Preparation Of Magnetic Gemcitabine Stealth Nano-liposomes And Its Targeted Antitumor Effects

Objectives:It is well recognized that traditional systemic chemotherapy has low therapeutic index and poor patients'compliance. To some extent the dose of received anticancer drugs by patients was excessive for best curative effect. Thus the chance of toxic side effect of the chemotherapy increased and not only tumor cells but some normal cells were killed. Targeting therapy for solid tumors, using specific carriers to locate anticancer drugs selectively to solid tumors under specific guiding mechanism, such as magnetism, may increase the drug concentration in the required sites. Such an approach would dramatically increase the anticancer drugs'therapeutic efficacy, reduce the drugs'toxic side effects and increase the patient's compliance.Methods:The nano-Fe₃O₄ magnetic fluid was prepared by chemical coprecipitation method and its acute toxicology was investigated. The acute toxic reaction and the main viscera pathologyical morphology of mice were evaluated after administered the nano-Fe₃O₄ magnetic fluid by intraperitoneal, oral and intravenous respectively with different doses. Using orthogonall test to optimize the recipe and technology, Magnetic Gemcitabine Stealth nano-liposomes (MGSL) was prepared by reverse-phase evaporation method, with Fe₃O₄ nanoparticles as magnetic core. We studies the physical characteristics including magnetic response, particle size, embedding ratio, and drug loading, etc. And the antitumor effect on breast cancer cell line MCF-7 in vitro was investigated. Additionally the apoptosis of MCF-7 induced by MGSL was studied. Then we investingated the pharmacyokinetic characterictics, magnetic response and targeting effect of MGSL in vivo. The therapeutic effect of MGSL on nude mice bearing breast cancer was also intensively studied.Results:1) LD50 (50% lethal dose)> 1624.5mg/kg, ED0 (maximum non-effect dose)= 339.60mg/kg by intraperitoneal; LD50>2166.00mg/kg,ED0=339.60mg/kg by oral;LD50>451.25mg/kg, ED0=169.80mg/kg by intravenous. Degeneration and necrosis of viscera were not found.2) Observation under electron microscopy showed the optimized MGSL had an average diameter value of 206nm. The drug loading and embedding ratio was (10.4±0.7)%, and(81.7±5.1)% respectively. And the saturated magnetization of 21.85emu/g at room temperature implied that MGSL had a good magnetic response.3) MCF-7 cell line was sensitive to MGSL and the cytotoxity was correlated with the loaded drug dose. The effect of apoptosis of MGSL on MCF-7 was obvious and the rate of apoptosis was 51.62%.4) The level of bcl-2,survivin and p53 were up-regulated in experimental groups detected by RT-PCR and Western-Blot.5) Not only in vitro, but also in vivo did MGSL have a good magnetic response. Therefore, MGSL was able to converge at the targeting tissue under tridimensional magnetic field and the gemcitabine concentrateion around it increased, while the amount of gemcitabine in other organs decreasing, such as in kidneys and heart.6) Treatment with MGSL via intravenous administration under tridimensional magnetic force near the tumor showed significant antitumor activety than any other modality.Conclusions:The present results suggested that as a new carrier of gemcitabine, MGSL could be more stable and be used to diliver gemcitabine effectively to the tumor under tridimensional magnetic field, and the gemcitabine concentrateion increased in the tumor and decreased the side effects of the heart and the kidneys. This new treatment approach involving a combination of magnet targeting to the tumor and intravenous administration of MGSL could effectively control the tumor growth. Briefly, our study indicated that MGSL, as a carrier of anticancer drug, had a wide widow of opportuneity to achieve even anticancer effects in clinical settings. Targeting therapy could be a novel approach to the cancer treatment.