Xiang Luo

Targeted delivery of epirubicin to tumor-associated macrophages by sialic acid-cholesterol conjugate modified liposomes with improved antitumor activity

With the knowledge that the receptors of sialic acid are overexpressed on the surface of tumor-associated macrophages (TAMs), which play a crucial role in the tumors progression and metastasis, a sialic acid-cholesterol conjugate (SA-CH) was synthesized and modified on the surface of epirubicin (EPI)-loaded liposomes (EPI-SAL) to improve the delivery of EPI to the TAMs. The liposomes were developed using remote loading technology via a pH gradient. The liposomes were evaluated for particle size, encapsulation efficiency, in vitro release, stability, in vitro cytotoxicity and pharmacokinetics. And the in vitro and in vivo cellular uptake studies demonstrated EPI-SAL achieved enhanced accumulation of EPI into TAMs. The antitumor studies indicated that EPI-SAL provided the strongest antitumor activity compared with the other formulations (EPI-S, EPI-CL and EPI-PL represent EPI solution, conventional liposomal EPI, PEGylated liposomal EPI, respectively), and the survival percent of tumor-bearing mice was 83.3%. The superior antitumor efficacy was probably attributed to the killing of TAMs by EPI-SAL, and modulating the tumor microenvironment with the depletion of TAMs. These findings suggested that SA-CH decorated EPI-loaded liposomes may present an effective strategy to eradicate TAMs, which may be a promising approach for cancer therapy.

Fabrication of Concentrated Fish Oil Emulsions Using Dual-Channel Microfluidization: Impact of Droplet Concentration on Physical Properties and Lipid Oxidation

Chemically unstable lipophilic bioactives, such as polyunsaturated lipids, often have to be encapsulated in emulsion-based delivery systems before they can be incorporated into foods, supplements, and pharmaceuticals. The objective of this study was to develop highly concentrated emulsion-based fish oil delivery systems using natural emulsifiers. Fish oil-in-water emulsions were fabricated using a highly efficient dual-channel high-pressure microfluidizer. The impact of oil concentration on the formation, physical properties, and oxidative stability of fish oil emulsions prepared using two natural emulsifiers (quillaja saponins and rhamnolipids) and one synthetic emulsifier (Tween-80) was examined. The mean droplet size, polydispersity, and apparent viscosity of the fish oil emulsions increased with increasing oil content. However, physically stable emulsions with high fish oil levels (30 or 40 wt %) could be produced using all three emulsifiers, with rhamnolipids giving the smallest droplet size (d < 160 nm). The stability of the emulsions to lipid oxidation increased as the oil content increased. The oxidative stability of the emulsions also depended on the nature of the emulsifier coating the lipid droplets, with the oxidative stability decreasing in the following order: rhamnolipids > saponins ≈ Tween-80. These results suggest that rhamnolipids may be particularly effective at producing emulsions containing high concentrations of ω-3 polyunsaturated fatty acids-rich fish oil.

Fabrication of β-carotene nanoemulsion-based delivery systems using dual-channel microfluidization: Physical and chemical stability

A considerable research effort is focused on developing effective delivery systems for hydrophobic nutraceuticals. β-carotene, a pro-vitamin A carotenoid, requires encapsulation to improve its water dispersibility and chemical stability in foods. In this study, β-carotene was encapsulated in oil-in-water nanoemulsions fabricated using high-pressure dual-channel microfluidization. Two types of natural emulsifier, quillaja saponins (Q-Naturale) and whey protein isolate (WPI), were capable of producing nanoemulsions (d32=0.14-0.16μm) using this novel homogenization method. The physical and chemical stability of these nanoemulsions were characterized during storage at neutral pH conditions at refrigeration (4°C), ambient (25°C), and elevated (55°C) temperatures. At 4 and 25°C, all nanoemulsions remained physically stable throughout 14days storage, with little change in particle size or evidence of creaming. At 55°C, WPI nanoemulsions were also physically stable, but a small amount of droplet aggregation occurred in saponin nanoemulsions. The rate of β-carotene degradation increased with increasing storage temperature, but did not depend strongly on emulsifier type. This study showed that dual-channel microfluidization is an efficient method of continuously producing carotenoid-loaded nanoemulsions from natural emulsifiers. This knowledge may be useful for developing nutraceutical delivery systems for application within commercial food, beverage, and pharmaceutical products.

Polysialic acid-modifying liposomes for efficient delivery of epirubicin, in-vitro characterization and in-vivo evaluation

Polysialic acid (PSA) serves as a hydrophilic polymer and affords conjugated biologically active molecules a longer circulation time in vivo. Furthermore, PSA could potentially target tumor tissues and help achieve better curative effects. In this study, PSA was conjugated with octadecyl dimethyl betaine (BS18) to yield a PSA-BS18 conjugate. The PSA-BS18 modified liposomal epirubicin (EPI-SL), had a particle size of 133.63±0.92nm, a zeta potential of -26.23±1.50mV and an encapsulation efficiency (%EE) of 96.23±1.16%. In vitro release studies showed that PSA-BS18 could delay EPI release from the modified liposomes. The MTT assay suggested that EPI-SL led to stronger cytotoxic activity than that exhibited by common and PEGylated liposomes. The pharmacokinetic study showed that EPI-SL prolonged the residence time of the EPI in the blood compared with that observed from common liposomes. Bio-distribution results obtained from tumor-bearing mice clearly demonstrated that PSA-BS18 increased the accumulation of modified liposomes in tumors compared with that of common liposomes. In the antitumor efficacy study, EPI-SL showed the best antitumor and life-prolonging effects among all of the tested formulations. These findings strongly indicate EPI-SL might have great potential as an effective approach for anticancer therapy.

Production of highly concentrated oil-in-water emulsions using dual-channel microfluidization: Use of individual and mixed natural emulsifiers (saponin and lecithin)

The fabrication of concentrated oil-in-water emulsions is useful for reducing storage and transportation costs, as well as for providing desirable textural, optical, stability, and release characteristics in commercial products. In this study, 50wt% oil-in-water emulsions were produced from natural emulsifiers using high-pressure dual-channel microfluidization (89.6MPa, 1 pass). The particle size and charge characteristics of emulsions stabilized using a hydrophilic biosurfactant (quillaja saponin) or mixtures of hydrophilic and hydrophobic biosurfactants (quillaja saponin+soy lecithin) were measured. The physical stability of the emulsions was determined during storage under quiescent conditions (pH7, 25°C). The mean droplet diameter and polydispersity decreased with increasing hydrophilic and hydrophobic biosurfactant concentration. Surface potential measurements indicated that interfacial composition depended on the amount of hydrophilic and hydrophobic biosurfactant present. The inclusion of hydrophobic emulsifier in the oil phase and hydrophilic emulsifier in the aqueous phase prior to homogenization, led to the formation of smaller oil droplets than using the hydrophilic emulsifier alone. The relatively small size and polydispersity of the droplets in the mixed-emulsifier systems led to a higher emulsion viscosity and a better aggregation stability, i.e., there was a smaller change in particle size during storage. However, some creaming was still observed in the emulsions due to the presence of a fraction of relatively large droplets. In summary, concentrated emulsions stabilized by mixed biosurfactants may be advantageous for commercial application in certain food, beverage, and pharmaceutical products.

Polysialic acid and Pluronic F127 mixed polymeric micelles of docetaxel as new approach for enhanced antitumor efficacy

Abstract In our previous study, polysialic acid-octadecyl dimethyl betaine (PSA-BS18) was synthesized and modified to liposomal EPI. Preliminary experiments revealed that the PSA-BS18 was a potential material for targeting tumor site with superior curative effects. In this study, PSA-BS18 and Pluronic F127 (F127) mixed polymeric micelles encapsulated docetaxel (DTX) (FP/DTX) were prepared by a self-assembly method. The FP/DTX was found to have a diameter of 34.83 ± 0.50 nm with a narrow polydispersity, the entrapment efficiency was 99.12 ± 1.17%, and the drug loading efficiency of 1.40 ± 0.01%. The storage and dilution stability of FP/DTX was fine. In vitro release studies demonstrated that FP/DTX had delayed the drug release from the micelles. In vitro cytotoxicity assay on B16 cells presented that FP/DTX led to a stronger cytotoxic activity in comparison to F127 micelles based DTX (F127/DTX) and Tween80-based DTX (Taxotere®). The in vivo imaging study showed that the accumulation of FP/DTX at tumor sites was more than F127/DTX. The in vivo antitumor activity of FP/DTX against B16 tumor xenograft model showed a significant higher inhibition and a lower toxicity compared with F127/DTX and Taxotere®. Taken together, the results obtained above showed that PSA-BS18 and F127 mixed polymeric micelles may be a promising strategy for antitumor delivery of DTX.

Neutrophil-mediated delivery of pixantrone-loaded liposomes decorated with poly(sialic acid)–octadecylamine conjugate for lung cancer treatment

Abstract Poly(sialic acid) (PSA) is a natural hydrophilic biodegradable and non-immunogenic biopolymer, receptors for its monomer are expressed on peripheral blood neutrophils (PBNs), which plays important roles in the progression and invasion of tumors. A poly(sialic acid)–octadecylamine conjugate (PSA–ODA) was synthesized and then anchor it on the surface of liposomal pixantrone (Pix-PSL), to achieve an improved anticancer effect. The liposomes were prepared using a remote loading method via a pH gradient, and then assessed for particle size, zeta potential encapsulation efficiency, in vitro release, and in vitro cytotoxicity. Simultaneously, in vitro and in vivo cellular uptake studies confirmed that PSA-decorated liposomes provided an enhanced accumulation of liposomes in PBNs. An in vivo study presented that the anti-tumor activity of Pix-PSL was superior to that of other Pix formulations, probably due to the efficient targeting of PBNs by Pix-PSL, after which PBN containing Pix-PSL (Pix-PSL/PBNs) in the blood circulation are recruited by the tumor microenvironment. These findings suggest that PSA-decorated liposomal Pix may provide a neutrophil-mediated drug delivery system (DDS) for the eradication of tumors, which represents a promising approach for the tumor targeting of chemotherapeutic treatments.

The effect of monosialylganglioside mix modifying the PEGylated liposomal epirubicin on the accelerated blood clearance phenomenon

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Enhanced Opsonization-Independent Phagocytosis and High Response Ability to Opsonized Antigen–Antibody Complexes: A New Role of Kupffer Cells in the Accelerated Blood Clearance Phenomenon upon Repeated Injection of PEGylated Emulsions

The accelerated blood clearance (ABC) phenomenon is an immune response against the first injection of PEGylated colloidal drug delivery systems (CDDSs), which causes the accelerated clearance of the second dose. The enhanced complement-mediated phagocytic activity of Kupffer cells is responsible for accelerated second-dose clearance. Nevertheless, few studies have focused on the role of Kupffer cells in the induction phase of the ABC phenomenon. In this study, the intrinsic phagocytic activity of Kupffer cells was significantly enhanced at 6 days after the initial injected PEGylated emulsions (PEs) using the carbon clearance test and single-pass liver perfusion experiment. Furthermore, PE could stimulate Kupffer cells activation, leading to enhanced cell viability of Kupffer cells and opsonization-independent cellular uptake. It was also found that the response ability of Kupffer cells to the antigen-antibody complexes was augmented by the first injection of PE. Conclusively, we proposed that, besides anti-PEG IgM and complement activation-mediated hepatic uptake, enhanced opsonization-independent phagocytosis of Kupffer cells and the high response ability to opsonized antigen-antibody complexes contribute to the accelerated clearance of the second administration. The results indicated that Kupffer cells play an indispensable role in the ABC phenomenon and provided novel insights into the current view on the mechanism of the ABC effect.

Targeted delivery of pixantrone to neutrophils by poly(sialic acid)-p-octadecylamine conjugate modified liposomes with improved antitumor activity

Graphical abstract Figure. No caption available. HighlightsPixantrone‐loaded liposomes decorated with poly(sialic acid)‐p‐octadecylamine conjugate (Pix‐PSL) were prepared.Pix‐PSL improved the delivery of Pix to peripheral blood neutrophils (PBNs) in vitro and in vivo.PBNs containing Pix‐PSL (Pix‐PSL/PBNs) could be recruited to tumor sites and exhibit an excellent antitumor activity with reducedsystemic toxicity. ABSTRACT Based on the knowledge that poly(sialic acid) is a critical element for tumour development and that the receptors for its monomer are expressed on neutrophils, which play important roles in the progression and invasion of tumours, a poly(sialic acid)‐p‐octadecylamine conjugate (PSA‐p‐ODA) was synthesised and used to modify the surface of liposomal pixantrone (Pix‐PSL) to improve the delivery of Pix to peripheral blood neutrophils (PBNs). The liposomes were fabricated using a remote loading technology via a pH gradient, and were then assessed for particle size, encapsulation efficiency, in vitro release, in vitro cytotoxicity, and pharmacokinetics. Simultaneously, in vitro and in vivo cellular uptake studies demonstrated that Pix‐PSL provided an enhanced accumulation of Pix in PBNs. An in vivo study showed that the anti‐tumour activity of Pix‐PSL was superior to that of other formulations, probably owing to the efficient targeting of PBNs by Pix‐PSL, after which PBNs containing Pix‐PSL (Pix‐PSL/PBNs) in the circulatory system are recruited by the tumour microenvironment. These findings suggest that PSA‐p‐ODA‐decorated liposomal Pix may provide a neutrophil‐mediated drug delivery system (DDS) for the eradication of tumours, and thus represents a promising approach for the tumour targeting of chemotherapeutic treatments.