesoporous NPs with hydrophobic inner pore walls and hydrophilic external surface. Such Janus-like NPs trap air inside the pores when dispersed in water. The precise measurement of the heating dynamics in situ enabled us to detect the excessive heat production by Janus-like NPs over their completely hydrophilic counterparts. The excessive heat is attributed to the high intensity cavitation in the suspension of Janus-like NPs. The present work elicits the potential of specifically designed Janus-like mesoporous silicon NPs in the field of nanotheranostics based on ultrasound radiation.

Iron oxide nanoparticles as nanocarriers to improve chlorin e6-based sonosensitivity in sonodynamic therapy

Background

Compared to the excitation light in photodynamic therapy, ultrasound in sonodynamic therapy (SDT) could easily penetrate into the deep tumor in liver. However, the photosensitizer chlorin e6 (E6) activated by ultrasound has been limited in its application in clinics for the poor water solubility of E6 and poor effect of SDT. Nanoparticles as cavitation promotors may be able to amplify the E6-mediated SDT effect and also improve its water solubility.

Objective

The objective of the study was to develop an E6-based sonosensitizer with improved SDT effect and good water solubility using nanotechnology.

Materials and methods

Polyethylene glycol (PEG)ylated iron oxide nanoparticles coated with E6 (PION@E6) was prepared by means of pyrolysis and phase transfer. Characterization of PION@E6 was performed by means of transmission electron microscopy, hydrate particle size analysis, and absorption and fluorescence spectra analysis. Uptake of PION@E6 by H22 cells (a murine hepatoma cell line) was measured by inductively coupled plasma atomic emission spectroscopy. The effect of SDT on H22 cells was studied by the combination of ultrasound treatment with PION@E6 incubation. Cell viability was measured using cell counting kit-8 assay. Cell apoptosis was analyzed by flow cytometry. ROS generation was measured using DCFH-DA (2',7'-dichlorodihydrofluorescein diacetate) probing kit.

Results

Absorption spectra of PION@E6 revealed successful loading of E6 onto the PIONs. It showed excellent water solubility and stability with a size of 37.86±12.90 nm in diameter. The fluorescence spectra of PION@E6 revealed a red-shift compared with free E6. When combined with ultrasound treatment, it showed a significantly better inhibitory effect on H22 cells and correspondingly higher level of intracellular ROS generation compared with free E6. Furthermore, either higher dose of PION@E6 or higher power intensity of ultrasound initiated significantly better SDT effect and correspondingly higher level of intracellular ROS generation compared with lower dose of PION@E6 or ultrasound, respectively.

Conclusion

PION@E6 is a superior potential sonosensitizer to E6 to treat tumors by SDT.