Vincristine-doxorubicin co-loaded artificial low-density lipoproteins towards solid tumours.

To construct an artificial low-density lipoprotein (aLDL) that highly mimics low-density lipoprotein (LDL) in vivo, and deliver vincristine (VCR) - doxorubicin (DOX) simultaneously, the 100 nm and 35 nm DOX-VCR-aLDLs (DV-aLDLs) were constructed, then the physicochemical characteristics were evaluated. Through in vitro inverse gravity diffusion experiment, the tumour cake and sphere model experiment, draw a conclusion that the diffusion of 35 nm DV-aLDLs was stronger than 100 nm DV-aLDLs, and the tumour retention of 35 nm DV-aLDLs was better than the DV-solution. In addition, the three-dimension (3D) in vivo distribution imaging of aLDLs was performed on HepG-2 tumour-bearing nude mice, followed by the biodistribution and therapeutic efficacy on these xenograft models. Taking advantage of better diffusion capacity in tumour tissue, as well as the synergistic effect of VCR and DOX, the 35 nm DV-aLDL had the strongest efficacy and the lowest toxicity. High entrapment efficiency and stability, both active and passive targeting, making aLDL a potential carrier for tumour-targeted therapy at the same time.

A novel preparative method for nanoparticle albumin-bound paclitaxel with high drug loading and its evaluation both in vitro and in vivo.

We developed a novel preparative method for nanoparticle albumin-bound (nab) paclitaxel with high drug loading, which was based on improved paclitaxel solubility in polyethylene glycol (PEG) and self-assembly of paclitaxel in PEG with albumin powders into nanoparticles. That is, paclitaxel and PEG were firstly dissolved in ethanol, which was subsequently evaporated under vacuum. The obtained liquid was then mixed with human serum albumin powders. Thereafter, the mixtures were added into phosphate-buffered saline and nab paclitaxel suspensions emerged after ultrasound. Nab paclitaxel was finally acquired after dialysis and freeze drying. The drug loading of about 15% (W/V) were realized in self-made nab paclitaxel, which was increased by approximately 50% compared to 10% (W/V) in Abraxane. Now this new preparative method has been authorized to obtain patent from China and Japan. The similar characteristics of self-made nab paclitaxel compared to Abraxane were observed in morphology, encapsulation efficiency, in vitro release, X-ray diffraction analysis, differential scanning calorimetry analysis, and circular dichroism spectra analysis. Consistent concentration-time curves in rats, biodistributions in mice, anti-tumor activities in mice, and histological transmutation in mice were also found between Abraxane and self-made nanoparticles. In a word, our novel preparative method for nab paclitaxel can significantly improve drug loading, obviously decrease product cost, and is considered to have potent practical value.

Development and Evaluation of Ropivacaine Loaded Poly(Lactic-Co-Glycolic Acid) Microspheres with Low Burst Release.

BACKGROUND: The local anesthetic drugs, especially ropivacaine, were considered favorable analgesia for postoperative management because of their effective local pain relief and low adverse effects. However, the short half-life and the resulting in bolus doses lead to the indistinctive improvement of these drugs in postoperative pain relief. Therefore, the ropivacaine microspheres with sustained release and low initial burst release were anticipated. METHODS: Three methods including oil in water (O/W), water in oil in water (W/O/W), and solid in oil in water (S/O/W) emulsion solvent evaporation method were used to optimize the ropivacaine loaded PLGA microspheres. The microspheres were evaluated both in vitro and in rats. The in vitro-in vivo correlation (IVIVC) was also investigated. RESULTS: The microspheres prepared by O/W method showed more satisfactory properties and the microspheres used for evaluation were prepared by O/W method. The particle size, drug loading, encapsulation efficiency and burst release were 11.19±1.24 µm, 28.37±1.15%, 98.15±3.98%, and 10.96±5.37% for microspheres with PLGA of 12 kDa, and 6.64±0.61 µm, 19.62±0.89%, 92.74±4.21%, and 18.42±5.12% for microspheres with PLGA of 8 kDa, respectively. These microspheres were also injected into rats by subcutaneous, intramuscular and intraperitoneal route, respectively. It was indicated that the detectable concentration of ropivacaine could last for at least 20 days for both kinds of microspheres in spite of injection routes. The low burst releases at 1 d were also manifested in rats and they were 6.62%, 6.99%, 6.48% for the microspheres with PLGA of 12 kDa, and 4.72%, 4.33%, 4.48% for the microspheres with PLGA of 8 kDa by intraperitoneal, intramuscular and subcutaneous route, respectively. A linear relationship between the in vitro release and the in vivo adsorption of ropivacaine from microspheres was also established. CONCLUSION: The ropivacaine microspheres with sustained release and low burst release were acquired, which indicated that the postoperative pain relief might last longer and the side effects might get lower. Therefore, the ropivacaine microspheres prepared in this paper have great potential for clinical use.

Establishment and evaluation of a Beagle model of grade III pancreatic trauma.

Pancreatic trauma (PT) is a severe abdominal injury that is often combined with multiple organ injury. It is a severe disease that is difficult to diagnose and has a high mortality rate, particularly for grade III PT. The pathogenesis, disease progress and complications have not been fully investigated due to the lack of a reliable animal model. To address this, a Beagle model of grade III PT was established in the present study using a procedure involving rupture of the main pancreatic duct. Peripancreatic effusions and the degree of pancreatic damage were examined by routine ultrasound and contrast-enhanced ultrasound (CEUS). Also, ascites were collected for the examination of amylase and lipase levels, and whole blood samples were collected for the analysis of amylase, lipase, C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels in the serum. Urine samples were also collected for the examination of trypsinogen activation peptide (TAP). In addition, the pancreas was sectioned and stained with hematoxylin and eosin. In comparison with routine ultrasound, CEUS showed a large area of focal trauma, with a depth greater than half of the anteroposterior diameter of the pancreas, with a clear boundary, clear capsular rupture and trauma induced by active bleeding. The volume of ascites peaked at 48 h post-trauma and decreased thereafter. Amylase and lipase levels in the ascites were elevated at 24 h post-trauma and significantly decreased at 48 and 72 h post-trauma (P<0.01). In addition, serum amylase and lipase levels increased to peak levels at 48 h post-trauma and then decreased (P<0.05), while serum CRP, IL-6 and TNF-α levels peaked at 24 h post-trauma and then decreased (P<0.05). Urinary TAP levels also peaked at 24 h post-trauma and subsequently decreased (P<0.05). At 72 h post-trauma, the pancreatic cells were loosely distributed, with damaged acini, hyperchromatic nuclei and severe inflammatory cell invasion. These results indicated that the Beagle model of grade III PT was satisfactorily established, and that CEUS is potentially useful as an auxiliary diagnosis method for PT. This animal model may be useful for studying the pathogenesis, disease progress and complications of PT.

Development and Evaluation of High Bioavailable Sustained-Release Nimodipine Tablets Prepared with Monolithic Osmotic Pump Technology.

BACKGROUND: Frequent administration caused by short half-life and low bioavailability due to poor solubility and low dissolution rate limit the further application of poorly water-soluble nimodipine, although several new indications have been developed. To overcome these shortcomings, sophisticated technologies had to be used since the dose of nimodipine was not too low and the addition of solubilizers could not resolve the problem of poor release. OBJECTIVE: The purpose of this study was to obtain sustained and complete release of nimodipine with a simple and easily industrialized technology. METHODS: The expandable monolithic osmotic pump tablets containing nimodipine combined with poloxamer 188 and carboxymethylcellulose sodium were prepared. The factors affecting drug release including the amount of solubilizing agent, expanding agent, retarding agent in core tablet and porogenic agent in semipermeable film were optimized. The release behavior was investigated both in vitro and in beagle dogs. RESULTS: It was proved that the anticipant release of nimodipine could be realized in vitro. The sustained and complete release of nimodipine was also realized in beagles because the mean residence time of nimodipine from the osmotic pump system was longer and Cmax was lower than those from the sustained-release tablets in market while there was no difference in AUC(0-t) of the monolithic osmotic pump tablets and the sustained release tablets in market. CONCLUSION: It was reasonable to believe that the sustained and complete release of poorly watersoluble nimodipine could be realized by using simple expandable monolithic osmotic pump technology combined with surfactant.

An Accelerated Release Method of Risperidone Loaded PLGA Microspheres with Good IVIVC.

BACKGROUND: A long release period lasting several days or several weeks is always needed and thereby it is tedious and time consuming to screen formulations of such microspheres with so long release period and evaluate their release profiles in vitro with conventional long-term or "real-time" release method. So, an accelerated release testing of such system is necessary for formulation design as well as quality control purpose. The purpose of this study is to obtain an accelerated release method of risperidone loaded poly(lactic-co-glycolic acid) (PLGA) microspheres with good in vitro/in vivo correlation (IVIVC). METHODS: Two formulations of risperidone loaded PLGA microspheres used for evaluating IVIVC were prepared by O/W method. The accelerated release condition was optimized by investigating the effect of pH, osmotic pressure, temperature and ethanol concentration on the release of risperidone from microspheres and the in vitro accelerated release profiles of risperidone from PLGA microspheres were obtained under this optimized accelerated release condition. The plasma concentration of risperidone were also detected after subcutaneous injection of risperidone loaded microspheres to rats. The in vivo cumulative absorption profiles were then calculated using Wagner-Nelson model, Loo- Riegelman model and numerical convolution model, respectively. The correlation between in vitro accelerated release and in vivo cumulative absorption were finally evaluated with Least Square Method. RESULTS: It was shown that temperature and ethanol concentration significantly affected the release of risperidone from the microspheres while pH and osmotic pressure of release media slightly affected the release behavior of risperidone. The in vitro release of risperidone from microspheres were finally undergone in PBS (pH7.0, 300mosm) with 20% (V/V) ethanol at 45°C. The sustained and complete release of risperidone was observed in both formulations under the accelerated release condition although these two release profiles were dissimilar. The correlation coefficients (R2) of IVIVC were all above 0.95 and the slopes were all between 0.9564 and 1.1868 in spite of fitted model and microsphere formulation. CONCLUSION: An in vitro accelerated release method of risperidone microspheres with good IVIVC was established in this paper and this accelerated release method was supposed to have great potential in both in vivo performance prediction and quality control for risperidone loaded PLGA microspheres.

In vitro toxicity assessment of nanocrystals in tissue-type cells and macrophage cells.

Nanocrystals (NCs), a type of innovative material particle, are a potential drug delivery platform that aims to improve the bioavailability of hydrophobic drugs. However, due to the lack of consideration of their toxicity, existing studies have not investigated whether the nanoscale properties of NCs, such as particle sizes, may lead to NC-induced toxicity. Because of the disparity between the rapid development of NCs and the lack of studies regarding NC toxicity, the present study investigated possible NC toxicity and clarified the relationship between particle sizes and NC toxicity. RAW264.7 and HepG2 cells were chosen as representatives of macrophage cells and tissue-type cells, respectively. Monosodium urate NCs were used as a drug model. Different particle sizes of monosodium urate NCs were prepared using precipitation methods. Methyl tetrazolium, lactate dehydrogenase, oxidative stress and apoptosis/necrosis assays were then used to evaluate cell damage and recovery. The results showed that small NC particle sizes produced higher toxicity than larger ones. In immune cells, these cytotoxic effects were greater than in tissue cells. After removal of small NCs, tissue cell damage could be significantly reversed, while immune cells were only slightly restored. However, after removal of large NCs, both cell types had almost no recovery. In summary, despite conventional wisdom, our research confirmed that NCs are not very safe and that NC particle sizes are closely related to the degree of NC toxicity.

Vincristine liposomes with smaller particle size have stronger diffusion ability in tumor and improve tumor accumulation of vincristine significantly.

The passive targeting is the premise of active targeting that could make nanocarrier detained in tumor tissue. The particle size is the most important factor that influences the diffusion and distribution of nanoparticle both in vivo and in vitro. In order to investigate the relationship between particle size and diffusion ability, two kinds of liposome loaded with Vincristine (VCR-Lip) were prepared. The diffusion behavior of VCR-Lip with different particle size and free VCR was compared through diffusion stability study. The diffusion ability from 12-well culture plate to Millipore transwell of each formulation reflected on HepG-2 cytotoxicity results. Different cell placement methods and drug adding positions were used to study the VCR-Lip diffusion behaviors, which influenced the apoptosis of HepG-2 cell. The different cell uptake of Nile red-Lip and free Nile red was compared when changed the adding way of fluorescent fluorescein. To study the penetration ability in HepG-2 tumor spheroids, we constructed 30 nm and 100 nm Cy5.5-Lip to compare with free Cy5.5. Then the anti-tumor effect, tissue distribution of free VCR injection, 30 nm and 100 nm VCR-Lip were further investigated on the HepG-2 tumor bearing nude mice. The results of these study showed that the diffusion ability of free drug and fluorescent fluorescein was remarkable stronger than which encapsulated in liposomes. Moreover, diffusion ability of smaller liposome was stronger than larger one. In this way, 30 nm liposome had not only faster and stronger tumor distribution than 100 nm liposome, but also higher tumor drug accumulation than free drug as well. Our study provided a new thinking to improve the targeting efficiency of nano drug delivery system, no matter passive or active targeting.

Simultaneous determination of metolazone and valsartan in plasma by on-line SPE coupled with liquid chromatography/tandem mass spectrometry.

Combination of metolazone (0.5 mg) and valsartan (80 mg) has been verified as a promising therapy treatment for hypertension. In order to facilitate to pharmacokinetic research, it needs a method for the simultaneously determination of metolazone and valsartan in biological samples. However, there are no relative reports so far. In order to facilitate to pharmacokinetic research, an on-line solid phase extraction coupled with liquid chromatography-tandem mass spectrometry method for the simultaneous determination of metolazone and valsartan in beagle dog plasma was developed and validated in this study. An on-line solid phase extraction column Retain PEP Javelin (10 mm × 2.1 mm) was used to remove impurities in plasma samples. The metolazone, valsartan and internal standard (losartan) were separated on a Poroshell 120 SB-C18 column (4.6 mm × 50 mm × 2.7 µm) with a gradient elution procedure. Acidified acetonitrile/water mixture was used as a mobile phase. The selected multiple-reaction monitoring mode in positive ion was performed and the parent to the product transitions m/z 366/259, m/z 436.2/291 and m/z 423.4/207 were used to measure the metolazone, valsartan and losartan. The method was linear over the range of 0.1-100 ng/mL and 1-1000 ng/mL for metolazone and valsartan, respectively. This method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability and then successfully applied to pharmacokinetic studies of the metolazone and valsartan combination tablets in beagle dogs.

Dual Tumor-Targeting Nanocarrier System for siRNA Delivery Based on pRNA and Modified Chitosan.

Highly specific and efficient delivery of siRNA is still unsatisfactory. Herein, a dual tumor-targeting siRNA delivery system combining pRNA dimers with chitosan nanoparticles (CNPPs) was designed to improve the specificity and efficiency of siRNA delivery. In this dual delivery system, folate-conjugated and PEGylated chitosan nanoparticles encapsulating pRNA dimers were used as the first class of delivery system and would selectively deliver intact pRNA dimers near or into target cells. pRNA dimers simultaneously carrying siRNA and targeting aptamer, the second class of delivery system, would specifically deliver siRNA into the target cells via aptamer-mediated endocytosis or proper particle size. To certify the delivering efficiency of this dual system, CNPPs, pRNA dimers alone, chitosan nanoparticles containing siRNA with folate conjugation and PEGylation (CNPS), and chitosan nanoparticles containing pRNA dimers alone (CN) were first prepared. Then, we observed that treatment with CNPPs resulted in increased cellular uptake, higher cell apoptosis, stronger cell cytotoxicity, and more efficacious gene silencing compared to the other three formulations. Higher accumulation of siRNA in the tumor site, stronger tumor inhibition, and longer circulating time were also observed with CNPPs compared to other formulations. In conclusion, this dual nanocarrier system showed high targeting and favorable therapeutic efficacy both in vitro and in vivo. Thereby, a new approach is provided in this study for specific and efficient delivery of siRNA, which lays a foundation for the development of pRNA hexamers, which can simultaneously carry six different substances.

Simultaneous Determination of Felodipine and Metoprolol in Beagle Dog Plasma by Online SPE-LC-MS/MS and Its Application in a Pharmacokinetic Study.

In order to overcome deficiencies for simultaneously determining felodipine (FDP) and metoprolol (MPL) with low recovery and low sensitivity, a new online SPE coupled with the liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method for the simultaneous quantitative determination of FDP and MPL in beagle dog plasma was established. The SPE extraction of FDP and MPL was performed on a Retain PEP Javelin column (10 × 2.1 mm, 5 µm), while the chromatographic separation was achieved on a ZORBAX SB-C18 (50 × 2.1 mm, 3.5 µm) analytical column. Multiple reaction monitoring operated in the positive ion mode was adopted in MS detection, and the precursors to the product ion transition values of m/z 384/338.1, 268/74.2 and 436.2/207.1 were used to measure FDP, MPL and the internal standard (valsartan). The high throughput, accurate and sensitive method for FDP and MPL was validated and applied to the bioavailability research of FDP and MPL in beagle dogs.

Dual-modified liposome codelivery of doxorubicin and vincristine improve targeting and therapeutic efficacy of glioma.

Therapeutic outcome for the treatment of glioma was often limited due to drug resistance and low permeability of drug across the multiple physiological barriers, including the blood-brain barrier (BBB), and the blood-tumor barrier (BTB). In order to overcome these hurdles, we designed T7 and DA7R dual peptides-modified liposomes (abbreviated as T7/DA7R-LS) to efficiently co-delivery doxorubicin (DOX) and vincristine (VCR) to glioma in this study. T7 is a seven-peptide ligand of transferrin receptors (TfR) capable of circumventing the BBB and then targeting glioma. DA7R is a d-peptide ligand of vascular endothelial growth factor receptor 2 (VEGFR 2) overexpressed on angiogenesis, presenting excellent glioma-homing property. By combining the dual-targeting delivery effect, the dual-modified liposomes displayed higher glioma localization than that of single ligand-modified liposomes or free drug. After loading with DOX and VCR, T7/DA7R-LS showed the most favorable antiglioma effect in vivo. In conclusion, this dual-targeting, co-delivery strategy provides a potential method for improving brain drug delivery and antiglioma treatment efficacy.

Apoferritin Nanocage for Brain Targeted Doxorubicin Delivery.

An ideal brain-targeted nanocarrier must be sufficiently potent to penetrate the blood-brain barrier (BBB) and sufficiently competent to target the cells of interest with adequate optimized physiochemical features and biocompatibility. However, it is an enormous challenge to the researchers to organize the above-mentioned properties into a single nanocarrier particle. New frontiers in nanomedicine are advancing the research of new biomaterials. Herein, we demonstrate a straightforward strategy for brain targeting by encapsulating doxorubicin (DOX) into a naturally available and unmodified apoferritin nanocage (DOX-loaded APO). APO can specifically bind to cells expressing transferrin receptor 1 (TfR1). Because of the high expression of TfR1 in both brain endothelial and glioma cells, DOX-loaded APO can cross the BBB and deliver drugs to the glioma with TfR1. Subsequent research demonstrated that the DOX-loaded APO had good physicochemical properties (particle size of 12.03 ± 0.42 nm, drug encapsulation efficiency of 81.8 ± 1.1%) and significant penetrating and targeting effects in the coculture model of bEnd.3 and C6 cells in vitro. In vivo imaging revealed that DOX-loaded APO accumulated specifically in brain tumor tissues. Additionally, in vivo tumor therapy experiments (at a dosage of 1 mg/kg DOX) demonstrated that a longer survival period was observed in mice that had been treated with DOX-loaded APO (30 days) compared with mice receiving free DOX solution (19 days).

Chiral analysis of ammuxetine enantiomers in dog plasma using online SPE/liquid chromatography with tandem mass spectrometric detection after precolumn chiral derivatization.

Ammuxetine (AMT), a novel chiral antidepressant candidate compound, exhibits better antidepression effects than duloxetine in different animal models. In this article, a chiral derivatization method, combined with online solid phase extraction (online SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed for the chiral separation of AMT enantiomers after administration of racemic AMT to dogs. The derivatization reaction employed 2,3,4,6-tetra-O-acetyl-b-glucopyr-anosyl isothiocyanate (GITC) as a precolumn chiral derivatization reagent. A SPE column Retain PEP Javelin (10 × 2.1 mm) was used to remove proteins and other impurities in plasma samples. The enantiomeric derivatives were separated on a ZORBAX SB-C18 column (50 × 2.1 mm × 3.5 µm) with an isocratic elution procedure. The selected multiple reaction monitoring mode of the positive ion was performed and the parent to the product transitions m/z 681.0/543.1 and m/z 687.4/543.1 were used to measure the derivatives of AMT and duloxetine (internal standard) with electrospray ionization. The method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability. The method was applied to a pharmacokinetics study of AMT racemate in dogs. The results suggested that the pharmacokinetic of AMT enantiomers might be stereoselective in dogs.

Protection Provided by a Gabexate Mesylate Thermo-Sensitive In Situ Gel for Rats with Grade III Pancreatic Trauma.

BACKGROUND/AIMS: This study investigated the protection provided by gabexate mesylate thermo-sensitive in-situ gel (GMTI) against grade III pancreatic trauma in rats. METHODS: A grade III pancreatic trauma model with main pancreatic duct dividing was established, and the pancreas anatomical diagram, ascites, and serum biochemical indices, including amylase, lipase, C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α), were examined. The pancreas was sliced and stained with hematoxylin eosin and subjected to terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. RESULTS: Ascites, serum amylase, lipase, CRP, IL-6, and TNF-α levels were significantly increased in the pancreas trauma (PT) groups with prolonged trauma time and were significantly decreased after GMTI treatment. The morphological structure of the pancreas was loose, the acinus was significantly damaged, the nuclei were irregular and hyperchromatic, and there was inflammatory cell invasion in the PT group compared to the control. After GMTI treatment, the morphological structure of the pancreas was restored, and the damaged acinus and inflammatory cell invasion were decreased compared to the PT group. Moreover, the cell apoptosis index was significantly increased in the PT group and restored to the same levels as the control group after GMTI treatment. CONCLUSIONS: GMTI, a novel formulation and drug delivery method, exhibited specific effective protection against PT with acute pancreatitis therapy and has potential value as a minimally invasive adjuvant therapy for PT with acute pancreatitis.

Thermal and magnetic dual-responsive liposomes with a cell-penetrating peptide-siRNA conjugate for enhanced and targeted cancer therapy.

Due to the absence of effective in vivo delivery systems, the employment of small interfering RNA (siRNA) in the clinic has been hindered. Here, we describe a novel siRNA targeting system that combines features of biological (cell-permeable peptides, CPPs) and physical (magnetic) siRNA targeting for use in magnetic hyperthermia-triggered release. A siRNA-CPPs conjugate (siRNA-CPPs) was loaded into thermal and magnetic dual-responsive liposomes (TML) (siRNA-CPPs/TML), and in vitro siRNA-CPPs thermosensitive release activity, targeted cellular uptake, gene silencing efficiency, in vivo targeted delivery and in vivo antitumor activity were determined. The results demonstrated that siRNA-CPPs/TML exhibited good physicochemical properties, effective cellular uptake, endosomal escape and a significant gene silencing efficiency in MCF-7 cells in vitro. Additionally, in the in vivo study, siRNA-CPPs/TML under an alternating current (AC) magnetic field displayed a superior in vivo targeted delivery efficacy, antitumor efficacy and gene silencing efficiency in a MCF-7 xenograft murine model. In conclusion, the application of siRNA-CPPs/TML under an AC magnetic field represents a new strategy for the selective and efficient delivery of siRNA.

Preparation and Evaluation of Oxaliplatin Thermosensitive Liposomes with Rapid Release and High Stability.

Oxaliplatin (OXP) was reported to show low anti-tumor activity when used alone and to display side effects; this low activity was attributed to high partitioning to erythrocytes and low accumulation in tumors. Thermosensitive liposomes (TSL) were considered able to specifically deliver drugs to heated tumors and to resolve the OXP distribution problem. Regretfully, TSL encapsulating doxorubicin did not demonstrate significant improvement in progression-free survival. Drug release below 41°C and significant leakage were considered major reasons for the failure. The purpose of this study was to acquire OXP TSL with rapid release at the triggered temperature and high stability at body temperature and at storage temperatures. A small quantity of poloxamer 188 was introduced into the TSL formulation to stabilize the encapsulated drug. It was shown that the addition of poloxamer 188 had no influence on the TSL characteristics. More than 90% of OXP was released within 10 min at 42°C, and less than 15% was released within 60 min at temperatures below 39°C. TSL were stable at 37°C for 96 h and at 4°C for 6 months. The anti-tumor activity of TSL at the dose of 2.5 mg/kg was certified to be equal to those of OXP injection and non-thermosensitive liposomes (NTSL) at the dose of 5 mg/kg, and significant improvement of tumor inhibition was observed in TSL compared with injection and NTSL at the same dose. It was also shown from the histological transmutation of tumors that TSL had stronger anti-tumor activity. Therefore, it could be concluded that TSL composed of a proper amount of poloxamer had rapid release and high stability, and OXP TSL would be anticipated to exert prominent anti-tumor activity in the clinic.

Polymer Nanoparticles Modified with Photo- and pH-Dual-Responsive Polypeptides for Enhanced and Targeted Cancer Therapy.

The cationic nature of cell penetrating peptides (CPPs) and their absence of cell selectivity restrains their applications in vivo. In this work, polymer nanoparticles (NPs) modified with photo- and pH-responsive polypeptides (PPPs) were successfully developed and respond to near-infrared (NIR) light illumination at the tumor site and a lowered tumor extracellular pH (pHe). In PPPs, the internalization function of CPPs (positively charged) is quenched by a pH-sensitive inhibitory peptide (negatively charged), which is linked via a photocleavable group. Small interfering RNA (siRNA) was loaded into NPs by a double-emulsion technique. In vivo experiments included siRNA loading, cellular uptake, cell apoptosis, siRNA transfection, tumor targeting delivery, and the in vivo antitumor efficacy. Results showed that the prepared PPP-NPs could selectively accumulate at the tumor sites and internalized into the tumor cells by the NIR light illumination and the lowered pHe at the tumor site. These studies demonstrated that PPP-NPs are a promising carrier for future tumor gene delivery.

Thermo-Sensitive Liposome co-Loaded of Vincristine and Doxorubicin Based on Their Similar Physicochemical Properties had Synergism on Tumor Treatment.

PURPOSE: To develop vincristine (VCR) and doxorubicin (DOX) co-encapsulated thermo-sensitive liposomes (VD-TSL) against drug resistance, with increased tumor inhibition rate and decreased system toxicity, improving drug targeting efficiency upon mild hyperthermia (HT) in solid tumor. METHODS: Based on similar physicochemical properties, VCR and DOX were co-loaded in TSL with pH gradient active loading method and characterized. The time-dependent drug release profiles at 37 and 42°C were assessed by HPLC. Then we analysed the phospholipids in filtrate after ultrafiltration and studied VD-TSL stability in mimic in vivo conditions and long-time storage conditions (4°C and -20°C). Cytotoxic effect was studied on PANC and sw-620 using MTT. Intracellular drug delivery was studied by confocal microscopy on HT-1080. In vivo imaging of TSL pharmacokinetic and biodistribution was performed on MCF-7 tumor-bearing nude mice. And therapeutic efficacy on these xenograft models were followed under HT. RESULTS: VD-TSL had excellent particle distribution (about 90 nm), high entrapment efficiency (>95%), obvious thermo-sensitive property, and good stability. MTT proved VD-TSL had strongest cell lethality compared with other formulations. Confocal microscopy demonstrated specific accumulation of drugs in tumor cells. In vivo imaging proved the targeting efficiency of TSL under hyperthermia. Then therapeutic efficacy revealed synergism of VCR and DOX co-loaded in TSL, together with HT. CONCLUSION: VD-TSL could increase drug efficacy and decrease system toxicity, by making good use of synergism of VCR and DOX, as well as high targeting efficiency of TSL.