In vitro study of low intensity ultrasound combined with different doses of PDT: Effects on C6 glioma cells

Sonodynamic Therapy and Sonosensitizers for Glioma Treatment: A Systematic Qualitative Review

Sonodynamic therapy (SDT) has emerged as an encouraging noninvasive technique that uses ultrasound to activate targeted agents to induce antitumor effects for the treatment of glioma. With extensive variation in the types of sonosensitizers, protocols for sonication, and model systems, a comprehensive overview of existing preclinical data on the efficacy of SDT in glioma treatment is warranted. Here, we conduct a systematic review of preclinical and early clinical literature on implementing SDT to treat in vitro and in vivo models of glioma. Our findings suggest that coupling sonosensitizers such as 5-aminolevulinic acid, hematoporphyrin monomethyl ether, and sinoporphyrin sodium with focused ultrasound induces robust cytotoxic activity in tumor cells (in vitro and in vivo). These effects are likely mediated by the oxidative stress induced by reactive oxygen species production, apoptotic signaling cascades, and intracellular calcium overload. Future research is needed to better understand the biochemical and mechanistic properties of SDT, and ongoing trials may help elucidate the clinical feasibility of glioma treatment with optimized sonically activated treatments.

Nanotechnology meets glioblastoma multiforme: Emerging therapeutic strategies

Glioblastoma multiforme (GBM) represents the most common and fatal form of primary invasive brain tumors as it affects a great number of patients each year and has a median overall survival of approximately 14.6 months after diagnosis. Despite intensive treatment, almost all patients with GBM experience recurrence, and their 5-year survival rate is approximately 5%. At present, the main clinical treatment strategy includes surgical resection, radiotherapy, and chemotherapy. However, tumor heterogeneity, blood-brain barrier, glioma stem cells, and DNA damage repair mechanisms hinder efficient GBM treatment. The emergence of nanometer-scale diagnostic and therapeutic approaches in cancer medicine due to the establishment of nanotechnology provides novel and promising tools that will allow us to overcome these difficulties. This review summarizes the application and recent progress in nanotechnology-based monotherapies (e.g., chemotherapy) and combination cancer treatment strategies (chemotherapy-based combined cancer therapy) for GBM and describes the synergistic enhancement between these combination therapies as well as the current standard therapy for brain cancer and its deficiencies. These combination therapies that can reduce individual drug-related toxicities and significantly enhance therapeutic efficiency have recently undergone rapid development. The mechanisms underlying these different nanotechnology-based therapies as well as the application of nanotechnology in GBM (e.g., in photodynamic therapy and chemodynamic therapy) have been systematically summarized here in an attempt to review recent developments and to identify promising directions for future research. This review provides novel and clinically significant insights and directions for the treatment of GBM, which is of great clinical importance. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Nanosensitizers for sonodynamic therapy for glioblastoma multiforme: current progress and future perspectives

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor, and it is associated with poor prognosis. Its characteristics of being highly invasive and undergoing heterogeneous genetic mutation, as well as the presence of the blood-brain barrier (BBB), have reduced the efficacy of GBM treatment. The emergence of a novel therapeutic method, namely, sonodynamic therapy (SDT), provides a promising strategy for eradicating tumors via activated sonosensitizers coupled with low-intensity ultrasound. SDT can provide tumor killing effects for deep-seated tumors, such as brain tumors. However, conventional sonosensitizers cannot effectively reach the tumor region and kill additional tumor cells, especially brain tumor cells. Efforts should be made to develop a method to help therapeutic agents pass through the BBB and accumulate in brain tumors. With the development of novel multifunctional nanosensitizers and newly emerging combination strategies, the killing ability and selectivity of SDT have greatly improved and are accompanied with fewer side effects. In this review, we systematically summarize the findings of previous studies on SDT for GBM, with a focus on recent developments and promising directions for future research.

Recent progress in sono-photodynamic cancer therapy: From developed new sensitizers to nanotechnology-based efficacy-enhancing strategies

Many sensitizers have not only photodynamic effects, but also sonodynamic effects. Therefore, the combination of sonodynamic therapy (SDT) and photodynamic therapy (PDT) using sensitizers for sono-photodynamic therapy (SPDT) provides alternative opportunities for clinical cancer therapy. Although significant advances have been made in synthesizing new sensitizers for SPDT, few of them are successfully applied in clinical settings. The anti-tumor effects of the sensitizers are restricted by the lack of tumor-targeting specificity, incapability in deep intratumoral delivery, and the deteriorating tumor microenvironment. The application of nanotechnology-based drug delivery systems (NDDSs) can solve the above shortcomings, thereby improving the SPDT efficacy. This review summarizes various sensitizers as sono/photosensitizers that can be further used in SPDT, and describes different strategies for enhancing tumor treatment by NDDSs, such as overcoming biological barriers, improving tumor-targeted delivery and intratumoral delivery, providing stimuli-responsive controlled-release characteristics, stimulating anti-tumor immunity, increasing oxygen supply, employing different therapeutic modalities, and combining diagnosis and treatment. The challenges and prospects for further development of intelligent sensitizers and translational NDDSs for SPDT are also discussed.

Development of porphyrin and titanium dioxide sonosensitizers for sonodynamic cancer therapy

Sonodynamic therapy for malignant tumours has gained much attention for its deep penetration effect and efficient tumour killing ability. The design, modification, and utilization of sonosensitizers are important aspects of sonodynamic therapy. As an essential factor in this process, highly effective sonosensitizers should be developed to facilitate the clinical applications of sonodynamic therapy. This review takes porphyrin- and titanium dioxide (TiO₂)-based systems as representative organic and inorganic sonosensitizers respectively, and summarizes their characteristics and biological effects as sonodynamic therapy. Upon discovery of novel sonosensitizers, sonodynamic therapy becomes an efficient means of adjuvant therapy for the treatment of malignant tumours.

Sonodynamic Therapy for the Treatment of Intracranial Gliomas

High-grade gliomas are the most common and aggressive malignant primary brain tumors. Current therapeutic schemes include a combination of surgical resection, radiotherapy and chemotherapy; even if major advances have been achieved in Progression Free Survival and Overall Survival for patients harboring high-grade gliomas, prognosis still remains poor; hence, new therapeutic options for malignant gliomas are currently researched. Sonodynamic Therapy (SDT) has proven to be a promising treatment combining the effects of low-intensity ultrasound waves with various sound-sensitive compounds, whose activation leads to increased immunogenicity of tumor cells, increased apoptotic rates and decreased angiogenetic potential. In addition, this therapeutic technique only exerts its cytotoxic effects on tumor cells, while both ultrasound waves and sensitizing compound are non-toxic per se. This review summarizes the present knowledge regarding mechanisms of action of SDT and currently available sonosensitizers and focuses on the preclinical and clinical studies that have investigated its efficacy on malignant gliomas. To date, preclinical studies implying various sonosensitizers and different treatment protocols all seem to confirm the anti-tumoral properties of SDT, while first clinical trials will soon start recruiting patients. Accordingly, it is crucial to conduct further investigations regarding the clinical applications of SDT as a therapeutic option in the management of intracranial gliomas.

Enhancement of Photodynamic Cancer Therapy by Physical and Chemical Factors

The viable use of photodynamic therapy (PDT) in cancer therapy has never been fully realized because of its undesirable effects on healthy tissues. Herein we summarize some physicochemical factors that can make PDT a more viable and effective option to provide future oncological patients with better-quality treatment options. These physicochemical factors include light sources, photosensitizer (PS) carriers, microwaves, electric fields, magnetic fields, and ultrasound. This Review is meant to provide current information pertaining to PDT use, including a discussion of in vitro and in vivo studies. Emphasis is placed on the physicochemical factors and their potential benefits in overcoming the difficulty in transitioning PDT into the medical field. Many advanced techniques, such as employing X-rays as a light source, using nanoparticle-loaded stem cells and bacteriophage bio-nanowires as a photosensitizer carrier, as well as integration with immunotherapy, are among the future directions.

Experimental Data-Mining Analyses Reveal New Roles of Low-Intensity Ultrasound in Differentiating Cell Death Regulatome in Cancer and Non-cancer Cells via Potential Modulation of Chromatin Long-Range Interactions

Background: The mechanisms underlying low intensity ultrasound (LIUS) mediated suppression of inflammation and tumorigenesis remain poorly determined. Methods: We used microarray datasets from NCBI GEO Dataset databases and conducted a comprehensive data mining analyses, where we studied the gene expression of 299 cell death regulators that regulate 13 different cell death types (cell death regulatome) in cells treated with LIUS. Results: We made the following findings: (1) LIUS exerts a profound effect on the expression of cell death regulatome in cancer cells and non-cancer cells. Of note, LIUS has the tendency to downregulate the gene expression of cell death regulators in non-cancer cells. Most of the cell death regulator genes downregulated by LIUS in non-cancer cells are responsible for mediating inflammatory signaling pathways; (2) LIUS activates different cell death transcription factors in cancer and non-cancer cells. Transcription factors TP-53 and SRF- were induced by LIUS exposure in cancer cells and non-cancer cells, respectively; (3) As two well-accepted mechanisms of LIUS, mild hyperthermia and oscillatory shear stress induce changes in the expression of cell death regulators, therefore, may be responsible for inducing LIUS mediated changes in gene expression patterns of cell death regulators in cells; (4) LIUS exposure may change the redox status of the cells. LIUS may induce more of antioxidant effects in non-cancer cells compared to cancer cells; and (5) The genes modulated by LIUS in cancer cells have distinct chromatin long range interaction (CLRI) patterns to that of non-cancer cells. Conclusions: Our analysis suggests novel molecular mechanisms that may be utilized by LIUS to induce tumor suppression and inflammation inhibition. Our findings may lead to development of new treatment protocols for cancers and chronic inflammation.

Sonodynamic and sono-photodynamic therapy in oncology

In the present publication, authors have analyzed the results of using sonodynamic and sono-photodynamic therapy with photosensitizing agents of various classes (hematoporphyrin, 5-aminolevulinic acid, chlorin derivatives, etc.) in experimental oncology. In a number of in vitro and in vivo studies, the high antitumor efficacy of the above treatment methods has been proven. Ultrasonic treatment with a pulse frequency of 1–3 MHz and an intensity of 0.7 to 5 W/cm2 , independently and in combination with photo-irradiation of experimental tumors, can significantly improve the cytotoxic properties of photosensitizers. This became the basisfor testing the methodsin patients with malignant neoplasms of various localizations. Scientists fromSouth-East Asia presented the preliminary results of the use of sonodynamic and sono-photodynamic therapy with photosensitizers in the treatment of malignant pathology of the mammary gland, stomach, esophagus, prostate, lung and brain. Analysis of the obtained data indicates the absence of serious adverse events and an increase in the antitumor efficacy of treatment, which included these treatment methods with chlorin-type photosensitizers. 

Dual-mode imaging and therapeutic effects of drug-loaded phase-transition nanoparticles combined with near-infrared laser and low-intensity ultrasound on ovarian cancer

Chemotherapy and photo-sonodynamic therapy (PSDT) can be combined through drug delivery nano-platforms to enhance the anti-tumor efficacy, however, which is limited by hypoxia in tumor, thereby causing chemotherapy resistance. Perfluoropentane (PFP) has the ability to carry oxygen and to enhance ultrasound or photoacoustic imaging after vaporization. Herein, we constructed a kind of nanoparticles (PTX/ICG and oxygen loaded PLGA nanoparticles (PIO_NPs)), which had PFP core carrying oxygen and PLGA shell loaded indocyanine green (ICG) and paclitaxel (PTX). PIO_NPs harbored good optical stability and the ability to transit phase. Moreover, it could rapidly release PTX and generate ROS under the mediation by near-infrared laser and low-intensity ultrasound. The PIO_NPs enhanced contrast of the ultrasound and PA imaging. In particular, PIO_NPs may be used to monitor and guide treatment for the accumulation of PIO_NPs at tumor site can be observed by PA imaging. Compared with PTX or other nanoparticles, PIO_NPs combined with laser and ultrasound (L.U) significantly induced apoptosis of SKOV3 cells and inhibited SKOV3 tumor growth. Therefore, PIO_NPs are of great potential in cancer imaging and therapy.

Inhibitory effect of aloe emodin mediated photodynamic therapy on human oral mucosa carcinoma in vitro and in vivo

We report a study on inhibition of human oral squamous cell carcinoma in vitro and in vivo, using novel photosensitizer (PS) aloe emodin (AE) mediated photodynamic therapy (PDT). Distinct morphology changes of oral mucosa carcinoma KB cells were observed under an optical microscope and cell migrations were inhibited owing to AE-PDT. The cell proliferation was blocked in G1 phase and the apoptosis increase were both caused by massive reactive oxygen species (ROS) generated from photoactivated AE. The upregulation of Caspase-3 and Bax protein levels and downregulation of Bcl-2 protein levels were observed after AE-PDT. The survival time of tumor mouse was prolonged without side effects ascribed to AE-PDT and its inhibitory effect on mice transplantation tumors was significant. It is indicated that AE mediated PDT is an innovative way to oral cancer treatment with the dominances of effectivity, minimal invasion, tissue integrity retention and none side effects on main organs.

Current status and future perspectives of sonodynamic therapy in glioma treatment

Malignant glioma is one of the most challenging central nervous system diseases to treat, and has high rates of recurrence and mortality. The current therapies include surgery, radiation therapy, and chemotherapy, although these approaches often failed to control tumor progression or improve patient survival. Sonodynamic therapy is a developing cancer treatment that uses ultrasound combined with a sonosensitizer to synergistically kill tumor cells, and has provided impressive results in both in vitro and in vivo studies. The ultrasound waves can penetrate deep tissues and reversibly open the blood-brain barrier to enhance drug delivery to the brain. Thus, sonodynamic therapy has a promising potential in glioma treatment. In this review, we summarize the studies that have confirmed the pre-clinical efficacy of sonodynamic therapy for glioma treatment, and discuss the future directions for this emerging treatment.

The effect of aloe-emodin-induced photodynamic activity on the apoptosis of human gastric cancer cells: A pilot study

The aim of the present study was to explore the effect of aloe-emodin (AE)-induced photodynamic activity in human gastric cancer cells. AE was used as a photosensitizer to explore the effect of photodynamic therapy (PDT) in human gastric cancer cells (SGC-7901). An MTT assay was used to detect the effect of AE-induced PDT in optimal concentrations and illumination energy densities in human gastric cancer cells. Following AE-induced PDT, morphological changes of the cells and the rate of cell death were evaluated by TUNEL assay and flow cytometry, respectively. The expression levels of caspase-9 and caspase-3 were determined by western blot analysis. The AE and AE-induced PDT demonstrated a significant inhibitive effect on the proliferation of human gastric cancer cells in dose-dependent and energy-dependent manners. For subsequent experiments, 10 µM AE and 12.8 J/cm² illumination energy density were used. Typical morphological changes of apoptosis were observed in the cells using a TUNEL assay 12 h subsequent to AE-induced PDT. The percentage of apoptotic cells treated with AE-induced PDT significantly increased when compared with the control group, the 10 µM AE group and the illumination group (P<0.05). Upregulation of caspase-9 and caspase-3 protein levels was also observed following AE-induced PDT. The present study revealed that 10 µM AE-induced PDT had an inhibitory effect on human gastric cancer cells, and it may induce cell apoptosis by upregulating caspase-9 and caspase-3, which indicated that the mitochondrial pathway may be involved. AE-induced PDT has the potential to be a novel therapy for the treatment of human gastric cancer. However, further investigations are required.

Cholesterol metabolism: A review of how ageing disrupts the biological mechanisms responsible for its regulation

Cholesterol plays a vital role in the human body as a precursor of steroid hormones and bile acids, in addition to providing structure to cell membranes. Whole body cholesterol metabolism is maintained by a highly coordinated balancing act between cholesterol ingestion, synthesis, absorption, and excretion. The aim of this review is to discuss how ageing interacts with these processes. Firstly, we will present an overview of cholesterol metabolism. Following this, we discuss how the biological mechanisms which underpin cholesterol metabolism are effected by ageing. Included in this discussion are lipoprotein dynamics, cholesterol absorption/synthesis and the enterohepatic circulation/synthesis of bile acids. Moreover, we discuss the role of oxidative stress in the pathological progression of atherosclerosis and also discuss how cholesterol biosynthesis is effected by both the mammalian target of rapamycin and sirtuin pathways. Next, we examine how diet and alterations to the gut microbiome can be used to mitigate the impact ageing has on cholesterol metabolism. We conclude by discussing how mathematical models of cholesterol metabolism can be used to identify therapeutic interventions.

Effect of photodynamic therapy combined with torasemide on the expression of matrix metalloproteinase 2 and sodium-potassium-chloride cotransporter 1 in rat peritumoral edema and glioma

Peritumoral edema is a key stage in the infiltration and recurrence of glioma. Photodynamic therapy (PDT) increases the extent of peritumoral edema, which leads to a decrease in the effectiveness of PDT in treating glioma. The present study evaluated the effects of PDT combined with torasemide on the levels of matrix metalloproteinase (MMP) 2 and sodium-potassium-chloride cotransporter (NKCC) 1 in peritumoral edema regions of rat glioma. Adult male Wistar rats were inoculated with rat glioma C6 cells, and the presence of glioma was confirmed using magnetic resonance imaging 7 days subsequent to injection. The rats were randomly assigned to 4 groups (n=15): Control group, the rats received no treatment; PDT group, the rats received PDT at 80 J/cm² for 10 min; torasemide group, the rats received 5 mg/kg torasemide intraperitoneally; and PDT + torasemide group, the rats received 5 mg/kg torasemide intraperitoneally for 3 days following PDT at 80 J/cm² for 10 min. A total of 5 rats from each group were sacrificed 21 days following injection and the peritumoral edema tissues were harvested. MMP2 and NKCC1 expression levels were detected in the tissues using immunohistochemistry and western blot analysis. The mRNA expression levels of MMP2 and NKCC1 were observed using reverse transcription-quantitative polymerase chain reaction. Peritumoral edema was measured using a wet-to-dry weight (W/D) ratio, and survival times of the remaining 10 rats in each group were evaluated. Compared with the control group, tumor growth was significantly suppressed in the PDT group and the survival time was prolonged through a reduction in the expression of MMP2 (P<0.05), and an increased W/D ratio resulted in significantly increased expression of NKCC1 (P<0.05). Compared with the PDT group, the expression of NKCC1 and the W/D ratio in the PDT + torasemide group were significantly decreased (P<0.05), while no significant difference was observed in the expression levels of MMP2. In conclusion, PDT combined with torasemide prolonged the survival time of rats by inhibiting the growth of glioma through a reduction in the expression of MMP2, and by reducing peritumoral edema through a reduction in the expression levels of NKCC1.

Sonodynamic action of chlorin e6 on Staphylococcus aureus and Escherichia coli

Bacteria remain a great threat to human health. In the present study, we examined whether sonodynamic action of chlorin e6 had antibacterial activity on gram-positive bacterial strain Staphylococcus aureus (S. aureus) and gram-negative bacterial strain Escherichia coli (E. coli). Colony forming unit (CFU) assay showed that sonodynamic treatment of chlorin e6 induced a 2-log reduction in CFU of E. coli cells, 7-log reduction in CFU of S. aureus. Fluorescent microscopy observed that dead cells remarkably increased whereas live cells decreased after sonodynamic treatment of chlorin e6 on S. aureus cells. We first demonstrated that sonodynamic action of chlorin e6 has antibacterial effect on both gram-positive and negative bacteria, more powerful on gram-positive bacteria.

The effect of aloe emodin-encapsulated nanoliposome-mediated r-caspase-3 gene transfection and photodynamic therapy on human gastric cancer cells

Gastric carcinoma (GC) has high incidence and mortality rates in China. Surgery and chemotherapy are the main treatments. Photodynamic therapy (PDT) has become a new treatment modality, appearing in recent experimental studies and clinical trials in various tumors. This study explores the combined effect of gene transfection with PDT on GC cells using aloe emodin (AE)-encapsulated nanoliposomes, which acted as gene carrier as well as one photosensitizer (PS). AE-encapsulated nanoliposomes (nano-AE) were prepared by reverse evaporation method. Electron microscopy and nano-ZS90 analyzer were used to detect its morphology, size, and wavelength. Western blot was used to detect the expression of the caspase-3 after transfection. MTT assay and flow cytometry were employed to determine the cytotoxic and apoptotic rates, respectively. Hoechst 33342 staining was adopted to detect the morphological changes in death gastric cancer cells. Cellular reactive oxygen species (ROS) contents were measured by DCFH-DA staining. Outcomes demonstrated that the nano-AE has good properties as gene delivery carriers as well as a PS. The group in which the recombinant plasmid of r-caspase-3 was transfected had higher protein expression of the caspase-3 than controls, meanwhile the proliferation rates of the transfected cells were inhibited by the nano-AE-mediated PDT in an energy-dependent manner. In addition, in the transfected cells, the death rate increased to 77.3% as assessed 12 h after PDT (6.4 J/cm(2) ). Hochest 33342 staining also revealed that the death rate increased significantly in the transfected group compared with other groups. Compared to control groups, the production of ROS in nano-AE PDT group had quadrupled in SGC-7901 cells as early as 1 h after PDT, while it is similar to the group of nano-AE transfection and PDT. Nano-AE-mediated r-caspase-3 gene transfection coupled with PDT could inhibit the proliferation rate and increase the apoptotic rate remarkably in human gastric cancer cells.

Anti-metastatic and pro-apoptotic effects elicited by combination photodynamic therapy with sonodynamic therapy on breast cancer both in vitro and in vivo

Sono-Photodynamic therapy (SPDT), a new modality for cancer treatment, is aimed at enhancing anticancer effects by the combination of sonodynamic therapy (SDT) and photodynamic therapy (PDT). In this study, we investigated the antitumor effect and possible mechanisms of Chlorin e6 (Ce6) mediated SPDT (Ce6-SPDT) on breast cancer both in vitro and in vivo. MTT assay revealed that the combined therapy markedly enhanced cell viability loss of breast cancer cell lines (MDA-MB-231, MCF-7 and 4T1) compared with SDT and PDT alone. Propidium iodide/hoechst33342 double staining reflected that 4T1 cells with apoptotic morphological characteristics were significantly increased in groups given combined therapy. Besides, the combined therapy caused obvious mitochondrial membrane potential (MMP) loss at early 1 h post SPDT treatment. The generation of intracellular reactive oxygen species (ROS) detected by flow cytometry was greatly increased in 4T1 cells treated with the combination therapy, and the loss of cell viability and MMP could be effectively rescued by pre-treatment with the ROS scavenger N-acetylcysteine (NAC). Further, Ce6-SPDT markedly inhibited the tumor growth (volume and weight) and lung metastasis in 4T1 tumor-bearing mice, but had no effect on the body weight. Hematoxylin and eosin staining revealed obvious tissue destruction with large spaces in the Ce6-SPDT groups, and TUNEL staining indicated tumor cell apoptosis after treatment. Immunohistochemistry analysis showed that the expression level of VEGF and MMP were significantly decreased in the combined groups. These results indicated that Ce6-mediated SPDT enhanced the antitumor efficacy on 4T1 cells compared with SDT and PDT alone, loss of MMP and generation of ROS might be involved. In addition, Ce6-mediated SPDT significantly inhibited tumor growth and metastasis in mouse breast cancer 4T1 xenograft model, in which MMP-9 and VEGF may play a crucial role.

Cellular Trojan horse based polymer nanoreactors with light-sensitive activity

Stimulus-sensitive systems at the nanoscale represent ideal candidates for improving therapeutic and diagnostic approaches by producing rapid responses to the presence of specific molecules or conditions either by changing properties or by acting "on demand". Here we introduce an optimized light-sensitive nanoreactor based on encapsulation of a photosensitizer inside polymer vesicles to serve as an efficient source of reactive oxygen species (ROS) "on demand". Two types of amphiphilic block copolymers, poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyloxazoline), PMOXA-PDMS-PMOXA, and poly(N-vinylpyrrolidone)-block-poly(dimethylsiloxane)-block-poly(N-vinylpyrrolidone), PNVP-PDMS-PNVP, were used to encapsulate Rose Bengal-bovine serum albumin (RB-BSA) inside the cavity of vesicles. The difference of copolymers molecular properties (hydrophobic to hydrophilic ratio, different chemical nature of the hydrophilic block) influenced the encapsulation ability, and uptake by cells, allowing therefore a selection of the most efficient polymer system. Nanoreactors were optimized in terms of (i) size, (ii) stability, and (iii) encapsulation efficiency based on a combination of light scattering, TEM, and UV-vis spectroscopy. By illumination, encapsulated RB-BSA conjugates generated in situ ROS, which diffused through the polymer membrane to the environment of the vesicles, as proved by electron spin resonance spectroscopy (ESR). Optimum illumination conditions were obtained based on the effect of the illumination time on the amount of ROS produced in situ by the encapsulated RB-BSA conjugates. ROS diffusion monitored by ESR was dependent on the molecular weight of copolymer that influences the thickness of the polymer membrane. Upon uptake into HeLa cells our nontoxic nanoreactors acted as a Trojan horse: they produced illumination-controlled ROS in sufficient amounts to induce cell death under photodynamic therapy (PDT) conditions. Straightforward production, stability, and Trojan horse activity inside cells support our light-sensitive nanoreactors for medical applications which require ROS to be generated with precise time and space control.

Impact of thermal effects induced by ultrasound on viability of rat C6 glioma cells

In order to have consistent and repeatable effects of sonodynamic therapy (SDT) on various cancer cells or tissue lesions we should be able to control a delivered ultrasound energy and thermal effects induced. The objective of this study was to investigate viability of rat C6 glioma cells in vitro depending on the intensity of ultrasound in the region of cells and to determine the exposure time inducing temperature rise above 43 °C, which is known to be toxic for cells. For measurements a planar piezoelectric transducer with a diameter of 20 mm and a resonance frequency of 1.06 MHz was used. The transducer generated tone bursts with 94 μs duration, 0.4 duty-cycle and initial intensity ISATA (spatial averaged, temporal averaged) varied from 0.33 W/cm(2) to 8 W/cm(2) (average acoustic power varied from 1 W to 24 W). The rat C6 glioma cells were cultured on a bottom of wells in 12-well plates, incubated for 24h and then exposed to ultrasound with measured acoustic properties, inducing or causing no thermal effects leading to cell death. Cell viability rate was determined by MTT assay (a standard colorimetric assay for assessing cell viability) as the ratio of the optical densities of the group treated by ultrasound to the control group. Structural cellular changes and apoptosis estimation were observed under a microscope. Quantitative analysis of the obtained results allowed to determine the maximal exposure time that does not lead to the thermal effects above 43 °C in the region of cells for each initial intensity of the tone bursts used as well as the threshold intensity causing cell death after 3 min exposure to ultrasound due to thermal effects. The averaged threshold intensity was found to be about 5.7 W/cm(2).

Comparison between sonodynamic and photodynamic effect on MDA-MB-231 cells

Photodynamic therapy (PDT) and sonodynamic therapy (SDT) are therapeutic modalities for tumors. In this study we investigated the combined cytotoxic effect of 0.36W/cm(2) and 0.72W/cm(2) ultrasound with various Ce6 concentrations (1, 2, 5, 10μg/ml), and that of 1μg/ml Ce6 with different laser light dose (650nm; 10.4mW/cm(2); 0.3, 0.6, 1.2 and 2.5J/cm(2)) on MDA-MB-231 cells. Both high reactive oxygen species (ROS) production and a decline in mitochondrial membrane potential (MMP) were detected with high Ce6 concentrations (5 and 10μg/ml) combined with 0.72W/cm(2) ultrasound and 1.2, 2.5J/cm(2) laser light with 1μg/ml Ce6. In addition, cell membrane integrity was evaluated by using propidium iodide (PI), revealing membrane damage was aggravated with the increasing ultrasound intensity, but no significant difference on cell membrane integrity could be observed after PDT treatment. These results suggest ROS may play an important role both in SDT and PDT. Besides, mitochondria may be an initial target in PDT while SDT can cause multi-site damages in MDA-MB-231 cells.