Nanocarrier improves the bioavailability, stability and antitumor activity of camptothecin.

Camptothecin (CPT) nanosuspension was prepared by anti-solvent precipitation with TPGS as stabilizer to improve the solubility, stability and antitumor activity of CPT. And an increased solubility, stability and dissolution rate was achieved after nanosuspension being prepared. While, enhanced intracellular accumulation and cellular cytotoxicity was also observed for CPT nanosuspension than that of CPT solution.In addition, nanosuspension could increase bioavailability and intratumor accumulation of CPT in vivo after intravenous administration, and then produced a much higher antitumor effect and biocompatibility than that of CPT solution. Meanwhile, an enhanced cellular CPT uptake in hypoxic or acid conditions could also be observed for nanosuspension. As a result, nanosuspension represents a potentially feasible formation for insoluble drug in antitumor research.

Characteristics of sequential targeting of brain glioma for transferrin-modified cisplatin liposome.

Methods on how to improve the sequential targeting of glioma subsequent to passing of drug through the blood-brain barrier (BBB) have been occasionally reported. However, the characteristics involved are poorly understood. In the present study, cisplatin (Cis) liposome (lipo) was modified with transferrin (Tf) to investigate the characteristics of potential sequential targeting to glioma. In bEnd3/C6 co-culture BBB models, higher transport efficiency across the BBB and cytotoxicity in basal C6 cells induced by Cis-lipo(Tf) than Cis-lipo and Cis-solution, suggest its sequential targeting effect. Interestingly, similar liposomal morphology as that of donor compartment was first demonstrated in the receptor solution of BBB models. Meanwhile, a greater acquisition in the lysosome of bEnd3, distributed sequentially into the nucleus of C6 cells were found for the Cis-lipo(Tf). Pre-incubation of chlorpromazine and Tf inhibited this process, indicating that a clathrin-dependent endocytosis is involved in the transport of Cis-lipo(Tf) across the BBB.

Glioma targeting and blood-brain barrier penetration by dual-targeting doxorubincin liposomes.

Effective chemotherapy for glioblastoma requires a carrier that can penetrate the blood-brain barrier (BBB) and subsequently target the glioma cells. Dual-targeting doxorubincin (Dox) liposomes were produced by conjugating liposomes with both folate (F) and transferrin (Tf), which were proven effective in penetrating the BBB and targeting tumors, respectively. The liposome was characterized by particle size, Dox entrapment efficiency, and in vitro release profile. Drug accumulation in cells, P-glycoprotein (P-gp) expression, and drug transport across the BBB in the dual-targeting liposome group were examined by using bEnd3 BBB models. In vivo studies demonstrated that the dual-targeting Dox liposomes could transport across the BBB and mainly distribute in the brain glioma. The anti-tumor effect of the dual-targeting liposome was also demonstrated by the increased survival time, decreased tumor volume, and results of both hematoxylin-eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling analysis. The dual-targeting Dox liposome could improve the therapeutic efficacy of brain glioma and were less toxic than the Dox solution, showing a dual-targeting effect. These results indicate that this dual-targeting liposome can be used as a potential carrier for glioma chemotherapy.

Evaluation of pluronic nanosuspensions loading a novel insoluble anticancer drug both in vitro and in vivo.

To improve the solubility, stability and the antitumor activity of a novel anticancer drug, 3-(4-bromopheny l)-2-(ethyl-sulfonyl)-6-methylquinoxaline1,4-dioxide (Q39), a poloxamer nanosuspension was developed by precipitation combined with high pressure homogenization in present study. In vitro characterizations of Q39 nanosuspension (Q39/NS), including particle size, polydispersity index (PI), morphology, crystalline, saturation solubility, stability and releases were evaluated. BABL/c nude mice bearing HepG2 cells were used as in vivo tumor models to evaluate the anti-tumor activity of Q39/NS after intravenous administration. The particle size and PI for Poloxamer188 nanosuspension (P188/NS) were (304±3) nm, and (0.123±0.005) respectively, and it was (307±5) nm and (0.120±0.007) for Poloxamer85 nanosuspension (P85/NS) correspondingly. The morphology of P188/NS was spherical shape while elliptoid shape for P85/NS. The crystalline of Q39/NS did not change as shown by the X-ray diffraction analysis. The stability of Q39/NS improved compared with the solution. The solubility of Q39 in P188/NS was 7.3 times higher than the original solubility, while it was 6 times for P85/NS. Sustained release as shown from the in vitro release test, together with the tumor-targeting as shown from in vivo NS distribution, may contribute to the enhanced in vivo antitumor activity of Q39/NS.

Overcoming drug resistance of MCF-7/ADR cells by altering intracellular distribution of doxorubicin via MVP knockdown with a novel siRNA polyamidoamine-hyaluronic acid complex.

Drug resistance is one of the critical reasons leading to failure in chemotherapy. Enormous studies have been focused on increasing intracellular drug accumulation through inhibiting P-glycoprotein (Pgp). Meanwhile, we found that major vault protein (MVP) may be also involved in drug resistance of human breast cancer MCF-7/ADR cells by transporting doxorubicin (DOX) from the action target (i.e. nucleus) to cytoplasma. Herein polyamidoamine (PAMAM) dendrimers was functionalized by a polysaccharide hyaluronic acid (HA) to effectively deliver DOX as well as MVP targeted small-interfering RNA (MVP-siRNA) to down regulate MVP expression and improve DOX chemotherapy in MCF-7/ADR cells. In comparison with DOX solution (IC50=48.5 µM), an enhanced cytotoxicity could be observed for DOX PAMAM-HA (IC50=11.3 µM) as well as enhanced tumor target, higher intracellular accumulation, increased blood circulating time and less in vivo toxicity. Furthermore, codelivery of siRNA and DOX by PAMAM-HA exhibited satisfactory gene silencing effect as well as enhanced stability and efficient intracellular delivery of siRNA, which allowed DOX access to nucleus and induced subsequent much more cytotoxicity than siRNA absent case as a result of MVP knockdown. This observation highlights a promising application of novel nanocarrier PAMAM-HA, which could co-deliver anticancer drug and siRNA, in reversing drug resistance by altering intracellular drug distribution.

Enhanced absorption of hydroxysafflor yellow A using a self-double-emulsifying drug delivery system: in vitro and in vivo studies.

Hydroxysafflor yellow A (HSYA), the main active ingredient of the safflower plant (Carthamus tinctorius L.), is a hydrophilic drug with low oral bioavailability. Water-in-oil-in-water (w/o/w) double emulsions may enhance the oral absorption of HSYA. In this study, we prepared a self-double-emulsifying drug delivery system (SDEDDS) to improve the absorption of HSYA. SDEDDS consists of water in oil emulsions and hydrophilic surfactants that can self-emulsify into w/o/w double emulsions in the aqueous gastrointestinal environment. Confocal laser scanning micrographs showed that spherical droplets were uniformly distributed in the dispersion medium with narrow particle size distribution and could form fine w/o/w double emulsions upon dilution in dispersion medium with gentle stirring. The dispersed oil droplets contained small dispersed aqueous droplets consistent with the characteristics of double emulsions. Furthermore, in vitro cellular experiments were performed to study the mechanism of the absorption promoting effect of SDEDDS. The accumulation of rhodamine-123 in Caco-2 cells was used to evaluate the efflux transport of p-glycoprotein inhibitor. Histopathologic studies on the rat intestine showed that SDEDDS can cause mucosal damage to a certain degree of toxicity, however this was not serious. These results suggest that SDEDDS can greatly improve the oral absorption of HSYA. Given the toxicity demonstrated to the small intestine, the formulation prescription should be improved to enhance security in the future.