|Year : 2020 | Volume
| Issue : 5 | Page : 1125-1128
Feasibility of computed tomography-guided irreversible electroporation for porcine kidney ablation
Tong-Yin Zhu1, Jing Ai2, Chun-Hui Nie1, Guan-Hui Zhou1, Xin-Hua Chen1, Yue-Lin Zhang1, Tan-Yang Zhou1, Sheng-Qun Chen1, Bao-Quan Wang1, Shu-Sen Zheng1, Li-Ming Wu1, Jun-Hui Sun1
1 Division of Hepatobiliary and Pancreatic Surgery, Hepatobiliary and Pancreatic Interventional Treatment Center, The First Affiliated Hospital, Zhejiang University School of Medicine; Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health; Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
2 Eye Centre, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
|Date of Submission||21-Aug-2019|
|Date of Decision||20-Mar-2020|
|Date of Acceptance||01-Jul-2020|
|Date of Web Publication||29-Sep-2020|
79 Qingchun Road, Hangzhou
Source of Support: None, Conflict of Interest: None
Objective: The objective was to evaluate the feasibility and safety of computed tomography (CT)-guided percutaneous irreversible electroporation (IRE) in porcine kidneys.
Materials and Methods: Under CT guidance, two monopole probes were used to precisely puncture through the renal parenchyma into the renal hilum in nine anesthetized adult Bama miniature pigs. After which, IRE ablation was performed. Biochemical and pathological examinations were carried out 2 h, 2, 7, and 14 days after the procedure.
Results: All procedures were performed successfully without any serious complications such as bleeding, infection, or death. All pigs survived until the end of the study. Pathological examinations showed that cells in the ablation area were dead within 2 days after the procedure, whereas the vascular endothelium showed only slight damage. After 2 days, endothelialization ensued and regrowth of smooth muscle cells was observed after 14 days. Hemogram tests indicated a transient increase but gradually returned to baseline levels 14 days after the procedure.
Conclusion: IRE was essentially safe, however further studies on tumor ablation using several different animal models are needed.
Keywords: Ablation, computerized tomographic scanning, irreversible electroporation, kidney
|How to cite this article:|
Zhu TY, Ai J, Nie CH, Zhou GH, Chen XH, Zhang YL, Zhou TY, Chen SQ, Wang BQ, Zheng SS, Wu LM, Sun JH. Feasibility of computed tomography-guided irreversible electroporation for porcine kidney ablation. J Can Res Ther 2020;16:1125-8
|How to cite this URL:|
Zhu TY, Ai J, Nie CH, Zhou GH, Chen XH, Zhang YL, Zhou TY, Chen SQ, Wang BQ, Zheng SS, Wu LM, Sun JH. Feasibility of computed tomography-guided irreversible electroporation for porcine kidney ablation. J Can Res Ther [serial online] 2020 [cited 2020 Oct 26];16:1125-8. Available from: https://www.cancerjournal.net/text.asp?2020/16/5/1125/296440
| > Introduction|| |
Irreversible electroporation (IRE) is a new nonthermal tumor ablation technology. Using this technology, the lipid bilayer is irreversibly perforated by high-voltage short pulses., This results in the increase in cell membrane permeability to induce cell death., Compared with other physical ablation methods such as radiofrequency and microwave ablation, IRE is not based on thermal damage., It does not damage the blood vessel structures and bile ducts in the ablated area of the kidneys, whereas radiofrequency ablation of kidney tumors may damage the collection system of the kidney and adjacent structures limiting its applicability. However, animal studies of IRE in the kidneys are scarce. The purpose of this study was to investigate the safety of IRE and to provide a clinical basis for the application of IRE ablation in the kidney.
| > Materials and Methods|| |
A total of nine healthy adult Bama miniature pigs were used in this study and were not limited to animal gender. The weight of the animals was between 25 and 30 kg. The animals were purchased and reared at the animal center of Zhejiang University School of Medicine. Animals were housed in standard approved cages under sanitary conditions with access to food and water.
Pigs were fasted for >12 h and water was restricted for >6 h before the ablation procedure. The ear vein was punctured to establish intravenous access. General anesthesia, tracheal intubation, and mechanical ventilation were performed. Heart rate and breathing were monitored by electrocardiogram (ECG). The skin in the abdominal area was prepped for surgery. Experimental pigs were secured on the computed tomography (CT) scanning bed, and the body surface was placed on the metal positioning grid. The renal parenchyma of the renal hilum was used as the ablation target area. The puncture path was designed to avoid the ribs, blood vessels, and other organs. The puncture point on the body surface was verified and marked and then disinfected. A 3 mm incision was made on the skin of the puncture point using a knife blade after which image guidance using a 256-slice spiral CT scanner (Philips Brilliance, scanning voltage 120 kV, slice thickness 5 mm, slice distance 5 mm) was performed. The ablation equipment was a NanoKnife (Angio Dynamics, Latham, NY) and was composed of a generator, ablation probe, and matched ECG simultaneous instrument. Two 19G monopole ablation probes were parallel punctured to the ablation target area based on the predetermined puncture path. The distance between the probes was 1.1 cm–2.0 cm, and the length of the electrode exposure was 2 cm [Figure 1]. First, muscle contraction was observed by a single electric pulse. If a slight muscle twitch did not result in probe displacement, then we started the ablation protocol. The R wave was automatically detected using a matched ECG monitor, and the generator was triggered. The electric pulse was generated after the generator was delayed for 50 ms. when was the ventricular refractory period, which could minimize the effect on the cardiac rhythm. Ablation parameters were as follows: current 50 A, voltage 3000 V, single pulse time 0.07 ms, and a total of 90 pulses were transmitted. After the ablation procedure, the probe was removed and spiral CT scan was performed again. After verifying the absence of serious complications, the puncture point was sterilized and sutured.
|Figure 1: (a and b) The image shows the two monopole probes in parallel puncturing the right renal hilum|
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(1) Intraoperative and postoperative complications were monitored, such as bleeding, perforation of the urinary tract, venous thrombosis, hematuria, and arrhythmia; (2) Routine blood and myocardial enzymograms were performed: blood samples were collected before the procedure to determine the baseline blood and myocardial enzymogram levels. Blood samples were collected again at 2 h, 2 days, 7 days, and 14 days after the procedure to observe any changes; (3) Pathological examination: experimental pigs were randomly selected and euthanized before the procedure (one pig), 2 h after the procedure (two pigs), 2 days after (two pigs), 7 days after (two pigs), and 14 days after the procedure (two pigs). Tissues in the ablated area were harvested and then immersed in formalin solution. Pathological sections were sliced and H and E staining was performed to observe tissue necrosis and repair.
| > Results|| |
Ablation was successfully performed in all the experimental pigs with no complications during intraoperative anesthesia. During electrical pulses, slight muscle twitching was observed with no obvious arrhythmia (ventricular tachycardia and atrial fibrillation). Three animals developed small amounts of renal capsular bleeding, but were resolved after 7 days. No hematuria, renal vein thrombosis, and perforation of the urinary tract were observed. All pigs were successfully resuscitated after the procedure with a recovery time of 1 h ± 0.35 h. Postprocedural physical activity and feeding patterns of all the animals were similar as before surgery.
Biochemical indicators showed that infiltration of inflammatory cells was present 2 days after ablation, but returned to preprocedural levels after 14 days [Figure 2] and [Figure 3].
|Figure 2: Leukocyte changes pre. and postablation: At 2 h after ablation, changes in leukocyte levels were significantly increased, at 2 days post ablation, there was a gradual decrease in leukocyte levels, whereas at 14 days post ablation, leukocyte levels were similar to preprocedural levels|
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|Figure 3: Changes of myocardial enzymogram (lactic dehydrogenase, creatine kinase-MB, hydroxybutyrate dehydrogenase) pre- and postablation: At 2 h post ablation, myocardial enzyme levels were increased significantly, at 2 days post ablation, there was a gradual decline and at 14 days post ablation, myocardial enzyme levels returned to preprocedural levels|
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H and E staining showed that cells in the ablation area were dead within 2 days after the procedure with the vascular endothelium slightly damaged. After 2 days, endothelialization occurred and regrowth of smooth muscle cells was observed [Figure 4].
|Figure 4: (H and E, ×200) pathological changes of irreversible electroporation ablation in the kidney: (a) Pathological comparison; (b) 2 h after ablation; (c) 2 days after ablation; (d) 7 days after ablation; (e) 14 days after ablation. After irreversible electroporation ablation, bleeding was observed, but relatively complete renal morphology was preserved. The glomeruli in the ablation area were intact. Slight edema in blood vessels and no structural damage was observed. At 2 h, 2 days, and 7 days after ablation, extensive cell death was observed in the ablated area, however normal renal tissue structure was preserved. Between 2 and 7 days after ablation, a large number of neutrophils and eosinophils had infiltrated the ablated area. The structure of larger vessels and renal tubules in the ablated area were preserved, but mild vasculitis, multifocal endothelial dysfunction, edema, myometrial separation, and neutrophil infiltration were observed|
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| > Discussion|| |
In this study, CT was used for guidance because of its high resolution and rapid scanning speeds. It could quickly and visually display the location of the ablation electrode probes with respect to its surrounding structures. In addition, it could detect in real-time complications such as bleeding and urinary tract perforation so as to ensure the accuracy and safety of the percutaneous puncture procedure.,,
Ablation was performed successfully in all pigs with no serious complications, such as arrhythmia and infection. Percutaneous puncture is a minimally invasive technique with less trauma and few complications.,, Only three pigs had a small amount of renal capsular bleeding caused by the puncture procedure. After the ablation procedure, all experimental pigs were successfully resuscitated with a recovery time of 1 h ± 0.35 h. However, the recovery time of some of the experimental pigs was longer, and we speculated that it was due to administration of muscle relaxants and the drop in body temperature. Therefore, we suggest that muscle relaxants should be administered with caution. It should be minimally administered as long as only minor muscle contraction during ablation is present and does not cause displacement of the ablation probe. In addition, the experimental animals should be kept warm during the procedure with the use of blankets to properly cover the nonsurgical areas.
We found that leukocyte, lactate dehydrogenase, creatine kinase isoenzyme, and hydroxybutyrate dehydrogenase were increased significantly 2 h after ablation and then gradually decreased 2 days postprocedure. Fourteen days postprocedure, all indicators returned to the baseline levels. IRE had a short-term stress response with damage to the myocardium being acute and temporary and was restored after a short period. Pathological examination showed that IRE could cause complete cell death in the ablated area, while the vessels and renal tubules that are rich in glia were preserved. This is consistent with the results reported in previous studies.,,,
There were several limitations to our study: (1) the experimental animal numbers were small, short follow-up period after ablation, lack of long-term follow-up to determine the extent of tissue repair, and regeneration in the ablated area; (2) only one single parameter for ablation, no comparison with different ablation parameters; (3) the use of only healthy experimental animals.
Future studies using IRE ablation in renal cell carcinoma pig models will be more clinically applicable and valuable.
| > Conclusion|| |
This study observed that IRE ablation of the porcine kidney was a safe procedure, however further studies are needed, specifically using kidney tumor models with different experimental animals to conclusively demonstrate the safety of the procedure before human clinical application.
Financial support and sponsorship
The present work was funded by the National Natural Science Foundation of China (Grant No. 81371658 and 81970381), Zhejiang Provincial Natural Science Foundation of China (Grant No.LZ18H180001), National S&T Major Project of China (No. 2018ZX10301201), the Key Research Development Program of Zhejiang province (Grant No. 2018C03018), Key Science and Technology Program of Zhejiang province (No.WKJ-ZJ-1923), and National Key R&D Program of China (No. 2017YFC0114102).
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]