Wen-Guo Wu

Preparation and in vitro antitumor effects of cytosine arabinoside-loaded genipin-poly-l-glutamic acid-modified bacterial magnetosomes

To solve the problem of synthesized magnetic nanoparticles in cancer therapy, a new drug delivery system synthesized from bacteria was used to load cytosine arabinoside (Ara-C). Genipin (GP) and poly-l-glutamic acid (PLGA) were selected as dual cross-linkers. The preparation and characterization of Ara-C-loaded GP-PLGA-modified bacterial magnetosomes (BMs) (ABMs-P), as well as their in vitro antitumor effects, were all investigated. Transmission electron micrographs (TEM) and Fourier transform infrared (FTIR) spectroscopy suggested that Ara-C could be bound to the membrane of BMs modified by GP-PLGA. The diameters of the BMs and ABMs-P were 42.0±8.6 nm and 74.9±8.2 nm, respectively. The zeta potential revealed that the nanoparticles were stable. Moreover, this system exhibited optimal drug-loading properties and long-term release behavior. The optimal encapsulation efficiency and drug-loading were 64.1%±6.6% and 38.9%±2.4%, respectively, and ABMs-P could effectively release 90% Ara-C within 40 days, without the release of an initial burst. In addition, in vitro antitumor experiments elucidated that ABMs-P is cytotoxic to HL-60 cell lines, with an inhibition rate of 95%. The method of coupling drugs on BMs using dual cross-linkers is effective, and our results reveal that this new system has potential applications for drug delivery in the future.

Construction of a Novel Magnetic Targeting Anti-Tumor Drug Delivery System: Cytosine Arabinoside-Loaded Bacterial Magnetosome

To ease the side effects triggered by cytosine arabinoside (Ara-C) for acute leukemia treatment, a novel magnetic targeting anti-tumor drug delivery system was constructed through bacterial magnetosomes (BMs) from Magnetospirillum magneticum AMB-1 combined with Ara-C by crosslinking of genipin (GP). The results showed that Ara-C could be bonded onto the membrane surface of BMs effectively through chemical crosslinking induced by dual hand reagents GP. The average diameters of BMs and Ara-C-coupled BMs (ABMs) were 42.0 ± 8.6 and 72.7 ± 6.0 nm respectively, and the zeta potentials (−38.1 ± 9.1) revealed that these systems were stable, confirming the stability of the system. The optimal encapsulation efficiency and drug loading were 89.05% ± 2.33% and 47.05% ± 0.64% respectively when crosslinking reaction lasted for 72 h. The system also presented long-term stability and release behaviors without initial burst release (Ara-C could be released 80% within three months). Our results indicate that BMs have great potential in biomedical and clinical fields as a novel anti-tumor drug carrier.

The in vitro and in vivo anti-tumor effects of MTX-Fe3O4-PLLA-PEG-PLLA microspheres prepared by suspension-enhanced dispersion by supercritical CO2

The in vitro and in vivo anti-tumor efficacy of methotrexate-loaded Fe3O4-poly-L-lactide-poly(ethylene glycol)-poly-L-lactide magnetic composite microspheres (MTX-Fe3O4-PLLA-PEG-PLLA MCMs, MMCMs), which were produced by co-precipitation (C) and microencapsulation (M) in a supercritical process, was evaluated at various levels: cellular, molecular, and integrated. The results at the cellular level indicate that MMCMs (M) show a better anti-proliferation activity than raw MTX and could induce morphological changes of cells undergoing apoptosis. At the molecular level, MMCMs (M) lead to a significantly higher relative mRNA expression of bax/bcl-2 and caspase-3 than MMCMs (C) at 10 μg mL−1 (P<0.01); and the pro-caspase-3 protein expression measured by Western blot analysis also demonstrates that MMCMs (M) can effectively activate pro-caspase-3. At the integrated level, mice bearing a sarcoma-180 tumor are used; in vivo anti-tumor activity tests reveal that MMCMs (M) with magnetic induction display a much higher tumor suppression rate and lower toxicity than raw MTX. Pharmacokinetic studies show that MMCMs (M) with magnetic induction significantly increase the accumulation of MTX in the tumor tissue compared with the other treatments. These results suggest that the MMCMs (M) prepared by the SpEDS process have great potential to play a positive role in the magnetic targeted therapy field.

Preparation of Chitosan-Based Hemostatic Sponges by Supercritical Fluid Technology

Using ammonium bicarbonate (AB) particles as a porogen, chitosan (CS)-based hemostatic porous sponges were prepared in supercritical carbon dioxide due to its low viscosity, small surface tension, and good compatibility with organic solvent. Fourier transform infrared spectroscopy (FTIR) spectra demonstrated that the chemical compositions of CS and poly-(methyl vinyl ether-co-maleic anhydride) (PVM/MA) were not altered during the phase inversion process. The morphology and structure of the sponge after the supercritical fluid (SCF) process were observed by scanning electron microscopy (SEM). The resulting hemostatic sponges showed a relatively high porosity (about 80%) with a controllable pore size ranging from 0.1 to 200 μm. The concentration of PVM/MA had no significant influence on the porosity of the sponges. Comparative experiments on biological assessment and hemostatic effect between the resulting sponges and Avitene® were also carried out. With the incorporation of PVM/MA into the CS-based sponges, the water absorption rate of the sponges increased significantly, and the CS-PVM/MA sponges showed a similar water absorption rate (about 90%) to that of Avitene®. The results of the whole blood clotting experiment and animal experiment also demonstrated that the clotting ability of the CS-PVM/MA sponges was similar to that of Avitene®. All these results elementarily verified that the sponges prepared in this study were suitable for hemostasis and demonstrated the feasibility of using SCF-assisted phase inversion technology to produce hemostatic porous sponges.

Codelivery of paclitaxel and small interfering RNA by octadecyl quaternized carboxymethyl chitosan-modified cationic liposome for combined cancer therapy

Conventional therapeutic approaches for cancer are limited by cancer cell resistance, which has impeded their clinical applications. The main goal of this work was to investigate the combined antitumor effect of paclitaxel with small interfering RNA modified by cationic liposome formed from modified octadecyl quaternized carboxymethyl chitosan. The cationic liposome was composed of 3β-[N-(N′, N′-dimethylaminoethane)-carbamoyl]-cholesterol, dioleoylphosphatidylethanolamine, and octadecyl quaternized carboxymethyl chitosan. The cationic liposome properties were characterized by Fourier transform infrared spectroscopy, dynamic light scattering and zeta potential measurements, transmission electron microscopy, atomic force microscopy, and gel retardation assay. The cationic liposome exhibited good properties, such as a small particle size, a narrow particle size distribution, a good spherical shape, a smooth surface, and a good binding ability with small interfering RNA. Most importantly, when combined with paclitaxel and small interfering RNA, the composite cationic liposome induced a great enhancement in the antitumor activity, which showed a significantly higher in vitro cytotoxicity in Bcap-37 cells than liposomal paclitaxel or small interfering RNA alone. In conclusion, the results indicate that cationic liposome could be further developed as a codelivery system for chemotherapy drugs and therapeutic small interfering RNAs.

Study of Lysozyme-Loaded Poly-L-Lactide (PLLA) Porous Microparticles in a Compressed CO2 Antisolvent Process

Lysozyme (LSZ)-loaded poly-L-lactide (PLLA) porous microparticles (PMs) were successfully prepared by a compressed CO2 antisolvent process in combination with a water-in-oil emulsion process using LSZ as a drug model and ammonium bicarbonate as a porogen. The effects of different drug loads (5.0%, 7.5% and 10.0%) on the surface morphology, particle size, porosity, tapped density and drug release profile of the harvested PMs were investigated. The results show that an increase in the amount of LSZ added led to an increase in drug load (DL) but a decrease in encapsulation efficiency. The resulting LSZ-loaded PLLA PMs (LSZ-PLLA PMs) exhibited a porous and uneven morphology, with a density less than 0.1 g·cm−3, a geometric mean diameter of 16.9–18.8 μm, an aerodynamic diameter less than 2.8 μm, a fine particle fraction (FPF) of 59.2%–66.8%, and a porosity of 78.2%–86.3%. According to the results of differential scanning calorimetry, the addition of LSZ improved the thermal stability of PLLA. The Fourier transform infrared spectroscopy analysis and circular dichroism spectroscopy measurement reveal that no significant changes occurred in the molecular structures of LSZ during the fabrication process, which was further confirmed by the evaluation of enzyme activity of LSZ. It is demonstrated that the emulsion-combined precipitation with compressed antisolvent (PCA) process could be a promising technology to develop biomacromolecular drug-loaded inhalable carrier for pulmonary drug delivery.

A novel controlled release formulation of the Pin1 inhibitor ATRA to improve liver cancer therapy by simultaneously blocking multiple cancer pathways

Abstract Hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths worldwide largely due to lack of effective targeted drugs to simultaneously block multiple cancer‐driving pathways. The identification of all‐trans retinoic acid (ATRA) as a potent Pin1 inhibitor provides a promising candidate for HCC targeted therapy because Pin1 is overexpressed in most HCC and activates numerous cancer‐driving pathways. However, the efficacy of ATRA against solid tumors is limited due to its short half‐life of 45 min in humans. A slow‐releasing ATRA formulation inhibits solid tumors such as HCC, but can be used only in animals. Here, we developed a one‐step, cost‐effective route to produce a novel biocompatible, biodegradable, and non‐toxic controlled release formulation of ATRA for effective HCC therapy. We used supercritical carbon dioxide process to encapsulate ATRA in largely uniform poly L‐lactic acid (PLLA) microparticles, with the efficiency of 91.4% and yield of 68.3%, and ˜ 4‐fold higher Cmax and AUC over the slow‐releasing ATRA formulation. ATRA‐PLLA microparticles had good biocompatibility, and significantly enhanced the inhibitory potency of ATRA on HCC cell growth, improving IC50 by over 3‐fold. ATRA‐PLLA microparticles exerted its efficacy likely through degrading Pin1 and inhibiting multiple Pin1‐regulated cancer pathways and cell cycle progression. Indeed, Pin1 knock‐down abolished ATRA inhibitory effects on HCC cells and ATRA‐PLLA did not inhibit normal liver cells, as expected because ATRA selectively inhibits active Pin1 in cancer cells. Moreover ATRA‐PLLA microparticles significantly enhanced the efficacy of ATRA against HCC tumor growth in mice through reducing Pin1, with a better potency than the slow‐releasing ATRA formulation, consistent with its improved pharmacokinetic profiles. This study illustrates an effective platform to produce controlled release formulation of anti‐cancer drugs, and ATRA‐PLLA microparticles might be a promising targeted drug for HCC therapy as PLLA is biocompatible, biodegradable and nontoxic to humans. Graphical abstract Figure. No Caption available.

Drug controlled release of novel alginate/poly-L-arginine microcapsules

a novel alginate/poly-L-arginine microcapsules were prepared by emulsification using bovine hemoglobin (Hb) as the model drug, and the impact of the release properties such as the molecular weight of poly-L-arginine, the concentration of sodium alginate and calcium chloride were investigated. The microcapsules made from middle molecular weight of poly-L-arginine (PLA) had obviously sustained release profile. The impact of sodium alginate concentration on the release properties was not obviously, the release rate of microcapsules made with 12% (w/v) CaCl2 were slightly faster, but the accumulative release rate were nearly the same. The microcapsules had so obviously sustained drug release that this novel microcapsules may be used as a promising drug delivery system for hydrophilic proteins and peptides.

Preparation of ALG-g-Lys and its application as a novel drug carrier

In order to improve alginate microbead stability and further broaden the application of alginate in biomaterials, a new biomaterial, ALG-g-Lys, was prepared and its possibility as a novel drug carrier investigated. The carrier exhibited a sustained release property and preserved activity with no initial burst release, and interestingly, GP-crosslinked ALG-g-Lys microspheres showed obvious fluorescence properties, which showed promising potential for the future drug delivery systems.

Effect of the Storage Temperatures on BRL-encapsulated-alginate-PLO-alginate(APornA) Microcapsules

To obtain long-term storage of cell-encapsulated alginate-PLO-alginate (APornA) microcapsules, the influences of storage temperatures on the microcapsule morphology, cell viability and metabolic activities were investigated. The results showed that the microcapsules exhibited the original morphological characteristics with smooth surface, good sphericity and overall integrity after 4 weeks preserved in liquid N2. 4°C and -20°C were presented to be the harsh conditions for cell propagation and the secretion of metabolic products compared to -80°C and -196°C. It can be concluded that lower temperature is beneficial for the cell recovery. These results supplied supplementary data for poly- L-ornithine (PLO) as a potential coating material in the future cell microencapsulated applications.