OBJECTIVETo study the distribution characteristics and the targeting feature of polyethylene glycol (PEG) modified 5-fluorouracil magnetic albumin microspheres (5-FU-MAMS) and 5-FU-MAMS in major organs of colorectal neoplasm nude mice under magnetic field, and to provide experimental evidence for targeting therapy.

METHODSEighteen mice were equally divided into PEG-5-FU-MAMS group(n=6), 5-FU-MAMS group(n=6), and 5-FU group(n=6). The colorectal neoplasm was exposed in the magnetic field of 3000 GS for 30 minutes. Three types of 5-FU were injected through the vena caudalis at the dose of 8 mg/kg. Thirty minutes later, the animals were immediately sacrificed after blood draw from the fossa orbitalis. The concentration of 5-FU in different organs including liver, lung, and tumor tissue were determined by the high performance liquid chromatography (HPLC).

RESULTSThe 5-FU concentrations in colorectal cancer tissue, liver, lung, and blood were(73.3±3.2), (22.1±2.7), (26.3±2.8), and(1.6±0.6) mg/L in the PEG-5-FU-MAMS group, and were(55.9±5.4), (46.3±8.2), (39.4±5.4), and(1.7±0.4) mg/L in the 5-FU-MAMS group. The 5-FU concentration in colorectal neoplasm was higher in the PEG-5-FU-MAMS group than that in the 5-FU-MAMS group(P<0.01), while the concentration was lower in the liver and the lung than that in the 5-FU-MAMS group(all P<0.01). There were no significant difference of 5-FU concentration in the blood sample(P>0.05).

CONCLUSIONBoth PEG-5-FU-MAMS and 5-FU-MAMS show significant magnetic targeting to the colorectal neoplasm, and passive target capacity of PEG-5-FU-MAMS to liver and the lung. PEG modification can decrease passive target capacity and the active target capacity can be enhanced, which efficiently reduces the toxicity of chemotherapeutic agents to important organs, and therefore provides a new initiative targeting chemotherapy for cancer.