The mechanism of enhancement on oral absorption of paclitaxel by N-octyl-O-sulfate chitosan micelles

The overall objective of the present investigation was to demonstrate the effect of N-octyl-O-sulfate chitosan (NOSC) micelles on enhancing the oral absorption of paclitaxel (PTX) in vivo and in vitro, and identify the mechanism of this action of NOSC. In vivo, the oral bioavailability of PTX loaded in NOSC micelles (PTX-M) was 6-fold improved in comparison with that of an orally dosed Taxol(?). In the Caco-2 uptake studies, NOSC micelles brought about a significantly higher amount of PTX accumulated in Caco-2 cells via both clathrin- and caveolae-mediated endocytosis, and NOSC had the effect on inhibiting PTX secreted by P-glycoprotein (P-gp), which was also proved by the studies on rhodamine 123 incorporated in NOSC micelles, fluorescence labeled micelles. The mechanism of NOSC on P-gp inhibition was demonstrated in connection with interfering the P-gp ATPase by NOSC rather than reducing the P-gp expression. Moreover, NOSC with the concentration approaching the critical micellar concentration (CMC) had the strongest effect on P-gp inhibition. In the Caco-2 transport studies, the presence of verapamil and NOSC both improved the transport of Taxol(?), which further certified the effect of NOSC on P-gp inhibition, and PTX-M enhanced the permeability of PTX compared with Taxol(?). The apparent permeability coefficient (Papp) of PTX-M decreased significantly at 4 °C in comparison with at 37 °C, which indicated a predominant active endocytic mechanism for the transport of PTX-M, a P-gp-independent way. Furthermore, the transcytosis of PTX-M was via clathrin-mediated rather than caveolae-mediated. In addition, the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers had no significant change during the transport study, which pointed out that NOSC had no effect on opening the intercellular tight junctions. Based on the obtained results, it is suggested that NOSC micelles might be a potentially applicable tool for enhancing the oral absorption of P-gp substrates.     

载基因壳聚糖纳米粒的研究

RNA干扰技术已被广泛应用于心血管领域,壳聚糖纳米粒以其良好的生物特性而作为基因递送载体成为现在研究的热点.就BNA干扰技术与纳米技术在心血管领域的应用及目前常采用的制备壳聚糖纳米粒的方法、影响质粒与壳聚糖纳米粒结合效率的因素、质粒壳聚糖复合物纳米粒转染的影响因素及体外释药行为作一简单的回顾.     

Multifunctional Pluronic P123/F127 mixed polymeric micelles loaded with paclitaxel for the treatment of multidrug resistant tumors

The aim of this study was to exploit the possibility of combination of active targeting function of folic acid by folate receptor-mediated endocytosis and overcoming multidrug resistance (MDR) by Pluronic block copolymers to promote drug delivery to MDR tumor following intravenous administration with paclitaxel (PTX) as model drug. Folic acid functionalized Pluronic P123/F127 mixed micelles encapsulating PTX (FPF-PTX) was firstly developed and tested in vitro and in vivo, while PTX-loaded Pluronic P123/F127 mixed micelles (PF-PTX) and Taxol were used as control. FPF-PTX was about 20 nm in diameter with spherical shape and high encapsulation efficiency. Cellular uptake of FPF-PTX was found to be higher than that of PF-PTX due to the folate receptor-mediated endocytosis effect. In vitro cytotoxicity, cell apoptosis and cell cycle arrest studies also revealed that FPF-PTX was more potent than those of PF-PTX and Taxol. In vivo pharmacokinetic study in rats showed that the polymeric micelles significantly enhanced the bioavailability of PTX (～3 fold) than Taxol. Moreover, in BALB/c mice bearing KBv MDR tumor xenografts, stronger antitumor efficacy was shown in FPF-PTX group, with good correlation between in vitro and in vivo. In conclusion, folate-conjugated Pluronic micelles could be a potential vehicle for delivering hydrophobic chemotherapeutic drugs to MDR tumors.     

载银水凝胶或载抗生素壳聚糖水凝胶在抑菌性能和细胞毒性方面的研究

目的研究壳聚糖水凝胶,壳聚糖载银水凝胶和壳聚糖载抗生素水凝胶短期的抑菌功效和细胞毒性。方法通过添加交联剂后制备壳聚糖水凝胶,并有效装载银离子或硫酸庆大霉素。进行抑菌实验和累计释放实验了解壳聚糖基水凝胶的抗菌性能和药物控释性。通过使用材料的浸提液检测这三种水凝胶的细胞毒性。结果抑菌实验结果表明壳聚糖水凝胶,壳聚糖载银水凝胶和壳聚糖载抗生素水凝胶均能有效抑制金黄色葡萄球菌的增殖。且壳聚糖载抗生素水凝胶具有最佳的抑菌性能且极大地抑制了生物膜的形成。体外药物释放显示抗生素在7天内的累计释放多于60%;而银离子的释放低于10%。细胞毒性实验表明这三个凝胶材料无明显细胞毒性。结论壳聚糖基水凝胶具有良好的短期抑菌效果,可降解,且无明显细胞毒性,在骨科应用方面有着巨大的前景。     

Well-defined, reversible disulfide cross-linked micelles for on-demand paclitaxel delivery

To minimize premature release of drugs from their carriers during circulation in the blood stream, we have recently developed reversible disulfide cross-linked micelles (DCMs) that can be triggered to release drug at the tumor site or in cancer cells. We designed and synthesized thiolated linear-dendritic polymers (telodendrimers) by introducing cysteines to the dendritic oligo-lysine backbone of our previously reported telodendrimers comprised of linear polyethylene glycol (PEG) and a dendritic cluster of cholic acids. Reversibly cross-linked micelles were then prepared by the oxidization of thiol groups to disulfide bond in the core of micelles after the self-assembly of thiolated telodendrimers. The DCMs were spherical with a uniform size of 28 nm, and were able to load paclitaxel (PTX) in the core with superior loading capacity up to 35.5% (w/w, drug/micelle). Cross-linking of the micelles within the core reduced their apparent critical micelle concentration and greatly enhanced their stability in non-reductive physiological conditions as well as severe micelle-disrupting conditions. The release of PTX from the DCMs was significantly slower than that from non-cross-linked micelles (NCMs), but can be gradually facilitated by increasing the concentration of reducing agent (glutathione) to an intracellular reductive level. The DCMs demonstrated a longer in vivo blood circulation time, less hemolytic activities, and superior toxicity profiles in nude mice, when compared to NCMs. DCMs were found to be able to preferentially accumulate at the tumor site in nude mice bearing SKOV-3 ovarian cancer xenograft. We also demonstrated that the disulfide cross-linked micellar formulation of PTX (PTX-DCMs) was more efficacious than both free drug and the non-cross-linked formulation of PTX at equivalent doses of PTX in the ovarian cancer xenograft mouse model. The anti-tumor effect of PTX-DCMs can be further enhanced by triggering the release of PTX on-demand by the administration of the FDA approved reducing agent, N-acetylcysteine, after PTX-DCMs have reached the tumor site.     

Synthesis,characterization, and biological activity of cross-linked chitosan biguanidine loaded with silver nanoparticles

Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, ¹H NMR and ¹³C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine. The obtained nanoparticles were uniform and spherical with average size of 9.6 ± 0.5 nm. The prepared CChG/AgNPs composites were characterized for their morphology, thermal properties, cytotoxicity and antimicrobial activity. The SEM images showed that the AgNPs are well imbedded in the CChG matrix. The thermal stability of CChG was improved with incorporation of AgNPs. The CChG and CChG/AgNPs showed less cytotoxicity to breast cancer cells (MCF-7). Compared with chitosan and CChG, the ChG and CChG/AgNPs showed better antimicrobial activity against Streptococcus pneumoniae and Bacillus subtilis as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum as fungi.     

白藜芦醇聚合物胶束的制备及质量评价

目的制备白藜芦醇(RES)聚合物胶束并对其进行质量评价。方法采用薄膜分散法,以聚乙烯己内酰胺-聚乙酸乙烯酯-聚乙二醇接枝共聚物(SPS)和D-α生育酚聚乙二醇1000琥珀酸酯(TPGS)为载体材料,制备白藜芦醇聚合物胶束(RES-SPS-TPGS-PMs);采用纳米粒度分析仪、差示扫描量热法(DSC)及傅立叶变换红外光谱法(FTIR)对其进行表征;采用高效液相色谱法测定聚合物胶束的包封率和载药量;采用动态膜透析法考察载药胶束的体外释放特性。结果制备的胶束平均粒径为(52.4±0.66)nm,多分散指数为0.06±0.01,包封率为(97.12±9.08)%,载药量为(2.37±0.22)%。白藜芦醇在聚合物胶束中可能以无定型或分子的形式存在,且白藜芦醇与载体材料之间形成了氢键。体外释放结果表明白藜芦醇聚合物胶束具有明显的缓释效果。结论该胶束制备工艺简单,其粒径、包封率、载药量可控,具有缓释作用。     

Characterization of pegylated copolymeric micelles and in vivo pharmacokinetics and biodistribution studies

The aim of this study was to evaluate the influence of pegylated copolymeric micelle carrier on the biodistribution of drug in rats. The copolymers were synthesized via a modified ring-opening copolymerization of lactone monomers (epsilon-caprolactone, delta-valerolactone, L-lactide) and poly(ethylene glycol) (PEG(10,000) and PEG(4000)). The molecular weights and the polydispersities of synthesized copolymers were in the range of 15,000-31,000 g/mol and 1.7-2.7, respectively. All of the pegylated amphiphilic copolymers were micelles formed with low CMC values in the range of 10(-7)-10(-8)M. The drug-loaded micelles were prepared via a dialysis method. The average particle size of micelles was around 150-200 nm. The cytotoxicity in terms of cell viability after treated with PCL-PEG, PVL-PEG, and PLA-PEG micelles was insignificant. PCL-PEG and PVL-PEG micelles without branch side chain in structures had higher drug loading than PLA-PEG micelles. In vitro release profiles indicated the release of indomethacin from these micelles exhibited a sustained release behavior. The similar phenomenon was also observed in vivo in rats. The pegylated copolymeric micelles not only decreased drug uptake by the liver and kidney, but also prolonged drug retention in the blood.     

Targeted and intracellular delivery of paclitaxel using multi-functional polymeric micelles

Natural paclitaxel (Taxol) is an effective anti-cancer drug, although a critical disadvantage is its non-targeting nature. To address this issue, cholesterol-grafted poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide-co-undecenoic acid) was synthesized with different starting monomer ratios via a free radical copolymerization route. Folate was subsequently attached to the hydrophilic segment of the polymer in order to target folate receptors-overexpressing cancer cells. The success of synthesis was confirmed with 1H-NMR carried out in CDCl3/D2O. Using a membrane dialysis method, the polymer was then self-assembled into micelles whose hydrophobic cores could be utilized to encapsulate paclitaxel, an extremely hydrophobic compound. The polymer had a low CMC of approximately 20 mg/L in water. Dynamic light scattering further showed that the sizes of blank micelles formed from the polymer were below 180 nm at different pH values tested and approximately 220 nm upon drug incorporation. More importantly, it was demonstrated that the micelles exhibited a useful pH-induced thermo-sensitivity, such that drug was released more rapidly at pH 5.0 (acidic endosomal/lysosomal environment) than at pH 7.4 (normal extracellular pH). In vitro cytotoxicity assays performed against KB cells then provided concluding evidences that the cellular uptake of micelles surface-functionalised with folate was indeed enhanced due to a receptor-assisted endocytosis process. This novel polymeric design thus has the potential to be a useful paclitaxel vehicle for the treatment of folate-receptor positive cancers.     

叶酸靶向载紫杉醇磷脂-聚合物杂化纳米粒的制备及其体外细胞评价

目的 制备具有叶酸靶向性的载紫杉醇磷脂-聚合物杂化纳米粒(PTX-FLPNPs),并研究其对乳腺癌细胞EMT-6的细胞毒性及体外细胞吞噬.方法 以聚己内酯-聚乙二醇-聚己内酯(PCL-PEG-PCL)、二硬脂酰基磷脂酰乙醇胺-甲氧基聚乙二醇(DSPE-mPEG2000)和叶酸偶联的磷脂(Folate-PEG(2000)-DSPE)为药物载体,通过薄膜水化法自组装制备PTX-FLPNPs,并对其进行表征;使用激光扫描共聚焦显微镜观察比较叶酸受体高表达的乳腺癌细胞EMT-6对叶酸靶向及无靶向杂化纳米粒的吞噬作用;采用MTS法研究PTX-FLPNPs对EMT-6细胞的细胞毒性.结果 成功制备了PTX-FLPNPs,其呈球形,粒径均匀,具有明显的“核-壳”结构.投药量为30％的PTX-FLPNPs的平均粒径为(279.9±8.7)nm,多分散系数为0.173±0.021,Zeta电位为(-17.5±1.1)mV,载药量为(27.36±0.91)％,包封率为(91.16±1.12)％.细胞吞噬实验表明,叶酸受体高表达的EMT-6细胞对叶酸靶向的杂化纳米粒的吞噬作用明显强于无靶向的杂化纳米粒(P＜0.05).细胞毒性实验结果表明,PTX-FLPNPs的细胞毒性低于紫杉醇注射剂,且对肿瘤细胞的抑制效果优于无靶向的杂化纳米粒.结论 PTX-FLPNPs具有较高载药量及包封率,粒径均匀,可通过主动靶向作用介导肿瘤细胞内吞,并增加药物在肿瘤细胞内的浓度,是一种能有效抑制肿瘤的靶向载药纳米制剂.     

Multifunctional liposomes loaded with paclitaxel and artemether for treatment of invasive brain glioma

Invasive brain glioma is the most lethal type of cancer and is highly infiltrating. This leads to an extremely poor prognosis and makes complete surgical removal of the tumor virtually impossible. Non-penetration of therapeutic drugs across the blood–brain barrier (BBB), brain cancer stem cells (CSCs), and brain cancer vasculogenic mimicry (VM) results in relapse after surgical and radio therapy. We developed a functional targeting chemotherapy for transporting drugs across the BBB, destroying VM channels, and eliminating CSCs and cancer cells in the brain. The studies were undertaken on brain glioma cells in vitro and in brain glioma-bearing rats. Using paclitaxel as the anticancer drug and artemether as the regulator of apoptosis and inhibitor of VM channels, a kind of functional targeting paclitaxel plus artemether liposomes was developed by modifying two new functional materials: a mannose-vitamin E derivative conjugate (MAN-TPGS₁₀₀₀) and a dequalinium-lipid derivative conjugate (DQA-PEG₂₀₀₀-DSPE). The transport mechanism across the BBB was associated with receptor-mediated endocytosis by MAN-TPGS₁₀₀₀ conjugate via glucose transporters and adsorptive-mediated endocytosis by DQA-PEG₂₀₀₀-DSPE conjugate via electric charge-based interactions. The efficacy was related to the destruction of VM channels by regulating VM indicators, as well as the induction of apoptosis in brain cancer cells and CSCs by activating apoptotic enzymes and pro-apoptotic proteins and inhibiting anti-apoptotic proteins. These data suggest that the chemotherapy using functional targeting paclitaxel plus artemether liposomes could provide a new strategy for treating invasive brain glioma.     

Cellular internalization of doxorubicin loaded star-shaped micelles with hydrophilic zwitterionic sulfobetaine segments

Four arm star-shaped poly(ε-caprolactone)-b-poly((N,N-diethylaminoethyl methacrylate)-r-(N-(3-sulfopropyl)-N-methacryloxyethy-N,N-diethylammoniumbetaine)) (4sPCLDEAS) micelles were loaded with anticancer drug doxorubicin to track their endocytosis in Hela cancer cell line. The effects of mean diameters and surface charges of the drug loaded micelles on the cellular uptake were studied in details. The results demonstrated that the internalization of micelles was both time and energy dependent process. Endocytic pathways including clathrin-mediated endocytosis, caveolae-mediated endocytosis and macropinocytosis were all involved in the internalization; caveolae-mediated endocytosis was the main pathway for the internalization of 4sPCLDEAS micelles. The assays for cell apoptosis and growth inhibition of tumor spheroids identified that these doxorubicin loaded micelles could induce cell apoptosis and inhibit tumor spheroids growth efficiently, which was even equal to free DOX·HCl. This study provided a rational design strategy for fabricating diverse micellar drug delivery systems with high anticancer efficiency.     

Decoration of polymeric micelles with cancer-specific peptide ligands for active targeting of paclitaxel

Polymeric micelles based on poly(ethylene oxide)-b-poly(ε-caprolactone) PEO-b-PCL or poly(ethylene oxide)-b-poly(α-benzyl carboxylate-ε-caprolactone) PEO-b-PBCL block copolymers were prepared and decorated with either c(RGDfK) or p160, a cancer cell-specific peptide ligand, on their surface. The cellular uptake of p160-decorated PEO-b-PBCL micelles containing DiI fluorescent label by MDA-MB-435 cancer cells was assessed and compared to that for c(RGDfK)-decorated micelles. The hydrophobic anticancer drug paclitaxel (PTX) was physically encapsulated into PEO-b-PCL or PEO-b-PBCL micelles (with and without peptide ligands) using a dialysis technique. The effect of the micellar formulation on the specificity of encapsulated PTX against cancer cells was assessed by investigating the in vitro cytotoxicity of free and encapsulated PTX against MDA-MB-435 cancer cell line versus two normal cells, Human Umbilical Vein Endothelial Cells (HUVEC) and MCF10A cells, using the MTT assay. Our results showed both peptide ligands to facilitate the association of micelles with MDA-MB-435 cells. The p160-micelles, however showed better binding and internalizing in MDA-MB-435 cells than c(RGDfK)-micelles. In general, peptide decoration enhanced the selective cytotoxicity of encapsulated PTX against MDA-MB-435 cells over normal HUVEC and MCF10A cells. The extent of this increase in cancer cell specificity for encapsulated PTX was more for p160-decorated micelles than c(RGDfK)-decorated ones.     

Tumor-penetrating codelivery of siRNA and paclitaxel with ultrasound-responsive nanobubbles hetero-assembled from polymeric micelles and liposomes

Drug resistance is a big problem in systemic chemotherapy of hepatocellular carcinoma (HCC), and nanomedicines loaded with both chemotherapeutic agents (e.g. paclitaxel, PTX) and siRNA's targeting antiapoptosis genes (e.g. BCL-2) possess the advantages to simultaneously overcome the efflux pump-mediated drug resistance and antiapoptosis-related drug resistance. However, tumor-penetrating drug delivery with this type of nanomedicines is extremely difficult due to their relatively big size compared to the single drug-loaded nanomedicines. Aiming at address this problem, US-responsive nanobubbles encapsulating both anti-cancer drug paclitaxel (PTX) and siRNA (PTX–NBs/siRNA) for HCC treatment were developed by hetero-assembly of polymeric micelles and liposomes in the present study. Utilizing an external low-frequency US force imposed to the tumor site, effective tumor-penetrating codelivery of siRNA and PTX was achieved via tail vein injection of PTX–NBs/siRNA into nude mice bearing human HepG2 xerografts. Consequently, the PTX treatment-inducible antiapoptosis in HepG2 cells was effectively suppressed by the codelivered siRNA targeting an antiapoptosis gene (BCL-2 siRNA) during chemotherapy. Owing to the synergistic anti-cancer effect of two therapeutic agents, tumor growth was completely inhibited using low-dose PTX in animal study. Our results highlight the great potential of this type of US-responsive hetero-assemblies carrying both anti-cancer drug and siRNA as an effective nanomedicinal system for HCC therapy.     

Cefepime loaded O-carboxymethyl chitosan microspheres with sustained bactericidal activity and enhanced biocompatibility

Cefepime (CFP) is a frequently used antibiotic for prevention of post-surgery infection. Systemic delivery of CFP in a bulk dose usually shows effective therapeutic effects, while cytotoxicity can also be generated. To avoid the drawback of systemic delivery of antibiotic, local and controlled administration of drug is being employed to prolong therapeutic effects and reduce cytotoxicity by sustaining drug release and minimizing drug exposure. In this work, CFP loaded polymer O-carboxymethyl chitosan (OCMC) microspheres (CFP-OCMC-MPs) were fabricated and their antimicrobial activity against Staphylococcus aureus as well as biocompatibility were evaluated. The microspheres possessed the spherical surface with diameter approximately 7 μm. Fourier transforms infrared spectral and wide-angle X-ray diffraction analysis showed that CFP was steadily incorporated. The drug loading content and encapsulation efficiency of the microspheres were 21.4 ± 0.5% and 42.3 ± 0.7%, respectively. The drug release profiles were found to be biphasic with an initial burst release followed by a gradual release phase, following the Higuchi model. In addition, the CFP-OCMC-MPs were able to kill all the bacteria cultured in suspension within 24 h and exhibited long-lasting bactericidal activity as demonstrated by inhibition zone study. Compared to CFP, CFP-OCMC-MPs showed a milder toxicity toward osteoblast-like cells over an 8 day period. All these results suggest that CFP-OCMC-MPs are endowed with sustained treatment of bacterial infection and enhanced biocompatibility.     

Polymeric micelles for the solubilization and delivery of cyclosporine A: pharmacokinetics and biodistribution

The aim of this study was to assess the potential of polymeric micelles to modify the pharmacokinetics and tissue distribution of cyclosporine A (CsA). Drug-loaded methoxy poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) micellar solutions in isotonic medium were prepared and administered intravenously to healthy Sprague-Dawley rats. Blood and tissues were harvested and assayed for CsA, and resultant pharmacokinetic parameters and tissue distribution of CsA in its polymeric micellar formulation were compared to its commercially available intravenous formulation (Sandimmune). In the pharmacokinetic assessment, a 6.1 fold increase in the area under the blood concentration versus time curve (AUC) was observed for CsA when given as polymeric micellar formulation as compared to Sandimmune. The volume of distribution and clearance of CsA as PEO-b-PCL formulation were observed to be 10.0 and 7.6 fold lower, respectively, compared to the commercial formulation. No significant differences in t(1/2) or MRT could be detected. In the biodistribution study, analysis of tissue samples indicated that the mean AUC of CsA in polymeric micelles was lower in liver, spleen and kidney (1.5, 2.1 and 1.4-fold, respectively). Similar to the pharmacokinetic study in these rats, the polymeric micellar formulation gave rise to 5.7 and 4.9-fold increase in the AUC of CsA in blood and plasma, respectively. Our results show that PEO-b-PCL micelles can effectively solubilize CsA, at the same time confining CsA to the blood circulation and restricting its access to tissues such as kidney, perhaps limiting the onset of toxicity.     

Pharmacokinetics and biodistribution of N-isopropylacrylamide copolymers for the design of pH-sensitive liposomes

The purpose of this work was to characterize the pharmacokinetics (PK) and biodistribution of pH-responsive N-isopropylacrylamide (NIPAAm) copolymers, and to determine the impact of some physicochemical parameters on their biological profiles. Radiolabeled copolymers of NIPAAm and methacrylic acid (MAA) of different molecular weight, amphiphilicity and lower critical solution temperature (LCST) were synthesized and injected intravenously to rats. The PK and excretion profiles were monitored over 48 h. It was found that elimination occurred mainly through urinary excretion, which was principally governed by molecular weight. Above a threshold of 32,000, the polymer chains avoided glomerular filtration and presented prolonged circulation times. Moreover, the presence of alkyl moieties at the chain extremity influenced circulation time and tissue distribution of polymer chains, hypothetically through formation of micellar structures. The polymers with an LCST situated below the physiological temperature did not circulate for prolonged periods in the bloodstream and were highly captured by the organs of the mononuclear phagocyte system. Finally, the complexation of an alkylated pH-sensitive polymer with a molecular weight of 10,000 to the bilayer of PEGylated liposomes produced a drastic change in the PK parameters, indicating that the polymer remained anchored in the phospholipid bilayer in the bloodstream. These data indicate that stable pH-sensitive liposomes can be produced using excretable NIPAAm copolymers.     

The efficiency of tumor-specific pH-responsive peptide-modified polymeric micelles containing paclitaxel

The acidic pH in tumor tissues could be used for targeting solid tumors. In the present study, we designed a tumor-specific pH-responsive peptide H₇K(R₂)₂, which could respond to the acidic pH in tumor tissues, and prepared H₇K(R₂)₂-modified polymeric micelles containing paclitaxel (PTX-PM-H₇K(R₂)₂) in order to evaluate their potential targeting of tumor cells and tumor endothelial cells and their anti-tumor activity in mice with tumor cells. PTX-PM-H₇K(R₂)₂ was prepared by a thin-film hydration method. The in vitro release of PTX from PTX-PM-H₇K(R₂)₂ was tested. The in vitro targeting characteristics of H₇K(R₂)₂-modified polymeric micelles on HUVEC (human umbilical vein endothelial cells) and MCF-7 (human breast adenocarcinoma cells) were evaluated. The in vivo targeting activity of H₇K(R₂)₂-modified polymeric micelles and the in vivo anti-tumor activity of PTX-PM-H₇K(R₂)₂ were also investigated in MCF-7 tumor-bearing mice. The released PTX from the PTX-PM-H₇K(R₂)₂ was not affected by the pH. The targeting activity of the H₇K(R₂)₂-modified polymeric micelles was demonstrated by in vitro flow cytometry and confocal microscopy as well as in vivo biodistribution. PTX-PM-H₇K(R₂)₂ produced very marked anti-tumor and anti-angiogenic activity in MCF-7 tumor-bearing mice in vivo.     

聚乙二醇修饰载血管紧张素转化酶RNA壳聚糖纳米粒治疗高血压

BACKGROUND: Traditional antihypertensive drugs always have a short half-life period, and show unsatisfactory treatment outcomes. Chitosan, as a gene vector, can carry target genes into the designated location. Polyethylene glycol (PEG) combined with DNA to form the nanoparticles, which can provide surface protection, stabilize the nanoparticles and lengthen the nanoparticle’s half-life. OBJECTIVE: To investigate the antihypertensive effect and the histological changes of heart after PEG-modified chitosan nanoparticles loaded with angiotensin converting enzyme (ACE)-shRNA injected into the rat models of spontaneous hypertension. METHODS: There were five groups: 32 rats with hypertension were randomized into model, chitosan experimental and positive drug groups (n=8 per group); another 8 healthy rats served as controls. The rats in the model and control groups were given the injection of the same amount of normal saline via tail vein, the rats in the chitosan group received the injection of 1 mg/kg chitosan via the tail vein, those in the experiment group received the injection of 1 mg/kg PEG-modified chitosan nanoparticles loaded with ACE-shRNA, and the positive drug group rats were treated with 0.5 mg/kg benazepril hydrochloride via gastric lavage at 1 and 10 days, respectively. RESULTS AND CONCLUSION: The blood pressure in the experimental group at 3 days after treatment was significantly lower than that at 1 day (P < 0.05). Aorta, renal and cardiac biopsies showed positive for green fluoresce in the experimental group, which was consistent with the in vivo distribution of ACE. At 3 days after treatment, compared with the model group, in the experimental group, ACE mRNA expression and levels of myocardial hypertrophy-related indicators were significantly decreased, and myocardial hypertrophy was significantly improved (P < 0.05). These results revealed that PEG-modified ACE-shRNA chitosan nanoparticles can reduce the blood pressure and repair the injured heart of rat models of hypertension, which may be associated with ACE.     

Overcoming drug-resistant lung cancer by paclitaxel loaded dual-functional liposomes with mitochondria targeting and pH-response

Mitochondrion-orientated transportation of smart liposomes has been developed as a promising strategy to deliver anticancer drugs directly to tumor sites, and these have a tremendous potential for killing cancer cells, especially those with multidrug resistance (MDR). Herein we report a novel dual-functional liposome system possessing both extracellular pH response and mitochondrial targeting properties to enhance drug accumulation in mitochondria and trigger apoptosis of drug-resistant cancer cells. Briefly, peptide _D[KLAKLAK]₂ (KLA) was modified with 2, 3-dimethylmaleic anhydride (DMA) and combined with 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) to yield a DSPE-KLA-DMA (DKD) lipid. This dual-functional DKD was then mixed with other commercially available lipids to fabricate liposomes. In vitro anticancer efficacy of this liposome system was evaluated in human lung cancer A549 cells and drug-resistant lung cancer A549/Taxol cells. At tumor extracellular pH (∼6.8), liposomes could reverse their surface charge (negative to positive), facilitating liposome internalization. After cellular uptake, KLA peptide directed delivery-enabled selective accumulation of these liposomes into mitochondria and favored release of their cargo paclitaxel (PTX) into desired sites. Specifically, enhanced apoptosis of MDR cancer cells through mitochondrial signaling pathways was evidenced by release of cytochrome c and increased activity of caspase-9 and -3. These dual-functional liposomes had the greatest efficacy for treating A549 cells and A549/Taxol cells in vitro, and in treating drug-resistant lung cancer A549/Taxol cells xenografted onto nude mice (tumor growth inhibition 86.7%). In conclusion, dual-functional liposomes provide a novel and versatile approach for overcoming MDR in cancer treatment.