The Experimental Study Of Portal Vein Chemotherapy Using Galactosylated Liposomes Doxorubicin For Hepatic Metastasis Of Gastrointestinal Cancer

The gastrointestinal (GI) tumors carry an extremely high occurrence rate of hepatic metastasis. Upon the occurrence of hepatic metastasis, only 10-20% of the patients may be surgically resected. Most patients have to receive medications. Composed of transcatheter hepatic arterial chemoembolization (TAE) and portal vein chemotherapy, interventional chemotherapy has been considered an effective therapeutic regimen for hepatic metastatic carcinoma. As one of commonly used chemotherapeutic agents, Doxorubicin has such a host of severe systemic toxic and side effects as cardiac injuries and bone marrow suppression that its clinical use is greatly limited. As a novel type of drug carrier, galactosylated liposome carries Doxorubicin so as to modify the pharmacokinetic characteristics and tissue distribution patterns of the latter. Located in the mammal hepatocytic membranes, asialoglycoprotein receptor (ASGPR) may mediate the specific binding of hepatocytes and galactoside-modified drug-carrying liposome and update drug via endocytosis. Thus the actively targeted hepatic therapy is achieved. On one hand, the therapeutic effect is boosted; on the other hand, the systemic toxic and side effects are reduced. For the present project, the nude mice model of GI tumor hepatic metastasis was employed. The spleen injection was used to mimic portal vein chemotherapy to study the advantages of galactosylated liposome Doxorubicin in the treatment of hepatic metastatic carcinoma.The methods of rotating evaporation and active drug-carrying were used to prepare galactosylated liposome Doxorubicin. Upon detection, the mean granular diameter was 134.8nm and the entrapment efficiency of Doxorubicin>95%. And its physicochemical properties conformed to the in vivo and in vitro experimental requirements.As demonstrated by the in vitro cytotoxicity assay, galactosylated liposome Doxorubicin had an obviously stronger killing effect upon the targeted cell HepG2 than its common counterpart. But two types of liposomes showed no marked difference in the inhibition of cell growth for non-targeted cell Hct-8. The targeting of galactosylated liposome for hepatocytes was thus confirmed. Furthermore, when two types of liposomes were injected into mice body via spleen and tail veins, the technique of ex vivo fluorescent imaging was employed to observe the body distributions of both. It was found that two types of liposomes were predominantly deposited in liver. And the intra-hepatic fluorescent intensity of galactosylated liposome was markedly higher than that of its common counterpart. It re-confirmed the hepatic targeting of galactosylated liposome and the spleen injection method was superior.The groups were established according to different drug formulations and injection methods. As revealed by the pharmacodynamics studies of HCT-8 colon cancer hepatic metastasis, the spleen dosing of galactosylated liposome Doxorubicin showed marked differences with the control group in terms of reducing the size of hepatic metastatic carcinoma and suppressing the metastasis of mesenteric lymph node. For the purposes of further confirming the killing effects of various drug doses and the in vivo protective effects of galactosylated liposome, the low, medium and high doses of 3mg,6mg and 9mg respectively were administered via the spleen route to conduct a pharmacodynamic study of BGC-823 gastric cancer hepatic metastasis. Due to a higher sensitivity of BGC-823 cell to Doxorubicin, three drug formulations in each dose group had no marked difference in the suppressing effect of hepatic carcinoma. Therefore a lower dose of 1.5mg was used. The results showed that galactosylated liposome Doxorubicin had the strongest tumor suppression. But there was no statistical difference in comparisons with common liposomes and nude drug. Despite this fact, the present study had partially demonstrated that galactosylated liposome had excellent hepatic-targeting effects. Additionally, based upon the characteristic self-fluorescence of Doxorubicin, the treated tumor and normal hepatic tissue were prepared for paraffin slides. Under vertical microscope, it was found that, after the therapy of galactosylated liposome Doxorubicin, the fluorescent intensity of tumor and normal hepatic tissue was markedly higher than that of counterparts in common liposome and nude drug therapy groups. It indicated that galactosylated liposome Doxorubicin had a higher intra-hepatic concentrating degree than that of other drug formulations.As demonstrated by the above experiments, galactosylated liposome Doxorubicin as prepared here had stable physicochemical properties and carried a definite hepatic-targeting attribute. It had achieved a satisfactory efficacy in the treatment of hepatic metastasis of GI tumors via portal vein chemotherapy. It is expected to become one of the novel chemotherapeutic drug formulations.