| Backgrounds and objectiveWith tumor ablation of IRE in clinical applications more widely,The ablation achieved better therapeutic effects,especially in the "ablation restricted zone" to thermal ablation.However,with the deepening of clinical research,it had been found that muscle contraction,uneven electric field distribution and incomplete local tumor ablation limited the clinical application of tumor ablation with IRE.At this time,a new generation of irreversible electroporation equipment was needed to solve these problems.After a series of exploration and innovation,the Electrical Engineering Academy of Chongqing University had optimized the relevant parameters on the basis of conventional IRE,and independently developed a novel IRE device of multiple pulses that could release high-frequency bipolar pulses,relieving muscle contraction and homogenizing electric field distribution in the ablation zone.This topic further evaluated the safety and effectiveness of hepatic ablation in swine by high-frequency IRE(H-FIRE)with bipolar bursts,and compared with conventional unipolar pulse ablation in order to prove its superiority as a new generation of irreversible electroporation equipment.Material and methodsSeveral swines(provided by the Animal Experimental Center of the Army Military Medical University)were randomly divided into two parts to experiment.The first part 15 pigs were selected to be randomly and divided into A(immediately after surgery),B(postoperative 3)Days,C(7 days after surgery),D(14 days after surgery),E(28 days after surgery)5 groups,according to the killing time,liver's three parts of each swine were selected for ablation with H-FIRE,testing the blood routine?liver function and kidney function of swines before ablation and execution,enhanced CT had been examinated before sacrifice,ablated liver tissue was taken for histopathological examinations(HE,vWF,Von Kossa,TUNEL staining).The general situation of swines was observed,their CT images and pathological examinations were analyzed in order to evaluate effects of hepatic ablation in swine by H-FIRE.In the second part,6 swines were randomly divided into two groups,3 in experimental group(H-FIRE)and 3 in control group(IRE).Ablation was performed on the liver tissue of the experimental group with H-FIRE,the control group with IRE,Three parts of liver in each swine were selected for ablation,the muscle contraction strength of swines during ablation was measured.All the swine in two groups were performed enhanced CT examination,and then killed in 3 days after ablation.Liver tissues were taken for histopathological examinations(HE,TUNEL staining),and the apoptotic index was calculated,and statistical analysis was performed.ResultsThe results of part one1.All the 15 swines were successfully completed the ablation procedure.The postoperative animals survived to the designated time.The general activities and daily food intake of the swines after 24 hours postoperation were not significant difference than be fore.No serious bleeding,neumothorax,infection,bile leakage and other serious complications occurred.The value P was > 0.05 between preoperation and postoperation of blood routine(WBC?RBC?PLT?Hb)?liver and kidney function(IN?Cr?ALT?AST?ALP?TBIL)tests,indicating that the blood routine?liver function and kidney function of swines after ablation were normal.2.Imaging performance the ablation area of immediately after surgery,presented clear visible boundary with low density in enhanced CT scan,without vascular and biliary tract injuring obviously and other serious complications,and a little bleeding could be seen in liver.the ablation zone was reduced gradually over time.The ablation zone showed fiber shadows and even disappeared in 28 days after ablation,and no obvious abnormalities were observed in vital tissues such as peripheral blood vessels and gallbladder.3.the observation period were 28 days.HE staining of immediate postoperation showed swelling and disordered cells in the ablation zone.A large number of deeply stained nuclei and inflammatory cells infiltrated in the ablation zone were observed in HE staining of 3 days postoperation.larges number of newborn hepatocytes grew from the periphery to the center,showing an increasing trend from 7 days,14 days,and 28 days of ablation;some dark brown calcium deposits were observed undestructively by Von-Kossa staining,and vascular endothelial cells were observed by vWF staining.TUNEL detection showed a large number of apoptotic cells in the ablation zone.The results of part two1.Six swines in both groups survived for 3 days after ablation.There was no significant difference in feeding and activity between the two groups.2.Maximum muscle contraction strength in the experimental group was(9.8 ±0.38)m/s2,the maximum muscle contraction strength of the control group was(48.6 ± 0.45)m/s2,Comparison of muscle contraction strength between the two groups(P=0.00<0.05)was statistically different?3.Imaging performance.Enhanced CT scan in Immediately postoperation and 3 days postoperation showed a low-density shadow and clear boundary in the ablation zone.There was no obvious abnormality in the ablation zone and its adjacent large blood vessels,no vascular stenosis and leakage of contrast agent.4.Pathological examinations The HE staining of the two groups showed that the ablation zone and the normal liver tissue were clearly separated.The fibrous tissue was intact,presenting amount of nuclear debris and inflammatory cells in the ablation zone.Calculation of apoptotic cells in each 9 ablation zone of two groups through TUNEL staining,the AI was(76.67±0.04)% in experimentalgroup?(64.03±0.05)% in conrol group,The difference between the two groups was statistically significant(t=4.79,P=0.001).ConclusionThe ablation of liver tissue in swines can safe and effective by High-frequency irreversible electroporation with bipolar bursts,without damaging intrahepatic vessels,bile ducts,and gallbladder.Compared with traditonal IRE,H-FIRE can reduce muscle contraction intensity and produce more apoptotic cells. |
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