Porcine Bile Duct Research Articles

Safety Parameters for the Use of Holmium:YAG Laser in the Treatment of Biliary Calculi: The Ex-Vivo Model.

Background and Objectives: While studies have demonstrated the efficacy of cholangioscopy-guided Holmium-Yttrium aluminum garnet (Ho:YAG) laser lithotripsy for the treatment of refractory bile duct stones, data regarding the safety of the operating parameters for laser lithotripsy are lacking. The aim of this study was to determine safe, yet effective, energy settings for Ho:YAG laser in the ex-vivo model. Materials and Methods: This ex vivo experimental study utilized the Ho:YAG laser on porcine bile duct epithelium and human gallstones. Ho:YAG laser lithotripsy was applied in different power settings from 8 to 15 Watts (W) to six explanted porcine bile ducts. Settings that appeared safe were then utilized to fragment seventy-three human gallstones. Results: The median bile duct perforation times with the Ho:YAG laser between 8-15 W were: >60 s (8 W); 23 s (9 W); 29 s (10 W); 27 s (12 W); 12 s (14 W); and 8 s (15 W). Statistically significant differences in the median perforation times were noted between 8 W vs. 15 W, 9 W vs. 15 W, 10 W vs. 15 W, and 12 W vs. 15 W (p < 0.05). When using a 365 µm Ho:YAG laser probe at 8-12 W, the fragmentation rates on various size stones were: 100% (<1.5 cm); 80-100% (1.6-2.0 cm) and 0-32% (>2.0 cm). Optimal fragmentation was seen utilizing 12 W with high energy (2.4 J) and low frequency (5 Hz) settings. Using a larger 550 µm probe at these settings resulted in 100% fragmentation of stones larger than 2 cm. Conclusions: The Ho:YAG laser appears to be safe and effective in the treatment of large bile duct stones when used between 8-12 W in 5 s bursts in an ex vivo model utilizing porcine bile ducts and human gallstones.

Glucagon- and insulin-immunopositive endocrine cells in porcine extrahepatic bile ducts and gallbladder

IntroductionPancreatic β-cells and α-cells have been found in the murine extrahepatic biliary ducts but not in the gallbladder. However, there has been no information reported in the specialized literature about the presence of glucagon- and insulin-expressing endocrine cells in porcine bile ducts and gallbladder.AimWe aimed to perform an immunohistochemical study to identify glucagon- and insulin-positive cells and their distribution in the porcine extrahepatic biliary ducts and gallbladder.MethodThe immunohistochemical method was used to detect the presence and distribution of glucagon- and insulin-positive endocrine cells in the common hepatic duct (ductus hepaticus communis), common bile duct (ductus choledochus), cystic duct (ductus cysticus), and gallbladder (vesica fellea) of male pigs. Chromogranin A was used as a typical marker for endocrine cells.ResultsThe density of chromogranin A-, glucagon- and insulin-positive cells per field was the largest in the common bile duct, followed by the common hepatic duct, cystic duct, and gallbladder. The three types of endocrine cells showed specific localization in the superficial and deep glands of the studied organs.Conclusion and clinical importanceThe distribution of glucagon- and insulin-immunopositive endocrine cells in the porcine extrahepatic biliary tract was established for the first time as a new source of these hormones. The presence of α- and β-cells in the epithelium of extrahepatic bile ducts can be applied in treatment of diabetes, taking into account the possibility to reprogram the biliary epithelium to mentioned pancreatic endocrine cell types.

Standardized construction of a porcine model for acute obstructive jaundice and training of endoscopic ultrasound-guided choledochoduodenostomy

BackgroundEndoscopic ultrasound-guided biliary drainage (EUS-BD) is an alternative to endoscopic retrograde cholangiopancreatography (ERCP) for patients with obstructive jaundice. However, it is still a challenge for many endoscopists because of its novelty and complexity. This study aimed to establish an ideal bile duct dilatation model for the training and practice of endoscopic ultrasound-guided choledochoduodenostomy (EUS-CDS).MethodsThe 34 healthy Bama miniature pigs were divided into the part of developing the standardized EUS-CDS (n=9) and the part of trainees training (n=25). Part one, two different methods were used to clip Vater’s ampulla using metal clips to establish an extrahepatic bile duct dilatation model. Part two, five trainees were trained on EUS-CDS with 25 pigs. Following a 2-week observation period, the feasibility and effectiveness of the technique were evaluated.ResultsIn the group with three metal clips perpendicular to the duodenal wall clipping Vater’s ampulla, the success rate of extrahepatic bile duct dilation greater than 1 cm in 24 h was 5/6, whereas the remaining one pig was 48 h. All five trainees can finally complete the EUS-CDS independently. No death occurred during the 2-week observation period.ConclusionClipping Vater’s ampulla with three metal clips perpendicular to the duodenal wall is an effective and stable method to create a porcine bile duct dilatation model.

Feasibility and safety of a novel 3D-printed biodegradable biliary stent in an in vivo porcine model: a preliminary study

To assess the feasibility and safety of a novel 3D-printed biodegradable biliary stent using polycaprolactone (PCL) in an in vivo porcine model. In this animal study using domestic pigs, biodegradable radiopaque biliary stents made of polycaprolactone (PCL) and barium sulfate were produced using 3D printing and surgically inserted into the common bile duct (CBD) of pigs (stent group, n = 12). Another five pigs were allocated to the control group that only underwent resection and anastomosis of the CBD without stent insertion. To check the position and status of the stents and stent-related complications, follow-up computed tomography (CT) was performed every month. The pigs were sacrificed 1 or 3 months after surgery, and their excised CBD specimens were examined at both the macroscopic and microscopic levels. Three pigs (one in the stent group and two in the control group) died within one day after surgery and were excluded from further analysis; the remaining 11 in the stent group and 3 in the control group survived the scheduled follow-up period (1 month, 5 and 1; and 3 months, 6 and 2 in stent and control groups, respectively). In all pigs, no clinical symptoms or radiologic evidence of biliary complications was observed. In the stent group (n = 11), stent migration (n = 1 at 3 months; n = 2 at 1 month) and stent fracture (n = 3 at 2 months) were detected on CT scans. Macroscopic evaluation of the stent indicated no significant change at 1 month (n = 3) or fragmentation with discoloration at 3 months (n = 5). On microscopic examination of CBD specimens, the tissue inflammation score was significantly higher in the stent group than in the control group (mean ± standard deviation (SD), 5.63 ± 2.07 vs. 2.00 ± 1.73; P = 0.039) and thickness of fibrosis of the CBD wall was significantly higher than that of the control group (0.46 ± 0.12 mm vs. 0.21 ± 0.05 mm; P = 0.012). Despite mild bile duct inflammation and fibrosis, 3D-printed biodegradable biliary stents showed good feasibility and safety in porcine bile ducts, suggesting their potential for use in the prevention of postoperative biliary strictures.

Development and validation of a novel porcine bile duct dilation model for EUS training.

Background and study aims Image-guided minimally invasive techniques have transformed the management of malignant and benign bile duct obstructions. These evolving techniques are being widely adopted and applied and hands-on training using high quality models is required to improve the proficiency of practitioners. This experimental study aimed to validate an in vivo porcine model created to simulate bile duct dilation for interventional endoscopic ultrasound (EUS) hands-on training curriculums. Materials and methods Thirty-six porcine models were involved and the procedures were performed in an experimental hybrid operating room under general anesthesia. Animals underwent endoscopic duodenal papilla clipping with several hemostatic metallic clips. After a survival period of 24 to 48 hours, the models with effective intrahepatic and extrahepatic bile duct dilatation were included in the hands-on training. Trainees and faculty were given structured evaluations of the model realism and usefulness. Results Extrahepatic bile duct and gallbladder dilation was achieved in all 36 of the models, and in 11 of the 36 models, a treatable intrahepatic duct dilatation was achieved. During the hands-on training, EUS-guided biliary drainage, EUS-guided transgastric gallbladder drainage, and EUS through-the-needle microbiopsy forceps procedures were feasible. Overall, 75 % of the experts and trainees evaluated the training as excellent. Conclusions We present a minimally invasive, reliable and time- effective model of extrahepatic dilation suitable for interventions. The model was less effective for intrahepatic ducts, which should be considered if intrahepatic biliary dilation is required for training.

Biosafety of a novel covered self-expandable metal stent coated with poly(2-methoxyethyl acrylate) in vivo.

Covered self-expandable metal stents (CSEMS) are often used for palliative endoscopic biliary drainage; however, the unobstructed period is limited because of sludge occlusion. The present study aimed to evaluate the biosafety of a novel poly(2-methoxyethyl acrylate)-coated CSEMS (PMEA-CSEMS) for sludge resistance and examine its biosafety in vivo. Using endoscopic retrograde cholangiopancreatography, we placed the PMEA-CSEMS into six normal porcine bile ducts and conventional CSEMS into three normal porcine bile ducts. We performed serological examination and undecalcified histological analysis at 1, 3, and 6 months during follow-up. In the bile ducts with PMEA-CSEMS or conventional CSEMS, we observed no increase in liver enzyme or inflammatory marker levels in the serological investigations and mild fibrosis but no inflammatory response in the histopathological analyses. Thus, we demonstrated the biosafety of PMEA-CSEMS in vivo.

Evaluating the tissue effects of balloon-based endobiliary radiofrequency ablation in porcine bile ducts

Background We developed a novel balloon-based endobiliary radiofrequency ablation (RFA) system to overcome the limitations of conventional RFA in treating malignant biliary strictures. This study aimed to evaluate the histological effects of balloon-RFA in porcine bile ducts. Methods Balloon-RFA of intrahepatic bile ducts from freshly resected porcine livers was performed for 60 s at 50, 60 and 70 °C. The specimens were subsequently sectioned for histological analysis and the slides were digitally scanned. Pseudo-coloring was applied based on the intensity of the ablation effect, and the area and estimated volume of ablation were measured. Results All samples showed epithelial sloughing and coagulative necrosis, and the entire internal circumference of the bile duct was evenly ablated. Complete transmural necrosis and involvement beyond the wall were found in 0% of samples ablated at 50 °C, in 33% at 60 °C and 100% at 70 °C. The mean depth and estimated volume of the ablation areas were 1.29 mm and 353.84 mm3, 1.44 mm, and 505.54 mm3 and 1.81 mm and 702.52 mm3 at 50, 60 and 70 °C, respectively. Conclusions Balloon-RFA leads to sloughing of the mucosa and coagulative necrosis. Ablation depth and volume increased in proportion to target temperature.

Autologous Adipose Tissue-Derived Mesenchymal Stem Cells Introduced by Biliary Stents or Local Immersion in Porcine Bile Duct Anastomoses.

Biliary complications (strictures and leaks) represent major limitations in living donor liver transplantation. Mesenchymal stem cells (MSCs) are a promising modality to prevent biliary complications because of immunosuppressive and angiogenic properties. Our goal was to evaluate the safety of adipose-derived MSC delivery to biliary anastomoses in a porcine model. Secondary objectives were defining the optimal method of delivery (intraluminal versus extraluminal) and to investigate MSC engraftment, angiogenesis, and fibrosis. Pigs were divided into 3 groups. Animals underwent adipose collection, MSC isolation, and expansion. Two weeks later, animals underwent bile duct transection, reanastomosis, and stent insertion. Group 1 received plastic stents wrapped in unseeded Vicryl mesh. Group 2 received stents wrapped in MSC-seeded mesh. Group 3 received unwrapped stents with the anastomosis immersed in an MSC suspension. Animals were killed 1 month after stent insertion when cholangiograms and biliary tissue were obtained. Serum was collected for liver biochemistries. Tissue was used for hematoxylin-eosin and trichrome staining and immunohistochemistry for MSC markers (CD44 and CD34) and for a marker of neoangiogenesis (CD31). There were no intraoperative complications. One pig died on postoperative day 3 due to acute cholangitis. All others recovered without complications. Cholangiography demonstrated no biliary leaks and minimal luminal narrowing. Surviving animals exhibited no symptoms, abnormal liver biochemistries, or clinically significant biliary stricturing. Group 3 showed significantly greater CD44 and CD34 staining, indicating MSC engraftment. Fibrosis was reduced at the anastomotic site in group 3 based on trichrome stain. CD31 staining of group 3 was more pronounced, supporting enhanced neoangiogenesis. In conclusion, adipose-derived MSCs were safely applied to biliary anastomoses. MSCs were locally engrafted within the bile duct and may have beneficial effects in terms of fibrosis and angiogenesis.

Study of Recellularized Human Acellular Arterial Matrix Repairs Porcine Biliary Segmental Defects.

With the popularity of laparoscopic cholecystectomy, common bile duct injury has been reported more frequently. There is no perfect method for repairing porcine biliary segmental defects. After the decellularization of human arterial blood vessels, the cells were cultured with GFP+ (carry green fluorescent protein) porcine bile duct epithelial cells. The growth and proliferation of porcine bile duct epithelial cells on the human acellular arterial matrix (HAAM) were observed by hematoxylin-eosin (HE) staining, electron microscopy, and immunofluorescence. Then, the recellularized human acellular arterial matrix (RHAAM) was used to repair biliary segmental defects in the pig. The feasibility of it was detected by magnetic resonance cholangiopancreatography, liver function and blood routine changes, HE staining, immunofluorescence, real-time quantitative PCR (RT-qPCR), and western blot. After 4weeks (w) of co-culture of HAAM and GFP+ porcine bile duct epithelial cells, GFP+ porcine bile duct epithelial cells grew stably, proliferated, and fused on HAAM. Bile was successfully drained into the duodenum without bile leakage or biliary obstruction. Immunofluorescence detection showed that GFP-positive bile duct cells could still be detected after GFP-containing bile duct cells were implanted into the acellular arterial matrix for 8 w. The implanted bile duct cells can successfully resist bile invasion and protect the acellular arterial matrix until the newborn bile duct is formed. The RHAAM can be used to repair biliary segmental defects in pigs, which provides a new idea for the clinical treatment of common bile duct injury.

Safety Evaluation of Paclitaxel-Eluting Biliary Metal Stent with Sodium Caprate in Porcine Biliary Tract.

Background/AimsMetallic stents designed to relieve malignant biliary obstruction are susceptible to occlusive tumor ingrowth or overgrowth. In a previous report, we described metallic stents covered with paclitaxel-incorporated membrane (MSCPM-I, II) to prevent occlusion from tumor ingrowth via antitumor effect. This new generation paclitaxel-eluting biliary stent is further endowed with sodium caprate (MSCPM-III) for enhanced drug delivery. The purpose of this study is to examine the safety of its drug delivery system in the porcine biliary tract.MethodsMSCPM-III (10% [wt/vol] paclitaxel) and covered metal stents (CMSs) were endoscopically inserted in porcine bile ducts in vivo. Histologic biliary changes, levels of paclitaxel released, and various serum analytes (albumin, alkaline phosphate, aspartate transaminase, alanine transaminase, total protein, total bilirubin, and direct bilirubin) were assessed.ResultsBased on the intensity of reactive inflammation and fibrosis, changes in porcine biliary epithelium secondary to implanted MSCPM-III were deemed acceptable (i.e., safe). Histologic features in the MSCPM-III and CMS groups did not differ significantly. In a related serum analysis, paclitaxel release from MSCPM-III stents was below the limit of detection for 28 days. Biochemical analyses were also similar for the two groups, and no evidence of hepatic or renal toxicity was found in animals receiving MSCPM-III stents.ConclusionsIn a prototypic porcine trial, this newly devised metal biliary stent incorporating both paclitaxel and sodium caprate appears to be safe in the porcine bile duct.

PS-166-Repopulation of decellularized porcine bile ducts with human cholangiocyte organoids for the generation of human-sized bioengineered biliary tissue

PS-166-Repopulation of decellularized porcine bile ducts with human cholangiocyte organoids for the generation of human-sized bioengineered biliary tissue

Многослойная тканеинженерная конструкция на основе биодеградируемых и биосовместимых материалов для восстановления поврежденных желчных путей (Multilayered Tissue-engineered Construct Based on Biodegradable and Biocompatible Materials for Injured Biliary Tract Repair)

Russian Abstract: Цель: Создать и оценить биологическую и физиологическую совместимость многослойной тканеинженерной конструкции желчного протока, основу которой составляет микроволокнистый каркас из биодеградируемого и биосовместимого полимера, с двухслойной адгезией на нем клеток, длительная дренажная функция которого обеспечивается его предварительной витализацией. Материал и методы: В работе использованы методы хирургического эксперимента, конфокальной и электронной микроскопии, иммуно-ферментного анализа, измерения клеточного индекса в реальном времени, гистологии, иммуногистохимии, а также комплекс методов клеточной биологии в условиях ЦКП «Регенеративная медицина». Образцы биосовместимых каркасов получены методом электроспиннинга из волокнистого поликапролактона, сополимеров молочной и гликолиевой кислот, диацетата целлюлозы и других полимеров. Методом эмульсионного электроформования были получены биосовместимые образцы микроволокнистого поликапролактона, содержащие биологически активные соединения GFP, EGF и генотерапевтический препарат «Неоваскулген» (плазмида VEGF165). Оценка высвобождения биологически активных соединений, их биологической активности in vitro и влияние на окружающие ткани проведены в лабораторных условиях, на клеточных культурах in vitro, а также при имплантации in vivo. Использовались 4 типа клеточных культур и 2 вида лабораторных животных. Проведены морфологические исследования эксплантированных образцов методами гистологии и иммуногистохимии. Для заселения биосовместимых микроволокнистых образцов использовались методы статичного, динамического и тканевого культивирования. Работа с лабораторными животными выполнялась в Центральном виварии Первого МГМУ им. И.М. Сеченова Минздрава России. Результаты и их новизна: Впервые разработан и обоснован дизайн тканеинженерной конструкции желчного протока из модифицированных и комбинированных материалов, которая предназначена для предотвращения возникновения не только ранних, но и поздних послеоперационных осложнений при восстановительных операциях на желчных путях. Определено, что физиологическая совместимость многослойных каркасов с физико-механическими свойствами, соответствующими свойствам нативных тканей, может быть достигнута при использовании метода эмульсионного электроспиннинга. Установлено, что витализация каркаса тканеинженерной конструкции препаратом «Неоваскулген» и эпидермальным фактором роста обеспечивает пролонгированный и контролируемый выход веществ по мере резорбции каркаса для обеспечения ангиогенной функционализации трансплантата. Степень и эффективность внедрения: Результаты диссертационной работы внедрены в учебный процесс на кафедре госпитальной хирургии лечебного факультета и в практическую деятельность Отдела передовых клеточных технологий Института регенеративной медицины Первого МГМУ им. И.М. Сеченова Минздрава России. Применение: Разработанные способы получения биологически и физиологически совместимых тканеинженерных конструкций могут быть использованы в качестве элементов биоконструктора для получения моделей полых эпителиальных органов. English Abstract: Design of bioengineered organs is still complicated due to the lack of understanding of biological mechanisms that stimulate physiologically relevant conditions and induce relevant cellular media. Systematic review identified qualitative and quantitative requirements for tissue-engineered construct of the common bile duct. Tissue-specific approach was used to select materials, biologics, and cells for creation of physiologically relevant construct for injured biliary tract repair. Samples of fibrous scaffolds from PCL, PGLA, PLCL, and cellulose diacetate were created by electrospinning method and evaluated with MTT assay for cytotoxicity assessment. Mechanical properties of human bile duct sample and fibrous scaffolds were evaluated for Young's modulus and for percentage of elongation. Mechanical properties of fibrous materials were evaluated in vitro during degradation and erosion in various media. Fibrous PCL-scaffolds were formed by emulsion electrospinning with incorporation of following biomolecules: Neovasculgen gene-therapy drug (VEGF165 plasmid), EGF and GFP. The fluorescent microscopy of fibers confirmed volume modification by biomolecules. ELISA-test confirmed prolonged exit of EGF biomolecules from PCL-scaffold in vitro. Implantation of Neovasculgen-modified PCL-scaffold in rats showed vascular density increase in the implantation zone. Experimental swine model of iatrogenic bile duct injury was created and follow-up implantation of tubular fibrous PCL-scaffold in porcine bile duct showed a tissue-specific physiological biocompatibility of fibrous PCL. Fibrous three-layered scaffolds from PCL and PLCL/PLGA were obtained by electrospinning method and were tested for mechanical properties. The sample of three-layered scaffold from modified fibrous PCL and PLGA with incorporation of EGF and Neovasculgen was two-side seeded with bone marrow-derived mesenchymal stem cells and bile duct epithelial cells to obtain the tissue-engineered construct.

Simple nanophotosensitizer fabrication using water-soluble chitosan for photodynamic therapy in gastrointestinal cancer cells

The polysaccharide chitosan has abundant cationic amine groups, and can form ion-complexes with anionic molecules such as the strong photosensitizer chlorin e6 (Ce6). In this study, water-soluble chitosan (WSC) was used to fabricate Ce6-incorporated nanophotosensitizers (Abbreviated as ChitoCe6 nanophotosensitizer) via a self-assembling process. This was accomplished by dissolving WSC in pure water and then directly mixing the solution with solid Ce6 causing ion complex formation between WSC and Ce6. The resulting nanophotosensitizer was spherical in shape and had a particle size of less than 300nm. The photodynamic effect of ChitoCe6 nanophotosensitizer was evaluated using gastrointestinal (GI) cancer cells. At in vitro study using SNU478 cholangiocarcinoma cells, ChitoCe6 nanophotosensitizer showed improved Ce6 uptake by tumor cells, reactive oxygen species production, and cellular phototoxicity. An in vivo study using SNU478-bearing nude mice showed that the ChitoCe6 nanophotosensitizer efficiently accumulated in the tumor tissue and inhibited tumor growth more than treatment with Ce6 alone. Furthermore, ChitoCe6 nanophotosensitizer was also efficiently absorbed through tissue layers in an ex vivo study using porcine bile duct explants. ChitoCe6 nanophotosensitizer showed enhanced photosensitivity and photodynamic effects against cancer cells in vitro and in vivo. We present ChitoCe6 nanophotosensitizer as a promising candidate for photodynamic therapy of GI cancer.

Integration of optical applicator with balloon catheter for photothermal treatment of biliary stricture.

Bile duct stricture is an uncommon disease in gastroenterology resulting from postoperative trauma. In spite of non-surgical treatments, clinical outcomes for the biliary strictures still encounter high restenosis and stent migration. The objective of the current study was to investigate the feasible application of a balloon catheter-integrated diffing applicator to thermally treat the bile duct stricture. 400-μm optical fibers were micro-machined and then integrated with an inflatable balloon catheter. The fabricated applicator was tested on porcine bile ducts with 20-W 980 nm laser light for 60 s, and a thermal camera was used to measure thermal response of the tissue. Due to mechanical pressure, the inflated balloon was able to expand the tissue lumen up to 6 mm in diameter. Compared to control, the inner area of the treated tissue was increased by four fold (i.e., 2.74±0.05 mm2 for treated vs. 0.73±0.14 mm2 for control) during the balloon catheter-assisted laser irradiation. The laser-induced tissue temperature reached up to 80.1±6.4 °C (thermal gradient = 1.2 °C/s). A thin layer of coagulation necrosis (0.5±0.1 mm) consistently formed around the lumen. The proposed balloon catheter-integrated diffusing applicator can be a feasible minimally invasive device to photothermally treat the obstructive bile ducts. Lasers Surg. Med. 49:781-786, 2017. © 2017 Wiley Periodicals, Inc.

Evaluation of bipolar radiofrequency ablation for occluded self-expandable metal stents in the bile duct: in vivo and in vitro study.

Endobiliary radiofrequency ablation (RFA) has been used to treat occluded self-expandable metal stents (SEMSs). The aim of this study was to determine the characteristics of bipolar RFA in occluded SEMSs using both in vivo and in vitro models. For the in vivo study, uncovered SEMSs were deployed in the bile ducts of three pigs; another pig was used as the control. RFA was performed at 10 W for 90 seconds. The bile duct was examined for histological changes. For the in vitro simulation of tissue ingrowth in SEMSs, RFA at 10 W for 30 seconds was performed on SEMS-occlusion polyacrylamide-gel phantoms. The ablation depth was markedly reduced in the stented porcine bile duct. RFA of uncovered SEMS-occlusion gel phantoms resulted in early termination of RFA when the coagulated area contacted the SEMS. This phenomenon was not observed in RFA of the covered SEMS-occlusion gel phantoms. The presence of SEMSs attenuated the effect of bipolar endobiliary RFA. Tumorous tissue outside the SEMS is unlikely to be affected.

Sa1440 Presence of Metal Stent in Porcine Bile Duct Attenuates the Effect of Radiofrequency Ablation: Results of a Pilot Study

Sa1440 Presence of Metal Stent in Porcine Bile Duct Attenuates the Effect of Radiofrequency Ablation: Results of a Pilot Study Won Jae Yoon*, Ebubekir S. Daglilar, Mari Mino-Kenudson, William R. Brugge Gastrointestinal Unit, Massachusetts General Hospital, Boston, MA; Pathology, Massachusetts General Hospital, Boston, MA Background: Endoscopically applied biliary radiofrequency ablation (RFA) in patients with unresectable malignant biliary stenosis has shown promising results. RFA may re-establish patency of occluded metal biliary stents. We have shown that application of RFA at 10 W for 90 seconds in the porcine bile duct results in transmural tissue ablation. However, there is little data on RFA in the bile duct containing a metal stent. Aims: The aims of this study were to determine the feasibility and performance characteristics of biliary RFA in the stented porcine bile duct. Methods: Four farm pigs weighing 40-50 kg were used for this study. Under general anesthesia and a laparotomy, a duodenotomy was performed. After identification of the bile duct opening, a 10-mm X 6-cm uncovered metal biliary stent (Zilver® stent, Cook Medical, Winston-Salem, NC) was deployed in 3 pigs; the stent was not deployed in 1 pig, serving as a control. The biliary bipolar RFA catheter (HabibTM EndoHPB catheter, EMcision Ltd., London, UK) was introduced through the stent lumen or the bile duct lumen. In the stented bile duct, RFA was applied at 10 W for 90 seconds, with a range of voltages among pigs (66 V [n 1], 132 V [n 1], and 190 V [n 1]). In the control bile duct (n 1), RFA was applied at 10 W and 190 V for 90 seconds. After the RFA, the pigs were euthanized and necropsied. The bile duct was examined for histological changes. Results: The retrograde insertion of the biliary RFA catheter through the metal stent or the bile duct orifice was easily achieved. Grossly, the ablated area was distributed only along the area adjacent to the electrodes of the RFA probe. In the unstented bile duct, RFA resulted in transmural ablation of the bile duct wall (Figure 1A). However, in the stented bile duct, the depth of ablation was reduced compared to the unstented bile duct. In detail, at 66 V (Figure 1B) and 132 V (Figure 1C), the ablation was limited to the superficial mucosa with no effect on the glands. At 190 V (Figure 1D), the ablation of the superficial mucosa including the superficial glands was noted. Conclusions: Biliary RFA through a metal stent seems technically feasible. However, at 10 W, biliary RFA was markedly attenuated by the presence of a metal stent. A greater power is probably needed to achieve deep ablation.

Su1358 Transection of Self-Expanding Metallic Stents by Using Argon Plasma Coagulation in Porcine Bile Ducts

Su1358 Transection of Self-Expanding Metallic Stents by Using Argon Plasma Coagulation in Porcine Bile Ducts

Comparison of Biomechanical Properties of Bile Duct Between Pigs and Humans for Liver Xenotransplant

BackgroundPigs have been regarded as the preferred source of organs for human xenotransplantation. The aim of the present study was to explore the biomechanical properties of the bile duct in pigs and humans to provide evidence for liver xenotransplantation. Materials and methodsFresh bile duct specimens obtained from 50 pigs aged 3 to 12 months and five deceased human donors. The diameters and wall thickness of the bile duct were measured using a computer imaging analysis system. The pressure-diameter of bile ducts was tested with biomechanical equipment. The corresponding parameters were calculated: incremental elastic moduli (Einc), pressure-strain elastic modulus (Ep), volume elastic modulus (Ev), and compliance. ResultsThe Einc, Ep, and Ev of porcine bile duct gradually decreases with age. However, the Einc, Ep, and Ev gradually increased after pigs aged 10 months. The Einc, Ep, and Ev of pig bile ducts aged 3 to 6, and 11 to 12 months were higher than that of humans aged 20 to 40 years (P < .01). The changes in compliance of the porcine bile duct with age oppose those in elastic modulus. There were no significant differences in the elastic modulus and compliance of the bile duct between pigs aged 7 to 10 months and adult humans (P > .05). ConclusionsThe biomechanical properties of the bile duct of pigs aged 7 to 10 months match that of adult humans. The correlation between age and biomechanical properties of bile ducts in pigs implied that a pig aged 7 to 10 months should be chosen for pig-to-human liver xenotransplantation.

Biopsy with thermally-responsive untethered microtools.

Thermally activated, untethered microgrippers can reach narrow conduits in the body and be used to excise tissue for diagnostic analyses. As depicted in the figure, the feasibility of an in vivo biopsy of the porcine bile duct using untethered microgrippers is demonstrated.

Porcine feasibility and safety study of a new paclitaxel-eluting biliary stent with a Pluronic-containing membrane

Metal stents for malignant biliary obstruction are susceptible to occlusion by tumor ingrowth or overgrowth. Therefore, we previously reported our use of a metal stent covered with a paclitaxel-incorporated membrane giving an antitumor effect to prevent occlusion from tumor ingrowth. We have also developed a new generation of paclitaxel-eluting biliary stent using a membrane containing Pluronic F-127 for effective drug delivery. The aim of this study was to investigate the safety and efficacy of drug delivery for this newly developed stent in the biliary tract. Metal stents were coated with paclitaxel and various concentrations of Pluronic F-127 in phosphate-buffered saline solution. Stents containing varying concentrations were placed in the bile ducts of eight pigs divided as follows: group I, 0% Pluronic + 0% paclitaxel; group II, 0% Pluronic + 10% paclitaxel; group III, 10% Pluronic + 10% paclitaxel; group IV, 20% Pluronic + 10% paclitaxel. The histology of the porcine bile duct and the amount of paclitaxel in the porcine serum were examined. The amount of paclitaxel released was also measured in vitro. Histologic changes in the porcine biliary epithelium were acceptable in terms of safety, based on inflammatory cell infiltration and fibrotic reaction. No significant differences in histology were observed between the groups. In the porcine serum analysis, released paclitaxel was detected for 28 days with the 10% Pluronic concentration (group III). However, released paclitaxel was observed for only 7 days in groups II and IV. In the in vitro experiments, long-lasting release of paclitaxel was also noted from the stent with 10% Pluronic. The new paclitaxel-eluting stent with 10% Pluronic F-127 is safe and provides enhanced local drug delivery.