Studies On 2-methoxyestradiol Lipid Nanparticles Loaded Hydrogel

Lymphatic metastasis or drug resistance of tumor often resulted in failure of local conventional therapy of subcutaneous or postoperative tumors such as breast cancer and prostate cancer. 2-methoxyestradiol as model anticancer drug and PLGA-PEG-PLGA as hydrogel material,a new two-phase drug delivery system,thermosensitive hydrogel loading lipid nanoparticles (solid lipid nanoparticles or liposomes) was designed. After their intratumoral and peritumoral injention, lipid nanoparticles could be released slowly from the hydrogel and target to tumor site, avoiding lipid nanoparticles rapidly cleared from the systemic circulation following systemic administration, which could overcome some disadvantages of local conventional therapy of tumors and achieve satisfactory antitumor effectiveness.First 2-ME SLN were prepared by hot homogenization-ultrasonication and optimized by single factor and orthogonal experiment. SLN prepared by Tween 80 and poloxamer 188 were marked with TSLN and FSLN, respectively. The particle sizes and zeta potentials of 2-ME TSLN were around 122 ± 18nm nm and -40mv,respectively. Differential scanning calorimetry measurement revealed that 2-ME could exist as amorphous state in TSLN prepared,respectively. The high drug entrapment efficiency (>85%) indicated that most 2-ME was incorporated in the TSLN. An in vitro drug release study showed that 2-ME was released from the SLN in a slow but time-dependent manner following Weibull model. 2-ME TSLN suspension was demonstrated to keep stable at room temperatrue for six weeks by determining change in particle size and entrapment efficiency. 2-ME TSLN power obtained by selecting 4% mannitol and 6% trehalose as freeze drying protectant was dissolved again without significant change in particle size and entrapment efficiency.The cytotoxicity of 2-ME SLN on breast cancer (MCF-7), prostatic carcinoma (PC-3)and glioma (SK-N-SH) was evaluated respectively by sulforhodamineB (SRB) method. 2-ME TSLN was about 17-fold on PC-3 cells and 6.7-fold on SK-N-SH cells more effective than the solution respectively, while on MCF-7 cells a lower sensitivity was achieved. The maximal growth inhibition rate of each cell line after their incubation with 2-ME SLN and 2-ME solution all achieved about 90% and 50%, respectively. Accordingly, cellular uptake percentages of 2-ME in TSLN in each cell line all were far higher than the solution,respectively. The surfactant may exert different effect on cytotoxicity of 2-MESLN depending on cell line. In addition, 2-ME TSLN was about 6.36-fold on 4T1 cells more effective than the solution.The in vitro characters of 2-ME TSLN loaded hydrogel were investigated, such as thermosensitiveness, viscosity, stability and nanoparticles release. The hydrogel loading 2-ME TSLN still revealed thermosensitivity. However, concentration of 2-ME TSLN influenced significantly its phase transition temperature. Stability of TSLN within and released from the hydrogel was confirmed by direct visualization by scan electron microscope (SEM), particle size measurement by laser light scattering, fluorescence labeled technique and free drug concentration determination in the release medium by ultracentrifugation. In the release medium, most 2-ME existed in the TSLN and intact 2-ME TSLN could be released from the hydrogel for prolonged period over 46 days following first-order model. On the release rate,their concentration showed significant effect, while their particle size and pH value of the release medium did not so.The in vivo characters of 2-ME TSLN loaded hydrogel were investigated, such as release,tissue distribution,biocompatibility,tumoral delivery and antitumor effects. The results indicated that the hydrogel could deliver fluorescence-marked 2-ME TSLN to tumor masses and tumor cells, exhibiting a controlled release of 2-ME TSLN over 46 days following a zero-order model. After treatment with the 2-ME TSLN hydrogel, BALB/c mice that had been inoculated with syngeneic 4T1 breast cancer cells displayed significantly more tumor growth suppression on 21 day than those treated with a 2-ME hydrogel,and corresponding tumor growth rate was 98% and 70%, respectively. Moreover, the mice treated with the 2-ME TSLN hydrogel or 2-ME hydrogel all did not exhibit a loss of body weight or abnormal levels of white blood cells compared to the control group,demonstrating their better biocompatibility.In addition, the in vitro and in vivo characters of 2-ME liposomes loaded hydrogel also were investigated.