Stephan Kersting

Transplantation of human islets without immunosuppression

Significance Diabetes mellitus type 1 is an autoimmune disease that results in irreversible destruction of insulin-producing beta cells. Substantial advances have been made in beta cell replacement therapies over the last decades. However, lack of eligible donor organs and the need for chronic immunosuppression to prevent rejection critically limit a widespread application of these strategies. In this paper we present the clinical success of using a bioartificial pancreas for the transplantation of insulin-producing islets without affecting the immune system. In a patient with long-standing type-1 diabetes we could demonstrate persistent graft function and regulated insulin secretion without the need for immune-modulating medication. This strategy opens up avenues for more widespread and safe application of various cell-based therapies. Transplantation of pancreatic islets is emerging as a successful treatment for type-1 diabetes. Its current stringent restriction to patients with critical metabolic lability is justified by the long-term need for immunosuppression and a persistent shortage of donor organs. We developed an oxygenated chamber system composed of immune-isolating alginate and polymembrane covers that allows for survival and function of islets without immunosuppression. A patient with type-1 diabetes received a transplanted chamber and was followed for 10 mo. Persistent graft function in this chamber system was demonstrated, with regulated insulin secretion and preservation of islet morphology and function without any immunosuppressive therapy. This approach may allow for future widespread application of cell-based therapies.

Google Goes Cancer: Improving Outcome Prediction for Cancer Patients by Network-Based Ranking of Marker Genes

Predicting the clinical outcome of cancer patients based on the expression of marker genes in their tumors has received increasing interest in the past decade. Accurate predictors of outcome and response to therapy could be used to personalize and thereby improve therapy. However, state of the art methods used so far often found marker genes with limited prediction accuracy, limited reproducibility, and unclear biological relevance. To address this problem, we developed a novel computational approach to identify genes prognostic for outcome that couples gene expression measurements from primary tumor samples with a network of known relationships between the genes. Our approach ranks genes according to their prognostic relevance using both expression and network information in a manner similar to Googles PageRank. We applied this method to gene expression profiles which we obtained from 30 patients with pancreatic cancer, and identified seven candidate marker genes prognostic for outcome. Compared to genes found with state of the art methods, such as Pearson correlation of gene expression with survival time, we improve the prediction accuracy by up to 7%. Accuracies were assessed using support vector machine classifiers and Monte Carlo cross-validation. We then validated the prognostic value of our seven candidate markers using immunohistochemistry on an independent set of 412 pancreatic cancer samples. Notably, signatures derived from our candidate markers were independently predictive of outcome and superior to established clinical prognostic factors such as grade, tumor size, and nodal status. As the amount of genomic data of individual tumors grows rapidly, our algorithm meets the need for powerful computational approaches that are key to exploit these data for personalized cancer therapies in clinical practice.

Pathohistological subtype predicts survival in patients with intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

Objective: To investigate different subtypes of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas and their prognostic value. Background: IPMNs of the pancreas are estimated to have a better prognosis than pancreatic ductal adenocarcinomas (PDACs). In addition to the different growth types (ie, main duct vs. branch duct types), the histological subtypes of IPMNs (ie, intestinal, pancreatobiliary, gastric, and oncocytic type) are prognostically relevant. These subtypes can be characterized by different mucin (MUC) expression patterns. In this study, we analyzed the IPMNs from 2 pancreatic cancer referral centers by correlating the MUC expression, histological subtype, and clinical outcome. Methods: We re-evaluated all resections due to a pancreatic tumor over a period of 15 years. Cases with IPMNs were identified, and the subtypes were distinguished using histopathological analysis, including the immunohistochemical analysis of MUC (ie, MUC1, MUC2, and MUC5AC) expression. Furthermore, we determined clinical characteristics and patient outcome. Results: A total of 103 IPMNs were identified. On the basis of the MUC profile, histopathological subtypes were classified into the following categories: intestinal type [n = 45 (44%)], pancreatobiliary type [n = 41 (40%)], gastric type [n = 13 (12%)], and oncocytic type [n = 4 (4%)]. The following types of resections were performed: pancreatic head resections [n = 77 (75%)], tail resections [n = 16 (15%)], total pancreatectomies [n = 5 (5%)], and segment resections [n = 5 (5%)]. The 5-year survival of patients with intestinal IPMNs was significantly better than pancreatobiliary IPMNs (86.6% vs. 35.6%; P < 0.001). The pancreatobiliary subtype was strongly associated with malignancy [odds ratio (OR): 6.76], recurrence (P < 0.001), and long-term survival comparable with that of PDAC patients. Conclusions: Evaluation of IPMN subtypes supports postoperative patient prognosis prediction. Therefore, subtype differentiation could lead to improvements in clinical management. Potentially identifying subgroups with the need for adjuvant therapy may be possible.

Quantitative Perfusion Analysis of Transabdominal Contrast-Enhanced Ultrasonography of Pancreatic Masses and Carcinomas

BACKGROUND & AIMS Preoperative differential diagnosis of pancreatic ductal adenocarcinoma (PDAC) and focal masses in patients with chronic pancreatitis (CP) can be challenging. There are fine differences in the vascularization of these lesions; ultrasound contrast agents can aid in their differentiation. We evaluated the value of software-aided quantitative analysis of transabdominal contrast-enhanced ultrasonography for differential diagnosis of PDAC vs focal masses. METHODS Sixty patients for whom it was not possible to differentiate between an inflammatory focal lesion of the pancreas and a pancreatic carcinoma underwent contrast-enhanced ultrasonography with a second-generation contrast agent. Time-intensity curves were obtained for all exams in 2 regions of interest within the lesion and within the normal pancreatic tissue. Images were processed using Axius ACQ software; the following parameters were obtained: maximum intensity, arrival time, time-to-peak, and area under the curve. Absolute values and differences between the lesion and the normal tissue were evaluated. RESULTS Histology analysis revealed 45 PDACs and 15 inflammatory masses in patients with CP. Time-dependent parameters (arrival time and time to peak) were significantly longer in PDACs compared to focal masses. Although markedly lower than in healthy pancreata, the maximum intensity and area under the curve parameters were not significantly different between PDACs and focal lesions in patients with CP. CONCLUSIONS In cases of CP, PDAC and focal masses exhibit different perfusion patterns at a capillary level that can be visualized using the small microbubbles of ultrasound contrast agents. Contrast quantification software supplements a subjective visual assessment with objective criteria to facilitate the differential diagnosis of focal lesions in pancreatic cancer and chronic pancreatitis.

Prognostic factors and evaluation of a clinical score for predicting survival after resection of colorectal liver metastases.

Background: Patient outcome after resection of colorectal liver metastases can be predicted by various prognostic factors.

Synergy of glucose and growth hormone signalling in islet cells through ICA512 and STAT5

Nutrients and growth hormones promote insulin production and the proliferation of pancreatic β-cells. An imbalance between ever-increasing metabolic demands and insulin output causes diabetes. Recent evidence indicates that β-cells enhance insulin gene expression depending on their secretory activity. This signalling pathway involves a catalytically inactive receptor tyrosine phosphatase, ICA512, whose cytoplasmic tail is cleaved on glucose-stimulated exocytosis of insulin secretory granules and then moves into the nucleus, where it upregulates insulin transcription. Here, we show that the cleaved cytosolic fragment of ICA512 enhances the transcription of secretory granule genes (including its own gene) by binding to tyrosine phosphorylated signal transducers and activators of transcription (STAT) 5 and preventing its dephosphorylation. Sumoylation of ICA512 by the E3 SUMO ligase PIASy, in turn, may reverse this process by decreasing the binding of ICA512 to STAT5. These findings illustrate how the exocytosis of secretory granules, through a retrograde pathway that sustains STAT activity, converges with growth hormone signalling to induce adaptive changes in β-cells in response to metabolic demands.

ICA512 signaling enhances pancreatic beta-cell proliferation by regulating cyclins D through STATs

Changes in metabolic demands dynamically regulate the total mass of adult pancreatic β-cells to adjust insulin secretion and preserve glucose homeostasis. Glucose itself is a major regulator of β-cell proliferation by inducing insulin secretion and activating β-cell insulin receptors. Here, we show that islet cell autoantigen 512 (ICA512)/IA-2, an intrinsic tyrosine phosphatase-like protein of the secretory granules, activates a complementary pathway for β-cell proliferation. On granule exocytosis, the ICA512 cytoplasmic domain is cleaved and the resulting cytosolic fragment (ICA512-CCF) moves into the nucleus where it enhances the levels of phosphorylated STAT5 and STAT3, thereby inducing insulin gene transcription and granule biogenesis. We now show that knockdown of ICA512 decreases cyclin D1 levels and proliferation of insulinoma INS-1 cells, whereas β-cell regeneration is reduced in partially pancreatectomized ICA512−/− mice. Conversely, overexpression of ICA512-CCF increases both cyclin D1 and D2 levels and INS-1 cell proliferation. Up-regulation of cyclin D1 and D2 by ICA512-CCF is affected by knockdown of STAT3 and STAT5, respectively, whereas it does not require insulin signaling. These results identify ICA512 as a regulator of cyclins D and β-cell proliferation through STATs and may have implication for diabetes therapy.

Reduction of postoperative lymphedema after oral tumor surgery with sodium selenite

The objective of this double-blind, randomized study was to establish whether sodium selenite administered orally or intravenously reduces postoperative lymphedema after oral tumor surgery and to study the effect of sodium selenite on glutathione peroxidase (GPX) activity and oxygen radical production. Twenty patients were enrolled in the study. Each of the participants received 1000 μg sodium selenite intravenously or orally daily for 3 wk during the pre-, intra-, and postoperative period. The extent of lymphedema was measured for 2 wk and the plasma and whole-blood selenium concentration, GPX, reactive oxygen species (ROS), NO, and malonic dialdehyde were measured for 1 yr postoperatively. There was an inverse correlation between the severity of the lymphedema and the wholeblood/plasma selenium concentration and GPX activity. In addition, a positive correlation between the ROS concentration and the extent of lymphedema was observed. A significant reduction of lymphedema occurred in the sodium selenite-treated group. It is concluded that sodium selenite represents a suitable adjuvant treatment of secondary lymphedema in surgically treated patients with tumors in the oral and maxillofacial areas. Treatment with sodium selenite is especially advantageous as it can be instituted immediately after surgery prior to wound healing when manual lymphatic decongestion therapy cannot be applied.

Preoperative CEA and CA 19-9 are prognostic markers for survival after curative resection for ductal adenocarcinoma of the pancreas – A retrospective tumor marker prognostic study

BACKGROUND The prognosis for patients with ductal adenocarcinoma of the pancreas (PDAC) remains poor even after curative resection. Carbohydrate antigen 19-9 (CA 19-9) and the carcinoembryonic antigen (CEA) are the most widely used serum-based tumor markers for the diagnosis and follow up of pancreatic cancer. In our analysis we aim to assess the prognostic value of a combination of both tumor markers in patients with pancreatic ductal adenocarcinoma (PDAC). PATIENTS AND METHODS Between 01/1995 and 08/2012 we performed a total of 264 pancreatic resections due to PDAC. Patients were stratified into 3 groups in regard to their preoperative tumor marker levels. Survival was compared between the groups using Kaplan Meier analysis and log rank test. Univariate subgroup analysis and multivariate analysis were performed. RESULTS For 259 cases complete follow up could be obtained. In patients with low preoperative CEA and CA 19-9 levels (group 1 n = 91) the mean survival was 33.3 month (CI 95% 25.1-41.5). If one of the analyzed tumor markers (CEA/CA19-9) was preoperatively elevated above the cut-off level (group 2 n = 106) mean survival was 28.5 month (CI 95% 22.1-35.1). 62 patients showed preoperative elevation of both, CEA and CA 19-9 (group 3); mean survival in this group was 23.9 month (CI 95% 13.9-33.9), p > 0.01. Multivariate analysis confirmed preoperative CEA/CA 19-9 level as independent prognostic factor (HR 1.299). CONCLUSION Preoperative CEA and CA 19-9 levels correlate with patient prognosis after curative pancreatic resection due to PDAC. This is especially true for the most frequently pT 3/4 stages of PDAC. Even if CEA and CA 19-9 might not be appropriate for screening, its serum levels should therefore be determined prior to operation and taken into account when resectability or operability is doubtful.

Colorectal liver metastasis surgery: analysis of risk factors predicting postoperative complications in relation to the extent of resection

Background/aimsDespite advances in diagnosis and treatment, the rate of complications after resection for colorectal liver metastases remains high. An awareness of risk factors is essential for the rates of morbidity and mortality to fall to optimal levels.Materials and methodsOf the 240 patients who underwent resection for the first manifestation of colorectal liver metastases, 49 patients with lobectomy or extended hepatectomy (major resections) and 58 with wedge resections within only one liver segment (minor resections) form the basis of this report. A total of 16 variables were analyzed to find the risk factors linked to postoperative morbidity and mortality.Results/findingsThirty-four patients (31.8%) suffered postoperative complications, and one patient died during the hospital stay (0.9%). In the major resection group, multivariate analysis showed that neoadjuvant chemotherapy [odds ratio (OR): 2.4; p = 0.005], vascular clamping (OR: 1.4; p = 0.008), and intraoperative blood loss with transfusion of three to six packed red cell units (OR: 1.2; p = 0.029) were significantly associated with postoperative morbidity. Vascular clamping was an independent predictor for biliary fistula (OR: 1.2; p = 0.029). Postoperative temporary liver failure was influenced by neoadjuvant chemotherapy (OR: 3.4; p = 0.010), vascular clamping (OR: 1.5; p = 0.015), and requirement of blood transfusion (OR: 2.1; p = 0.016). After minor resections, only a decreased postoperative serum cholinesterase B level was an independent predictor for complications (OR: 2.2; p = 0.001), as well as for hemorrhage (OR: 1.6; p = 0.023). Postoperative mortality was not predicted by any of the factors that were analyzed.Interpretation/conclusionFactors for complications differ depending on the extent of colorectal liver metastasis resection. Only knowledge and particular consideration of these factors may provide for an optimal postoperative outcome for the individual patient.