Medição automática de valva mitral a partir de ecocardiograma utilizando processamento digital de imagens / Automatic measurement of the mitral valve based on echocardiography using digital image processing

Fundamento: A avaliação da área valvar mitral por meio da reconstrução multiplano na ecocardiografia tridimensional é restrita a softwares específicos e à experiência dos ecocardiografistas. Eles precisam selecionar manualmente o frame do vídeo que contenha a área de abertura máxima da valva mitral, dimensão fundamental para a identificação de estenose mitral. Objetivo: Automatizar o processo de determinação da área de abertura máxima da valva mitral, por meio da aplicação de Processamento Digital de Imagens (PDI) em exames de ecocardiograma, desenvolvendo um algoritmo aberto com leitura de vídeo no formato avi. Método: Este estudo piloto observacional transversal foi realizado com vinte e cinco exames diferentes de ecocardiograma, sendo quinze com abertura normal e dez com estenose mitral reumática. Todos os exames foram realizados e disponibilizados por dois especialistas, com autorização do Comitê de Ética em Pesquisa, que utilizaram dois modelos de aparelhos ecocardiográficos: Vivid E95 (GE Healthcare) e Epiq 7 (Philips), com sondas multiplanares transesofágicas. Todos os vídeos em formato avi foram submetidos ao PDI através da técnica de segmentação de imagens. Resultados: As medidas obtidas manualmente por ecocardiografistas experientes e os valores calculados pelo sistema desenvolvido foram comparados utilizando o diagrama de Bland-Altman. Observou-se maior concordância entre valores no intervalo de 0,4 a 2,7 cm². Conclusão: Foi possível determinar automaticamente a área de máxima abertura das valvas mitrais, tanto para os casos advindos da GE quanto da Philips, utilizando apenas um vídeo como dado de entrada. O algoritmo demonstrou economizar tempo nas medições quando comparado com a mensuração habitual. (AU)

Background: The evaluation of mitral valve area through multiplanar reconstruction in 3-dimensional echocardiography is restricted to specific software and to the experience of echocardiographers. They need to manually select the video frame that contains the maximum mitral valve opening area, as this dimension is fundamental to identification of mitral stenosis. Objective: To automate the process of determining the maximum mitral valve opening area, through the application of digital image processing (DIP) in echocardiography tests, developing an open algorithm with video reading in avi format. Method: This cross-sectional observational pilot study was conducted with 25 different echocardiography exams, 15 with normal aperture and 10 with rheumatic mitral stenosis. With the authorization of the Research Ethics Committee, all exams were performed and made available by 2 specialists who used 2 models of echocardiographic devices: Vivid E95 (GE Healthcare) and Epiq 7 (Philips), with multiplanar transesophageal probes. All videos in avi format were submitted to DIP using the image segmentation technique. Results: The measurements obtained manually by experienced echocardiographers and the values calculated by the developed system were compared using a Bland-Altman diagram. There was greater agreement between values in the range from 0.4 to 2.7 cm². Conclusion: It was possible to automatically determine the maximum mitral valve opening area, for cases from both GE and Philips, using only 1 video as input data. The algorithm has been demonstrated to save time on measurements when compared to the usual method. (AU)

Switching on prodrugs using radiotherapy.

Chemotherapy is a powerful tool in the armoury against cancer, but it is fraught with problems due to its global systemic toxicity. Here we report the proof of concept of a chemistry-based strategy, whereby gamma/X-ray irradiation mediates the activation of a cancer prodrug, thereby enabling simultaneous chemo-radiotherapy with radiotherapy locally activating a prodrug. In an initial demonstration, we show the activation of a fluorescent probe using this approach. Expanding on this, we show how sulfonyl azide- and phenyl azide-caged prodrugs of pazopanib and doxorubicin can be liberated using clinically relevant doses of ionizing radiation. This strategy is different to conventional chemo-radiotherapy radiation, where chemo-sensitization of the cancer takes place so that subsequent radiotherapy is more effective. This approach could enable site-directed chemotherapy, rather than systemic chemotherapy, with 'real time' drug decaging at the tumour site. As such, it opens up a new era in targeted and directed chemotherapy.

Establishment of a bladder cancer cell line expressing both mesenchymal and epithelial lineage-associated markers.

Several experimental models including patient biopsies, animal models, and cell lines have been recommended to study the mechanism of bladder cancer development. After several passages in culture, cell lines lose some original features, and no longer resemble the cells of their original tumor. This makes it necessary to establish various cell lines. In an attempt to establish a new cell line for bladder cancer, JAM-ICR (RRID: CVCL_A9QB) was derived from a 64-year-old man diagnosed with a high-grade tumor. This cell line was characterized in multiple experiments involving morphological studies, immunophenotyping (by immunohistochemistry and flow cytometry), karyotyping, short tandem repeat analysis, colony-forming assays, migration and invasion assays, and chemosensitivity to anti-cancer drugs. JAM-ICR cells are pale with an irregular polygonal shape, and show some similarities to mesenchymal stem cells but with a wider shape and shorter arms. Phenotypic assessment demonstrated the simultaneous expression of mesenchymal-(vimentin, desmin, CD29, CD90, and CD106) and epithelial lineage (pan-cytokeratin) markers, which supports a phenotype similar to epithelial-mesenchymal transition for this cell line. JAM-ICR displayed high metastatic potential and stem-like properties, i.e., self-renewal, colony forming, and the coexpression of TRA-1 with CD44 and CD166. Furthermore, this cell line was significantly more resistant to doxorubicin in comparison to the 5637 cell line. These features make JAM-ICR a new bladder cancer cell line with metastatic potential and stem-like properties, which may be potentially useful as a model to elucidate the molecular and cellular mechanisms of bladder cancer pathogenesis or evaluate new drugs.

In vitro irradiation of doxorubicin with 18F-FDG Cerenkov radiation and its potential application as a theragnostic system.

Doxorubicin (DOX), an effective chemotherapeutic agent, has a wide excitation band centred at 480 nm. Cerenkov radiation (CR) is considered an internal light source in photodynamic therapy (PDT). DOX could be photoactivated by CR and thus, enhancing its cytotoxicity. In this work, 18F-FDG was used to evaluate the effect of Cerenkov radiation on DOX, in comparison to irradiation with a 450-nm laser beam, in terms of ROS production. The production of 1O2 and O2⁎- reactive species during DOX irradiation was detected indirectly by ABMA and DCPIP bleaching, respectively. The cytotoxic effect of the DOX / 18F-FDG CR system was evaluated in the T47D breast cancer cell line. The irradiation of DOX produced 1O2 and O2⁎- species using both 18F-FDG CR and a 450-nm laser beam. The majority reactive species produced in both cases was 1O2; a favourable result, given the greater cytotoxicity of this species. The viability of T47D cells in presence of DOX (5 nM), 18F-FDG (37.5 µCi) and DOX (5 nM)/18F-FDG (37.5 µCi) was (86 ± 9)%, (84 ± 8)% and (64 ± 5)%, respectively; these results suggest a synergistic cytotoxic effect derived from the cytotoxic activity of DOX and its photoactivation by 18F-FDG CR. It is worth noting that the system could be optimized in terms of DOX concentration and 18F-FDG activity for better results. Due to the fact that 18F-FDG is widely used in nuclear imaging, the DOX/18F-FDG system also possesses theragnostic characteristics. Thus, in this work, it is demonstrated that DOX can be used in a dual therapy system based on chemotherapy-PDT when 18F-FDG CR is used as a DOX excitation source.

Doxorubicin-loaded PLGA nanoparticles for the chemotherapy of glioblastoma: Towards the pharmaceutical development.

Brain delivery of drugs by nanoparticles is a promising strategy that could open up new possibilities for the chemotherapy of brain tumors. As demonstrated in previous studies, the loading of doxorubicin in poly(lactide-co-glycolide) nanoparticles coated with poloxamer 188 (Dox-PLGA) enabled the brain delivery of this cytostatic that normally cannot penetrate across the blood-brain barrier in free form. The Dox-PLGA nanoparticles produced a very considerable anti-tumor effect against the intracranial 101.8 glioblastoma in rats, thus representing a promising candidate for the chemotherapy of brain tumors that warrants clinical evaluation. The objective of the present study, therefore, was the optimization of the Dox-PLGA formulation and the development of a pilot scale manufacturing process. Optimization of the preparation procedure involved the alteration of the technological parameters such as replacement of the particle stabilizer PVA 30-70 kDa with a presumably safer low molecular mass PVA 9-10 kDa as well as the modification of the external emulsion medium and the homogenization conditions. The optimized procedure enabled an increase of the encapsulation efficiency from 66% to >90% and reduction of the nanoparticle size from 250 nm to 110 nm thus enabling the sterilization by membrane filtration. The pilot scale process was characterized by an excellent reproducibility with very low inter-batch variations. The in vitro hematotoxicity of the nanoparticles was negligible at therapeutically relevant concentrations. The anti-tumor efficacy of the optimized formulation and the ability of the nanoparticles to penetrate into the intracranial tumor and normal brain tissue were confirmed by in vivo experiments.

Photo-oxidative degradation of doxorubicin with siloxane MOFs by exposure to daylight.

Doxorubicin (DOX) is a chemotherapeutic agent from anthracycline class, which acts unselectively on all cells; thus, it may have genotoxic and/or mutagenic effects and cause serious environmental problems. Herein, the decomposition of a diluted solution of DOX hydrochloride for injection has been investigated under photo-oxidative conditions, in ambient light and without pH modification, using hydrogen peroxide as oxidizing agent and hydrophobic siloxane-based metal-organic frameworks (MOFs) as heterogeneous catalysts. The kinetics of the photodegradation process was followed by UV-Vis spectroscopy and by ESI-MS. According to UV-Vis data, two pseudo-first-order kinetic steps describe the process, with rate constants in the order of 10-3-10-2 min-1 for the rate-determining one. ESI-MS provided more accurate information, with a rate constant of 2.6 · 10-2 min-1 calculated from the variation of DOX ion abundance. Complete decomposition of DOX was achieved after 120 min in the shade and after only 20 min by exposure to sunlight. The analysis of the residual waters by mass spectrometry and 1D and 2D NMR spectroscopy showed complete disappearance of DOX in all cases, excluded any anthracycline species, which are destroyed in the tested conditions, and proved formation of an un-harmful compound-glycerol, while no trace of metal was detected by XRF. Preliminary data also showed decomposition of oxytetracycline in similar conditions. By this study, we bring into attention a less-addressed pollution issue and we propose a mild and effective method for the removal of drug emerging pollutants.

Photoactivatable Prodrug of Doxazolidine Targeting Exosomes.

Natural lipid nanocarriers, exosomes, carry cell-signaling materials such as DNA and RNA for intercellular communications. Exosomes derived from cancer cells contribute to the progression and metastasis of cancer cells by transferring oncogenic signaling molecules to neighboring and remote premetastatic sites. Therefore, applying the unique properties of exosomes for cancer therapy has been expected in science, medicine, and drug discovery fields. Herein, we report that an exosome-targeting prodrug system, designated MARCKS-ED-photodoxaz, could spatiotemporally control the activation of an exquisitely cytotoxic agent, doxazolidine (doxaz), with UV light. The MARCKS-ED peptide enters a cell by forming a complex with the exosomes in situ at its plasma membrane and in the media. MARCKS-ED-photodoxaz releases doxaz under near-UV irradiation to inhibit cell growth with low nanomolar IC50 values. The MARCKS-ED-photodoxaz system targeting exosomes and utilizing photochemistry will potentially provide a new approach for the treatment of cancer, especially for highly progressive and invasive metastatic cancers.

Extracellular vesicles based self-grown gold nanopopcorn for combinatorial chemo-photothermal therapy.

Here, we generated a popcorn-like gold nanostructure exploiting extracellular vesicles (EVs). EVs can first serve as the vehicle for chemotherapeutic drug doxorubicin (DOX). Taking advantages of EVs, gold nanoparticles can be then self-grown surrounding the EVs, assembling into popcorn-like nanostructure. The formulated nanopopcorn, consisting of self-grown gold nanoparticles and EVs encapsulated with DOX, retained the photothermal transduction from gold nanoparticle assemblies and cytotoxicity of DOX. Under external near infrared irradiation, gold nanopopcorn can produce hyperthermia to induce tumor ablation and trigger drug release, achieving combinatorial chemo-photothermal therapy. The nanoplatform demonstrated improved cellular internalization, controlled drug release, enhanced antitumor efficacy with tumor inhibitory rate up to 98.6% and reduced side effects. Our design of popcorn-like nanostructure will contribute a novel modality for facile and green synthesis of complex metal nanostructures exploiting natural properties of EVs for combinational therapy.

pH/NIR-responsive semiconducting polymer nanoparticles for highly effective photoacoustic image guided chemo-photothermal synergistic therapy.

Multifunctional drug delivery nanoplatform (PDPP3T@PSNiAA NPs) based on NIR absorbing semiconducting polymer nanoparticles for pH/NIR light-controllably regulated drug release has been successfully prepared. In this strategy, pH/thermal-sensitive multifunctional polymer polystyrene-b-poly(N-isopropylacrylamide-co-acrylic acid) (PSNiAA) was meticulously designed and synthesized using the reversible addition fragmentation chain transfer (RAFT) polymerization method. Furthermore, PSNiAA was used to functionalize diketopyrrolopyrrole-based semiconducting polymer (PDPP3T) to combine photothermal capacity and pH/thermo-responsive drug release in one entity. The prepared PDPP3T@PSNiAA NPs exhibited high photothermal conversion efficiency (η = 34.1%) and excellent photoacoustic (PA) brightness. Meanwhile, benefiting from the photothermal effect of PDPP3T and the pH/thermal-responsive properties of PSNiAA, Dox-loaded PDPP3T@PSNiAA NPs (PDPP3T@PSNiAA-Dox NPs) were able to controllably regulate the release of Dox by pH/NIR light, in which the enhanced drug release at acidic condition upon NIR irradiation phenomenon would minimize unnecessary drug release in normal tissues and was highly beneficial for precise synergistic chemo- and photothermal therapy.

PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy.

Graphene oxide (GO) owns huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological conditions. Chemical modification of GO with hydrophilicpolymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weights were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.

Focused Ultrasound Hyperthermia Mediated Drug Delivery Using Thermosensitive Liposomes and Visualized With in vivo Two-Photon Microscopy.

The future of nanomedicines in oncology requires leveraging more than just the passive drug accumulation in tumors through the enhanced permeability and retention effect. Promising results combining mild hyperthermia (HT) with lyso-thermosensitive liposomal doxorubicin (LTSL-DOX) has led to improved drug delivery and potent antitumor effects in pre-clinical studies. The ultimate patient benefit from these treatments can only be realized when robust methods of HT can be achieved clinically. One of the most promising methods of non-invasive HT is the use of focused ultrasound (FUS) with MRI thermometry for anatomical targeting and feedback. MRI-guided focused ultrasound (MRgFUS) is limited by respiratory motion and large blood vessel cooling. In order to translate exciting pre-clinical results to the clinic, novel heating approaches capable of overcoming the limitations on clinical MRgFUS+HT must be tested and evaluated on their ability to locally release drug from LTSL-DOX. Methods: In this work, a new system is described to integrate focused ultrasound (FUS) into a two-photon microscopy (2PM) setting to image the release of drug from LTSL-DOX in real-time during FUS+HT in vivo. A candidate scheme for overcoming the limitations of respiratory motion and large blood vessel cooling during MRgFUS+HT involves applying FUS+HT to 42°C in short ~30s bursts. The spatiotemporal drug release pattern from LTSL-DOX as a result is quantified using 2PM and compared against continuous (3.5min and 20min at 42°C) FUS+HT schemes and unheated controls. Results: It was observed for the first time in vivo that these short duration temperature elevations could produce substantial drug release from LTSL-DOX. Ten 30s bursts of FUS+HT was able to achieve almost half of the interstitial drug concentration as 20min of continuous FUS+HT. There was no significant difference between the intravascular area under the concentration-time curve for ten 30s bursts of FUS+HT and 3.5min of continuous FUS+HT. Conclusion: We have successfully combined 2PM with FUS+HT for imaging the release of DOX from LTSL-DOX in vivo in real-time, which will permit the investigation of FUS+HT heating schemes to improve drug delivery from LTSL-DOX. We have evaluated the ability to release DOX in short 30s FUS+HT bursts to 42°C as a method to overcome limitations on clinical MRgFUS+HT and have found that such exposures are capable of releasing measurable amounts of drug. Such an exposure has the potential to overcome limitations that hamper conventional MRgFUS+HT treatments in targets that are associated with substantial tissue motion.

Self-Assembled Upconversion Nanoparticle Clusters for NIR-controlled Drug Release and Synergistic Therapy after Conjugation with Gold Nanoparticles.

Fabricated three-dimensional (3D) upconversion nanoclusters (abbreviated as EBSUCNPs) are obtained via an emulsion-based bottom-up self-assembly of NaGdF4:Yb/Er@NaGdF4 nanoparticles (abbreviated as UCNPs), which comprise a NaGdF4:Yb/Er core and a NaGdF4 shell. The EBSUCNPs were then coated with a thin mesoporous amino-functionalized SiO2 shell (resulting in EBSUCNPs@SiO2 precursor) and further conjugated with gold nanoparticles to give the novel EBSUCNPs@SiO2@Au material. Finally, EBSUCNPs@SiO2@Au was applied as a biocompatible and efficient drug carrier for doxorubicin (DOX), thus giving rise to a multifunctional EBSUCNPs@SiO2-DOX@Au nanocomposite. This final material, EBSUCNPs@SiO2-DOX@Au, and the precursor nanoparticles, EBSUCNPs@SiO2@Au, were both fully characterized and their luminescence was investigated in detail. In addition, the drug release properties and photothermal effects of EBSUCNPs@SiO2-DOX@Au were also discussed. Interestingly, when under NIR irradiation, an increasing DOX release was achieved owing to the thermal effect of the Au NPs after absorbing the green light from the upconversion nanoclusters based on the fluorescence resonance energy transfer (FRET) effect. Thus, a near-infrared (NIR)-controlled "on-off" pattern of drug release behavior can be achieved. Moreover, compared with a single therapy method, the assembled nanocomposites exhibit a good synergistic therapy against cancer cells that combines chemotherapy with photothermal therapy. In addition, the in vitro fluorescence microscopy images of EBSUCNPs@SiO2-DOX@Au show a higher enhancement in the red region due to the loading of DOX molecules with respect to EBSUCNPs@SiO2@Au. Therefore, this novel multifunctional 3D cluster architecture can be used in the biomedical field after modification and may pave a new way in other application areas of UCNPs clusters.

Photo- and thermo-responsive multicompartment hydrogels for synergistic delivery of gemcitabine and doxorubicin.

Hydrogels have found promising applications in drug delivery due to their biocompatibility, high drug loading capability, and tunable release profiles. However, hydrogel-based carriers are primarily employed for delivering hydrophilic payloads while hydrophobic drugs cannot be efficiently delivered due to the lack of hydrophobic domains within conventional hydrogel matrices. Herein, we report that thermo- and photo-responsive hydrogels could be constructed from amphiphilic triblock copolymers, poly(N-isopropylacrylamide)-b-poly(4-acryloylmorpholine)-b-poly(2-((((2-nitrobenzyl)oxy)carbonyl) amino)ethyl methacrylate) (PNIPAM-b-PNAM-b-PNBOC), and the resulting hydrogels could be further engineered a new carrier for both hydrophilic gemcitabine (GCT) and hydrophobic doxorubicin (DOX). PNIPAM-b-PNAM-b-PNBOC triblock copolymers were first self-assembled into micelles with hydrophobic photosensitive PNBOC cores, hydrophilic PNAM inner shells, and thermoresponsive PNIPAM coronas below the lower critical solution temperature (LCST), while hydrogels of physically cross-linked micellar nanoparticles were achieved at elevated polymer concentrations and high temperatures above the critical gelation temperature (CGT). Rheological experiments revealed that the CGT was highly dependent on polymer compositions and concentrations, that is, a longer hydrophobic PNBOC block or a higher polymer concentration led to a decreased CGT. However, the CGT prior to UV irradiation (CGT0) could be drastically elevated after UV irradiation (CGTUV) as a result of UV irradiation-induced concurrently cross-linking and hydrophobic-to-hydrophilic transition within PNBOC cores. As such, gel-to-sol transition could be accomplished by either temperature decrease or exposure to UV irradiation at a fixed temperature lower than the CGTUV. Note that both GCT and DOX could be simultaneously encapsulated into the hydrogels due to the coexistence of extramicellar aqueous phase and hydrophobic micellar cores. Intriguingly, the subsequent co-release of GCT and DOX could be regulated by taking advantage of either temperature or UV irradiation-mediated gel-to-sol transitions.

Effect of High-Intensity Focused Ultrasound on Drug Release from Doxorubicin-Loaded PEGylated Liposomes and Therapeutic Effect in Colorectal Cancer Murine Models.

The goal of the study described here was to evaluate the use of high-intensity focused ultrasound (HIFU) in drug release and its application in cancer therapy. HIFU was set to minimize hyperthermia, particularly non-specific hyperthermia, of exposed areas. An in vitro temperature-sensitive hydrogel phantom model determined the parameters of HIFU under mild condition settings (spatial average temporal average intensity [ISATA] = 83.35 W/cm(2)). PEGylated liposomal indocyanine green (LCLP-ICG) and PEGylated liposomal doxorubicin (LCLP-Dox) were prepared with the same mole ratio to allow direct comparison of drug release in vitro and in vivo. We induced drug release with HIFU treatment using LCLP-ICG coupled with optical imaging in vitro and in vivo. The size distribution changes in LCLP-ICG in vitro and fluorescence intensity changes in ICG after intra-tumoral injection of LCLP-ICG into CT26 solid tumors in vivo followed by HIFU confirmed the feasibility of the system. We validated the therapeutic effect of HIFU treatment of the CT26 mouse tumor model. The tumor growth rate was significantly reduced (p < 0.05) only in the group administered LCLP-Dox followed by cycles of HIFU treatment, and the chemotherapy of the CT26 solid tumors was found to be highly efficient.

A hyaluronic acid nanogel for photo-chemo theranostics of lung cancer with simultaneous light-responsive controlled release of doxorubicin.

The combined delivery of photo- and chemo-therapeutic agents is an emerging strategy to overcome drug resistance in treating cancer, and controlled light-responsive drug release is a proven tactic to produce a continuous therapeutic effect for a prolonged duration. Here, a combination of light-responsive graphene, chemo-agent doxorubicin and pH-sensitive disulfide-bond linked hyaluronic acid form a nanogel (called a graphene-doxorubicin conjugate in a hyaluronic acid nanogel) that exerts an activity with multiple effects: thermo and chemotherapeutic, real-time noninvasive imaging, and light-glutathione-responsive controlled drug release. The nanogel is mono-dispersed with an average diameter of 120 nm as observed by using TEM and a hydrodynamic size analyzer. It has excellent photo-luminescence properties and good stability in buffer and serum solutions. Graphene itself, being photoluminescent, can be considered an optical imaging contrast agent as well as a heat source when excited by laser irradiation. Thus the nanogel shows simultaneous thermo-chemotherapeutic effects on noninvasive optical imaging. We have also found that irradiation enhances the release of doxorubicin in a controlled manner. This release synergizes therapeutic activity of the nanogel in killing tumor cells. Our findings demonstrate that the graphene-doxorubicin conjugate in the hyaluronic acid nanogel is very effective in killing the human lung cancer cell line (A549) with limited toxicity in the non-cancerous cell line (MDCK).

Near infrared light mediated release of doxorubicin using upconversion nanoparticles.

Lanthanide doped upconversion nanoparticles grafted with a photocaged analog of doxorubicin allow near IR-release of doxorubicin.

In vitro localized release of thermosensitive liposomes with ultrasound-induced hyperthermia.

Localized drug delivery with ultrasound-induced hyperthermia can enhance the therapeutic index of chemotherapeutic drugs by improving efficacy and reducing systemic toxicity. A novel in vitro method for the activation of drug-loaded thermosensitive liposomes is described. In particular, a dual-compartment, acoustically transparent container is used in which thermosensitive liposomes suspended in cell culture medium are immersed in a thermally absorptive medium, glycerol. Hyperthermia is induced with ultrasound in the glycerol, which in turn heats the culture medium by thermal conduction. The method approximately mimics the in vivo scenario of thermosensitive liposomes collected in the interstitial spaces of tumors, where ultrasound induces hyperthermia in the tumor tissue, which in turn heats the thermosensitive liposomes by conduction and induces release of the encapsulated drug. The acoustic conditions for the desired hyperthermia are derived theoretically and validated experimentally. Eighty percent release of doxorubicin from thermosensitive liposomes is achieved.

Free radicals generated by tantalum implants antagonize the cytotoxic effect of doxorubicin.

Little is known about the interaction between antineoplastic drugs and implants in bone cancer patients. We investigated the interaction between commercially available porous tantalum (Ta) implants and the chemotherapeutic drug, Doxorubicin (DOX). DOX solutions were prepared in the presence of Ta implant. The changes in fluorescence intensity of the DOX chromophore were measured by spectrofluorometry and the efficacy of DOX was evaluated by viability of rabbit rectal tumor cells (VX2). After 5 min interaction of the DOX solution (5 µg/ml) with the Ta implant, the fluorescent intensity of the DOX solution was 85% degraded, and only 20% the drug efficacy to kill VX2 cells was retained. However, after adding a reducing agent, Dithiothreitol (DTT, 10 µg/ml), 80% of the original fluorescence and 50% of the drug efficacy were restored while UV irradiation enhanced drug degradation in the presence of Ta implant. The action of DTT and UV irradiation indicated that reactive oxygen species (ROS) were involved in the drug degradation mechanism. We detected that Ta implants in aqueous medium produced hydroxyl radicals. Cells showed higher intracellular ROS activity when culture medium was incubated with the Ta implant prior to cell culture. It is concluded that the porous Ta implant antagonizes the cytotoxicity of DOX via ROS generation of the porous Ta implant.

Doxorubicin promotes transcriptional upregulation of Cdc25B in cancer cells by releasing Sp1 from the promoter.

Cdc25B phosphatases have a key role in G2/M cell-cycle progression by activating the CDK1-cyclinB1 complexes and functioning as important targets of checkpoints. Overexpression of Cdc25B results in a bypass of the G2/M checkpoint and illegitimate entry into mitosis. It can also cause replicative stress, which leads to genomic instability. Thus, fine-tuning of the Cdc25B expression level is critical for correct cell-cycle arrest in response to DNA damage. In response to genotoxic stress, Cdc25B is mainly regulated by post-transcriptional mechanisms affecting either Cdc25B protein stability or translation. Here, we show that upon DNA damage Cdc25B can be regulated at the transcriptional level. Although ionizing radiation downregulates Cdc25B in a p53-dependent pathway, doxorubicin transcriptionally upregulates Cdc25B in p53-proficient cancer cells. We show that in the presence of wild-type p53, doxorubicin activates the Cdc25B promoter by preventing the binding of Sp1 and increasing the binding of NF-Y on the Cdc25B promoter, thus preventing p53 from downregulating this promoter. Our results highlight the mechanistically distinct regulation of the three Cdc25 phosphatases by checkpoint signalling following doxorubicin treatment.

Enhancement of focused ultrasound with microbubbles on the treatments of anticancer nanodrug in mouse tumors.

Ultrasound sonication with microbubbles (MBs) has the potential to enhance the delivery of nanoparticles into the sonicated tumors. In this study, we investigated the feasibility of focused ultrasound (FUS) sonication with MBs to improve nanodrug delivery and tumor treatment. Tumor-bearing mice were first injected with MBs (SonoVue) intravenously, were then sonicated at the tumors with FUS sonication, and were finally injected with the PEGylated liposomal doxorubicin (DOX). The accumulation of DOX in tumors with time, the tumor growth responses for initial treated tumor size and DOX dosage, and the response for an additional sonication after DOX injection were studied. The results demonstrate that FUS sonication with MBs can significantly enhance DOX accumulation in the sonicated tumor at 24 hours after treatment. A significant hindrance to tumor growth is achieved for a small tumor with a low dose, whereas large tumors require a higher dose.