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The transplantation of glucose-responsive, insulin-producing cells offers the potential for restoring glycemic control in individuals with diabetes. Pancreas transplantation and the infusion of cadaveric islets are currently implemented clinically, but these approaches are limited by the adverse effects of immunosuppressive therapy over the lifetime of the recipient and the limited supply of donor tissue. The latter concern may be addressed by recently described glucose-responsive mature beta cells that are derived from human embryonic stem cells (referred to as SC-β cells), which may represent an unlimited source of human cells for pancreas replacement therapy. Strategies to address the immunosuppression concerns include immunoisolation of insulin-producing cells with porous biomaterials that function as an immune barrier. However, clinical implementation has been challenging because of host immune responses to the implant materials. Here we report the first long-term glycemic correction of a diabetic, immunocompetent animal model using human SC-β cells. SC-β cells were encapsulated with alginate derivatives capable of mitigating foreign-body responses in vivo and implanted into the intraperitoneal space of C57BL/6J mice treated with streptozotocin, which is an animal model for chemically induced type 1 diabetes. These implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control. Implants retrieved after 174 d contained viable insulin-producing cells.

Transcription Factor 7-Like 2 Regulates β-Cell Survival and Function in Human Pancreatic Islets Luan Shu 1 , Nadine S. Sauter 1 , Fabienne T. Schulthess 1 , Aleksey V. Matveyenko 1 , José Oberholzer 2 and Kathrin Maedler 1 1 Larry L. Hillblom Islet Research Center, Department of Medicine, University of California, Los Angeles, Los Angeles, California 2 Division of Transplantation, University of Illinois at Chicago, Chicago, Illinois Address correspondence and reprint requests to Kathrin Maedler, PhD, Centre for Biomolecular Interactions Bremen, University of Bremen, NW2, Box 33 04 40, D-28334 Bremen, Germany. E-mail: kmaedler{at}uni-bremen.de Abstract OBJECTIVE —Type 2 diabetes is characterized by impaired insulin secretion in response to increased metabolic demand. This defect in β-cell compensation seems to result from the interplay between environmental factors and genetic predisposition. Genome-wide association studies reveal that common variants in transcription factor 7-like 2 (TCF7L2) are associated with increased risk of type 2 diabetes. The aim of the present study was to establish whether TCF7L2 plays a role in β-cell function and/or survival. RESEARCH DESIGN AND METHODS —To investigate the effects of TCFL7L2 depletion, isolated islets were exposed to TCF7L2 small interfering RNA (siRNA) versus scrambled siRNA, and β-cell survival and function were examined. For TCF7L2 overexpression, islets were cultured in glucose concentrations of 5.5–33.3 mmol/l and the cytokine mix interleukin-1β/γ-interferon with or without overexpression of TCF7L2. Subsequently, glucose-stimulated insulin secretion (GSIS), β-cell apoptosis [by transferase-mediated dUTP nick-end labeling assay and Western blotting for poly(ADP-ribose) polymerase and Caspase-3 cleavage], and β-cell proliferation (by Ki67 immunostaining) were analyzed. RESULTS —Depleting TCF7L2 by siRNA resulted in a 5.1-fold increase in β-cell apoptosis, 2.2-fold decrease in β-cell proliferation ( P < 0.001), and 2.6-fold decrease in GSIS ( P < 0.01) in human islets. Similarly, loss of TCF7L2 resulted in impaired β-cell function in mouse islets. In contrast, overexpression of TCF7L2 protected islets from glucose and cytokine-induced apoptosis and impaired function. CONCLUSIONS —TCF7L2 is required for maintaining GSIS and β-cell survival. Changes in the level of active TCF7L2 in β-cells from carriers of at-risk allele may be the reason for defective insulin secretion and progression of type 2 diabetes. DAPI, 4,6-diamidino-2-phenylindole FITC, fluorescein isothiocyanate GLP-1, glucagon-like peptide 1 GSIS, glucose-stimulated insulin secretion IFN-γ, γ-interferon IL, interleukin KRBB, Krebs-Ringer bicarbonate buffer PARP, poly(ADP-ribose) polymerase siRNA, small interfering RNA siScr, scrambled control siRNA siTCF7L2, islets depleted for TCF7L2 by siRNA to TCF7L2 SNP, single nucleotide polymorphism TCF7L2, transcription factor 7-like 2 TUNEL, transferase-mediated dUTP nick-end labeling Footnotes Published ahead of print at http://diabetes.diabetesjournals.org on 10 December 2007. DOI: 10.2337/db07-0847. N.S.S. and F.T.S. contributed equally to this study. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Received June 21, 2007. Accepted November 29, 2007. DIABETES

Host recognition and immune-mediated foreign body response to biomaterials can compromise the performance of implanted medical devices. To identify key cell and cytokine targets, here we perform in-depth systems analysis of innate and adaptive immune system responses to implanted biomaterials in rodents and non-human primates. While macrophages are indispensable to the fibrotic cascade, surprisingly neutrophils and complement are not. Macrophages, via CXCL13, lead to downstream B cell recruitment, which further potentiated fibrosis, as confirmed by B cell knockout and CXCL13 neutralization. Interestingly, colony stimulating factor-1 receptor (CSF1R) is significantly increased following implantation of multiple biomaterial classes: ceramic, polymer and hydrogel. Its inhibition, like macrophage depletion, leads to complete loss of fibrosis, but spares other macrophage functions such as wound healing, reactive oxygen species production and phagocytosis. Our results indicate that targeting CSF1R may allow for a more selective method of fibrosis inhibition, and improve biomaterial biocompatibility without the need for broad immunosuppression. By studying the immune responses of animals to different types of biomaterial implants, colony stimulating factor-1 receptor is revealed as an important mediator of the foreign body reaction and a possible target for fibrosis inhibition.

Implantable medical devices have revolutionized modern medicine. However, immune-mediated foreign body response (FBR) to the materials of these devices can limit their function or even induce failure. Here we describe long-term controlled-release formulations for local anti-inflammatory release through the development of compact, solvent-free crystals. The compact lattice structure of these crystals allows for very slow, surface dissolution and high drug density. These formulations suppress FBR in both rodents and non-human primates for at least 1.3 years and 6 months, respectively. Formulations inhibited fibrosis across multiple implant sites—subcutaneous, intraperitoneal and intramuscular. In particular, incorporation of GW2580, a colony stimulating factor 1 receptor inhibitor, into a range of devices, including human islet microencapsulation systems, electrode-based continuous glucose-sensing monitors and muscle-stimulating devices, inhibits fibrosis, thereby allowing for extended function. We believe that local, long-term controlled release with the crystal formulations described here enhances and extends function in a range of medical devices and provides a generalized solution to the local immune response to implanted biomaterials.

Monounsaturated Fatty Acids Prevent the Deleterious Effects of Palmitate and High Glucose on Human Pancreatic β-Cell Turnover and Function Kathrin Maedler 1 , José Oberholzer 2 , Pascal Bucher 2 , Giatgen A. Spinas 1 and Marc Y. Donath 1 1 Division of Endocrinology and Diabetes, University Hospital, Zurich, Switzerland 2 Division of Surgical Research, Department of Surgery, University of Geneva Medical Center, Geneva, Switzerland Abstract Glucotoxicity and lipotoxicity contribute to the impaired β-cell function observed in type 2 diabetes. Here we examine the effect of saturated and monounsaturated fatty acids at different glucose concentrations on human β-cell turnover and secretory function. Exposure of cultured human islets to saturated fatty acid and/or to an elevated glucose concentration for 4 days increased β-cell DNA fragmentation and decreased β-cell proliferation. In contrast, the monounsaturated palmitoleic acid or oleic acid did not affect DNA fragmentation and induced β-cell proliferation. Moreover, each monounsaturated fatty acid prevented the deleterious effects of both palmitic acid and high glucose concentration. The cell-permeable ceramide analogue C 2 -ceramide mimicked both the palmitic acid-induced β-cell apoptosis and decrease in proliferation. Furthermore, the ceramide synthetase inhibitor fumonisin B1 blocked the deleterious effects of palmitic acid on β-cell turnover. In addition, palmitic acid decreased Bcl-2 expression and induced release of cytochrome c from the mitochondria into the cytosol, which was prevented by fumonisin B1 and by oleic acid. Finally, each monounsaturated fatty acid improved β-cell secretory function that was reduced by palmitic acid and by high glucose. Thus, in human islets, the saturated palmitic acid and elevated glucose concentration induce β-cell apoptosis, decrease β-cell proliferation, and impair β-cell function, which can be prevented by monounsaturated fatty acids. The deleterious effect of palmitic acid is mediated via formation of ceramide and activation of the apoptotic mitochondrial pathway, whereas Bcl-2 may contribute to the protective effect of monounsaturated fatty acids. Footnotes Address correspondence and reprint requests to Marc Y. Donath, MD, Division of Endocrinology and Diabetes, Department of Medicine, University Hospital, CH-8091 Zurich, Switzerland. E-mail: marc.donath{at}dim.usz.ch . Received for publication 13 June 2002 and accepted in revised form 21 November 2002. FFA, free fatty acids; TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. DIABETES

Type 1 diabetes (T1D) and type 2 diabetes (T2D) are both hallmarked by loss of insulin-producing pancreatic beta cells. Kathrin Maedler and her colleagues now show that the kinase MST1 is upregulated by diabetic conditions in beta cells, resulting in their dysfunction and their apoptosis. They also show that genetic knockout of the gene encoding Mst1 results in protection from diabetes in T1D and T2D mouse models. Apoptotic cell death is a hallmark of the loss of insulin-producing beta cells in all forms of diabetes mellitus. Current treatments fail to halt the decline in functional beta cell mass, and strategies to prevent beta cell apoptosis and dysfunction are urgently needed. Here, we identified mammalian sterile 20–like kinase-1 (MST1) as a critical regulator of apoptotic beta cell death and function. Under diabetogenic conditions, MST1 was strongly activated in beta cells in human and mouse islets and specifically induced the mitochondrial-dependent pathway of apoptosis through upregulation of the BCL-2 homology-3 (BH3)-only protein BIM. MST1 directly phosphorylated the beta cell transcription factor PDX1 at T11, resulting in the latter's ubiquitination and degradation and thus in impaired insulin secretion. MST1 deficiency completely restored normoglycemia, beta cell function and survival in vitro and in vivo . We show MST1 as a proapoptotic kinase and key mediator of apoptotic signaling and beta cell dysfunction and suggest that it may serve as target for the development of new therapies for diabetes.

OBJECTIVE: To assess long-term metabolic and immunological follow-up of microencapsulated human islet allografts in nonimmunosuppressed patients with type 1 diabetes (T1DM). RESEARCH DESIGN AND METHODS: Four nonimmunosuppressed patients, with long-standing T1DM, received intraperitoneal transplant (TX) of microencapsulated human islets. Anti-major histocompatibility complex (MHC) class I–II, GAD65, and islet cell antibodies were measured before and long term after TX. RESULTS: All patients turned positive for serum C-peptide response, both in basal and after stimulation, throughout 3 years of posttransplant follow-up. Daily mean blood glucose, as well as HbA1c levels, significantly improved after TX, with daily exogenous insulin consumption declining in all cases and being discontinued, just transiently, only in patient 4. Anti-MHC class I–II and GAD65 antibodies all tested negative at 3 years after TX. CONCLUSIONS: The grafts did not elicit any immune response, even in the cases where more than one preparation was transplanted, as a unique finding, compatible with encapsulation-driven \"bioinvisibility\" of the grafted islets. This result had never been achieved with the recipient’s general immunosuppression.

We present a novel pumpless microfluidic array driven by surface tension for studying the physiology of pancreatic islets of Langerhans. Efficient fluid flow in the array is achieved by surface tension-generated pressure as a result of inlet and outlet size differences. Flow properties are characterized in numerical simulation and further confirmed by experimental measurements. Using this device, we perform a set of biological assays, which include real-time fluorescent imaging and insulin secretion kinetics for both mouse and human islets. Our results demonstrate that this system not only drastically simplifies previously published experimental protocols for islet study by eliminating the need for external pumps/tubing and reducing the volume of solution consumption, but it also achieves a higher analytical spatiotemporal resolution due to efficient flow exchanges and the extremely small volume of solutions required. Overall, the microfluidic platform presented can be used as a potential powerful tool for understanding islet physiology, antidiabetic drug development, and islet transplantation.

Background/Objectives: The aim of this study was to investigate the association between intraoperative blood transfusion (BT) and the short-term outcomes of pancreatoduodenectomy (PD) for patients with periampullary malignancies. Methods: In a retrospective two-center cohort analysis, we utilized a logistic and mixed-effects ordinal regression, nonparametric partial correlation, and mediation analysis, complemented by propensity score matching (PSM) and weighting. Results: A total of 491 patients were included. Of these, 18 (3.7%) received an intraoperative BT. An intraoperative BT was associated with blood loss (odds ratio (OR) per 100 mL = 1.42; 95% CI 1.27 to 1.62; p < 0.001) and relatively high ASA classes (OR = 3.75; 95% CI 1.05 to 17.74; p = 0.041). Intraoperative blood loss (r = 0.27; p < 0.001) but not intraoperative BT (r = 0.015; p = 0.698) was associated with postoperative complications. Intraoperative BT was associated with postoperative complications according to the unadjusted regression (OR = 1.95; 95% CI 1.38–2.42, p < 0.001) but not the multivariable ordinal regression. In the mediation analysis for relative risk (RR), intraoperative BT was beneficial (RR = 0.51; 95% CI: 0.01–0.78), and blood loss (RR = 2.49; 95% CI: 1.75–177.34) contributed to the occurrence of major postoperative complications. After PSM, analyses revealed that an intraoperative BT did not have a significant impact on the rates of postoperative major complications (OR = 1.048; p = 0.919), clinically relevant postoperative pancreatic fistula (OR = 0.573; p = 0.439) or postoperative 90-day mortality (OR = 0.714; p = 0.439). Conclusions: When adjusting for intraoperative blood loss, intraoperative BT is not associated with postoperative complications.