Cui-Tao Lu

Phospholipids-based microbubbles sonoporation pore size and reseal of cell membrane cultured in vitro.

Objective: To investigate phospholipids-based microbubbles induced sonoporation and cell membrane reseal in vitro under various conditions. Methods: A breast cancer cell line SK-BR-3 was used to investigate ultrasonic sonoporation under various conditions. Atomic force microscopy (AFM) scanning techniques were employed to observe the change of membrane pores. Results: Normal SK-BR-3 cells membrane pores were evenly distributed and less than 1 μm. After ultrasound exposure, membrane pores were enlarged at different degree depending on ultrasound exposure durations, filling gas species and microbubble suspension concentration. With microbubble suspension concentration being increased to 5% or ultrasound exposure reached 30 s, membrane pores in fluorocarbon (C3F8 or SF6)-filled microbubble groups exceeded 1 μm, which were significantly larger than that of air-filled microbubble group. Membrane pores were about 2–3 μm under ultrasound 60 s with 5% fluorocarbon-filled microbubble suspension. After 24 h of incubation, most of the enlarged membrane pores could reseal to normal size, which corresponded to cell viability. Conclusions: Membrane pores can be obviously enlarged by ultrasonic sonoporation of fluorocarbon-filled microbubbles, whose reseal time depended on ultrasound exposure duration and microbubble suspension concentration.

Current approaches to enhance CNS delivery of drugs across the brain barriers

Although many agents have therapeutic potentials for central nervous system (CNS) diseases, few of these agents have been clinically used because of the brain barriers. As the protective barrier of the CNS, the blood–brain barrier and the blood–cerebrospinal fluid barrier maintain the brain microenvironment, neuronal activity, and proper functioning of the CNS. Different strategies for efficient CNS delivery have been studied. This article reviews the current approaches to open or facilitate penetration across these barriers for enhanced drug delivery to the CNS. These approaches are summarized into three broad categories: noninvasive, invasive, and miscellaneous techniques. The progresses made using these approaches are reviewed, and the associated mechanisms and problems are discussed.

Potential and problems in ultrasound-responsive drug delivery systems.

Ultrasound is an important local stimulus for triggering drug release at the target tissue. Ultrasound-responsive drug delivery systems (URDDS) have become an important research focus in targeted therapy. URDDS include many different formulations, such as microbubbles, nanobubbles, nanodroplets, liposomes, emulsions, and micelles. Drugs that can be loaded into URDDS include small molecules, biomacromolecules, and inorganic substances. Fields of clinical application include anticancer therapy, treatment of ischemic myocardium, induction of an immune response, cartilage tissue engineering, transdermal drug delivery, treatment of Huntington’s disease, thrombolysis, and disruption of the blood–brain barrier. This review focuses on recent advances in URDDS, and discusses their formulations, clinical application, and problems, as well as a perspective on their potential use in the future.

Selection of high efficient transdermal lipid vesicle for curcumin skin delivery

Curcumin shows effective anti-inflammatory activities but is seldom used in clinic because of its poor solubility in water and vulnerablity to sunshine ultraviolet effect. Novel lipid vesicles have been developed as carriers for skin delivery. In this paper, lipid vesicles-propylene glycol liposomes (PGL), Ethosomes and traditional liposomes, were prepared as curcumin carriers respectively. Their morphology, particle size and encapsulation efficiency and drug release behavior in vitro were evaluated. Transdermal efficiency and deposition quantity in abdominal skin were also measured with Franz diffusion device. Carrageenan-induced paw edema was established to evaluate the anti-inflammatory effect. From the result, the particle size order of lipid vesicles was: PGL (182.4 ± 89.2 nm)<Ethosomes (289 ± 132.1 nm)<traditional liposomes (632.9 ± 184.1 nm). The order of particle dispersion coefficient was as the same as that of particle size. The sequence of encapsulation efficiency was: PGL>Ethosomes>traditional liposomes. PGL had the best encapsulation efficiency of 92.74 ± 3.44%. From anti-inflammatory experiment, PGL showed the highest and longest inhibition on the development of paw edema, followed by Ethosomes and Traditional liposomes. With the elevated entrapment efficiency, good transdermic ability and sustained-release behavior, PGL may represent an efficient transdermal lipid vesicle for skin delivery.

Gelatin nanostructured lipid carriers-mediated intranasal delivery of basic fibroblast growth factor enhances functional recovery in hemiparkinsonian rats

UNLABELLEDnLipid nanoparticles with solid matrix have been given increasing attention due to their biodegradable status and ability to entrap a variety of biologically active compounds. In this study, new phospholipid-based gelatin nanoparticles encapsulating basic fibroblast growth factor (bFGF) were developed to target the brain via nasal administration. Treatment effects were assessed by quantifying rotational behavior, monoamine neurotransmitter levels and tyrosine hydroxylase expression in 6-hydroxydopamine induced hemiparkinsonian rats. The gelatin nanostructured lipid carriers (GNLs) were prepared by a water-in-water emulsion method and then freeze-dried. The GNLs possessed better profile than gelatin nanoparticles (GNs), with particle size 143±1.14nm and Zeta potential -38.2±1.2mV. The intranasal GNLs efficiently enriched exogenous bFGF in olfactory bulb and striatum without adverse impact on the integrity of nasal mucosa and showed obvious therapeutic effects on hemiparkinsonian rats. Thus, GNLs are attractive carriers for nose-to-brain drug delivery, especially for unstable macromolecular drugs such as bFGF.nnnFROM THE CLINICAL EDITORnThis team of authors reports the development of phospholipid-based gelatin nanoparticles encapsulating basic fibroblast growth factor to target the brain via intranasal administration. A rat model of hemiparkinsonism was applied demonstrating a good safety profile and an obvious therapeutic effect.

Experiment on the feasibility of using modified gelatin nanoparticles as insulin pulmonary administration system for diabetes therapy

Polymeric nanoparticles are widely used as targeted carriers for biomacromolecules. In this paper, modified gelatin nanoparticles were prepared and their feasibility as insulin pulmonary administration system was investigated. d,l-glyceraldehyde and poloxamer 188 were used for gelatin nanoparticle preparation. Novel water-in-water emulsion technique was used to prepare insulin-loaded nanoparticles. Morphological examination of insulin-loaded nanoparticles was carried out using scanning electron microscopy (SEM). Intratracheal instillation of insulin-loaded nanoparticles was performed to evaluate animal hypoglycemic effect. With fluorescence labeling of insulin, alveolar deposition and absorption of insulin-loaded nanoparticles were investigated. Histological changes in the lung were also observed to evaluate the safety. From the micromorphology observation, insulin-loaded nanoparticles under gelatin–poloxamer 188 ratio at 1:1 showed smooth and uniform surface, with average particle size 250xa0nm and Zeta potential −21.1xa0mV. From animal experiment, insulin-loaded nanoparticles under gelatin–poloxamer 188 ratio at 1:1 promoted insulin pulmonary absorption effectively and showed good relative pharmacological bioavailability. Proved by alveolar deposition result, FITC-insulin-loaded nanoparticle group was characterized by an acute and rapid hypoglycemic effect. In addition, nanoparticles could guarantee the safety of lung by reducing insulin deposition in lung. A transient weak inflammatory response was observed at 1xa0day after administration. With good physical characterization, high bioavailability, fast and stable hypoglycemic effect, insulin-loaded nanoparticles might be developed as a novel insulin pulmonary system for diabetes therapy.

Characterization and anti-tumor activity of chemical conjugation of doxorubicin in polymeric micelles (DOX-P) in vitro.

Characterization and anti-tumor activity of chemical conjugation of doxorubicin (DOX) in polymeric micelles were investigated. Polymeric micelles with chemical conjugation of doxorubicin (DOX-P) were prepared. Succinic anhydride activated pluronic F68 was first synthesized and the primary amine group in doxorubicin was conjugated to the terminal carboxyl of pluronic F68 via a amide. The resulting polymeric micelles in aqueous solution were characterized by measurement of size, ξ-potential, drug loading and critical micelle concentration. From characterization results, DOX-P micelles had superiorities over physically-loaded DOX micelles in loading efficiency, diameter and CMC value. From drug release experiment in vitro, DOX-P micelles reached a sustained release profile for DOX. The cytotoxic activity of the micelles against A549/DOX cells was greater than free DOX. Fluorescence microscope observation and flow cytometry analysis supported the enhanced cellular uptake of the micelles. From A549/DOX cells experiments, DOX-P micelles could enhance DOX anti-tumor activity and circumvent the multi-drug resistance (MDR) of A549/DOX cells. With low CMC value, high loading efficiency, nanometer diameter, good penetration ability and controlled release behaviour, DOX-P micelles might be developed as a new cancer targeted delivery system.

Epirubicin loaded with propylene glycol liposomes significantly overcomes multidrug resistance in breast cancer

Multidrug resistance (MDR) is one of the major reasons for the failure of cancer chemotherapy. A newly reported liposome carrier, propylene glycol liposomes (EPI-PG-liposomes) were made to load epirubicin (EPI) which enhanced EPI absorption in MDR tumor cells to overcome the drug resistance. MDA-MB 435 and their mutant resistant (MDA-MB 435/ADR) cells were used to examine the cellular uptake and P-gp function in vitro for EPI-PG-liposomes by fluorescence microscopy and FCM, respectively. Mammary tumor model was also established to investigate the tumor growth inhibition and pharmacodynamics of EPI-PG-liposomes in vivo. Morphology evaluation showed that EPI-PG-liposomes had a homogeneous spherical shape with an average diameter of 182 nm. Based on cell viability assay, fluorescent microscopy examination, and EPI uptake assay, EPI-PG-liposomes exhibited an effective growth inhibition not only in MDA-MB-435 cells, but also in MDA-MB 435/ADR cells. EPI-PG-liposomes have high permeability not only on tumor cell membrane, but also on cell nucleus membrane. P-gp function assay showed that the anticancer action of EPI-PG-liposomes was not related to P-gp efflux pump, suggesting that PG-liposomes would not affect the normal physiological functions of membrane proteins. EPI-PG-liposomes also showed a better antitumor efficacy compared to EPI solution alone. With high entrapment efficiency, spherical morphology and effective inhibition on MDR cancer cells, EPI-PG-liposomes may represent a better chemotherapeutic vectors for cancer targeted therapy.

Enhancing chemotherapeutic drug inhibition on tumor growth by ultrasound: an in vivo experiment

An in vivo study on enhancing epirubicin hydrochloride (EPI) inhibition on tumor growth by ultrasound (US) was reported. Five-week-old male nude mice were used and HL-60 cells were s.c. (subcutaneous injection) inoculated in axilla of these mice. Six groups were designed and five consecutive treatments were applied to investigate the inhibition on tumor growth and body weight growth. US applied locally to the tumor resulted in a substantially increased drug uptake in tumor cells. The inhibition on tumor growth depended on the position of drug injection and phospholipid-based microbubble (PMB) application. Tumor growth rate under group 1 (PMB+US) was similar to that of blank control. The order of the inhibition on tumor volume growth was: group 4 (s.c. EPI+PMB+US) > group 5 intraperitoneal (i.p. EPI+PMB+US) > group 2 (i.p. EPI) > group 3 (s.c. EPI+US) > group 1 (PMB+US). Similar conclusion was obtained from experimental measurements of tumor weight change. The order of animal survival status for EPI administration groups was: group 4 > group 5 > group 2 > group 3. Chemotherapeutic drug inhibition on tumor growth could be enhanced by local US combined with PMB, which might provide a potential application for US-mediated chemotherapy.

Synthesis and characterization of Poloxamer 188-grafted heparin copolymer

Background: Poloxamer 188 is a safe biocompatible polymer that can be used in protein drug delivery system. Aim: In this study, a new heparin–poloxamer 188 conjugate (HP) was synthesized and its physicochemical properties were investigated. HP structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and Hydrogen-1 nuclear magnetic resonance spectroscopy (1H-NMR). Content of the conjugated heparin was analyzed using Toluidine Blue. The critical micelle concentration (CMC) of the copolymer was determined by a fluorescence probe technique. The effect of HP on the gelation of poloxamer 188 was characterized by the rheological properties of the HP–poloxamer hydrogels. Solubility and viscosity of HP were also evaluated compared with poloxamer 188. Results: From the results, the solubility of the conjugated heparin was increased compared with free heparin. The content of heparin in HP copolymer was 62.9%. The CMC of HP and poloxamer 188 were 0.483 and 0.743 mg/mL, respectively. The gelation temperature of 0.4 g/mL HP was 43.5°C, whereas that of the same concentration of poloxamer 188 was 37.3°C. With HP content in poloxamer 188 solution increasing, a V-shape change of gelation temperature was observed. Conclusion: Considering the importance of poloxamer 188 in functional material, HP may prove to be a facile temperature-sensitive material for protein drug-targeted therapy.