| Background Hepatocellular carcinoma(HCC) is one of the most common fatal malignant tumors world wide, it is the fifth most common cancer. Surgical resection is the first choice for the patients whose lesion is local and the liver function is good, but most patients were told a late stage at the time of diagnosis, losing the chance of operation. HCC is not sensitive to chemotherapy, radiotherapy and hormone therapy. It is reported that the tissues would suffer coagulative necrosis when the temperature is more than46degree, so many patients choose percutaneous ablation, including radiofrequency ablation(RF), laser, microwave and high-intensity focused ultrasound(HIFU). But there are so many limitations about ablation, for example, thermal dose is uneven in tissues, thermal damage on normal tissues is occurred in many conditons, playing a limited role in tumors which are large and deep, so it is not popularized in the clinical. After the development of nearly20years, transarterial chemoembolization(TACE) has become the first choice for patients who are inoperable, by selectively blocking the arteries which supply the tumor, together with the cytotoxic effects of the chemotherapy drugs, play a role in antineoplastic, its efficiency is up to30%-70%. But single arterial chemoembolization can not obtain satisfactory results, studies found that after arterial chemoembolization, the arteries supplying the tumor is blocked, then tumor tissue hypoxia increase, which can cause potentially high recurrence and metastasis. Therefore, it is imperative to seek more effective treatment for HCC.Recent years, many scholars had done much reasearch on magnetic arterial embolization hyperthermia(MAEH). MAEH is a product of the combination of arterial embolization therapy and magnetic induction hyperthermia, supplemented by hyperthermia, given its double blow on the basis of embolization of tumor blood vessels, so as to achieve the purpose of treatment of cancer. The advantage is fewer side effects, can carry out repeated non-invasive treatments, and additionally, the tumor cells are in a hypoxic state after embolization,which are more relatively sensitive to heat, an d thus more conducive to the inactivation of tumor cells. About artery embolization magnetic induction hyperthermia, the more research directions include:embolism medium, the magnetic field generating device, heating rate and tumor inhibition rate. And the most studied magnetic embolism media mainly focus on nanoscale Fe3O4and γ-Fe2O3, these magnetic nanoparticals mixed with iodized oil is called magnetic fluid. Some scholars believe that the magnetic fluid has excellent permeability in the tissues, and require lower strength of the external magnetic field, so has more potential in the hyperthermia. But the limitation is that these nanoscale ferromagnetic particles can easily pass through the capillary network and enter into the systemic circulation, which is not safe. Therefore, some scholars think that the magnetic embolism media should be micron-sized, which can make sure the tumor capillary embolized, then will not entered into the venous circulation.CIP (with trade name of Ferronyl(?), ISP pharmaceuticals) has been approved by American Food and Drug Administration (FDA) for dietary iron supplement by oral administration due to its low toxicity and excellent bioavailability. The particle size ranges from2to10μm. Our previous in vitro and in vivo experiments showed that carbonyl iron powder was safe, had excellent biocompatibility and inductive heating characteristics, think that it has the potential to be an magnetic embolism medium. And the other hand about the security is the distribution of the magnetic particles in the tumor tissue and other vital organs. when nontarget embolization occurred during embolization, it will cause mechanical and thermal damage to other normal tissues and organs, then the therapeutic ratio of gains decreased, at the same time, the distribution of the particals decided the therapeutic efficacy. The purpose of the presented work is to explore the distribution and metabolic pathways of the carbonyl iron powder-lipiodol suspension in the rabbit VX2liver tumor tissue and other vital organs, and preliminarily study its efficacy and mechanism of action of arterial embolization hyperthermia.Part I The distribution of CIP in normal rabbit liver after arterial embolization mediated by CIP-lipiodol suspensionsObjective To explore the distribution of the CIP-lipiodol suspension in the normal liver tissue and normal liver cells as a arterial embolization hyperthermia medium, to provide a reference for further tumor-bearing rabbits experiments.Methods CIP-lipiodol suspension were injected into the the hepatic artery of8normal New Zealand white rabbits, then we sacrificed all of the rabbits one day after the embolization, taken out the liver tissue, immediately immersed in10%formalin solution, embedded in paraffin, sliced, HE and Prussian blue staining, pathological histological examination. Paraffin sections were restructured, by use of ultrathin section examination.Results HE staining showed liver tissue necrosis around the CIP deposited, Prussian blue staining showed that the CIP accumulated in the hepatic artery catheter, and some iron powder entered into the hepatic cords, sinusoidal, Disses cavity, part of CIP into the liver cells, and even into the liver cell nuclei. The TEM ultramicrotomy further confirmed that part of the CIP entered into the liver nuclei and deposited in the nucleolus.Conclusions After hepatic artery embolization with CIP-lipiodol suspension, cell necrosis of the area which the blood supply to happened, some of the CIP entered into the liver cell nucleus, provided a theoretical basis for the intracellular hyperthermia, and had a certain research value of the drug-oriented cell heat chemotherapy. Part II Analysis of the distribution and metabolic pathways of CIP in the rabbit VX2liver tumor and other vital organs after arterial embolization mediated by CIP/lipiodol suspensionsObjective To analysis qualitatively and quantitatively the distribution of the CIP in the rabbit VX2liver tumor and other vital organs after arterial embolization mediated by CIP/lipiodol suspensions, to explore its metabolic pathways, and provide a theoretical basis for the follow-up efficacy analysis and mechanism study.Methods Eigthteen days after tumor implantation, the40rabbits bearing VX2liver tumor were randomly divided into two parts:Part I, eight rabbits, underwent MRI scan before embolization, and1,3,14days after embolization as well, after the last MRI scan, these8rabbits were sacrificed, the tumors and other vital organs were removed for histopathological examination; Part Ⅱ,32rabbits, divided into four groups:eight rabbits were sacrificed instantly, eight were sacrificed the first day after embolization, the third eight were sacrificed the third day after embolization, and the remaining eight were sacrificed the14th day after embolization, then the tumor, normal liver tissue, lung, spleen, gallbladder of all the rabbits were removed immediately after sacrificed, these isolated tissues were put in the oven(110℃) drying to constant weight, grouded into powder, for inductively coupled plasma atomic emission spectrometry(ICP-AES) examination of iron content.Results (1)After embolization, the tumor tissue iron content was significantly higher than that before embolization, as well as the normal liver tissue(P<0.001). At all time points after embolization, the mean ratio of the iron content of the tumor tissue compared with the normal liver tissue is4.55:1.(2) The iron content of the lung tissue had no significant change both before and after embolization(P>0.05).(3) At all time points after embolization, the iron content of the spleen tissue had significantly increased than that before embolization(P<0.001).(4) At each time point after embolization, the iron content of the gallbladder tissue had significantly increased than that before embolization(P<0.001), but as time went on, the iron content of the gallbladder was significantly lower at the3th,14th day after embolization compared with that the1st day after embolization.Conclusions MRI can detect a certain concentration of iron in the liver tissue, and can determine whether there were excessive iron deposited in the normal liver tissue, thereby avoiding thermal damage that caused by the high concentrantion iron of the normal liver tissue in the applied alternating magnetic field. The embolization mediated by CIP-lipiodol suspension of the rabbit VX2liver tumor had a special targeting action, provided a theoretical basis for both single and multiple hyperthermia, but also provided a theoretical basis for follow-up efficacy analysis and mechanism study. There were no significant change of the iron content in the lung tissue both before and after the embolization, which further confirmed the safety of the embolization. The liver, spleen and bile duct-intestinal tract may be three metabolic ways for the CIP-lipiodol suspension. Part Ⅲ Efficacy analysis and mechanism study of the rabbit VX2liver tumor after arterial embolization hyperthermia Objective To analysis the efficacy and mechanism of action of the rabbit VX2liver tumor after arterial embolization hyperthermia.Methods Eigthteen days after tumor implantation,32rabbits bearing VX2liver tumor were randomly divided into four groups, including the control group(Group A), lipiodol embolization group(Group B), CIP-lipiodol suspensions embolization group(Group C) and CIP-lipiodol suspensions embolization hyperthermia group(Group D). Rabbits of each group underwent MRI and CT scanning before and fourteen days after embolization, respectively. Tumor size was measured, volume and tumor-inhibition rates of tumors were calculated. The survival time for each group of rabbits were observed. The changes of tumors were observed macroscopically and microscopically. SABC immunohistochemistry methods were used to detect the expression of VEGF and MMP-9of the tumor tissue.Results (1) There were no significant difference of the tumor volume between the four groups before embolization(P>0.05). At the time of the rabbits sacrificed, the tumor volume in group B, C, D were significantly smaller than group A(P<0.001), and those in group D were even smaller than group B and C (P<0.001), but there were no significant difference between group B and C(P>0.05). The tumor-inhibition rates of group B, C, D were64.67%,74.60%,95.86%, respectively.(2) Either on macroscopically or microscopically observeion, the tumor growth were inhibited obviously in group B, C, D comparing with group A, the lung metastases in group D were less and smallar than the other three groups. There were two rabbits had spleen metastasis, one had kidney metastasis, and one had abdominal metastasis in group A, while other three groups had no distant metastasis other than the lung tissue. Microscopically, almost complete necrosis for group D were observed, there were only some residual scattered cancer cancer nests around the areas of necrosis. Deposition of carbonyl iron powders and iodized oil in arteriole could be seen in group C and D, there were a small amount of carbonyl iron powder or iodized oil remained in the normal liver tissue arterioles of rabbits in group B, C and D, litter liver tissue surrounding embolized arterioles occured atrophy and degeneration. And the lung tissue of all the rabbits had no atrophy, degeneration and necrosis.(3) Compared to the other three groups, the survival time of the rabbits of group D was significantly extended (P<0.001), the survival time of group B and C was also longer than group A(P<0.05, P<0.001), and there was no significant difference between group B and C(P>0.05).(4) The positive rate of VEGF and MMP-9in the AEH group were significantly lower than group A, B and C(P<0.001). And those of group B, C were significantly lower than that in the control(P<0.001), but there was no significantly difference between group B and C(P>0.05).Conclusions CIP-lipiodol suspensions mediated arterial embolizati-on hyperthermia can effectively suppress the growth of VX2liver tumors, extend the survival time of the rabbits, injury tumor vessels and inhibit the positive expression of VEGF and MMP-9, and decrease the invasion and distant metastasis. |
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