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Aminopeptidase N (APN), recognized by Asn-Gly-Arg (NGR) peptides, is expressed in the pericytes associated with the BBB, and the main objective of this study is to confirm the hypothesis that NGR-modified DSPE-PEG micelles containing paclitaxel (NGR-M-PTX) can bind to and kill brain tumor angiogenic blood vessels and penetrate into the brain tumor interstitial space, resulting in direct cell death. NGR-M-PTX is prepared by a thin-film hydration method. The in vitro targeting characteristics of NGR-modified micelles on BMEC (murine brain microvascular endothelial cells) were investigated. The effect of NGR-M-PTX on BMEC proliferation and the cytotoxicity of NGR-M-PTX in C6 glioma cells were also tested. The antitumor activity NGR-M-PTX was evaluated in C6 glioma tumor-bearing rats in vivo. The particle size of NGR-M-PTX was approximately 54.2 nm. The drug encapsulation efficiency of NGR-M-PTX was 82.11 ± 2.82%. The cellular coumarin-6 level of NGR-M-coumarin-6 in the BMEC was about 2.2-fold higher than that of M-coumarin-6. BMEC proliferation was significantly inhibited by NGR-M-PTX. NGR-M-PTX had a much lower IC(50) value than M-PTX and free drug. The growth of C6 glioma tumor was markedly inhibited by NGR-M-PTX compared with Taxol. In conclusion, our results show that antiangiogenic therapy using NGR-M-PTX exhibits potent in vivo antitumor activity in a C6 glioma-bearing animal model.

The purpose of this study was to prepare a novel paclitaxel (PTX) microemulsion containing a reduced amount of Cremophor EL (CrEL) which had similar pharmacokinetics and antitumor efficacy as the commercially available PTX injection, but a significantly reduced allergic effect due to the CrEL. The pharmacokinetics, biodistribution, in vivo antitumor activity and safety of PTX microemulsion was evaluated. The results of pharmacokinetic and distribution properties of PTX in the microemulsion were similar to those of the PTX injection. The antitumor efficacy of the PTX microemulsion in OVCRA-3 and A 549 tumor-bearing animals was similar to that of PTX injection. The PTX microemulsion did not cause haemolysis, erythrocyte agglutination or simulative reaction. The incidence and degree of allergic reactions exhibited by the PTX microemulsion group, with or without premedication, were significantly lower than those in the PTX injection group (P < .01). In conclusion, the PTX microemulsion had similar pharmacokinetics and anti-tumor efficacy to the PTX injection, but a significantly reduced allergic effect due to CrEL, indicating that the PTX microemulsion overcomes the disadvantages of the conventional PTX injection and is one way of avoiding the limitations of current injection product while providing suitable therapeutic efficacy.

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Abstract. The purpose of this present study was to evaluate the antiangiogenic activity of sterically stabilized liposomes containing paclitaxel (SSL-PTX). The SSL-PTX was prepared by the thin-film method. The release of paclitaxel from SSL-PTX was analyzed using a dialysis method. The effect of SSL-PTX on endothelial cell proliferation and migration was investigated in vitro. The antitumor and antiangiogenic activity of SSL-PTX was evaluated in MDA-MB-231 tumor xenograft growth in BALB/c nude mice. The release of paclitaxel from SSL-PTX was 22% within 24 h. Our in vitro results indicated that SSL-PTX could effectively inhibit the endothelial cell proliferation and migration at a concentrationdependent manner. We also observed that metronomic SSL-PTX induced marked tumor growth inhibition in MDA-MB-231 xenograft model via the antiangiogenic mechanism, unlike that in paclitaxel injection (Taxol) formulated in Cremophor EL (CrEL). Overall, our results suggested that metronomic chemotherapy with low-dose, CrEL-free SSL-PTX should be feasible and effective.

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