| Hepatocellular carcinoma (HCC) is the most common primary liver cancer,the mortality of HCC is the second place of all cancers in our country. The effect of the clinical treatment and prognosis of patients depends on early detection, early diagnosis. Clinical commonly used detection methods including serum AFP and various imaging tests. Alpha-fetoprotein (AFP) is a typical tumor-specific marker for the HCC, hence it can be used as an efficient and specific imaging target. If the anti-AFP antibody with some contrast agents or (and) cancer drugs are linked together, we can achieve target imaging and targeted therapy of liver cancer, which makes the imaging diagnosis and clinical treatment at the same time for possible.This experiment intended to construct AFP-targeted ultra-small superparamagnetic nanoparticles. Through comparing MR imaging to histopathology result on SD rats liver cancer model which is induced by small doses of diethylnitrosamine, the targeted imaging and distribution of AFP-targeted nanoparticles in HCC were studied. This study mainly includes two parts.The first part:Establishing SD rats liver cancer model and AFP-USPIO targeted MR imaging performancesObjective:To establish rats liver cancer model,enhancement scan with USPIO marked by AFP antibody as contrast agents was conducted, and the hepatoma specific MRI imaging of rats was observed.Methods:The0.1mg/ml DENA aqueous solution was regularly formulated for25male SD rats to drink freely for14weeks, afterwards, the rats were fed with pure drinking water instead of DENA solution. In the16th-18th week,20rat hepatoma models which were beneficial to experimental observation were selected and divided into two groups completely and randomly:10in Experimental Group,10in Control Group. MRI T2WI plain scan was made firstly on rats. Then AFP-USPIO (targeted group) was injected in rats of Experimental Group, while USPIO (non-targeted group) was injected in rats of Control Group. And2h later, T2WI enhancement scan was carried out to observe signal change of lesions and measure the intensity of signals in lesions and liver before and after enhancement, and their contrast to noise ratio (CNR) were calculated; After that rats were put to death, lesion specimens were taken and analyzed with HE and AFP immunohistochemical staining as well as Pearl’s blue staining.Results:Through scanning T2WI via MRI, the results showed multiple unequal-sized nodule images with high, slightly high and mixed signals in the liver, then the nodules whose diameter not less than3mm were chosen as subjects to observe. Lesions were well-defined, and most of signals were uniform, high or slightly high signals. Rats in Experimental Group and Control Group were injected with AFP-USPIO and USPIO, and2h later, enhancement scan was conducted. The CNR in rat liver-tumor before and after AFP-USPIO injection was10.0±2.45and4.73±2.51respectively, with statistically significant difference (P<0.001, t=11.23). And the CNR in rat liver-tumor before and after USPIO injection was9.15±1.24and9.96±1.63respectively, without statistically significant difference (P=0.186, t=-1.43).Pathological results of HE staining revealed that, the lesions selected for MRI observation were all hepatocellular carcinoma (HCC); AFP immunohistochemical results showed that, AFP were expressed largely in hepatoma cell plasma. The results of Pearl’s blue staining indicated that, more blue-stained iron particles were seen in tumor tissue space and inside tumor cells in Experimental Group, while there were less blue-stained iron particles in tumor tissues in Control Group.Conclusion:DENA-induced SD rats liver cancer model is convenient, and get high tumor formation rate. After AFP-USPIO enhanced scanning,targeted contrast agent aggregated in rat liver tissue, reduced the signal of tumor tissue.Although the contrast noise ratio of liver tumor decreased, but it helps to qualitative diagnosis of liver cancer. The second part:Study on the enhanced MR Imaging and distribution changes of AFP-SPIO in SD rats with liver cancerObjective:Study antibody labeling superparamagnetic iron oxide nanoparticles (AFP USPIO) in rat hepatocellular carcinoma tissue distribution changes with time, provide theoretical support to the next step--distribution changes of the nanoparticles coupling with tumor chemotherapy drug in hepatocellular carcinoma tissue.Methods:10SD rat liver model, as the above methods and requirements. For MR T2WI scan, and then radomized grouping into the experimental group (n=5), inject of AFP-USPIO, the control group (n=5), inject of USPIO.The rats were enhanced scanned after0.5hour,1hour,2hours6hours,12hours,24hours, then measure the lesion and liver tissue signal intensity, at each point in time.At last calculate the contrast to noise ratio (CNR) and signal intensity decreased percentage of the tumors (PSIL).Results:The MRI scan on T2WI sequences tumor tissue was high, slightly high signal, or mix signal. In experimental group:0.5-1hour after targeted contrast agent injection,decreases of tumor tissue T2signal intensity is not obvious, between2-8hour signal intensities decreasing extended gradually going on with time, at the point of4-8h signal intensities decresing peaked, and also persistent reinforcement,between12-24hours signal of tumors began to rise. Control group:tumors signal intensities did not decrease or rise at each time point after contrast medium injection.Tumors signal value differences was statistically significant in experimental group and control group (F=164.5, P<0.01), the signal of the liver differences do not have statistical significance between the experimental group and control group(F=4.6, P>4.6). The experimental group and control group of tumor-liver CNR calculated value differences statistically significant (F=132.7, P<0.01).Conclusion:By MR scanning dynamic observing AFP-USPIO enhanced tumor signal change, inferring the distribution changes in tumor tissues. Enhanced2h-8h tumors over time, the persistent reinforcement,8h of nanoparticles in tumor tissue gathered to peak, phasing out after12h. |
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