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Abstract Background CCR8-expressing regulatory T cells (Tregs) are selectively localized within tumors and have gained attention as potent suppressors of anti-tumor immunity. This study focused on CCR8+ Tregs and their interaction with CD8+ T cells in the tumor microenvironment of human lung cancer. We evaluated their spatial distribution impact on CD8+ T cell effector function, specifically granzyme B (GzmB) expression, and clinical outcomes. Methods A total of 81 patients with lung squamous cell carcinoma (LSCC) who underwent radical surgical resection without preoperative treatment were enrolled. Histological analyses were performed, utilizing an automated image analysis system for double-stained immunohistochemistry assays of CCR8/Foxp3 and GzmB/CD8. We investigated the association of CCR8+ Tregs and GzmB+ CD8+ T cells in tumor tissues and further evaluated the prognostic impact of their distribution profiles. Results Histological evaluation using the region of interest (ROI) protocol showed that GzmB expression levels in CD8+ T cells were decreased in areas with high infiltration of CCR8+ Tregs, suggesting a suppressive effect of CCR8+ Tregs on T cell cytotoxicity in the local tumor microenvironment. Analysis of the association with clinical outcomes showed that patients with more CCR8+ Tregs and lower GzmB expression, represented by a low GzmB/CCR8 ratio, had worse progression-free survival. Conclusions Our data suggest that local CCR8+ Treg accumulation is associated with reduced CD8+ T cell cytotoxic activity and poor prognosis in LSCC patients, highlighting the biological role and clinical significance of CCR8+ Tregs in the tumor microenvironment. The GzmB/CCR8 ratio may be a useful prognostic factor for future clinical applications in LSCC.

Abstract Purpose The NY‐ESO‐1 antigen is highly immunogenic and often spontaneously induces an immune response in patients with cancer. We conducted a large‐scale multicenter cohort study to investigate the utility of serum NY‐ESO‐1 and p53 antibodies as predictive markers for the postoperative recurrence of gastric cancer. Here, we examined the usefulness of pre‐treatment NY‐ESO‐1 and p53 antibodies as tumor markers for the diagnosis of gastric cancer in combination with carcinoembryonic antigen (CEA) and carbohydrate antigen 19‐9 (CA19‐9). Methods A total of 1031 patients with cT3‐4 gastric cancer were enrolled in the study. NY‐ESO‐1 and p53 antibodies were assessed prior to treatment. The positivity of NY‐ESO‐1 and p53 antibodies, CEA, and CA19‐9 was evaluated before treatment. Results Serum NY‐ESO‐1 and p53 antibodies were positive in 12.6% and 18.1% of the patients, respectively. Positive NY‐ESO‐1 antibody response was correlated with male gender, higher cStage, and upper tumor location. However, a positive p53 antibody response was not associated with tumor factors. The combination of NY‐ESO‐1 or p53 antibody response with CEA and CA19‐9, or the 4‐factors, was positive in 45.1%, 49.6%, and 53.8% of patients, respectively. Moreover, the 4‐factor combination was able to detect >60% of cStage III‐IV diseases, which was 14% higher than that with the combination of CEA and CA19‐9. Conclusion The combination of NY‐ESO‐1 and p53 antibody responses to CEA and CA19‐9 increases the diagnostic accuracy of gastric cancer. Serum NY‐ESO‐1 and p53 antibodies may be useful tumor markers for gastric cancer.

Abstract Background A diaphragmatic hernia is a prolapse of the abdominal organs into the thoracic cavity through a hole in the diaphragm. Traumatic diaphragmatic injuries are rare and usually occur after blunt or penetrating thoracic or abdominal traumas. Blunt diaphragmatic rupture rarely accounts for immediate mortality and may go clinically silent until complications occur which can be life threatening. It usually present late with intrathoracic herniation of abdominal viscera and carry a high mortality rate. We experienced a very rare case who showed repeated colon incarcerations 7 years after injury. And, we operated laparoscopically. Case presentation A 64-year-old man presented with multiple left rib fractures that occurred during an accident. After 7 years, he visited the emergency department with the chief complaint of left shoulder pain and epicardial pain after eating. He was diagnosed with transverse colon incarceration due to a left diaphragmatic hernia by computed tomography (CT) and X-ray imaging. Surgical repair was recommended, but he refused as the symptoms improved. Fourteen months later, the patient revisited the hospital in similar symptoms and improved spontaneously. He consulted our hospital for the surgical indication. We recommended that he undergo surgery, showing images of the X-ray and CT when his transverse colon was obstructed and he felt pain and when symptoms improved. Finally, he decided to undergo surgery. We performed diaphragmatic hernia repair with laparoscopic direct suturing in good view. The patient experienced an uneventful postoperative recovery period. The absence of diaphragmatic herniation recurrence was confirmed seven months after surgery. Conclusions We experienced a traumatic diaphragmatic hernia with repeated colon incarcerations 7 years after injury and performed surgical repair laparoscopically.

Abstract Objectives Flexible endoscopy does not have a system that can automatically evacuate surgical smoke generated in the gastrointestinal lumen. We aimed to investigate the feasibility and potential usefulness of automatic smoke evacuation systems in flexible endoscopy. Methods [Bench] After surgical smoke generated in the stomach was evacuated by the evacuator, the degree of residual smoke and gastric luminal collapse were evaluated to optimize the evacuator settings. [Animal] Insufflation, suction, and total operation time to complete the protocol of 10 cauterizations of the gastric mucosa were measured in three groups: “manual suction only,” “manual suction with automatic evacuation (50% force),” and “manual suction with automatic evacuation (70% force).” The stability of endoscopic visualization and operability was evaluated by 10 endoscopists blinded to those suction settings, and the number of manual suctions, insufflations, and total operation time were measured. Results [Bench] The degree of residual smoke and gastric luminal collapse were inversely correlated. [Animal] When the automatic evacuator was partially used, there was no difference in the insufflation time, but the suction time (vs 50%; p = 0.011, vs. 70%; p = 0.011) and total operation time (vs. 50%; p = 0.012, vs. 70%; p = 0.036) were significantly reduced compared to manual operation only. Furthermore, manual suction with automatic evacuation (50% force) significantly improved the stability of endoscopic visualization and operability compared to manual operation only (p = 0.041, p = 0.0085). Conclusions The automatic smoke evacuation in flexible gastrointestinal endoscopy was potentially feasible and useful by improving the device setting.

Abstract Background and aims In our previous study, we visualized and systematically evaluated gas leakage from the forceps plug of the gastrointestinal endoscope system using the Schlieren system. In order to minimize the potential risk of infection from gas leakage from the gastrointestinal endoscope, the development of a new forceps plug was considered urgent. In this study, we analyzed the structure of commercially available forceps plugs and attempted to develop new forceps plugs with improvements. Methods Microfocus computed tomography was used to nondestructively analyze the structural changes that occur when forceps are inserted into a commercially available forceps plug. Based on the findings, the basic structure of the newly developed forceps plug was set. We examined the airtightness of these newly developed plugs using the Schlieren system and also compared their fractional resistance with those of commercially available plugs. Results As a result of the nondestructive analysis, all of the commercially available plugs had a single valve, and the cleavage created in the valve during forceps, insertion was large in the case of plugs with slit‐type entrances. In the newly developed forceps plugs, all four types of plugs showed less gas leakage and similar or better usability compared to the commercially available plugs. Conclusions The structural weaknesses of the existing gastrointestinal endoscopic forceps plugs were identified. Based on the findings, we froze the design of a prototype of a new forceps plug that was airtight and not inferior in usability compared to commercially available plugs.

Abstract Background Severe scoliosis can cause reflux esophagitis, and is a risk factor for Barrett's adenocarcinoma of the esophagus. Severe scoliosis is associated with respiratory dysfunction, impaired operative tolerance, and anatomical difficulty in surgical manipulation, and is, therefore, considered a high surgical risk. In this report, we describe the case of a young patient with Barrett's esophageal adenocarcinoma with severe scoliosis who underwent salvage surgery after radical chemoradiotherapy. Case presentation The patient was a 39-year-old male. Although he had severe scoliosis and paraplegia of both lower limbs since childhood, he was independent in activities of daily living. His previous doctor, who diagnosed the esophageal cancer, determined that surgery was not indicated due to the coexistence of severe scoliosis, so he underwent chemoradiotherapy with curative intent. After chemoradiotherapy, the patient was referred to our hospital for a second opinion because of a tumor remnant. After various additional examinations, thoracoscopic and laparoscopic subtotal esophagectomy for esophageal cancer was performed, along with ante-thoracic route reconstruction using a narrow gastric tube. Although the patient had symptoms associated with postoperative reflux, he recovered well overall and was discharged home about 4 weeks after surgery. Conclusions We report the case of an esophageal cancer patient with severe scoliosis at high surgical risk who underwent successful minimally invasive esophagectomy.

Abstract Background Familial gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the digestive tract caused by germline gain-of-function mutations in the KIT gene or platelet-derived growth factor receptor alpha gene (PDGFRA). These mutations cause not only multiple GISTs but also diffuse hyperplasia of interstitial cells of Cajal (ICCs), which is related to esophageal motility disorder. Case presentation A 53-year-old man was referred to our hospital because of anemia and dysphagia. Fifteen years earlier, he had undergone a laparoscopic partial gastrectomy for multiple gastric GISTs with a germline mutation in exon 17 of the KIT gene. An upper gastrointestinal endoscopy revealed that the patient had multiple gastric GISTs and a large esophageal diverticulum directly above the esophagogastric junction. The largest gastric tumor was 7 cm, with a delle that might cause bleeding. Because the patient presented with dysphagia, we performed video-assisted thoracic esophagectomy and laparoscopic-assisted proximal gastrectomy simultaneously. The patient had survived without metastasis for 4 years after surgery and dysphagia had improved. Conclusions This is the first report of successful laparoscopic–thoracoscopic surgery for a patient with familial gastric GISTs accompanied with a large esophageal diverticulum.

Abstract Background The development of systemic chemotherapy including immune checkpoint inhibitors (ICIs) has provided patients with unresectable advanced non-small cell lung cancer (NSCLC) an opportunity to undergo surgical intervention after initial treatment. However, no consensus regarding the indication for salvage surgery in these patients has been reached. Methods We conducted a retrospective study of patients who underwent salvage surgery for advanced NSCLC (cStage IIIA–IVB) after treatment with ICIs from January 2018 to December 2022 at Aizu Medical Center and Fukushima Medical University Hospital. We evaluated the patients’ clinical data, calculated disease-free survival (DFS) and overall survival (OS), and assessed the survival benefit using the Kaplan–Meier method. Results Thirteen patients underwent salvage surgery after immunotherapy. All patients achieved downstaging after initial chemotherapy. Eleven patients underwent lobectomy, and one patient underwent extirpation of intra-abdominal lymph nodes. The mean surgery time and intraoperative blood loss were 242.2 min and 415.1 g, respectively. The mean drainage period was 4.2 days (range, 2–9 days). Grade ≥ 3 postoperative complications were confirmed in three patients. The 2-year DFS rate was 71.2%, and the 2-year OS rate was 76.2%. A pathological complete response compatible with ypStage 0 was achieved in four (30.8%) patients. Patients with ypStage 0 and I achieved significantly better OS than those with ypStage ≥ II (p = 0.044), and patients without severe complications achieved significantly better DFS and OS than those with severe complications (p = 0.001 and p

Impaired reperfusion in ischemic brain disease is a condition that we are increasingly confronted with owing to recent advances in reperfusion therapy. In the present study, rat models of reperfusion were investigated to determine the causes of acute seizures using magnetic resonance imaging (MRI) and histopathological specimens. Rat models of bilateral common carotid artery ligation followed by reperfusion and complete occlusion were created. We compared the incidence of seizures, mortality within 24 h, MRI, and magnetic resonance spectroscopy (MRS) to evaluate ischemic or hemorrhagic changes and metabolites in the brain parenchyma. In addition, the histopathological specimens were compared with those observed on MRI. In multivariate analysis, the predictive factors of mortality were seizure (odds ratios (OR), 106.572), reperfusion or occlusion (OR, 0.056), and the apparent diffusion coefficient value of the striatum (OR, 0.396). The predictive factors of a convulsive seizure were reperfusion or occlusion (OR, 0.007) and the number of round-shaped hyposignals (RHS) on susceptibility-weighted imaging (SWI) (OR, 2.072). The incidence of convulsive seizures was significantly correlated with the number of RHS in the reperfusion model. RHS on SWI was confirmed pathologically as microbleeds in the extravasation of the brain parenchyma and was distributed around the hippocampus and cingulum bundle. MRS analysis showed that the N-acetyl aspartate level was significantly lower in the reperfusion group than in the occlusion group. In the reperfusion model, RHS on SWI was a risk factor for convulsive seizures. The location of the RHS also influenced the incidence of convulsive seizures.

Abstract Background Exon 18 D842V, which is a point mutation from aspartic acid to valine at codon 842, is the most frequent mutation in Platelet-Derived Growth Factor Receptor alpha (PDGFRA)-mutated gastrointestinal stromal tumor (GIST). In the Japanese GIST guidelines, no standard systematic therapy is available for this type of GIST, which is refractory after recurrence. Recently, pimitespib (PIMI), a novel heat shock protein 90 (HSP90) inhibitor, was approved for the treatment of advanced GIST in a phase III study. This report presents a case of a long-term response to PIMI in GIST with PDGFRA D842V mutation. Case presentation A 55-year-old woman was diagnosed with primary GIST of the stomach and underwent partial gastrectomy. Eight years after the operation, recurrent GISTs were identified as multiple recurrent peritoneal GISTs in the upper right abdomen and pelvic cavity. We administered tyrosine kinase inhibitors, but they achieved poor effects. After failure of the standard treatment, PIMI was administered and achieved a partial response in the patient. The highest reduction rate was 32.7%. After PIMI failed, we performed multiplex gene panel testing, which revealed the PDGFRA D842V mutation. Conclusions We report the first case of long-term response to PIMI in PDGFRA D842V mutant GIST. Pimitespib may be effective for treating GIST harboring this mutation by inhibiting HSP90.

Abstract Background Although perioperative treatment has been the standard of care for resectable gastric cancer in the West, postoperative adjuvant chemotherapy is still the standard in Japan. We conducted the first phase 2 trial to investigate the efficacy and safety of neoadjuvant docetaxel, oxaliplatin, and S‐1 (DOS) chemotherapy for cStage III gastric or esophagogastric junction (EGJ) adenocarcinoma in Japan. Methods Eligibility criteria included cStage III adenocarcinoma of the stomach or EGJ. Patients received docetaxel (40 mg/m2, day 1), oxaliplatin (100 mg/m2, day 1), or S‐1 (80 mg/m2, days 1–14) during a 3‐week cycle. After two or three cycles of DOS, patients underwent surgical resection. The primary endpoint was progression‐free survival (PFS). Results Between June 2015 and March 2019, 50 patients were enrolled from four institutions. Of 48 eligible patients (37 gastric and 11 EGJ adenocarcinoma), 42 (88%) completed two or three DOS cycles. Grade 3–4 neutropenia and diarrhea occurred in 69% and 19% of patients, respectively, but there were no treatment‐related deaths. R0 resection was achieved in 44 (92%) patients, and the pathological response rate (≥ grade 1b) was 63% (30/48). The 3‐year PFS, overall survival, and disease‐specific survival rates were 54.2%, 68.7%, and 75.8%, respectively. Conclusion Neoadjuvant DOS chemotherapy had a sufficient antitumor effect and tolerable safety profile in patients with gastric or EGJ adenocarcinoma. The survival benefit of a neoadjuvant strategy using our DOS regimen should be validated in phase 3 trials.

This is the first study to determine the clinical importance of circulating bacterial DNA in patients with renal cell carcinoma (RCC). We performed 16S rRNA metagenomic analysis of serum extracellular vesicles (EVs) from 88 patients with RCC and 10 healthy donors and identified three abundant bacterial DNA: Bacteroidia, TM7-1, and Sphingomonadales. Combining characteristic bacterial DNA information (three bacteria-derived DNA), a BTS index was created to diagnose patients with RCC. The BTS index showed high sensitivity not only in the discovery cohort, but also in the validation cohort, suggesting that it was useful as a screening test. Furthermore, in nivolumab treatment of RCC, patients with higher levels of Bacteroidia DNA in serum EVs had significantly poorer progression-free and overall survival than did those with lower levels. This study showed that circulating Bacteria-derived DNA could be used as a biomarker for RCC.

Intraoperative electrocorticography (iECoG) is widely performed to identify irritative zones in the cortex during brain surgery; however, several limitations (e.g., short recording times and the effects of general anesthesia) reduce its effectiveness. The present study aimed to evaluate the utility of iECoG for localizing epileptogenic zones. We compared the results of iECoG and chronic electrocorticography (cECoG) in 25 patients with refractory epilepsy. Subdural electrodes were implanted with iECoG under general anesthesia (2% sevoflurane). cECoG recordings were performed for 3-14 days. The distribution of iECoG spikes was compared with cECoG spike, seizure onset zone, and resection areas. The concordance patterns of each distribution were classified into four patterns: Group 1: No spike in iECoG, Group 2: concordant (2a: iECoG smaller, 2b: iECoG larger, Group 3: discordant >50%). The concordance rate of interictal spikes, seizure onset zones, and resection areas were 88.0% (Group 2a: 72.0%, Group 2b: 16.0%), 70.0% (Group 2a: 25.0%, Group 2b: 45.0%), and 81.0% (Group 2a: 42.9%, Group 2b: 38.1%), respectively. The resection of iECoG spike areas significantly correlated with good surgical outcomes. The indication and limitations of iECoG need to be realized, and the complementary use of iECoG and cECoG may enhance clinical utility.

Introduction We report a case of abdominal compartment syndrome due to hydroperitoneum after endoscopic combined intrarenal surgery. Case presentation A 56‐year‐old woman with a left staghorn calculus underwent endoscopic combined intrarenal surgery as a two‐staged procedure and developed a distended abdomen, cyanosis of both legs, and hypotension immediately after the second operation. A computed tomography scan showed hydroperitoneum. We performed urgent laparotomy and evacuated approximately 2 L of nearly transparent fluid. No peritoneal injury was detected. Postoperatively, she required intensive care for shocked liver and acute kidney injury. Conclusion Hydroperitoneum after endoscopic combined intrarenal surgery is a rare complication and may lead to abdominal compartment syndrome or a condition where intra‐abdominal pressure exceeds 20 mmHg, causing impaired organ perfusion. Delayed drainage can be fatal.

Cisplatin-based chemotherapy has been associated with durable disease control in a small subset of patients with metastatic urothelial cancer. However, the mechanistic basis for this phenomenon has remained elusive. Antitumor immunity may underlie these exceptional responders. In a phase II trial evaluating a phased schedule of gemcitabine and cisplatin followed by gemcitabine and cisplatin with ipilimumab for metastatic urothelial cancer, 4 of 36 patients achieved durable disease-free treatment-free survival (DDFTFS) and remain in remission over 5 years after enrolment on the study. We sought to identify the genomic and immunological mechanisms associated with functional cures of such patients. Whole exome sequencing was performed on pretreatment archival tumor tissue. Neoantigen prediction and ranking were performed using a novel pipeline. For a subset of patients with available biospecimens, selected peptides were tested for neoantigen-specific T cell reactivity in peripheral blood CD4+ and CD8+ T cells cultured with autologous antigen-presenting cells at baseline, postchemotherapy, and postchemotherapy and ipilimumab timepoints. Multiplex assays of serum protein analytes were also assessed at each time point. Serum proteomic analysis revealed that pretreatment, patients achieving DDFTFS demonstrated an immune activated phenotype with elevations in TH1 adaptive immunity, costimulatory molecules, and immune checkpoint markers. After combination cisplatin-based chemotherapy and ipilimumab treatment, DDFTFS patients again displayed enrichment for markers of adaptive immunity, as well as T cell cytotoxicity. CD27 was uniquely enriched in DDFTFS patients at all timepoints. Neoantigen reactivity was not detected in any patient at baseline or post two cycles of chemotherapy. Both CD4+ and CD8+ neoantigen-specific T cell reactivity was detected in two of two DDFTFS patients in comparison to zero of five non-DDFTFS patients after combination cisplatin-based chemotherapy and ipilimumab treatment. Antitumor immunity may underlie functional cures achieved in patients with metastatic urothelial cancer treated with cisplatin-based chemotherapy and immune checkpoint blockade. Probing the mechanistic basis for DDFTFS may facilitate the identification of biomarkers, therapeutic components, and optimal treatment sequences necessary to extend this ultimate goal to a larger subset of patients.

Abstract Background Esophageal squamous cell carcinoma (ESCC) is one of the most severe cancers and is characterized by chemotherapy resistance and poor prognosis associated with epithelial-mesenchymal transition (EMT). In a previous study, a low mitochondrial DNA (mtDNA) copy number was associated with poorer prognosis and induced EMT in ESCC. However, the detailed mechanism related to mtDNA copy number and EMT is unclear. The aim of this study was to clarify the mechanism by which a change in mtDNA copy number contributes to EMT and to examine treatment of chemotherapy resistance in ESCC. Methods The association between low mtDNA copy number and chemotherapy resistance was investigated using specimens from 88 patients who underwent surgery after neoadjuvant chemotherapy. Then, the mtDNA content of human ESCC cell lines, TE8 and TE11, was depleted by knockdown of mitochondrial transcription factor A expression. The present study focused on modulation of mitochondrial membrane potential (MMP) and DNA methylation as the mechanisms by which mtDNA copy number affects EMT. mRNA and protein expression, chemotherapy sensitivity, proliferation, MMP and DNA methylation were evaluated, and in vitro and in vivo assays were conducted to clarify these mechanisms. Results ESCC patients with decreased mtDNA copy number who underwent R0 resection after neoadjuvant chemotherapy had significantly worse pathological response and recurrence-free survival. Additionally, low mtDNA copy number was associated with resistance to chemotherapy in vitro and in vivo. mtDNA controlled MMP, and MMP depolarization induced EMT. Depletion of mtDNA and low MMP induced DNA methylation via a DNA methylation transcription factor (DNMT), and a DNMT inhibitor suppressed EMT and improved chemotherapy sensitivity in mtDNA-depleted ESCC cells, as shown by in vitro and in vivo assays. Conclusion This study showed that decreased mtDNA copy number induced EMT via modulation of MMP and DNA methylation in ESCC. Therapeutic strategies increasing mtDNA copy number and DNMT inhibitors may be effective in preventing EMT and chemosensitivity resistance.

Electrical cortical stimulation is widely performed and is the gold standard for functional mapping in intractable epilepsy patients; however, a standard protocol has not yet been established. With respect to stimulation methods, two techniques can be applied: monopolar and bipolar stimulation. We compared the threshold to induce clinical symptoms between these two stimulation techniques. Twenty patients with intractable epilepsy who underwent electrical cortical stimulation for functional mapping were retrospectively investigated. We evaluated the stimulation intensity thresholds required to induce motor, sensory, and language symptoms. A total of 114 electrodes in 20 patients were used to investigate motor, sensory, and language symptoms. The thresholds required to induce motor (median value, bipolar: 4 mA, monopolar: 5 mA, p < 0.05) and language symptoms (bipolar: 8 mA, monopolar: 10 mA, p < 0.0005) were significantly higher for monopolar stimulation than those for bipolar stimulation. However, for sensory symptoms, no significant differences were found in the required thresholds between monopolar and bipolar stimulation (bipolar: 4 mA, monopolar: 4 mA, p = 0.474). Bipolar cortical stimulation required lower intensities to produce clinical motor and language symptoms and thus would be safe and suitable for screening of the eloquent area in functional mapping.

Summary: Introduction: Peripherally inserted central venous catheter (PICC) has a risk of causing phlebitis and thrombus occlusion. We coated the surfaces of the PICC with a specialized coating material (SEC-1) which may prevent thrombogenicity and phlebitis. This study aimed to evaluate SEC-1 coating PICCs using big animal. Methods: SEC-1 coating was used to both the internal and external surface of the catheter. In internal coating evaluation, the swine blood was filled up to 10 cm from the tip of the catheter into both non-coated and SEC-1-coated PICC (4Fr). Then we attempted to release the catheter occlusion at 5, 15 and 30 min while measuring the occlusion pressure by a digital pressure gauge. In external coating evaluation, after optimizing the phlebitis model using milk vein in swine, both PICCs inserted at a depth of 15 cm in the vein were forcibly withdrawn a distance of 5 cm and re-inserted 100 times. After 2days, we assessed inflammatory cell infiltration by histological evaluation. Result: The catheter occlusion release pressure at 5 min was measured at the non-coated: 2 and SEC-1-coated PICC:2 kPa. At 15 min, 7 and 4 kPa (p=0.38). At 30 min, 30 and 4 kPa (p=0.01). In external coating evaluation, there was no clear difference between the non-coated and the SEC-1-coated PICC in terms of inflammatory cell infiltration. Conclusion: The results of this study suggest that antithrombotic coating (SEC-1 coating) of PICC catheters may inhibit thrombogenicity. However, we were unable to confirm that it was effective in the control of phlebitis.

IntroductionRegulatory T cells (Tregs) have attracted attention as a novel therapeutic target to augment the clinical efficacy of immunotherapy. We conducted phase Ia and Ib trials to examine the safety and efficacy of the anti-CCR4 antibody, KW-0761 (mogamulizumab), which may eliminate effector Tregs (eTregs). We herein overviewed the results of these trials, presented cases with a durable clinical response, and investigated factors associated with the clinical effects of KW-0761.MethodsForty-nine patients with CCR4-negative solid cancers were enrolled in the phase Ia and Ib trials on KW-0761. An integral analysis of safety, clinical responses, prognosis, blood laboratory data, and cancer testis antigen-specific immune responses was performed.ResultsGrade 3-4 treatment-related adverse events were reported in 21 (42.9%) out of 49 patients, all of which were manageable. A partial response and stable disease were observed in 1 and 9 patients, respectively. A durable clinical response was noted in 2 esophageal and 2 lung cancer patients. eTreg depletion in peripheral blood was confirmed in most patients, and eTreg depletion was sustained during the KW-0761 treatment. High lymphocyte levels at baseline and 2 weeks after the initiation of KW-0761 were associated with a favorable clinical outcome.ConclusionsA durable clinical response was noted in some patients, and high lymphocyte levels before treatment initiation may be a biomarker for the efficacy of KW-0761. The synergistic effect of KW-0761 for depleting Tregs and other immunotherapies is expected in the future.

Elimination of regulatory T cells via the anti-CCR4 monoclonal antibody, mogamulizumab, is expected to augment anti-tumour immune response. Authors show here that although regulatory T cell targeting is successful, clinical improvement remains minimal in patients with solid tumours due to concomitant and unintended depletion of central memory CD8+ T cells.

Immune-checkpoint inhibitors (ICIs) play a crucial role in the treatment of advanced nonsmall cell lung cancer (NSCLC); however, most patients fail this treatment after a limited period. We here report a patient with a pathological complete response after treatment with ICI for stage IV pulmonary adenocarcinoma. A 73-year-old man was referred to our hospital because of hoarseness. A roentgenogram and chest CT scan revealed a huge (78-mm diameter) pulmonary tumor in the right upper lobe and a tumor with cavitation in the left lower lobe. A CT scan also showed enlarged upper mediastinal lymph nodes (LNs). Transbronchial lung biopsy of the tumors showed adenocarcinomas in both. The tumor in the right upper lobe was considered to be the primary with mediastinal LNs metastasis and that in the left lower lobe a pulmonary metastasis. The disease was determined to be cT4N2M1a stage IVA. He was treated with first-line chemotherapy comprising cisplatin, pemetrexed, and bevacizumab for 6 cycles. However, 6 months after initial treatment, the primary and metastatic tumors enlarged, and he was treated with second-line anti-programed death 1 therapy for 7 months with a partial response. 18-fluorodeoxyglucose positron emission tomography (FDG-PET) revealed weak accumulation of FDG in the primary tumor only with no accumulation in the left pulmonary metastasis or mediastinal lymph node (LNs), despite the LNs still being enlarged. He was diagnosed as having ycT1bN0M0 stage IA2 disease and underwent right upper lobectomy. Postoperative pathological findings revealed that cancer tissues had been replaced by scar tissue and that CD4-positive T cells, rather than CD8-positive T cells, were predominant. It was also noted that he had a lower neutrophil-to-lymphocyte ratio (NLR) during immunotherapy than before immunotherapy and after surgery. He was diagnosed to be ypT0N0M0 stage 0 (Ef.3). His postoperative course was uneventful, and he remained well for 12 months after surgery with no further treatment. Neoadjuvant chemotherapy with ICIs for advanced NSCLC may be a promising modality, even for clinical stage IV disease, in the near future. Furthermore, NLR during immunotherapy may be a promising biomarker of ICIs treatment.

Abstract Background Esophageal squamous cell carcinoma (ESCC) is the deadliest of all human squamous cell carcinomas and is characterized by chemotherapy resistance and poor prognosis associated with the epithelial–mesenchymal transition (EMT). A subset of ESCC displays loss‐of‐function mutations in genes encoding Notch receptor family members, including NOTCH3. Although Notch signaling regulates EMT in ESCC cells, the role of NOTCH3 in EMT and chemotherapy resistance remains elusive. This study aimed to examine the role of NOTCH3 in EMT and chemotherapy resistance, and determine whether NOTCH3 expression can be used to predict the response to chemotherapy. Methods In vitro and in vivo assays were conducted to clarify the contribution of NOTCH3 to chemotherapy resistance. Using specimens from 120 ESCC patients treated with neoadjuvant chemotherapy, we compared the expression levels of NOTCH3 and genes involved in EMT according to the degree of chemotherapy sensitivity. Results In ESCC cells, chemotherapy resistance was associated with NOTCH3 downregulation and concurrent activation of EMT. RNA interference to silence NOTCH3 resulted in induction of the EMT marker Vimentin (VIM), leading to chemotherapy resistance in ESCC cells. Conversely, ectopic expression of the activated form of NOTCH3 suppressed EMT and sensitized cells to chemotherapy. Results of chromatin immunoprecipitation assays suggested that NOTCH3 may repress transcription of the VIM. Conclusions Our findings suggest that NOTCH3 may control chemotherapy sensitivity by regulating EMT. NOTCH3 may serve as a novel biomarker to predict better clinical outcomes in ESCC patients.

Abstract Perioperative systemic inflammation induced by surgical stress elevates the risk of hematogenous cancer metastasis. This study investigated the anti-metastatic effects and mechanisms of methylprednisolone (MP) administration for surgical stress. We examined the effects of MP on the expression of adhesion molecules in human vascular endothelial cells and in a murine hepatic metastasis model under lipopolysaccharide (LPS) administration, which mimics systemic inflammation induced by surgical stress. Serum E-selectin level was measured in blood samples obtained from 32 gastric cancer patients who were randomly assigned to treat preoperatively with or without MP. The expression of E-selectin in LPS-induced vascular endothelial cells was suppressed by MP. An adhesion assay showed the number of LPS-induced adherent tumour cells was significantly lower following MP. In the in vivo study, LPS significantly elevated the number of hepatic metastases, but pretreatment with MP before LPS significantly inhibited this elevation. The LPS-induced expression of E-selectin in the vascular endothelium of the portal vein was suppressed by MP. In human clinical samples, serum E-selectin level was significantly decreased by preoperative MP. Suppression of surgically induced systemic inflammation by MP administration might prevent hematogenous cancer metastases by suppressing the induction of E-selectin expression in the vascular endothelium.

Abstract Background Self‐assembling peptides (TDMs) comprise synthetic amphipathic peptides that immediately react to changes in pH and/or inorganic salts to transform into a gelatinous state. The first generation of these peptides (TDM‐621) is currently used as a hemostatic agent in Europe. However, TDM‐621 exhibits slow gel‐formation and low retention capabilities on tissue surfaces. The second generation (TDM‐623) was therefore developed to encourage faster gel‐formation and better tissue‐sealing capabilities. Aim The aim of this study was to verify the efficacy of TDM‐623 in terms of its hemostatic effect in endoscopic surgery. Materials and methods Evaluation of the hemostatic effect in endoscopic surgery (animal study) was performed using eight porcine in spine position. Following systemic heparinization, we established a “bleeding model” by endoscopic grasping forceps on the anterior walls of the stomach and duodenum. In the hemostasis method, an endoscope with a distal hood was brought into contact with the bleeding point, and 1 ml TDM‐623 was applied to the wound. After TDM‐623 gelation, the endoscope was removed, and the acute hemostatic effect (after 2 min) was confirmed. Result In the endoscopic bleeding model, 17 of the 23 cases (74%) showed complete hemostatic effects on the anterior wall of the stomach, and 18 of the 20 cases (80%) on the anterior wall of the duodenum, respectively. None of the applied gels were displaced from the anterior walls of the stomach and duodenum. Conclusion The new self‐assembling peptide (TDM‐623) showed high hemostatic effects. TDM‐623 had potential usefulness for upper gastrointestinal endoscopic surgery.

Abstract Introduction Animal experiments with large living animals are essential for the development of medical devices and the training of surgical procedures. Swine are frequently used in animal experiments due to their similar size and anatomy compared to humans. However, it is well known that swine has less local bleeding than humans. The aim of the study was to verify whether animal models with appropriate local bleeding capability could be established. Methods The activated clotting time (ACT) was measured for eight swine (piglet, 35 kg) under general anesthesia. The flexible endoscope was advanced orally, and the gastric mucosa was intentionally traumatized to bleed by biopsy forceps, and the time until spontaneous hemostasis was obtained (mucosal bleeding time). Then, heparin (50 U/kg) was administered intravenously. After 10 min, the ACT was remeasured, and the gastric mucosa was again damaged to bleed by biopsy forceps. The mucosal bleeding time was remeasured. The above measurements were repeated until the ACT exceeded 200 s. Results The median ACT values (seconds) were 83 (no heparin), 155 (50 U/kg heparin), and 204 (100 U/kg heparin), which were significantly increased. The median mucosal bleeding times (seconds) were 152 (no heparin), 283 (50 U/kg), and 423 (100 U/kg), which were significantly extended. Conclusion A bleeding animal model for surgical and endoscopic training was successfully established by bolus heparin administration.

Abstract Objectives Endoscopic submucosal dissection (ESD) has become popular, but complications such as postoperative bleeding remain an issue. Although some methods of closing a mucosal defect with a snare and clips have been reported to be effective and safe, the snare is not a dedicated device, and the procedure is difficult and time‐consuming. We aimed to find an alternative method for defect closure after ESD by developing a dedicated device. Methods We have improved five prototypes. The load on the stopper when starting to tighten and loosen a loop and the maximum load on the stopper and the movement distance of the thread when sliding the stopper were measured five times for each prototype. With the 5th prototype, we finalized the design and named it FLEXLOOP. Additionally, the material and shape of the outer tube were improved. Then, the usability of FLEXLOOP was evaluated in pigs. The operation time for closing mucosal defects with the snare or FLEXLOOP was measured five times. Results We made FLEXLOOP, which had a lower load when sliding and a higher load when loosening than the snare. The improvement of the outer tube significantly reduced the load on the sheath when sliding it. We confirmed the feasibility of mucosal defect closure with FLEXLOOP in pigs. The median operation time was 563 s (range 340–679 s) with the snare and 355 s (range 303–455 s) with FLEXLOOP (p = 0.047). Conclusions FLEXLOOP can be a promising option for defect closure after ESD.

Undifferentiated pleomorphic sarcoma (UPS) was previously known as malignant fibrous histiocytoma (MFH). This sarcoma occurs preferentially in the extremities and retroperitoneal space; primary pulmonary UPS/MFH is rare. We report a 52-year-old woman referred to our hospital with dyspnea and severe cough. Chest computed tomography (CT) revealed a pulmonary mass in the left upper lobe and pleural effusion. Cytology of the effusion showed no malignancy; however, the tumor increased rapidly in size, and the patient’s respiratory symptoms worsened. The tumor occupied almost all of the left upper lobe and involved the adjacent pericardium. She underwent left upper lobectomy with pericardial resection and reconstruction. Postoperative pathology of the resected specimen showed undifferentiated pulmonary sarcoma, pT4N0M1a stage IV A, and genetic analyses revealed the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation. The patient’s dyspnea recurred 1 month postoperatively, and CT showed marked pleural effusion. An 18F-fluorodeoxyglucose positron emission tomography demonstrated abnormal diffuse accumulation of 18F-fluorodeoxyglucose in the left pleural cavity. We initiated five cycles of chemotherapy with doxorubicin and ifosfamide, and the patient has been well without recurrence for 24 months after multidisciplinary treatment with surgery followed by systemic combination chemotherapy. We successfully treated our patient with primary pulmonary UPS/MFH using a multidisciplinary approach, even though this sarcoma carries a poor prognosis and is insensitive to both chemotherapy and radiotherapy.

Abstract Background The intestinal epithelial barrier allows absorption of dietary nutrients and prevents passage of pathogens and toxins into the body. Severe insults have a negative impact on the intestinal environment, which may decrease intestinal barrier function and cause bacterial translocation. Bacterial translocation, which can cause infectious complications, is defined as the passage of microbes from the gastrointestinal tract across the mucosal barrier to extraintestinal sites. The aim of this study was to investigate the correlation between concentrations of preoperative fecal organic acids and the occurrence of postoperative infectious complications in patients with esophageal cancer. Methods Fifty-five patients with esophageal cancer who underwent esophagectomy were enrolled in this study. Perioperative synbiotics were administered to all patients. Perioperative clinical characteristics and concentrations of preoperative fecal organic acids were compared between patients with and without postoperative infectious complications. Results Postoperative infectious complications occurred in 10 patients. In patients with complications, the concentrations of acetic acid and propionic acid were significantly lower than in patients without complications (p = 0.044 and 0.032, respectively). The concentration of butyric acid was nonsignificantly lower in patients with complications, while the concentration of lactic acid was nonsignificantly higher. The calculated gap between the concentrations of fecal acetic acid plus propionic acid plus butyric acid minus lactic acid was significantly lower in patients with complications. Multivariate analysis revealed that a low gap between acetic acid plus propionic acid plus butyric acid minus lactic acid was an independent risk factor for postoperative infectious complications (p = 0.027). Conclusions Preoperative fecal concentrations of organic acids had a clinically important impact on the occurrence of postoperative infectious complications in patients with esophageal cancer. To reduce postoperative infectious complications, it may be useful to modulate the intestinal environment and maintain concentrations of fecal organic acids before surgery.

Xanthine oxidoreductase (XOR) is an enzyme that catalyzes hypoxanthine to xanthine and xanthine to uric acid, respectively. However, the underlying mechanisms of increased plasma XOR and its pathological roles in systemic diseases, such as atherosclerosis, are not fully understood. In this study, we found that changes in plasma XOR activity after bariatric surgery closely associated with those in liver enzymes, but not with those in BMI. In a mouse model of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH), plasma XOR activity markedly increased. Besides, purine catabolism was accelerated in the plasma per se of NASH mice and human patients with high XOR activity. In our NASH mice, we observed an increased vascular neointima formation consisting of dedifferentiated vascular smooth muscle cells (SMCs), which was significantly attenuated by topiroxostat, a selective XOR inhibitor. In vitro, human liver S9–derived XOR promoted proliferation of SMCs with phenotypic modulation and induced ROS production by catabolizing hypoxanthine released from human endothelial cells. Collectively, the results from human and mouse models suggest that increased plasma XOR activity, mainly explained by excess hepatic leakage, was involved in the pathogenesis of vascular injury, especially in NAFLD/NASH conditions.

Abstract Background Extended sleeve lobectomy is rarely applied to pulmonary surgery for primary lung cancer to avoid a pneumonectomy. As there is a size discrepancy between main bronchus and peripheral bronchus, ingenuity to improve anastomosis is required in the bronchoplasty. We report herein a case in which successful reconstruction of extended sleeve lobectomy with bronchial wall flap. Case presentation We report on a 64-year-old man suffering from hemoptysis, cough, mild fever and dyspnea. His computed tomography (CT) scan showed solid tumor of 40 mm in diameter in left lower bronchus, which obstructed the lower bronchus and caused obstructive pneumonia of left lower lobe and expanded to second carina and pulmonary artery. His bronchoscopy showed that tumor was exposed in the bronchial lumen and infiltrated to left main bronchus and upper bronchus even though the scope could pass through the exposed tumor of upper bronchus. Transbronchial lung biopsy showed squamous cell carcinoma. He had undergone left sleeve lingular segmentectomy and left lower lobectomy. Reconstruction was performed with bronchial wall flap. Pathological findings revealed pT3N0M0 stage IIB according to UICC 8th edition. Postoperative bronchoscopic findings showed no troubles at the anastomotic site. He has been well for eighteen months without recurrence after surgery. Conclusions We experienced a successful case who was reconstructed with bronchial wall flap (wine cup stoma) after extended sleeve lobectomy. This technique might be also useful for other types of extended sleeve lobectomy and lung transplantation to adjust caliber changes of bronchi.

An 83-year-old man was referred to our hospital for a detailed evaluation for vomiting. Esophagogastroduodenoscopy and abdominal computed tomography showed duodenal stenosis with wall thickness. Biopsy including endoscopic ultrasound-guided fine-needle aspiration of the thickened wall showed inflammation without malignancy. During the clinical course, wall thickening of the distal bile duct appeared. Biopsy under endoscopic retrograde cholangiography showed papillary adenocarcinoma. Surgery revealed that the tumor had widely invaded the duodenal wall from the outside; therefore, only gastrojejunostomy was performed. It was hypothesized that the cholangiocarcinoma had progressed to the serosal side, disseminated in the peritoneum, infiltrated the duodenal serosa, and caused duodenal stenosis.

Gastric neuroendocrine tumors (GNETs) are rare lesions characterized by enterochromaffin-like cells of the stomach. Optimal management of GNETs has not yet been definitively determined. Endoscopic resection is approximately recommended for small GNETs associated with hypergastrinemia. However, endoscopic resection might present risk of perforation or positive vertical margin because neuroendocrine tumors occur in the deep mucosa, with some invading the submucosa. In this case, a patient with type A chronic atrophic gastritis had a small subepithelial lesion in a deep submucosal layer, and we diagnosed it as GNET using endoscopic ultrasound-guided fine-needle aspiration biopsy using a forward-viewing and curved linear-array echoendoscope. Moreover, our results show that laparoscopic and endoscopic cooperative surgery with regional lymph node dissection is a safe and feasible procedure for GNETs, especially those that cross to the muscularis propria. We suggest this approach as one therapeutic option for GNETs because it safely minimizes resection and is less invasive.

Ovarian cancer often occurs distant metastasis to the peritoneum, liver, lungs, and lymph nodes. However, there has been no reported case of direct metastasis to the duodenal major papilla. We herein reported 72-year-old woman with history of ovarian cancer surgery 11 years ago presenting with obstructive jaundice. Abdominal CT showed a small mass in the distal bile duct. Forceps biopsy from the small mass was done under endoscopic retrograde cholangiography, and histologic examination revealed adenocarcinoma. Pancreaticoduodenectomy was performed and diagnosed immunohistochemically direct metastasis to the papilla from ovarian cancer. The duodenal major papilla is known to be rich in lymph vessels, and these lymph vessels are considered the likely pathway of metastasis in this case.

Carbon-neutral and biodegradable materials such as wood and poly-L-lactic acid play an important role in reducing environmental loads. Therefore, this study theoretically analyzed the thermoelectroelastic problem for a solid cylinder with D∞ symmetry subjected to a distributed torsional shear stress as a mechanical input and to a nonuniform temperature distribution as a thermal disturbance, in order to gain an elementary understanding of the thermal effects on the electroelastic field in cylindrical bodies with D∞ symmetry. The displacement components are expressed in terms of the elastic displacement potential function, the piezoelastic displacement potential function, and the thermoelastic displacement potential functions, and the electric field components are expressed in terms of the electric potential function. Subsequent to presenting the fundamental equations for thermoelectroelasticity, the governing equations for the above potential functions are derived based on the above fundamental equations. These governing equations are solved by a Fourier transform technique, and the theoretical solutions of the thermoelectroelastic field quantities are obtained. Furthermore, by performing numerical calculations, the distributions of the field quantities are illustrated graphically, and the structures of the thermoelectroelastic field are discussed qualitatively and quantitatively. Moreover, by quantitatively evaluating the ratio of the thermally disturbed electric displacement to the undisturbed electric displacement reflecting the mechanical input, the necessity of the thermoelectroelastic analyses, as treated in this paper, is clearly demonstrated.

Obtaining viable islets is a crucial step for successful islet transplantation. Adenosine triphosphate (ATP) is a marker of cell viability. However, little is known about any changes in the energy status of the tissues that are being digested during the digestion phase. We herein examined whether the ATP content in serially digested pancreatic tissue samples could be specific objective parameters that signal the optimal point to stop the digestion process. We obtained partial pancreata (body to tail) from 4- to 5-year-old pigs from a slaughterhouse. The tissue samples were preserved in M-Kyoto solution for less than 3 h. They were digested using an automated enzymatic and mechanical dissociation system at 37°C for 90 min following intraductal injection of Liberase HI. Samples were collected from the digestive circuit every 5 or 10 min to determine the ATP level, total adenine nucleotide (TAN) level, islet count (count/g), and yield of islet equivalent (IEQ) in the serial digestive fluids. The ATP and TAN levels, IEQ and islet count were increased and then decreased during digestion process. The profile of these parameters differed from case to case. However, when ATP changing ratio (respective value/precedent value) was compared with IEQ changing ratio, a greater than threefold increase in the ATP changing ratio followed by an increase in the islet count changing ratio within 5 min was consistently observed, indicating the optimal time to stop the digestion. The ATP levels of the handpicked islets in the digested samples were lower in the overdigested phase in comparison to those in the earlier digested phase. These results indicate that the ATP level in digested fluid could be an effective indicator to estimate the viability of cells as well as determine the optimal time to terminate the digestion process in order to obtain viable islets.

The recovery of all of the islets contained in a pancreas is the goal of islet isolation for transplantation. This study reveals an environment that injures the isolated islets during digestion and proposes a new model for optimal islet isolation. Islets were isolated from Wistar rat pancreases by stationary collagenase digestion while the digestion time was varied at 15, 30, 60, and 120 min. The digested pancreas and islets were analyzed histologically and adenosine nucleotides were measured. Overnight cultured islets (40 islets) were cocultured for 30 min with the supernatants obtained from pancreatic collagenase digestion at different digestion periods in order to assess the toxic environment. The peak yields of islets were obtained at 30 min of digestion. The histological study of digested pancreas showed that the exocrine cells lost their cellular integrity at 120 min of digestion, but the islet cells were left intact. Accordingly, the ATP levels of the pancreatic tissue decreased during the digestion period. The coculture experiment demonstrated that the islets cultured with the supernatants from the collagenase digestion showed digestion time-dependent disruption of the cellular integrity of islets in accordance with a rapid decrease of ATP levels in the islets. The addition of serine protease inhibitors into this coculture clearly showed protection of islets, which maintained high ATP levels in association with intact membrane integrity as assessed by AO/PI staining. Morphological deterioration of islets as well as a marked ATP decrease was evident in the entire digested pancreas as well as in islets cocultured in the supernatants from the collagenase digestion. Various factors toxic to the islets can therefore be analyzed in future experiments using this coculture model for obtaining a good yield of viable islets.

Mizoribine (MZ) inhibits the differentiation and proliferation of helper T and B cells after antigen recognition by suppressing the purine biosynthesis pathway and nucleic acid synthesis. MZ has been used in kidney transplantation, but distinct data are unavailable for islet transplantation. The present study investigated the efficacy of MZ for islet xenotransplantation. Immunosuppressive effects of MZ were determined by mixed lymphocyte reaction (MLR) assay in vitro. Toxicities for Wistar rat islets were determined by adenosine triphosphate (ATP) contents of islets during 3-day culture and stimulation index in response to glucose after culture. Immunosuppressive effects in vivo were tested in a Wistar-to-B6 islet xenotransplantation model. MZ was administered continuously for 28 days subcutaneously or intramuscularly. MZ inhibited MLR response by approximately 50% at 0.1 μg/ml. ATP contents decreased with MZ >100 μg/ml, while stimulation index was maintained. Continuous infusion of MZ at 10 mg/kg maintained blood concentrations at 0.13–0.19 μg/ml, while intramuscular injection of MZ at 100 mg/kg/day (peak 520 μg/ml at 1 h postinjection) resulted in below measurable levels (

One of the goals of islet transplantation is to transplant viable islets without host immunosuppression. The present study was designed to determine whether pretreatment of islets with mitomycin-C (MMC) followed by culture enhances islet survival in a rat-to-mouse xenogeneic combination. WS(RT1k) rat islets pretreated with various concentrations of MMC (0, 3.2, 10, 32, 100, 320, and 1000 μg/ml) were tested for viability by in vitro insulin secretory capacity and vital staining of islets. The MMC-treated islets (10 μg/ml) cultured for various periods (4, 20, or 40 h, 3 or 7 days) were transplanted into the renal subcapsular space of STZ-induced diabetic C57BL/6 (B6: H-2b) mice. MMC-treated or nontreated islets were subjected to microarray gene analysis and immunohistological study. Evaluation of in vitro insulin secretory capacity and vital staining of islets indicated that MMC at a dose ≤32 μg/ml is nontoxic and preserves islet function. Marked prolongation of graft survival was noted with half of islet grafts surviving indefinitely (>100 days) when 10 μg/ml of MMC-treated islets was transplanted after 40 h or 3 days in culture, but not when they were transplanted within 4 h following treatment or at 7 days following treatment, indicating that there is a critical culture period necessary for successful islet graft survival. Microarray analysis suggested possible genes for this prolongation with TGF-β highly expressed in MMC-treated islets subjected to culture for 3 days. Our results indicate that MMC treatment followed by a critical culture period induces marked prolongation of rat islet xenograft survival in nonimmunosuppressed recipient mice, offering a strategy for islet transplantation without immunosuppression.

We have previously shown that mitomycin C (MMC) treatment of donor tissue resulted in significant prolongation of graft survival in allo- and xenotransplantation models. However, the mechanisms involved in this prolongation are not clearly understood. This study aims to shed light on the immune responses to MMC-treated islet xenografting under the kidney capsule. Collagenase-digested WS (RT1 k ) rat islets incubated for 30 min with MMC and subsequently cultured for 20 h were transplanted into the renal subcapsular space of streptozotocin-induced diabetic C57BL/6 (B6;H-2 b ) mice. The grafts were harvested on postgrafting day 7 and sections were prepared and stained by hematoxylin and eosin (H&E). Histological study of the grafts in a group not treated with MMC showed marked cellular infiltration and destruction of islet clusters, whereas that of MMC-treated grafts demonstrated a bleb formation under the kidney capsule, in which islet cell clusters were reorganized, creating a layer of cells fixed to the interior of the bleb. Minimal invasion by inflammatory cells was observed only at the edge of the bleb, and most islet cells were protected from these infiltrating cells. In conclusion, MMC treatment induces remodeling of islet structure and forms a bleb under the kidney capsule, where no inflammatory cell infiltration occurs, suggesting that this site is a kind of immunologically privileged environment for xenografted islets.