| Targeting therapy for solid tumors, using specific carriers to locate anticancer drugs selectively to solid tumors under specific guiding mechanism, 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.The current study investigated the magnetic nano-liposome designed to act as interferon -α2b(IFN-α2b) carrier, which could be effectively delivered to solid tumors via intravenous administration. Magnetic interferon-α2b nano-liposome(MIL) was prepared by the reverse-phase evaporation method. We studied the response of MIL to the magnetite both out of and within the body, investigated the biological distribution of the MIL in the nude mice bearing colon cancer. The therapeutic effect of MIL to nude mice bearing colon cancer was also intensively studied. We also studied the aeutetoxieity and haemolysis of MIL by i.v. Double antibody sandwich ELISA analysis was used for testing drug concentration in serum and tissues after i.v. of IFN,MIL (in the presence of magnetic field) and MIL(in the absence of magnetic field) in mice.To study the growth inhibitory effect and apoptosis inducing effect of MIL on tumor Bel- 7402 cells by MTT, Cell counting, Acridine Orange and DNA ladder test. And to study treatment with MIL via intravenous administration under magnetic force fixed in the surface of the tumor by analyse of the mRNA expression and Western blot.The main results of this study are as follows:1. The particle size of MIL was 170nm, the concentration of IFN-α2b in MIL was 5000 IU IFN/ml, and the entrapment rate of IFN-α2b was about 62.71%. Different lipid ratio, drug lipid ratio, organic solvent and ratio of water/oil phase may influence the particle size of MIL and the entrapment rate of IFN-α2b. The leakage rate of IFN-α2b in MIL was very low within the preservative 8 hours under 4℃and -20℃after preparation. 2. MIL had a good response to the magnetite both out of and within the body. Administration of MIL under magnetic field could be used to deliver IFN-α2b effectively to the targeted site, increasing IFN-α2b concentration in the tumor and decreasing IFN-α2b concentration in other tissues and organs.3. The experiment of aeutetoxieity and haemolysis of MIL showed that the MIL was safe if it was inject by i.v. Double antibody sandwich ELISA analysis was used for testing drug concentration in serum and tissues after i.v. of IFN,MIL (in the presence of magnetic field) and MIL(in the absence of magnetic field) in mice. The result showed: the drug concentration of liver and kidney of MIL with magnetic field group was remarkable higher than those of free IFN group and MIL without magnetic field group, but that of normal liver and tissues outside liver was lower. The drug selective index of liver and kidney tumor of the with magnetic field group was significantly higher than those of other groups, and the drug selective index of liver and kidney tumor of MIL without magnetic field group was also higher than that of free IFN group. All of them had statistical meaning (P<0.01).4. Tumor cell Bel-7402 treated by the free IFN, ML, IL, MIL, which had high level of inhibitory action, was detected by MTT, Cell counting, Acridine Orange and DNA ladder test. It was found that the growth of Bel-7402 was inhibited and the apoptosis was happened. And the tumor cell Bel-7402 inhibition rate and apoptosis rate of MIL group and IL group was remarkably higher than those of the IFN group. And the tumor cell Bel-7402 inhibition rate and apoptosis rate of free IFN group was remarkably higher than those of the ML group and Control group. All of them had statistical meaning (p<0.05). The result shows that the MIL had inhibitory action for tumor cell Bel-7402. The mechanism was making the apoptosis happen.5. Treatment with MIL via intravenous administration under magnetic force fixed in the surface of the tumor showed significant greater anticancer activity than any other modality. The tumor inhibition rate of MIL group was 62.50% , which was remarkably higher than those of the IFN group (27.61%) and IL group (28.17%). RT-PCR showed that the mRNA expression of VEGF of MIL group is the lowest of all groups (P<0.01) and the mRNA expression of Caspase-3 of MIL group is the highest of all groups (P<0.01) . Western blot showed that the VEGF165 protein (monomer, P21) expression is the lowest of all groups (P<0.01) and the cleaved Caspase-3 protein (P17) expression is the highest of all groups (P<0.01) .The present results suggested that as a new carrier of IFN-α2b, MIL could be used to deliver IFN-α2b effectively to the tumor fixed in the surface of its with a permanent magnet, increasing IFN-α2b concentration in the tumor and decreasing the side effects of other tissues and organs. This new treatment approach involving a combination of magnet implantion in the center of the tumor and intravenous administration of MIL could effectively control the tumor growth.In summary, this study indicated that magnetic nano-liposome, as an carrier of anticancer drug, had a wide window of opportunity to achieve even anticancer effects in clinical settings. Targeting therapy could be a novel approach to the cancer treatment.
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