Oily core/amphiphilic polymer shell nanocapsules change the intracellular fate of doxorubicin in breast cancer cells

The aim of this work was to develop and test the in vitro biological activity of nanocapsules loaded with a doxorubicin (DOX) free base dissolved in a core of castor oil shelled by poly(methyl vinyl ether-co-maleic anhydride) conjugated to n-octadecylamine residues. This system was stable and monodisperse, with a hydrodynamic diameter of about 300 nm. These nanocapsules changed the intracellular distribution of DOX, from the nuclei to the cytoplasm, and exhibited higher toxicity towards cancer cells - 4T1 and MCF-7 - and significantly lower toxicity towards normal cells - NIH-3T3 and MCF-10A - in vitro. In conclusion, these nanocapsules are suitable DOX carriers, which remain to be studied in in vivo tumor models.

Organ burden of inhaled nanoceria in a 2-year low-dose exposure study: dump or depot?

No detailed information on in vivo biokinetics of CeO₂ nanoparticles (NPs) following chronic low-dose inhalation is available. The CeO₂ burden for lung, lung-associated lymph nodes, and major non-pulmonary organs, blood, and feces, was determined in a chronic whole-body inhalation study in female Wistar rats undertaken according to OECD TG453 (6 h per day for 5 days per week for a 104 weeks with the following concentrations: 0, 0.1, 0.3, 1.0, and 3.0 mg/m³, animals were sacrificed after 3, 12, 24 months). Different spectroscopy methods (ICP-MS, ion-beam-microscopy) were used for the quantification of organ burden and for visualization of NP distribution patterns in tissues. After 24 months of exposure, the highest CeO₂ lung burden (4.41 mg per lung) was associated with the highest aerosol concentration and was proportionally lower for the other groups in a dose-dependent manner. Imaging techniques confirmed the presence of CeO₂ agglomerates of different size categories within lung tissue with a non-homogenous distribution. For the highest exposure group, after 24 months in total 1.2% of the dose retained in the lung was found in the organs and tissues analyzed in this study, excluding lymph nodes and skeleton. The CeO₂ burden per tissue decreased from lungs > lymph nodes > hard bone > liver > bone marrow. For two dosage groups, the liver organ burden showed a low accumulation rate. Here, the liver can be regarded as depot, whereas kidneys, the skeleton, and bone marrow seem to be dumps due to steadily increasing NP burden over time.

Docetaxel-loaded solid lipid nanoparticles prevent tumor growth and lung metastasis of 4T1 murine mammary carcinoma cells

BACKGROUND

Metastasis causes the most breast cancer-related deaths in women. Here, we investigated the antitumor effect of solid lipid nanoparticles (SLN-DTX) when used in the treatment of metastatic breast tumors using 4T1-bearing BALB/c mice.

RESULTS

Solid lipid nanoparticles (SLNs) were produced using the high-energy method. Compritol 888 ATO was selected as the lipid matrix, and Pluronic F127 and Span 80 as the surfactants to stabilize nanoparticle dispersion. The particles had high stability for at least 120 days. The SLNs' dispersion size was 128 nm, their polydispersity index (PDI) was 0.2, and they showed a negative zeta potential. SLNs had high docetaxel (DTX) entrapment efficiency (86%), 2% of drug loading and showed a controlled drug-release profile. The half-maximal inhibitory concentration (IC₅₀) of SLN-DTX against 4T1 cells was more than 100 times lower than that of free DTX after 24 h treatment. In the cellular uptake test, SLN-DTX was taken into the cells significantly more than free DTX. The accumulation in the G2-M phase was significantly higher in cells treated with SLN-DTX (73.7%) than in cells treated with free DTX (23.0%), which induced subsequent apoptosis. TEM analysis revealed that SLN-DTX internalization is mediated by endocytosis, and fluorescence microscopy showed DTX induced microtubule damage. In vivo studies showed that SLN-DTX compared to free docetaxel exhibited higher antitumor efficacy by reducing tumor volume (p < 0.0001) and also prevented spontaneous lung metastasis in 4T1 tumor-bearing mice. Histological studies of lungs confirmed that treatment with SLN-DTX was able to prevent tumor. IL-6 serum levels, ki-67 and BCL-2 expression were analyzed and showed a remarkably strong reduction when used in a combined treatment.

CONCLUSIONS

These results indicate that DTX-loaded SLNs may be a promising carrier to treat breast cancer and in metastasis prevention.

Photodynamic therapy mediated by aluminium-phthalocyanine nanoemulsion eliminates primary tumors and pulmonary metastases in a murine 4T1 breast adenocarcinoma model

Photodynamic therapy (PDT) is effective in the treatment of different types of cancer, such as basal cell carcinoma and other superficial cancers. However, improvements in photosensitizer delivery are still needed, and the use of PDT against more deeply located tumors has been the subject of many studies. Thus, the goal of this study was to evaluate the efficacy of a nanoemulsion containing aluminium-phthalocyanine (AlPc-NE) as a mediator of photodynamic therapy (PDT-AlPc-NE) against grafted 4T1 breast adenocarcinoma tumors in mice (BALB/c). Short after the appearance of the tumor, the animals were divided into groups (n = 5) as follows: untreated; only AlPc-NE and treated with PDT-AlPc-NE. The tumor volume was measured with a digital calliper at specific times. The presence of metastasis in the lungs was evaluated by microtomography and histopathological analyses. The results show that the application of PDT-AlPc-NE eradicated the transplanted tumors in all the treated animals, while the animals from control groups presented a robust increase in the tumor volume. Still more significantly, microtomography showed the animals submitted the PDT-AlPc-NE to be free of detectable metastasis in the lungs. The histological analysis of the lungs further confirmed the results verified by the microtomography. Therefore, this study suggests that PDT-AlPc-NE is effective in the elimination of experimentally grafted breast tumors in mice and also in preventing the formation of metastasis in the lungs.

Nanocapsules for the co-delivery of selol and doxorubicin to breast adenocarcinoma 4T1 cells in vitro

Nanocapsules (NCS-DOX) with an oily core of selol and a shell of poly(methyl vinyl ether-co-maleic anhydride) covalently conjugated to doxorubicin were developed. These nanocapsules are spherical, with an average hydrodynamic diameter of about 170 nm, and with negative zeta potential. NCS-DOX effectively co-delivered the selol and the doxorubicin into 4T1 cells and changed the intracellular distribution of DOX from the nuclei to the mitochondria. Moreover, a significantly increased cytotoxicity against 4T1 cells was observed, which is suggestive of additive or synergic effect of selol and doxorubicin. In conclusion, PVM/MA nanocapsules are suitable platforms to co-deliver drugs into cancer cells.

High throughput toxicity screening and intracellular detection of nanomaterials

With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety—preferably using in vitro approaches, to avoid the ethical dilemmas associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read‐across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter‐experimental variation, and makes substantial savings in time and cost. HTS/HCA approaches facilitate the classification of key biological indicators of NM‐cell interactions. Validation of in vitroHTS tests is required, taking account of relevance to in vivo results. HTS/HCA approaches are needed to assess dose‐ and time‐dependent toxicity, allowing prediction of in vivo adverse effects. Several HTS/HCA methods are being validated and applied for NM testing in the FP7 project NANoREG, including Label‐free cellular screening of NM uptake, HCA, High throughput flow cytometry, Impedance‐based monitoring, Multiplex analysis of secreted products, and genotoxicity methods—namely High throughput comet assay, High throughput in vitro micronucleus assay, and γH2AX assay. There are several technical challenges with HTS/HCA for NM testing, as toxicity screening needs to be coupled with characterization of NMs in exposure medium prior to the test; possible interference of NMs with HTS/HCA techniques is another concern. Advantages and challenges of HTS/HCA approaches in NM safety are discussed. WIREs Nanomed Nanobiotechnol 2017, 9:e1413. doi: 10.1002/wnan.1413

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Neurofibromatosis and neural crest neoplasms: primary acquired melanosis and malignant melanoma of the conjunctiva

With an occurrence of approximately 1 in 3000 births, von Recklinghausen neurofibromatosis (NF) is one of the most common inherited human disorders. NF is considered a neurocristopathy, a disorder of neural crest derived cells. One of the complications of NF is the development of neural crest derived malignancies such as malignant schwannoma, pheochromocytoma, and malignant melanoma of the skin and choroid. The case history of a patient with NF and conjunctival malignant melanoma which developed in an eye with primary acquired melanosis is yet another example of a neural crest malignancy developing in a NF patient.

The effects of lidocaine on the canine ECG and electrophysiologic properties of Purkinje fibers

Effects of selected plasma lidocaine concentrations on the action potentials of isolated canine Purkinje fibers were studied with microelectrode techniques and a method for perfusing PF with the arterial blood of a normokalemic dog. Lidocaine was administered to the donor as an intravenous injection of 0.5 to 2.0 mg. per kilogram or as an intravenous infusion of 4 to 50 mug per kilogram per minute and plasma concentrations were determined by gas chromatography. At plasma lidocaine concentrations from 0.2 to 9.9 mug per milliliter no significant changes in donor arterial pressure, heart rate, or electrocardiographic P-R and QRS intervals occurred, and Purkinje fiber resting membrane potential was unchanged. Donor Q-T intervals were unchanged at lower lidocaine concentrations (up to 4.0 mug per milliliter) and decreased at higher levels (4.1 to 9.9 mug per milliliter). Purkinje fiber AP changes commenced in 2 to 3 minutes of lidocaine injection. At lower lidocaine levels AP amplitude, maximum slope of phase 0 depolarization (Vmax) AP duration, and effective refractory period decreased, membrane responsiveness was depressed, and automaticity of spontaneously firing Purkinje fibers decreased. These changes were accentuated at higher lidocaine concentrations. Conduction usually was unchanged or slowed at lower plasma lidocaine levels and slowed at higher concentrations. When ouabain-intoxicated preparations were studied, lidocaine exerted a depressant effect on the AP. These studies indicate that the mechanisms whereby therapeutic lidocaine concentrations may modify arrhythmias are not unlike those of other local anesthetics and include depression of Vmax, membrane responsiveness, and conduction.

Mechanisms of digitalis toxicity. Effects of ouabain on phase four of canine Purkinje fiber transmembrane potentials

Microelectrode technics were used to study effects of ouabain (O), 2x10 –7 moles/liter, on phase 4 of Purkinje fiber (PF) transmembrane potentials (TMP). Perfusion for 25-35 min with O caused an increase in phase 4 depolarization which resulted in either increased automaticity or occurrence of low-amplitude potentials (LAP). Increased automaticity was more frequent when PF had been stretched, when [K + ] o = 2.5 mmoles/liter, and when O caused a marked decrease in resting membrane potential (RMP). LAP occurred at all [K + ] o (2.5, 4.0, and 5.0 mmoles/liter), and were the typical response of unstretched fibers in which RMP had not decreased markedly. The magnitude of the LAP increased at [K + ] o = 4.0 mmoles/liter and at faster stimulus rates. Threshold potential (TP) was decreased to a slightly greater extent than RMP. Although LAP did not result in spontaneous action potentials, superimposition of subthreshold depolarizations on LAP resulted in excitation. Whether O-induced increases in phase 4 slope result in automaticity or LAP depends on interrelationships between RMP, TP, and level of membrane potential reached during phase 4. Although hearts developing LAP due to digitalis toxicity may not demonstrate increased automaticity, the presence of phase 4 depolarization in the form of LAP may cause an impairment of conduction which is dependent on cycle length.