Role of Bile-Derived Extracellular Vesicles in Hepatocellular Proliferation after Partial Hepatectomy in Rats.

Although liver regeneration has been extensively studied, the effects of bile-derived extracellular vesicles (bile EVs) on hepatocytes has not been elucidated. We examined the influence of bile EVs, collected from a rat model of 70% partial hepatectomy (PH), on hepatocytes. We produced bile-duct-cannulated rats. Bile was collected over time through an extracorporeal bile duct cannulation tube. Bile EVs were extracted via size exclusion chromatography. The number of EVs released into the bile per liver weight 12 h after PH significantly increased. Bile EVs collected 12 and 24 h post-PH, and after sham surgery (PH12-EVs, PH24-EVs, sham-EVs) were added to the rat hepatocyte cell line, and 24 h later, RNA was extracted and transcriptome analysis performed. The analysis revealed that more upregulated/downregulated genes were observed in the group with PH24-EVs. Moreover, the gene ontology (GO) analysis focusing on the cell cycle revealed an upregulation of 28 types of genes in the PH-24 group, including genes that promote cell cycle progression, compared to the sham group. PH24-EVs induced hepatocyte proliferation in a dose-dependent manner in vitro, whereas sham-Evs showed no significant difference compared to the controls. This study revealed that post-PH bile Evs promote the proliferation of the hepatocytes, and genes promoting cell cycles are upregulated in hepatocytes.

Pancreatic perfusion imaging method that reduces radiation dose and maintains image quality by combining volumetric perfusion CT with multiphasic contrast enhanced-CT.

OBJECTIVES: The aim of this study is to propose and evaluate a new method of volumetric perfusion computed tomography (PCT) incorporated into pancreatic multiphasic contrast enhanced (CE)-CT in the clinical setting. METHODS: In this ethically approved study, PCT was incorporated into our existing scanning protocol in 17 patients and effective doses related to PCT were evaluated. CT values and signal-to-noise ratio (SNR) of anatomical structure were compared in diagnostic images that were acquired using 320-detector volumetric scan mode and 64-detector helical scan mode. In addition, focal lesion depiction was qualitatively assessed in the two groups. Perfusion parameters in normal pancreas were measured by two radiologists and the interobserver-reliability was assessed. RESULTS: The effective dose of PCT was 5.1 ± 0.3 mSv. The actual effective dose (AED) including the dose used in volumetric scans for diagnostic imaging was 22.8 ± 5.3 mSv and the putative effective dose (PED) was 21.9 ± 9.1 mSv on average. There was no significant difference between AED and PED (p = 0.404). Compared with conventional helical scans, volumetric scans did not decrease CT values or SNR, but rather significantly increased those of the aorta in the arterial phase. Both groups had acceptable qualitatively assessed image quality with no significant difference in the depiction of each structure. There was almost perfect interobserver agreement in the measurement of perfusion parameters (mean ICCs > 0.9). CONCLUSIONS: Our scanning protocol for pancreatic perfusion CT provides high-quality images while requiring lower radiation doses than conventional methods.

Safety of bovine milk derived extracellular vesicles used for delivery of RNA therapeutics in zebrafish and mice.

Extracellular vesicles are endogenous biological nanoparticles that have potential for use as therapeutic nanoparticles or as delivery vehicles for therapeutic agents. Milk nanovesicles (MNV) are extracellular vesicles isolated from bovine milk that have been explored for use as delivery vehicles for RNA therapeutics such as small interfering RNA (siRNA). We performed in vivo toxicological studies of MNV or therapeutic MNV (tMNV) loaded with siRNA as a prelude to their clinical use. Development toxicity was assessed in zebrafish embryos. Acute toxicity was assessed in both mice and zebrafish whereas safety, biochemical, histological and immune effects after multiple dosing were assessed in mice. Zebrafish embryo hatching was accelerated with MNV and tMNV. While acute toxicity or effects on mortality were not observed in zebrafish, developmental effects were observed at high concentrations of MNV. There was a lack of discernable toxicity, mortality and systemic inflammatory or immunological responses in mice following administration of either MNVs or tMNVs. The tolerability and lack of discernable developmental or systemic in vivo toxicity support their use as biological nano-therapeutics. Adoption of a standardized protocol for systematic analysis of in vivo safety and toxicity will facilitate preclinical assessment of EV based formulations for therapeutic use.

[Hypopituitarism associated with autoimmune pancreatitis: a case report].

We herein report the case of a 64-year-old male patient with hypopituitarism associated with autoimmune pancreatitis (AIP). The patient was previously diagnosed with AIP based on the presence of a swollen pancreas, elevated serum immunoglobulin G4, and narrowing of the pancreatic duct by imaging. Magnetic resonance imaging revealed a pituitary stem tumor, and loading test showed a decrease in the function of the anterior lobe suggesting severe failure of growth hormone secretion. Treatment with steroids was effective in reducing the pituitary lesion and improving the function of the anterior lobe. The present case illustrates the importance of pituitary function evaluation before steroid treatment in patients with AIP.

BAP1 dependent expression of long non-coding RNA NEAT-1 contributes to sensitivity to gemcitabine in cholangiocarcinoma.

BACKGROUND: Genetic alterations in chromatin modulators such as BRCA-1 associated protein-1 (BAP1) are the most frequent genetic alteration in intrahepatic cholangiocarcinomas (CCA). We evaluated the contribution of BAP1 expression on tumor cell behavior and therapeutic sensitivity to identify rationale therapeutic strategies. METHODS: The impact of BAP1 expression on sensitivity to therapeutic agents was evaluated in CCA cells with a 7-fold difference in BAP1 expression (KMBC-low, HuCCT1-high) and genetically engineered haplo-insufficient BAP1 knockout cells. We also identified long non-coding RNA genes associated with loss of BAP1 and their role in therapeutic sensitivity. RESULTS: Sensitivity to gemcitabine was greater in low BAP1 expressing or BAP1 knockout cells compared with the high BAP1 expressing cells or control haplo-insufficient cells respectively. Similar results were observed with TSA, olaparib, b-AP15 but not with GSK126. A differential synergistic effect was observed in combinations of gemcitabine with olaparib or GSK126 in KMBC cells and TSA or bAP15 in HuCCT1 cells, indicating BAP1 dependent target-specific synergism and sensitivity to gemcitabine. A BAP1 dependent alteration in expression of lncRNA NEAT-1 was identified by RT-PCR based lncRNA expression profiling, and an inverse relationship between this lncRNA and BAP1 was observed in analysis of the Tumor Cancer Genome Atlas cholangiocarcinoma dataset. Exogenous modulation of NEAT-1 and/or BAP1 expression altered tumor cell phenotype and modulated sensitivity to gemcitabine. CONCLUSIONS: NEAT-1 is a downstream effector of gemcitabine sensitivity in CCA. The expression of BAP1 is a determinant of sensitivity to therapeutic drugs that can be exploited to enhance responses through combination strategies.

Non-coding RNA in hepatocellular carcinoma: Mechanisms, biomarkers and therapeutic targets.

The majority of the human genome is not translated into proteins but can be transcribed into RNA. Even though the resulting non-coding RNAs (ncRNAs) do not encode for proteins, they contribute to diseases such as cancer. Here, we review examples of the functions of ncRNAs in liver cancer and their potential use for the detection and treatment of liver cancer.

Extracellular vesicles in liver diseases.

Extracellular vesicles (EVs) are membrane-bound vesicles that are released by cells into their extracellular environment, have selective enrichment of specific proteins and RNA, and can mediate intercellular communication. In this review we highlight recent observations of the role of EVs in liver injury, viral hepatitis, alcoholic or nonalcoholic liver disease, biliary tract disease, and liver cancers. Potential applications as markers of diseases or for therapeutic applications are outlined to emphasize the new opportunities that are arising from the study of EVs.

Extracellular vesicles from bone marrow-derived mesenchymal stem cells protect against murine hepatic ischemia/reperfusion injury.

Hepatic ischemia/reperfusion injury (IRI) and associated inflammation contributes to liver dysfunction and complications after liver surgery and transplantation. Mesenchymal stem cells (MSCs) have been reported to reduce hepatic IRI because of their reparative immunomodulatory effects in injured tissues. Recent studies have highlighted beneficial effects of extracellular vesicles from mesenchymal stem cells (MSC-EV) on tissue injury. The effects of systemically administered mouse bone marrow-derived MSC-EV were evaluated in an experimental murine model of hepatic IRI induced by cross-clamping the hepatic artery and portal vein for 90 minutes followed by reperfusion for periods of up to 6 hours. Compared with controls, intravenous administration of MSC-EV 30 minutes prior to IRI dramatically reduced the extent of tissue necrosis, decreased caspase 3-positive and apoptotic cells, and reduced serum aminotransferase levels. MSC-EV increased hepatic messenger RNA (mRNA) expression of NACHT, LRR, and PYD domains-containing protein 12, and the chemokine (C-X-C motif) ligand 1, and reduced mRNA expression of several inflammatory cytokines such as interleukin 6 during IRI. MSC-EV increased cell viability and suppressed both oxidative injury and nuclear factor kappa B activity in murine hepatocytes in vitro. In conclusion, the administration of extracellular vesicles derived from bone marrow-derived MSCs may ameliorate hepatic IRI by reducing hepatic injury through modulation of the inflammatory response.Liver Transplantation 23 791-803 2017 AASLD.

In vitro toxicology studies of extracellular vesicles.

Extracellular vesicles (EVs) are membrane-bound vesicles released from cells into the extracellular environment. There is emerging interest in the use of EVs as potential therapeutic interventions. We sought to evaluate the safety of EVs that may be therapeutically used by performing in vitro toxicological assessments. EVs were obtained from mesenchymal stem cells (MSC-EV) or from bovine milk (BM-EV) by differential ultracentrifugation, and quantitated using nanoparticle tracking analysis. Genotoxic effects, hematological effects, immunological effects and endotoxin production were evaluated at two dose levels. Neither MSC-EVs nor BM-EVs elicited detectable genotoxic effects using either the alkaline comet assay or micronucleus assay. Hemolysis was observed with BM-EVs but not with MSC-EVs. MSC-EVs did not have any significant effect on either spontaneous or collagen-induced platelet aggregation. In contrast, BM-EVs were noted to increase collagen-induced platelet aggregation, even though no spontaneous increase in platelet aggregation was noted. Both types of EVs induced leukocyte proliferation, which was greater with BM-EV. Neither MSC-EVs nor BM-EVs induced HL-60 phagocytosis, although BM-EVs decreased zymosan-induced phagocytosis. Furthermore, neither MSC-EVs nor BM-EVs induced nitric oxide production. Unlike MSC-EVs, BM-EVs tested positive for endotoxin and induced complement activation. There are significant differences in toxicological profiles between MSC-EVs and BM-EVs that may reflect variations in techniques for EV isolation, EV content or cross-species differences. The safety of MSC-EV supports their use for disease therapeutics, whereas detailed safety and toxicological assessment will be necessary before the use of BM-EVs. Copyright © 2016 John Wiley & Sons, Ltd.

The Rapid Development of Squamous Cell Carcinoma on the Nasal Dorsum of a Patient Receiving Immunosuppressive Therapy.

The risk of cancer is significantly increased in patients undergoing renal transplant surgery than in the general population. In particular, skin cancer is the most commonly occurring cancer in these patients.A 34-year-old man underwent living renal transplantation for focal segmental glomerulosclerosis. After 18 months, he developed a lesion on the nasal dorsum, approximately 1 cm in size, and the lesion rapidly expanded to cover the entire dorsum.Owing to its rapid expansion, the lesion was suspected to be a malignant tumor and wide excision was planned.We removed the lesion with a 6-mm margin. Squamous cell carcinoma was diagnosed through intraoperative rapid pathological examination. The nasal bone and septum were invaded by the tumor and, as a result, the entire external nose was removed. The patient's nose was subsequently reconstructed using a free forearm flap for lining, iliac bone graft for the nasal frame, and a scalping forehead flap for skin coverage.Selective target radiotherapy was administered at the closest margin around the lesion, and the dosage of immunosuppressants was reduced.At >2 years postoperatively, the patient showed good cosmetic results with no relapse or metastasis of the tumor.We report the unusual case of a young man who developed a rapidly progressing squamous cell carcinoma on his nasal dorsum after 18 months of immunosuppression. Squamous cell carcinoma in organ transplant recipients may be more aggressive and may progress differently than in regular patients. Therefore, special attention is required for patients who take immunosuppressive drugs after renal transplant surgery.

High Glucose Accelerates Cell Proliferation and Increases the Secretion and mRNA Expression of Osteopontin in Human Pancreatic Duct Epithelial Cells.

BACKGROUND: The incidence of pancreatic cancer is increasing year-by-year in Japan. Among the diseases that complicate pancreatic cancer, diabetes is the most common. Recently, it has become evident that patients suffering from diabetes and obesity show increased expression of osteopontin (OPN). The purpose of this study was to investigate the effect of high glucose and high insulin culture conditions on a human pancreatic duct epithelial cell line (HPDE-6), focusing particularly on OPN expression. METHODS: HPDE-6 were cultured under various conditions, employing several combinations of glucose (normal, 6 mM high, 30 mM, and 60 mM) and insulin (0.1 nM, 1 nM) concentration. RESULTS: HPDE-6 cell proliferation was significantly accelerated under high glucose culture conditions in comparison to samples in 6 mM glucose, and was more prominent under high insulin conditions. At the same time, the expression of OPN mRNA was also increased significantly. In comparison with 6 mM glucose, the expression of 8-OHdG DNA was increased in high glucose culture. CONCLUSION: HPDE-6 cells show accelerated proliferation and increased OPN expression when cultured under high glucose and high insulin conditions. Furthermore, the cells show increased oxidative stress in the presence of high glucose.

A case of pancreatic intraepithelial neoplasia-3 with autoimmune pancreatitis.

We report a case of pancreatic intraepithelial neoplasia-3 (PanIN-3) with autoimmune pancreatitis (AIP). The patient, a 75-year-old man, had been diagnosed to have AIP with stenosis of the main pancreatic duct. After six years, computed tomography demonstrated dilatation of the main pancreatic duct in the mid-pancreas. Although we could not confirm the presence of any pancreatic tumor on the basis of imaging modalities alone, cytological examination of the pancreatic juice obtained by endoscopic retrograde pancreatography revealed atypical cells. Therefore, we performed pancreatoduodenectomy and obtained a pathologic diagnosis of PanIN-3 with AIP. The present case is informative in the context of pancreatic carcinogenesis in AIP.

Differentiating localized autoimmune pancreatitis and pancreatic ductal adenocarcinoma using endoscopic ultrasound images with deep learning.

Objectives: Localized autoimmune pancreatitis is difficult to differentiate from pancreatic ductal adenocarcinoma on endoscopic ultrasound images. In recent years, deep learning methods have improved the diagnosis of diseases. Hence, we developed a special cross-validation framework to search for effective methodologies of deep learning in distinguishing autoimmune pancreatitis from pancreatic ductal adenocarcinoma on endoscopic ultrasound images. Methods: Data from 24 patients diagnosed with localized autoimmune pancreatitis (8751 images) and 61 patients diagnosed with pancreatic ductal adenocarcinoma (20,584 images) were collected from 2016 to 2022. We applied transfer learning to a convolutional neural network called ResNet152, together with our innovative imaging method contributing to data augmentation and temporal data process. We divided patients into five groups according to different factors for 5-fold cross-validation, where the ordered and balanced datasets were created for the performance evaluations. Results: ResNet152 surpassed the endoscopists in all evaluation metrics with almost all datasets. Interestingly, when the dataset is balanced according to the factor of the endoscopists' diagnostic accuracy, the area under the receiver operating characteristic curve and accuracy were highest at 0.85 and 0.80, respectively. Conclusions: It is deduced that image features useful for ResNet152 correlate with those used by endoscopists for their diagnoses. This finding may contribute to sample-efficient dataset preparation to train convolutional neural networks for endoscopic ultrasonography-imaging diagnosis.

[Association between high altitude and depression in the Himalayas and the Andes].

AIM: Suicide rates in the United States are higher in higher altitude areas, and hypoxia has been cited as a factor in these higher rates. There may be a significant correlation between rates of depression and altitude, but little data exist outside the United States. The purpose of the present study is to conduct a survey of depression among the elderly residing in the Himalayas and the Andes. METHOD: We visited Ladakh (altitude 3,800-4,800 m) in India, Qinghai (3,700 m) in China and Puyca (3,600 m) in Peru between July 2009 and July 2011. We recruited 114 farmers from Domkhar in Ladakh (mean age, 69.2 years; female-male ratio, 58.8%), 206 nomads from Changthang in Ladakh (55.1 years; 43.7%), 173 Tibetan subjects from Qinghai (66.5 years; 61.3%) and 103 indigenous Andean subjects from Puyca (69.0 years; 68.0%). The two-item Patient Health Questionnaire (PHQ-2) was administered to the subjects. A psychiatrist interviewed the residents with single or double positive scores on the PHQ-2. RESULT: The ratio of subjects with one or more positive score in PHQ-2 was significantly higher in Qinghai than in other regions. (Domkhar vs. Changthang vs. Qinghai vs. Puyca = 7.0% vs. 5.3% vs. 36.9% vs. 15.5%, P<0.001). However, prevalence of depression by interview did not change in these regions. (1.8% vs. 1.9% vs. 2.3% vs. 2.9%). CONCLUSION: Despite the high altitude, the prevalence of depression was low in elderly highlanders in the Himalayas and the Andes. These results may relate to being presumed to related to a deep devotion to a religion and tight interpersonal networks.

Increased secretion of insulin and proliferation of islet ß-cells in rats with mesenteric lymph duct ligation.

BACKGROUND & AIMS: It has been suggested that intestinal lymph flow plays an important role in insulin secretion and glucose metabolism after meals. In this study, we investigated the influence of ligation of the mesenteric lymph duct on glucose metabolism and islet ß-cells in rats. METHODS: Male Sprague-Dawley rats (10 weeks old) were divided into two groups: one underwent ligation of the mesenteric lymph duct above the cistern (ligation group), and the other underwent a sham operation (sham group). After 1 and 2 weeks, fasting plasma concentrations of glucose, insulin, triglyceride, glucose-dependent insulinotropic polypeptide (GIP), and the active form of glucagon-like peptide-1 (GLP-1) were measured. At 2 weeks after the operation, the oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT) were performed. After the rats had been sacrificed, the insulin content of the pancreas was measured and the proliferation of ß-cells was assessed immunohistochemically using antibodies against insulin and Ki-67. RESULTS: During the OGTT, the ligation group showed a significant decrease in the plasma glucose concentration at 120 min (p<0.05) and a significant increase in the plasma insulin concentration by more than 2-fold at 15 min (p<0.01). On the other hand, the plasma GIP concentration was significantly decreased at 60 min (p<0.01) in the ligated group, while the active form of GLP-1 showed a significantly higher level at 90 min (1.7-fold; p<0.05) and 120 min (2.5-fold; p<0.01). During the IVGTT, the plasma insulin concentration in the ligation group was significantly higher at 2 min (more than 1.4-fold; p<0.05). Immunohistochemistry showed that the ratios of ß-cell area/acinar cell area and ß-cell area/islet area, and also ß-cell proliferation, were significantly higher in the ligation group than in the sham group (p<0.05, p<0.01 and p<0.01, respectively). The insulin content per unit wet weight of pancreas was also significantly increased in the ligation group (p<0.05). CONCLUSIONS: In rats with ligation of the mesenteric lymph duct, insulin secretion during the OGTT or IVGTT was higher, and the insulin content and ß-cell proliferation in the pancreas were also increased. Our data show that mesenteric lymph duct flow has a role in glucose metabolism.

[A new curriculum to strengthen pharmacology and clinical pharmacology training in fundamental nursing education].

Among medical care incidents in Japan, an increase in medicine-related errors by nurses have been reported. These errors may be caused by a lack of knowledge of clinical pharmacology and drug interactions. It is important for nurses to acquire risk-management skills based on clinical pharmacology. In order to improve fundamental knowledge in pharmacology and clinical pharmacology for nurses, various training programs exist. We reviewed a number of educational programs in medicine and report our results. Based on our results, it is necessary for medical education programs to include the following 5 essential elements: 1) An analysis of frequently-occurring medication errors in the field of clinical pharmacology, 2) drugs administer for patient characteristic and patient observation practices, 3) an emphasis on the interactions between drugs and food or other drugs, 4) assessment of patient symptoms, risk-management, and the efficacy of drugs, 5) the necessity of using the package inserts. In a new curriculum, it is necessary to have systematic, step by step training in pharmacology and clinical pharmacology. It is also necessary to develop these teaching methods in cooperation with specialists and experts in the field.

A case of successful removal of a migrated fish bone in the bile duct after pancreaticoduodenectomy using overtube-assisted cholangioscopy.

Fish bone migration into the bile duct in patients with surgically altered anatomy is a very rare cause of bile duct stones. Recently, balloon-assisted endoscopic retrograde cholangiopancreatography (BAERCP) is performed for biliary lesions in patients with surgically altered anatomy. We report on a 73-year-old Japanese man with a history of pancreaticoduodenectomy for intraductal papillary mucinous adenoma. A 20 mm long linear hyperattenuating structure in the left intrahepatic bile duct was noted on routine follow-up computed tomography 14 years postoperatively. The linear structure persisted until follow-up computed tomography performed 15 years postoperatively, and the left intrahepatic bile duct was shown to be dilated. We performed BAERCP for the diagnosis and treatment of the linear structure but could not visualize the linear structure in the left intrahepatic bile duct via enteroscopy and fluoroscopy. We removed the enteroscope, leaving the overtube, and inserted the cholangioscope through the overtube over the guide wire. We observed a brown rod-shaped linear structure in the left intrahepatic bile duct and removed it under direct visualization via overtube-assisted cholangioscopy. We conclude that overtube-assisted cholangioscopy was useful for assessing undiagnosed biliary lesions using conventional BAERCP and removing fish bones in the bile duct of the patient with altered gastrointestinal anatomy.

Effects of hesperidin on the progression of hypercholesterolemia and fatty liver induced by high-cholesterol diet in rats.

The protective effects of hesperidin against hypercholesterolemia and fatty liver were examined in male Wistar rats fed a high-cholesterol diet for 12 weeks. Compared with a standard diet, a high-cholesterol diet not only increased body weights, liver weights, and serum concentration of cholesterol, but also induced the fatty degeneration (steatosis) of liver. Hesperidin (0.08%) reduced levels of hepatic steatosis, adipose tissue and liver weights (P < 0.05), serum total cholesterol and retinol binding protein (RBP) 4 concentrations (P < 0.05) in rats fed with high-cholesterol diet, while reduction in low-density lipoprotein cholesterol levels and triglyceride concentrations was not significant. It also attenuated the marked changes in mRNA expression of lipid metabolism-related proteins: RBP, heart fatty acid-binding protein (H-FABP), and cutaneous fatty acid-binding protein (C-FABP), in liver and adipose tissue. According to the results of gas chromatography, serum concentrations of total cholesterol and biomarkers of cholesterol synthesis (lathosterol) and absorption (campesterol, ß-sitosterol) were lower, and concentrations of cholesterol in feces were higher in the rats given hesperidin (P < 0.05). Hesperidin may improve hypercholesterolemia and fatty liver by inhibiting both the synthesis and absorption of cholesterol and regulating the expression of mRNA for RBP, C-FABP, and H-FABP.

A case of a smooth transition to subsequent percutaneous transjejunal biliary intervention for hepatolithiasis after biliary reconstruction by adding jejunostomy during an emergency operation for perforation due to balloon-assisted endoscopy.

Treatments for hepatolithiasis include peroral endoscopy, percutaneous cholangioscopy, and surgery. Balloon-assisted endoscopic retrograde cholangiopancreatography (BAERCP) has been widely performed in recent years for patients with hepatolithiasis after biliary reconstruction. However, accidental bowel perforation caused by BAERCP may need emergency surgery. Here, we describe a 77-year-old Japanese woman diagnosed with acute cholangitis due to hepatolithiasis after biliary reconstruction (a biliary diversion operation for pancreaticobiliary maljunction). She underwent BAERCP for treatment of hepatolithiasis, however, a small-bowel perforation occurred. She underwent an emergency operation to suture the perforation and add a catheter jejunostomy. She had no postoperative complications after surgery and was discharged 11 days after surgery. One month later, she was readmitted and underwent percutaneous transjejunal cholangioscopy-guided lithotripsy with complete removal of the calculi. Although endoscopists should be careful to avoid small-bowel perforation during BAERCP, if perforation occurs, addition of a catheter jejunostomy during emergency surgery can be easily transitioned to subsequent treatment of the hepatolithiasis.

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.