Novel brain-targeted nanomicelles for anti-glioma therapy mediated by the ApoE-enriched protein corona in vivo.

BACKGROUND: The interactions between nanoparticles (NPs) and plasma proteins form a protein corona around NPs after entering the biological environment, which provides new biological properties to NPs and mediates their interactions with cells and biological barriers. Given the inevitable interactions, we regard nanoparticle‒protein interactions as a tool for designing protein corona-mediated drug delivery systems. Herein, we demonstrate the successful application of protein corona-mediated brain-targeted nanomicelles in the treatment of glioma, loading them with paclitaxel (PTX), and decorating them with amyloid ß-protein (Aß)-CN peptide (PTX/Aß-CN-PMs). Aß-CN peptide, like the Aß1-42 peptide, specifically binds to the lipid-binding domain of apolipoprotein E (ApoE) in vivo to form the ApoE-enriched protein corona surrounding Aß-CN-PMs (ApoE/PTX/Aß-CN-PMs). The receptor-binding domain of the ApoE then combines with low-density lipoprotein receptor (LDLr) and LDLr-related protein 1 receptor (LRP1r) expressed in the blood-brain barrier and glioma, effectively mediating brain-targeted delivery. METHODS: PTX/Aß-CN-PMs were prepared using a film hydration method with sonication, which was simple and feasible. The specific formation of the ApoE-enriched protein corona around nanoparticles was characterized by Western blotting analysis and LC-MS/MS. The in vitro physicochemical properties and in vivo anti-glioma effects of PTX/Aß-CN-PMs were also well studied. RESULTS: The average size and zeta potential of PTX/Aß-CN-PMs and ApoE/PTX/Aß-CN-PMs were 103.1 nm, 172.3 nm, 7.23 mV, and 0.715 mV, respectively. PTX was efficiently loaded into PTX/Aß-CN-PMs, and the PTX release from rhApoE/PTX/Aß-CN-PMs exhibited a sustained-release pattern in vitro. The formation of the ApoE-enriched protein corona significantly improved the cellular uptake of Aß-CN-PMs on C6 cells and human umbilical vein endothelial cells (HUVECs) and enhanced permeability to the blood-brain tumor barrier in vitro. Meanwhile, PTX/Aß-CN-PMs with ApoE-enriched protein corona had a greater ability to inhibit cell proliferation and induce cell apoptosis than taxol. Importantly, PTX/Aß-CN-PMs exhibited better anti-glioma effects and tissue distribution profile with rapid accumulation in glioma tissues in vivo and prolonged median survival of glioma-bearing mice compared to those associated with PMs without the ApoE protein corona. CONCLUSIONS: The designed PTX/Aß-CN-PMs exhibited significantly enhanced anti-glioma efficacy. Importantly, this study provided a strategy for the rational design of a protein corona-based brain-targeted drug delivery system. More crucially, we utilized the unfavorable side of the protein corona and converted it into an advantage to achieve brain-targeted drug delivery.

Efficient Anti-Glioma Therapy Through the Brain-Targeted RVG15-Modified Liposomes Loading Paclitaxel-Cholesterol Complex.

BACKGROUND: Glioma is the most common primary malignant brain tumor with a dreadful overall survival and high mortality. One of the most difficult challenges in clinical treatment is that most drugs hardly pass through the blood-brain barrier (BBB) and achieve efficient accumulation at tumor sites. Thus, to circumvent this hurdle, developing an effectively traversing BBB drug delivery nanovehicle is of significant clinical importance. Rabies virus glycoprotein (RVG) is a derivative peptide that can specifically bind to nicotinic acetylcholine receptor (nAChR) widely overexpressed on BBB and glioma cells for the invasion of rabies virus into the brain. Inspired by this, RVG has been demonstrated to potentiate drugs across the BBB, promote the permeability, and further enhance drug tumor-specific selectivity and penetration. METHODS: Here, we used the RVG15, rescreened from the well-known RVG29, to develop a brain-targeted liposome (RVG15-Lipo) for enhanced BBB permeability and tumor-specific delivery of paclitaxel (PTX). The paclitaxel-cholesterol complex (PTX-CHO) was prepared and then actively loaded into liposomes to acquire high entrapment efficiency (EE) and fine stability. Meanwhile, physicochemical properties, in vitro and in vivo delivery efficiency and therapeutic effect were investigated thoroughly. RESULTS: The particle size and zeta potential of PTX-CHO-RVG15-Lipo were 128.15 ± 1.63 nm and -15.55 ± 0.78 mV, respectively. Compared with free PTX, PTX-CHO-RVG15-Lipo exhibited excellent targeting efficiency and safety in HBMEC and C6 cells, and better transport efficiency across the BBB in vitro model. Furthermore, PTX-CHO-RVG15-Lipo could noticeably improve the accumulation of PTX in the brain, and then promote the chemotherapeutic drugs penetration in C6luc orthotopic glioma based on in vivo imaging assays. The in vivo antitumor results indicated that PTX-CHO-RVG15-Lipo significantly inhibited glioma growth and metabasis, therefore improved survival rate of tumor-bearing mice with little adverse effect. CONCLUSION: Our study demonstrated that the RVG15 was a promising brain-targeted specific ligands owing to the superior BBB penetration and tumor targeting ability. Based on the outstanding therapeutic effect both in vitro and in vivo, PTX-CHO-RVG15-Lipo was proved to be a potential delivery system for PTX to treat glioma in clinic.

Improving antitumor outcomes for palliative intratumoral injection therapy through lecithin- chitosan nanoparticles loading paclitaxel- cholesterol complex.

BACKGROUND: Intratumoral injection is a palliative treatment that aims at further improvement in the survival and quality of life of patients with advanced or recurrent carcinomas, or cancer patients with severe comorbidities or those with a poor performance status. METHODS: In this study, a solvent-injection method was used to prepare paclitaxel-cholesterol complex-loaded lecithin-chitosan nanoparticles (PTX-CH-loaded LCS_NPs) for intratumoral injection therapy, and the physicochemical properties of NPs were well characterized. RESULTS: The particle size and zeta potential of PTX-CH-loaded LCS_NPs were 142.83±0.25 nm and 13.50±0.20 mV, respectively. Release behavior of PTX from PTX-CH-loaded LCS_NPs showed a pH-sensitive pattern. The result of cell uptake assay showed that PTX-CH-loaded LCS_NPs could effectively enter cells via the energy-dependent caveolae-mediated endocytosis and macropinocytosis in company with the Golgi apparatus. Meanwhile, PTX-CH-loaded LCS_NPs had a better ability to induce cell apoptosis than PTX solution. The in vivo antitumor results suggested that PTX-CH-loaded LCS_NPs effectively inhibited mouse mammary cancer growth and metastasis to distant organs and significantly improved the survival rate of tumor-bearing mice by intratumoral administration. CONCLUSION: In general, our study demonstrated that PTX-CH-loaded LCS_NPs used for palliative treatment by intratumoral injection showed improved safety and antitumor efficacy, which provided an alternative approach in the field of palliative chemotherapy.

Development of solid lipid nanoparticles containing total flavonoid extract from Dracocephalum moldavica L. and their therapeutic effect against myocardial ischemia-reperfusion injury in rats.

Total flavonoid extract from Dracocephalum moldavica L. (TFDM) contains effective components of D. moldavica L. that have myocardial protective function. However, the cardioprotection function of TFDM is undesirable due to its poor solubility. In order to improve the solubility and efficacy of TFDM, we developed TFDM-loaded solid lipid nanoparticles (TFDM-SLNs) and optimized the formulation of TFDM-SLNs using central composite design and response surface methodology. The physicochemical properties of TFDM-SLNs were characterized, and the pharmacodynamics was investigated using the myocardial ischemia-reperfusion injury model in rats. The nanoparticles of optimal formulation for TFDM-SLNs were spherical in shape with the average particle size of 104.83 nm and had a uniform size distribution with the polydispersity index value of 0.201. TFDM-SLNs also had a negative zeta potential of -28.7 mV to ensure the stability of the TFDM-SLNs emulsion system. The results of pharmacodynamics demonstrated that both TFDM and TFDM-SLN groups afforded myocardial protection, and the protective effect of TFDM-SLNs was significantly superior to that of TFDM alone, based on the infarct area, histopathological examination, cardiac enzyme levels and inflammatory factors in serum. Due to the optimal quality and the better myocardial protective effect, TFDM-SLNs are expected to become a safe and effective nanocarrier for the oral delivery of TFDM.

Inhibiting the proliferation, migration and invasion of triple negative breast cancer cells through anti-tumor human serum albumin nanoparticles loading aziditaxel as a novel taxane derivative.

Triple negative breast cancer (TNBC) is a severe breast cancer subtype with the high mortality rate, and still is lack of effective therapeutic means so far. Aziditaxel, a water-insoluble compound, is a novel taxane derivative with strong anti-tumor activity. In this study, we constructed an aziditaxel-loaded nano drug delivery system using human serum albumin as a carrier, and further investigated its anti-tumor effect on TNBC in vitro. An emulsion solvent evaporation method was employed to prepare aziditaxel-loaded human serum albumin nanoparticles (AT-NPs). Their physicochemical properties were characterized according to morphology, particle size, zeta potential, reconstitution stability and in vitro drug release. The in vitro anti-tumor effects of AT-NPs on TNBC were evaluated using a 4T1 murine triple negative mammary cancer cell lines as the TNBC model. The results showed that AT-NPs could be effectively taken up by 4T1 cells in a time-dependent manner. Cell Counting Kit-8 assay showed that the IC50 of AT-NPs was 0.17 µg/ml. Meanwhile, compared with AT, AT-NPs had a better ability to promote apoptosis and induce G2/M cycle arrest. On the other hand, AT-NPs had significantly inhibitory effects on the 4T1 cell adhesion, migration and invasion with the respective average inhibition ratios of 32.53%, 83.26% and 75.78%. Thus, our study revealed that AT-NPs had favorable antitumor activity in vitro and exhibited a good prospect for application in the field of TNBC therapy.

Lx2-32c-loaded polymeric micelles with small size for intravenous drug delivery and their inhibitory effect on tumor growth and metastasis in clinically associated 4T1 murine breast cancer.

Lx2-32c is a novel taxane derivative with a strong antitumor activity. In this study, we developed Lx2-32c-loaded polymeric micelles (Lx2-32c-PMs) with small size and investigated their antitumor efficacy against tumor growth and metastasis on 4T1 murine breast cancer cell line with Cremophor EL-based Lx2-32c solution as the control. In this study, copolymer monomethoxy polyethylene glycol2000-polylactide1300 was used to prepare Lx2-32c-PMs by film hydration method, and their physicochemical properties were characterized as well, according to morphology, particle size, zeta potential, in vitro drug release, and reconstitution stability. Under confocal laser scanning microscopy, it was observed that Lx2-32c-PMs could be effectively taken up by 4T1 cells in a time-dependent manner. Cell Counting Kit-8 assay showed that the IC50 of Lx2-32c-PMs was 0.3827 nM. Meanwhile, Lx2-32c-PMs had better ability to promote apoptosis and induce G2/M cycle block and polyploidy formation, compared with Lx2-32c solution. More importantly, in vivo animal studies showed that compared to Lx2-32c solution, Lx2-32c-PMs possessed better ability not only to effectively inhibit the tumor growth, but also to significantly suppress spontaneous and postoperative metastasis to distant organs in 4T1 orthotopic tumor-bearing mice. Consequently, Lx2-32c-PMs have significantly prolonged the survival lifetime of tumor-bearing mice. Thus, our study reveals that Lx2-32c-PMs had favorable antitumor activity and exhibited a good prospect for application in the field of antitumor therapy.

[The development of cell-penetrating peptides in drug delivery system].

Cell membrane serves as the natural barrier. Cell-penetrating peptides(CPPs) have been a powerful vehicle for the intracellular delivery of a large variety of cargoes cross the cell membrane. The efficiency of intracellular delivery of drugs, proteins, peptides and nucleic acid, as well as various nanoparticulate pharmaceutical carriers(e.g., liposomes, polymeric micelles and inorganic nanoparticles) has been demonstrated both in vitro and in vivo. This review focuses on the CPPs-based strategy for intracellular delivery of small molecule drugs, proteins, peptides, nucleic acid and CPP-modified nanocarriers.

Inhibition of murine breast cancer growth and metastasis by survivin-targeted siRNA using disulfide cross-linked linear PEI.

Biodegradable disulfide-containing polyethyleneimine (PEI) derivatives showed great potential as siRNA vectors for the treatment of cancer due to the reduction-sensitive property. In this study, we developed and characterized a hyperbranched disulfide cross-linked PEI (lPEI-SS) based on linear PEI (lPEI) by ring-opening reaction of propylene sulfide. We evaluated the efficiency of lPEI-SS as a siRNA vector in vitro with luciferase reporter gene system, and investigated the anti-tumor efficacy of survivin-targeted siRNA (siRNA(sur)) on 4T1 murine breast cancer model using lPEI-SS synthesized here. Results from cytotoxicity and hemolysis assay proved that lPEI-SS showed favorable cell and blood compatibility. lPEI-SS/siRNA polyplexes prepared under the optimized condition were compact spherical particles with the average size of 229.0nm and zeta potential of 42.67mV. Cellular uptake of lPEI-SS/siRNA polyplexes was significantly improved due to the higher branching degree of lPEI-SS over the parent lPEI. lPEI-SS/siRNA(sur) exhibited great anti-proliferation effect on 4T1 cell line, which was found to be caused by the induction of apoptosis. Most importantly, results of tumor volume, tumor weight and histological observation demonstrated that lPEI-SS/siRNA(sur) polyplexes effectively inhibited the tumor growth and metastasis of 4T1 murine breast cancer model.

High gene delivery efficiency of alkylated low-molecular-weight polyethylenimine through gemini surfactant-like effect.

To our knowledge, the mechanism underlying the high transfection efficiency of alkylated low-molecular-weight polyethylenimine (PEI) is not yet well understood. In this work, we grafted branched PEI (molecular weight of 1,800 Da; bPEI1800) with lauryl chains (C12), and found that bPEI1800-C12 was structurally similar to gemini surfactant and could similarly assemble into micelle-like particles. Stability, cellular uptake, and lysosome escape ability of bPEI1800-C12/DNA polyplexes were all greatly enhanced after C12 grafting. bPEI1800-C12/DNA polyplexes exhibited significantly higher transfection efficiency than Lipofectamine 2000 in the presence of serum. Bioluminescence imaging showed that systemic injection of bPEI1800-C12/DNA polyplexes resulted in intensive luciferase expression in vivo and bioluminescence signals that could be detected even in the head. Altogether, the high transfection efficacy of bPEI1800-C12 was because bPEI1800-C12, being an analog of gemini surfactant, facilitated lysosome escape and induced the coil-globule transition of DNA to assemble into a highly organized micelle-like structure that showed high stability.

Evaluation of doxorubicin-loaded pH-sensitive polymeric micelle release from tumor blood vessels and anticancer efficacy using a dorsal skin-fold window chamber model.

AIM: To evaluation the doxorubicin (DOX)-loaded pH-sensitive polymeric micelle release from tumor blood vessels into tumor interstitium using an animal vessel visibility model, the so-called dorsal skin-fold window chamber model. METHODS: DOX-loaded pH-sensitive polyHis-b-PEG micelles and DOX-loaded pH-insensitive PLLA-b-PEG micelles were prepared. The uptake of the micelles by MDA-MB-231 breast cancer cells in vitro and in vivo was examined using flow cytometry. The pharmacokinetic parameters of the micelles were determined in SD rats after intravenous injection of a DOX dose (6 mg/kg). The release of the micelles from tumor vasculature and the antitumor efficacy were evaluated in MDA-MB-231 breast cancer xenografted in nude mice using a dorsal skin-fold window chamber. RESULTS: The effective elimination half-life t1/2 of the pH-sensitive, pH-insensitive polymeric micelles and DOX-PBS in rats were 11.3 h, 9.4 h, and 2.1 h, respectively. Intravital microscopy in MDA-MB-231 breast cancer xenografted in nude mice showed that the pH-sensitive polymeric micelles rapidly extravasated from the tumor blood vessels, and DOX carried by the pH-sensitive micelles was preferentially released at the tumor site as compared to the pH-insensitive polymeric micelles. Furthermore, the pH-sensitive polymeric micelles exhibited significant greater efficacy in inhibition of tumor growth in the nude mice. CONCLUSION: When DOX is loaded into pH-sensitive polymeric micelles, the acidity in tumor interstitium causes the destabilization of the micelles and triggers drug release, resulting in high local concentrations within the tumor, thus more effectively inhibiting the tumor growth in vivo.

Improved anti-tumor efficiency against prostate cancer by docetaxel-loaded PEG-PCL micelles.

This study primarily focused on the systematic assessment of both in vitro and in vivo anti-tumor effects of docetaxel-loaded polyethylene glycol (PEG)2000-polycaprolactone (PCL)2600 micelles on hormone-refractory prostate cancer (HRPC). By using solvent evaporation method, PEG-PCL was chosen to prepare doxetaxel (DTX)-loaded mPEG-PCL micelles (DTX-PMs), with the purpose of eliminating side effects of the commercial formulation (Tween 80) and prolonging the blood circulation time. The prepared DTX-PMs had an average particle size of 25.19±2.36 nm, a zeta potential of 0.64±0.15 mV, a polydispersity index of 0.56±0.03, a drug loading of (8.72±1.05)%, and an encapsulation efficiency of (98.1±8.4)%. In vitro cytotoxicity studies indicated that DTX-PMs could effectively kill LNCap-C4-2B cells and show a dose- and time-dependent efficacy. The hemolysis test showed that DTX-PMs had less hemocytolysis than the commercial product of Duopafei®. A sustained in vitro release behavior and prolonged circulation time in blood vessels were observed in the DTX-PMs. Furthermore, when compared with Duopafei®, the DTX-PMs dramatically reduced the prostate specific antigen (PSA) level and tumor growth of prostate tumor-bearing nude mice in vivo. In conclusion, the DTX-PMs can lower systemic side effects, improve anti-tumor activity with prolonged blood circulation time, and will bring an alternative to patients with HRPC.

Preparation and characterization of polymeric nanoparticles for siRNA delivery to down-regulate the expressions of exogenous and endogenous target genes.

Gene silencing induced by RNA interference using small interfering RNA (siRNA) provides a promising therapeutic approach for cancers. However, the lack of siRNA delivery vector has limited the development of siRNA therapy. The purpose of this study was to use the novel copolymer (mPEG5k-PCL1.2k)1.4-g-PEl10k to prepare siRNA-loaded nanoparticles for siRNA delivery. The results suggested that (mPEG5k-PCL1.2k)1.4-g-PEl10k could load siRNA to form nanoparticles with particle size less than 200 nm in a narrow distribution. Moreover, a certain density of positive charge existed onto the surfaces of nanoparticles. MTT assay results demonstrated that (mPEG5k-PCL1.2k)1.4-g-PEl10k/siRNA nanoparticles showed very low cytotoxicity. The gene silencing efficiency of (mPEG5k-PCL1.2k)1.4-g-PEl10k/siRNA nanoparticles was investigated through luciferase reporter gene assays. The expression of exogenous luciferase gene was significantly downregulated at a range of N/P ratio from 50 to 125, and was maximally inhibited at the N/P ratio of 125 with 54% and 59% reduction in MCF-7 and HepG2 cells, respectively. In the 4T1-luc cell line expressing luciferase stably, the silencing of endogenous luciferase gene also has a similar overall profile with maximal 54% reduction of luciferase expression. These results suggested that (mPEG5k-PCL1.2k)1.4-g-PEI10k/SiRNA nanoparticles could serve as a kind of highly efficient siRNA delivery system for down-regulating the expression of exogenous and endogenous target genes.

[Preparation and in vitro evaluation of pH-sensitive TAT peptide conjugated micelles].

Doxorubicin loaded micelles were prepared by film-hydration method using stearyl sulfadiazine (SA-SD) which is pH sensitive, methoxy (polyethylene glycol)-2000-1, 2-dioleoyl-sn-glycero-3-phosphoethanolamine (mPEG-DOPE) and transactivator of transcription (TAT) peptide conjugated PEG-DOPE. Mean diameter of the pH-sensitive micelles was about 20 nm with a (99.1 +/- 2.1) % drug entrapment efficiency at pH 7.4. Flow cytometry studies revealed that the simple TAT micelles was taken up rapidly at the same level at pH 6.8 and pH 7.4. However, the pH-sensitive micelles entered the tumor cell less at pH 7.4 and significantly increase at pH 6.8. After 1 h incubation at pH 6.8, the amount of the pH-sensitive micelles taken up by cancer cell 4T1 was almost similar to simple TAT micelles. The confocal microscopy indicated that the pH-sensitive micelles entered the 4T1 cells at pH 6.8 more than at pH 7.4. It was indicated that the pH-sensitive micelles could shield TAT peptide at normal pH 7.4 and deshield it at pH 6.8. Hence, TAT peptides lead the drug-loaded micelles into the tumor cells and killed them selectively. The pH-sensitive micelle may provide a novel strategy for design of cancer targeting drug delivery system.

[Small interfering RNA delivery mediated by mPEG-PCL-g-PEI polymer nanoparticles].

The aim of this paper is to report the synthesis of the mPEG-PCL-g-PEI copolymers as small interfering RNA (siRNA) delivery vector, and exploration of the siRNA delivery potential of mPEG-PCL-g-PEI in vitro. The diblock copolymers mPEG-PCL-OH was prepared through the ring-opening polymerization. Then, the hydroxyl terminal (-OH) of mPEG-PCL-OH was chemically converted into the carboxy (-COOH) and N-hydroxysuccinimide (NHS) in turn to prepare mPEG-PCL-NHS. The branched PEI was reacted with mPEG-PCL-NHS to synthesize the ternary copolymers mPEG-PCL-g-PEI. The structure of mPEG-PCL-g-PEI copolymers was characterized with Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The mPEG-PCL-g-PEI/siRNA nanoparticles were prepared by complex coacervation, and the nanoparticles size and zeta potential were determined, separately. The cytotoxicities of mPEG-PCL-g-PEI/siRNA nanoparticles and PEI/siRNA nanoparticles were compared through cells MTT assays in vitro. The inhibition efficiencies of firefly luciferase gene expression by mPEG-PCL-g-PEI/ siRNA nanoparticle at various N/P ratios were investigated through cell transfection in vitro. The experimental results suggested that the ternary (mPEG5k-PCL(1.2k))1.4-g-PEI(10k) copolymers were successfully synthesized. (mPEG(5k)-PCL(1.2k))1.4-g-PEI(10k) could condense siRNA into nanoparticles (50-200 nm) with positive zeta potential. MTT assay results showed that the cytotoxicity of (mPEG(5k)-PCL(1.2k))1.4-g-PEI(10k)/siRNA nanoparticles was significantly lower than that of PEI(10k)/siRNA nanoparticles (P < 0.05). The expression of firefly luciferase gene could be significantly down-regulated at a range of N/P ratio from 50 to 150 (P < 0.01), and maximally inhibited at the N/P ratio of 125. The mPEG-PCL-g-PEI polymers could delivery siRNA into cells to inhibit the expression of target gene with very low cytotoxicity, which suggested that mPEG-PCL-g-PEI could serve as a new type of siRNA delivery vector.

Prevention of metastasis in a 4T1 murine breast cancer model by doxorubicin carried by folate conjugated pH sensitive polymeric micelles.

This study primarily focused on the anti-metastatic activity of doxorubicin (DOX) loaded in a pH-sensitive mixed polymeric micelle formed from two block polymers: poly(L-lactide) (PLLA) (Mn 3000)-b-poly(ethylene glycol) (PEG) (Mn 2000)-folate and poly(L-histidine) (PHis) (Mn 4700)-b-PEG (Mn 2000). Tumor formation and metastasis in mice were examined using a murine mammary carcinoma cell of 4T1 which is one of the most aggressive metastatic cancer cell lines. The efficacy was evaluated by tumor size, body weight change, survival rate, dorsal skin fold window chamber model, and histological observation of the lung, heart, liver and spleen after treatment with various DOX formulations. When the tumor reached 50-100 mm³ in size, the mice were treated 4 times at a 3-day interval at a dose of 10 mg DOX/kg. The mixed micelle formulation resulted in retarded tumor growth, no weight loss, and no death for 4-5 weeks. In another set of the in vivo test for histological evaluation of the organs, the mice were similarly treated but the formulations were injected one day after 4T1 cell inoculation. The treatment by DOX loaded mixed micelle showed no apparent metastasis till 28 days. However, significant metastasis to the lung and heart was observed on Day 28 when the mice were treated with DOX carried by PBS, PLLA-b-PEG micelle and PHis-b-PEG micelle.

[Current status of non-viral vectors for siRNA delivery].

RNA interference (RNAi) is a newly developed technology. It is the different levels of gene silencing induced by specific degradation of targeted genes in vivo, and both exogenous and endogenous double-stranded RNAs could induce the specific degradation. RNAi has been applied in tumor therapy, viral infection, hepatitis B and many other diseases. siRNA is the effector molecule which induces the RNAi in vivo. But naked siRNA is easily degradated by RNases in vivo, and the half-life is short. Meanwhile, the transfection efficiency of the naked siRNA is comparatively low. So the naked siRNA needs the help of vectors to penetrate the cell membrane and take action. Viral vectors have the potential immunogenicity and mutagenicity in gene therapy. Therefore, non-viral vectors are drawing more and more attention. The latest development of the non-viral vectors is summarized in this review.

Multifunctional nanoparticles for targeting cancer therapy.

Chemotherapy drug Doxorubicin and MRI imaging agent Iron Oxide were encapsulated in dual functional nanoparticles which is compose of PEG-Foliate acid polymers. The particle size was about 45 nm with a mono-dispersion measured by zeta-sizer instrument. The contrast of images in liver was enhanced after injection Nanoparticles via rabbit ear vein. PEG-FA coated Iron Oxide nanoparticles can selectively target to tumor site and effectively inhibit tumor growth which is subcutaneously bearing A2780 Overran cancer cells. It is feasible for cancer treatment with MRI imaging and chemotherapy simultaneously in vivo by injection dual functional nanoparticles.

Thermal reversible microemulsion system for poorly water-soluble YH439 for oral delivery.

To improve bioavailability of poorly water-soluble YH439, a thermal reversible microemulsion system was prepared using modified fatty acids such as capric acid and palmitic acid with PEG 400. A combination of Capric-PEG 400 and Palmitic-PEG 400 with a ratio of 1 : 3 used as a lipid matrix and Cremophor RH40 and Neobee M-5 were selected as an oil and a surfactant, respectively. The microemulsion with melting point of 36.5 degrees C was produced by mixing the lipid matrices, Cremophor RH40 and Neobee M-5 with a volume ratio of 5 : 4 : 1. After the microemulsion was dispersed in the aqueous medium, the average particle size of 28 nm was obtained. At the release measurements of YH439 after 45 min suspension in pH 1.2 aqueous medium, about 80%, 65%, 10% and less than 5% of drug were released from the thermal reversible microemulson, Gelucire formulation, 5% Ca-carboxymethylcellulose (CMC) suspension and YH439 powder, respectively. The apparent permeability of YH439 in microemulsion either from apical to basolateral or basolateral to apical after measuring YH439 across a Caco-2 cell monolayer in a Transwell larger than Gelucire formulation or 5% Na-CMC suspension. The area under the drug concentration-time curves (AUC) and maximal blood concentration (C(max)) after oral administration of YH439 loaded on thermal reversible microemulsion were significantly increased than drug loaded on either Gelucire formulation or 5% Na-CMC suspension. Thus, the present work demonstrates that the thermal reversible microemulsion system of YH439 greatly enhances the bioavailability of YH439 after oral administration due to the improvement of solubility and dispersion of the drug in the artificial gastrointestinal tract without pepsin.

In vivo evaluation of doxorubicin-loaded polymeric micelles targeting folate receptors and early endosomal pH in drug-resistant ovarian cancer.

The second generation of pH-sensitive micelles composed of poly(l-histidine-co-l-phenlyalanine(16 mol %))(MW:5K)-b-PEG(MW:2K) and poly(l-lactic acid)(MW:3K)-b-PEG(MW:2K)-folate (80/20 wt/wt %) was previously optimized by physicochemical and in vitro tests for both folate receptor and early endosomal pH targeting (pH approximately 6.0). In this study, the therapeutic efficacy of the doxorubicin (DOX)-loaded micelles (DOX loading content: 20 wt %) was evaluated using in vivo tests. Multidrug-resistant (MDR) ovarian tumor-xenografted mouse models were employed. The skin-fold dorsal window chamber model was applied for visualization of extravasation and drug retention for the initial one hour after iv injection. Noninvasive imaging followed, providing evidence of drug accumulation in the tumor after the first hour. The biodistribution study further supported the long circulation of the drug carrier, tumor-selective accumulation and intracellular drug delivery. Comprehensive tumor growth inhibition experiments examined the collective efficacy of the pH-sensitive micelles. The micelle formulation effectively suppressed the growth of existing MDR tumors in mice for at least 50 days by three iv injections at a 3-day interval at a dose of 10 mg of DOX/kg. The body weight of the animals treated with the test micelle formulation gradually increased over the experimental time period, rather than decreasing. The micelle formulation was superior to its first generation, which targeted pH 6.8 and folate receptor.

[Recent advances in the applications of ultrasonic microbubbles as gene or drug vectors].

With the research and application of the new ultrasound microbubble contrast agents, ultrasonic microbubbles can not only help to image, but they can also be used as genes or drug carriers. The microbubbles as genes or drug carriers can pass across the endothelial cell barrier and release genes and drug under the action of ultrasound field, which achieve target treatment effect. Based on the relevant materials, the bioeffects, early successes with gene and drug delivery, and potential clinical applications are reviewed.