Ryuichi Nishimura

Tacrolimus Inhibits the Revascularization of Isolated Pancreatic Islets

Aims Immunosuppressive drugs could be crucial factors for a poor outcome after islet allotransplantation. Unlike rapamycin, the effects of tacrolimus, the current standard immunosuppressant used in islet transplantation, on graft revascularization remain unclear. We examined the effects of tacrolimus on islet revascularization using a highly sensitive imaging system, and analyzed the gene expression in transplanted islets by introducing laser microdissection techniques. Methods Islets isolated from C57BL/6-Tg (CAG-EGFP) mice were transplanted into the nonmetallic dorsal skinfold chamber on the recipients. Balb/c athymic mice were used as recipients and were divided into two groups: including a control group (nu200a=u200a9) and tacrolimus-treated group (nu200a=u200a7). The changes in the newly-formed vessels surrounding the islet grafts were imaged and semi-quantified using multi-photon laser-scanning microscopy and a Volocity system. Gene expression in transplanted islets was analyzed by the BioMark dynamic system. Results The revascularization process was completed within 14 days after pancreatic islet transplantation at subcutaneous sites. The newly-formed vascular volume surrounding the transplanted islets in the tacrolimus-treated group was significantly less than that in the control group (p<0.05). Although the expression of Vegfa (p<0.05) and Ccnd1 (p<0.05) was significantly upregulated in the tacrolimus-treated group compared with that of the control group, no differences were observed between the groups in terms of other types of gene expression. Conclusions The present study demonstrates that tacrolimus inhibits the revascularization of isolated pancreatic islets without affecting the characteristics of the transplanted grafts. Further refinements of this immunosuppressive regimen, especially regarding the revascularization of islet grafts, could improve the outcome of islet allotransplantation.

Effects of Glucagon-Like Peptide 1 Analogue on the Early Phase of Revascularization of Transplanted Pancreatic Islets in a Subcutaneous Site

OBJECTIVEnThe subcutaneous space is an ideal site for pancreatic islet transplantation. However, one of the main obstacles is poor revascularization. Recently, glucagon-like peptide 1 (GLP-1) analogues are emerging as a new treatment option for patients with type 2 diabetes, because they have been shown to decrease β-cell apoptosis. Therefore, we hypothesized that administration of a GLP-1 analogue in the early phase may facilitate revascularization of transplanted pancreatic islets by decreasing apoptotic changes of vascular endothelial cells within and without the graft. In this study, we evaluated the effects of GLP-1 analogue liraglutide on revascularization at a subcutaneous site with the use of a highly sensitive imaging system. We combined a dorsal skinfold chamber (DSC) technique with multiphoton laser-scanning microscopy (MPLSM).nnnMETHODSnDonor pancreatic islets isolated from C57BL/6-Tg (CAG-EGFP) mice were syngeneically transplanted into a dorsal skinfold chamber mounted on recipient mice. Male C57BL/6N mouse as recipients were divided into 3 groups: control, donor islet-treated, and recipient-treated groups. In the donor islet-treated group, the pancreatic islets were cultured with liraglutide (1 μmol/L) for 24 hours. The recipient-treated mice were injected with liraglutide (100 μg/kg subcutaneously) twice daily for 8 days. The time-dependent changes of newly formed vessels surrounding the islet grafts were imaged with MPLSM on days 1, 4, and 7. To evaluate islet graft revascularization, we measured vascular volume surrounding the islet with the Volocity system.nnnRESULTSnIn the first 4 days after pancreatic islet transplantation, no significant difference was detected in newly formed vessels among the 3 groups. Also, no significant difference was detected to increase rates at 7 days after transplantation.nnnCONCLUSIONSnIn this study, administration of GLP-1 analogue liraglutide in the early phase after pancreatic islet transplantation did not promote revascularization of transplanted islet grafts.

Assessment for Revascularization of Transplanted Pancreatic Islets at Subcutaneous Site in Mice with a Highly Sensitive Imaging System

BACKGROUNDnThe subcutaneous space is one of the ideal sites for pancreatic islet transplantation, owing to the minimal invasiveness and easy access. However, the results of pancreatic islet transplantation in subcutaneous sites remain unsatisfactory. One of the main obstacles to successful pancreatic islet transplantation in subcutaneous sites is poor revascularization. Therefore, the aim of this study was to evaluate the revascularization process at subcutaneous sites with a highly sensitive imaging system combining a dorsal skinfold chamber (DSC) technique and multiphoton laser scanning microscopy (MPLSM).nnnMETHODSnA few pancreatic islets isolated from C57BL/6-Tg (CAG-EGFP) mice were syngeneically transplanted into nonmetallic DSCs mounted on the backs of C57BL/6J mice. Time-dependent changes in the newly formed vessels of pancreatic islets were imaged using MPLSM on days 1, 4, 7, 11, and 14 (n = 6). Texas Red was injected intravenously to visualize blood vessels. To evaluate islet graft revascularization, we measured vascular volume surrounding the islet using the Volocity system (Improvision).nnnRESULTSnThe percentages of vascular volume at days 1 and 14 were assumed to be 0 and 100%, respectively. The vascular volume on each day was 9.4 ± 6.5% (day 4), 34.9 ± 11.2% (day 7), and 21.1 ± 4.6% (day 11).nnnCONCLUSIONSnThe present study showed that a highly sensitive imaging system combining the DSC technique and MPLSM was a useful tool to analyze the revascularization process of pancreatic islets in a subcutaneous site.

Analysis of the Association of Posttransplant Donor-Specific HLA Antibody with Liver Fibrosis After Pediatric Liver Transplantation

Objectives Although the short-term outcomes of pediatric liver transplantation (LT) have improved, the long-term outcomes, which are especially important in pediatric LT, have not improved to the same extent. This is partly caused by immunological progression of liver graft fibrosis. However, liver function test results are commonly normal even among patients with liver fibrosis; therefore, the indication and timing of liver graft biopsy have not been established. The aim of this study was to identify predictive factors of immunological graft fibrosis during long-term follow-up after pediatric LT. Methods We retrospectively identified 90 patients who underwent pediatric living donor LT (LDLT) at our institution between July 1991 and October 2013. Out of 90 LDLT patients, donor-specific antibody (DSA) screening was performed for 71 patients. After the DSA screening, liver biopsies were subsequently performed and graft fibrosis plus findings of chronic rejection were evaluated for 18 patients. Patients were divided into two groups based on histological findings, and clinical characteristics among patients with immunological graft fibrosis were assessed. The degree of fibrosis was diagnosed based on the Metavir fibrosis staging, and the fibrosis group included patients with fibrosis of F2 or more and patients with F1 fibrosis plus findings of chronic rejection, especially including C4d deposition. The cut-off for a positive reaction of Single Antigen Beads assay was set at a mean fluorescence intensity (MFI) of 1,000 or more. Results Of 18 patients, seven were included in the fibrosis group. No significant between-group differences were found regarding pretransplant characteristics, including age, sex, primary disease, ABO incompatibility, and immunosuppressive regimen. Episodes of biopsy-proven acute rejection and non-adherence to immunosuppressive drugs were comparable between the two groups. The mean fluorescence intensity (MFI) for anti-DR DSAs was significantly higher in the fibrosis group than the non-fibrosis group (1655 vs. 216; p = 0.019). There were significant between-group differences regarding the positive rate of anti-DR DSAs (86% vs. 28%; p = 0.012). The MFI for anti-DQ DSA was higher among patients with liver fibrosis, although this between-group difference did not reach statistical significance. The immunosuppression minimization rate was more prevalent among patients with liver fibrosis, although this between-group difference did not reach statistical significance (71% vs. 45%; p = 0.37). Conclusion Posttransplant development of anti-DR DSA is a risk factor of liver fibrosis during long-term follow-up. This finding provides useful information for the implementation of valid histological examinations of liver grafts for patients with higher MFI, especially for anti-DR DSA, after pediatric LT. JSPS KAKENHI Grant Numbers JP17K16502. JSPS KAKENHI Grant Numbers JP26861036.

Treatment of nonocclusive mesenteric ischemia with type B aortic dissection using intra-arterial catheterization after trauma surgery: case report

BackgroundNonocclusive mesenteric ischemia (NOMI) is a mesenteric arterial spasm and intestinal ischemia. This disease is a highly lethal disease because diagnosis and decision of appropriate treatments are often difficult. Operations cannot resolve the spasms and may worsen the situation. However, the safety and effectiveness of catheterization for NOMI with aortic dissection (AD) have not yet been elucidated. Here, we report a successful case of early diagnosis and treatment of NOMI with type B AD involving the superior mesenteric artery (SMA) using the intra-arterial infusion of a vasodilator via the SMA.Case presentationAn 83-year-old man was admitted to our hospital because of abdominal pain after a motor accident. We performed intestinal resection and splenectomy for intestinal perforation and splenic hemorrhage and treated conservatively for acute AD, liver injury, renal hematoma, and pneumothorax. On postoperative day (POD) 2, the patient had localized abdominal pain. Follow-up computed tomography suggested a smaller superior mesenteric vein sign and segmental lack of enhancement in the intestinal wall and ascites without SMA occlusion. Thus, the patient was diagnosed with NOMI. Although the patient had type B AD including the SMA, we performed selective mesenteric arteriography and transcatheter papaverine infusion via the SMA and prostaglandin via the peripheral vein. Seven days post treatment, mesenteric blood flow improved and intestinal wall enhancement was restored.ConclusionThe intra-arterial infusion of a vasodilator is highly efficient and safety treatment option for NOMI with type B AD. Prompt and accurate management can prevent massive small bowel resection, and this procedure is essential in resolving a spasm independent of whether a necrotic bowel has been resected.

Surgical strategy for an adult patient with a catecholamine-producing ganglioneuroblastoma and a cerebral aneurysm: a case report

BackgroundGanglioneuroblastomas, particularly those that produce catecholamine, are extremely rare in adults. Here, we report an interesting surgical case of an adult patient with a catecholamine-producing ganglioneuroblastomas in her adrenal gland, suspected to be a pheochromocytoma, and with a cerebral aneurysm.Case presentationThe patient was a 73-year-old woman under treatment for hypertension. During a health check-up, a cystic retroperitoneal tumor was incidentally found in the superior pole of her right kidney. Her blood adrenaline level was slightly elevated, and her urinary adrenaline, noradrenaline, and dopamine levels were above the upper reference limits. In addition, 24-h urinary excretion of metanephrine, normetanephrine, and vanillylmandelic acid were all increased. 123I-Meta-iodobenzylguanidine scintigraphy showed an abnormal accumulation of the marker in the cyst wall. She was, therefore, diagnosed with a pheochromocytoma and scheduled for tumor resection. However, preoperatively, 8-mm-diameter cerebral aneurysm was incidentally found in her basilar artery. This required careful preoperative discussion. The aneurysm was difficult to approach and treat, and based on its position, shape, and size, the risk of rupture was low. Because hypertension is a major risk factor for aneurysmal rupture, we decided to proceed with the tumor resection. A lumbar catheter was placed to monitor the cerebral aneurysm for intraoperative rupture, and her transcranial motor-evoked potential and somatosensory-evoked potentials were monitored to track her intraoperative neurological function. During surgery, we carefully monitored fluctuations in blood pressure and resected the tumor with minimal mobilization. Postoperatively, head computed tomography confirmed that there was no sign of rupture. Histopathologically, the tumor was diagnosed as a catecholamine-producing ganglioneuroblastoma. The postoperative course was good, and the patient’s blood pressure improved.ConclusionsCareful perioperative management is needed for a patient with both a catecholamine-producing tumor and cerebral aneurysm.

Amyand’s hernia complicated with appendix perforation treated by two-stage surgery consisting of laparoscopic appendectomy followed by elective inguinal hernioplasty: a case report

Highlights • Amyand’s hernia with appendix perforation is an extremely rare condition.• Very few cases of Amyand’s hernia with appendix perforation used laparoscope as a therapeutic tool.• Laparoscopic approach is diagnostic and enables two stage operation to the perforated cases.