ABSTRACT
The clinical tumor therapy was greatly challenged due to the complex characteristics of tumor microenvironment, however, which also provide arena for novel therapeutic strategies. In this study, poly(2-ethyl-2-oxazoline)-poly(lactic acid)-SS-poly(β-amino ester (PEOz-PLA-SS-PBAE) triblock copolymers with pH and GSH double response were synthesized, polymer micelles were prepared by thin film hydration method for loading of silybin to improve its antitumor activity. The critical micelle concentration was determined by pyrene fluorescence method as 1.8 μg·mL-1. The particle size was 155.30 ± 1.80 nm as determined by dynamic light scattering, with polydispersity index of 0.168 ± 0.004. The drug loading and entrapment efficiency of the micelles were determined by HPLC as (5.48 ± 0.04)% and (68.52 ± 0.48)%, respectively. The in vitro drug release profiles showed that the micelles have low pH sensitivity and high GSH responsiveness, and exhibited sustained release profiles. The good biocompatibility of the material was proved by measuring the hemolysis rate and cytotoxicity of the blank micelle. The cytotoxicity and apoptosis rate of tumor cells showed that the drug loaded PEOz-PLA-SS-PBAE micelles had significant inhibitory effect and apoptosis-inducing effect on MDA-MB-231 cells. The results of wounding healing assay and Transwell invasion test showed that the drug loaded PEOz-PLA-SS-PBAE micelles could significantly inhibit the metastasis of MDA-MB-231 cells. The PEOz-PLA-SS-PBAE drug-loaded micelles prepared in this study have good inhibitory effect on tumor growth and anti-tumor metastasis in vitro, which lays the foundation for the further application of silybin.
ABSTRACT
Objective: To investigate the pharmacokinetics and the distribution in tumor tissues of docetaxel nanomicelles. Method: The docetaxel nanomicelles was prepared by filming-rehydration method.HPLC was employed to determine the content of docetaxel in biological samples and the corresponding methodological evaluation was carried out.The mouse Lewis lung carcinoma model was established,when dosage of administration in tail vein was 20 mg·kg-1,and then the effect of free drug(DTX),non-pH-sensitive drug-loaded micelles(PELA-DTX) and pH-sensitive drug-loaded micelles(PBAE-DTX) on the pharmacokinetics and tissue distribution of tumor-bearing mice were investigated. Result: The docetaxel nanomicelles(PELA-DTX and PBAE-DTX) were successfully prepared.The method for the determination of docetaxel in mice was established by HPLC,the linearity,precision of the method and the recovery rate of samples all met the requirements.In the pharmacokinetic study,the plasma concentration of PBAE-DTX was always at a high level within 24 h.Compared with PELA-DTX and DTX,the areas under the curve(AUC0-∞) of PBAE-DTX were increased by 3.63% and 8.96%,the mean residence times(MRT) were extended by 2.86% and 6.43%,the half-life and the drug blood circulation time were prolonged.In the tissue distribution study,it was found that three docetaxel preparations were distributed in the heart,liver,spleen,lung,kidney and tumor tissue within 1 h after administration,but the distribution of these drugs in the tissues was reduced along with the extension of time,the accumulation of PBAE-DTX in tumor tissue was significantly higher than that in DTX and PELA-DTX at 24 h. Conclusion: PBAE-DTX can prolong the circulation time of docetaxel in the blood,increase its bioavailability,and significantly increase its distribution in tumor tissue.
ABSTRACT
Docetaxel-loaded nanomicelles were prepared in this study to improve the solubility and tumor targeting effect of docetaxel(DTX),and further evaluate their anticancer effects in vitro. PBAE-DTX nanomicelles were prepared by film-hydration method with amphiphilic block copolymer polyethyleneglycol methoxy-polylactide(PELA) and pH sensitive triblock copolymer polyethyleneglycol methoxy-polylactide-poly-β-aminoester(PBAE) were used respectively to prepare PELA-DTX nanomicelles and PBAE-DTX nanomicelles. The nanomicelles were characterized by physicochemical properties and the activity of mice Lewis lung cancer cells was studied. The results of particle size measurement showed that the blank micelles and drug-loaded micelles had similar particle sizes, ranging from 10 to 100 nm. The particle size of PBAE micelles was changed under weak acidic conditions, with good pH response. The encapsulation efficiency of the above two types of DTX-loaded nanomicelles determined by HPLC was(93.8±1.70)% and(87.2±4.10)%, and the drug loading amount was(5.3±0.10)% and(4.9±0.05)%,respectively. Furthermore,the DTX micelles also showed significant inhibitory effects on Lewis lung cancer cells by MTT assay, and pH-sensitive PBAE-DTX showed better cytotoxicity. The results of flow cytometry indicated that,the apoptosis rate of lung cancer Lewis cells was(20.72±1.47)%,(29.71±2.38)%,and(40.91±1.90)%(P<0.05) at 48 h after treatment in DTX,PELA-DTX,and PBAE-DTX groups. The results showed that different docetaxel preparations could promote the apoptosis of Lewis cells, and PBAE-DTX had stronger apoptotic-promoting effect. The pH-sensitive DTX-loaded micelles are promising candidates in developing stimuli triggered drug delivery systems in acidic tumor micro-environments with improved inhibitory effects of tumor growth on Lewis lung cancer.