Mesenchymal stromal cell secretory molecules improve the functional survival of human islets

This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.AIMS: Human islet transplantation as a therapy for type 1 diabetes is compromised by the loss of functional beta cells in the immediate post-transplantation period. Mesenchymal stromal cells (MSCs) and MSC-derived secretory peptides improve the outcomes of islet transplantation in rodent models of diabetes. Here, we utilized a mouse model for human islet transplantation and assessed the effects of a cocktail of MSC-secreted peptides (screened by MSC-secretome for human islet GPCRs) on the functional survival of human islets. METHODS: Human islets from nine donors (Age: 36-57; BMI: 20-35) were treated with a cocktail of human recombinant annexin A1 (ANXA1), stromal cell-derived factor-1 (SDF-1/CXCL12) and complement component C3 (C3a). Glucose-stimulated insulin secretion (GSIS) was assessed in static incubation, and cytokine-induced apoptosis was assessed by measuring caspase 3/7 activity. mRNA expression levels were determined by qPCR. Human islet function in vivo was assessed using a novel model for human islet transplantation into a T1D mouse model. Human islet function in vivo was assessed using islet transplantation under the kidney capsule of immunodeficient mice prior to STZ destruction of endogenous mouse beta cells to model T1DM. RESULTS: Pretreatment with a cocktail of MSC-secreted peptides increased GSIS in vitro and protected against cytokine-induced apoptosis in human islets isolated from nine donors. Animals transplanted with either treated or untreated human islets remained normoglycaemic for up to 28 days after STZ-administration to ablate the endogenous mouse beta cells, whereas non-transplanted animals showed significantly increased blood glucose immediately after STZ administration. Removal of the human islet graft by nephrectomy resulted in rapid increases in blood glucose to similar levels as the non-transplanted controls. Pretreating human islets with the MSC-derived cocktail significantly improved glucose tolerance in graft recipients, consistent with enhanced functional survival of the treated islets in vivo. CONCLUSION: Pretreating human islets before transplantation with a defined cocktail of MSC-derived molecules could be employed to improve the quality of human islets for transplantation therapy for type 1 diabetes.Medical Research Council (MRC)Diabetes Research and Wellness FoundationKing’s Health Partners Research & Development Fun

Human Mesenchymal Stem Cells Protect Human Islets from Pro-Inflammatory Cytokines

Transplantation of human islets is an attractive alternative to daily insulin injections for patients with type 1 diabetes. However, the majority of islet recipients lose graft function within five years. Inflammation is a primary contributor to graft loss, and inhibiting pro-inflammatory cytokine activity can reverse inflammation mediated dysfunction of islet grafts. As mesenchymal stem cells (MSCs) possess numerous immunoregulatory properties, we hypothesized that MSCs could protect human islets from pro-inflammatory cytokines. Five hundred human islets were co-cultured with 0.5 or 1.0×106 human MSCs derived from bone marrow or pancreas for 24 hours followed by 48 hour exposure to interferon-γ, tumor necrosis factor-α and interleukin 1β. Controls include islets cultured alone (± cytokines) and with human dermal fibroblasts (± cytokines). For all conditions, glucose stimulated insulin secretion (GSIS), total islet cellular insulin content, islet β cell apoptosis, and potential cytoprotective factors secreted in the culture media were determined. Cytokine exposure disrupted human islet GSIS based on stimulation index and percentage insulin secretion. Conversely, culture with 1.0×106 bMSCs preserved GSIS from cytokine treated islets. Protective effects were not observed with fibroblasts, indicating that preservation of human islet GSIS after exposure to pro-inflammatory cytokines is MSC dependent. Islet β cell apoptosis was observed in the presence of cytokines; however, culture of bMSCs with islets prevented β cell apoptosis after cytokine treatment. Hepatocyte growth factor (HGF) as well as matrix metalloproteinases 2 and 9 were also identified as putative secreted cytoprotective factors; however, other secreted factors likely play a role in protection. This study, therefore, demonstrates that MSCs may be beneficial for islet engraftment by promoting cell survival and reduced inflammation

Validation of <i>N</i>-myristoyltransferase as Potential Chemotherapeutic Target in Mammal-Dwelling Stages of <i>Trypanosoma cruzi</i>

BACKGROUND:Trypanosoma cruzi causes Chagas disease, an endemic and debilitating illness in Latin America. Lately, owing to extensive population movements, this neglected tropical disease has become a global health concern. The two clinically available drugs for the chemotherapy of Chagas disease have rather high toxicity and limited efficacy in the chronic phase of the disease, and may induce parasite resistance. The development of new anti-T. cruzi agents is therefore imperative. The enzyme N-myristoyltransferase (NMT) has recently been biochemically characterized, shown to be essential in Leishmania major, Trypanosoma brucei, and T. cruzi¸ and proposed as promising chemotherapeutic target in these trypanosomatids. METHODOLOGY/PRINCIPAL FINDINGS:Here, using high-content imaging we assayed eight known trypanosomatid NMT inhibitors, against mammal-dwelling intracellular amastigote and trypomastigote stages and demonstrated that three of them (compounds 1, 5, and 8) have potent anti-proliferative effect at submicromolar concentrations against T. cruzi, with very low toxicity against human epithelial cells. Moreover, metabolic labeling using myristic acid, azide showed a considerable decrease in the myristoylation of proteins in parasites treated with NMT inhibitors, providing evidence of the on-target activity of the inhibitors. CONCLUSIONS/SIGNIFICANCE:Taken together, our data point out to the potential use of NMT inhibitors as anti-T. cruzi chemotherapy

Ultrasound Image Segmentation Using Feature Asymmetry and Shape Guided Live Wire

Ultrasound (US) is a versatile, low cost, real-time, widely available imaging modality. Manual segmentation for volumetric US measurements can be difficult and very time consuming, requiring slice-by-slice segmentations. However, automatic segmentation of ultrasound images can prove challenging due to the presence of speckle, attenuation, missing boundaries, signal dropouts, and artefacts. Semi-automatic segmentation techniques can improve the speed and accuracy of such measurements, taking advantage of clinical expertise while allowing user interaction. This paper presents a novel solution for interactive image segmentation on B-mode ultrasound images. The proposed method builds on the Live Wire framework and introduces two new sets of Live Wire costs, namely a Feature Asymmetry (FA) cost to localise edges and a weak shape constraint cost to aid the selection of appropriate boundaries in the presence of missing information or artefacts. The resulting semi-automatic segmentation method follows edges based on structural relevance rather than intensity gradients, adapting the method to ultrasound images, where the object boundaries are normally fuzzy. The new method is applied in the context of fetal arm adipose tissue quantification, the adipose tissue being an indicator of the fetal nutritional state. A quantitative and qualitative evaluation is performed with respect to related segmentation techniques. The method was tested on 48 manually segmented ultrasound images of the fetal arm across gestation, showing similar accuracy to the intensity-based Live Wire approach but superior repeatability while requiring significantly less time and user interaction. © 2013 SPIE

Ponds and the importance of their history: an audit of pond numbers, turnover and the relationship between the origins of ponds and their contemporary plant communities in south-east Northumberland, UK

An increasing focus of interest in ponds over the last two decades arose largely because of concerns at the loss of ponds in intensively developed landscapes. In the UK, pond numbers declined from approximately 800,000 in the nineteenth century to 200,000 by the 1980s. Since then pond numbers have started to increase. The focus on overall pond numbers overlooks the importance of the history and origins of different pond types. This study combines a detailed map based audit of pond numbers in south-east Northumberland, UK, recorded at seven time intervals since the mid nineteenth century with a survey of contemporary plant communities in ponds with known and distinct histories to examine changes to numbers of ponds and communities associated with ponds with different origins. 222 ponds were recorded in the study area in the midnineteenth century, 257 in 2005/08. However, only 23 of the original ponds had survived with substantial losses and gains at all the map survey dates linked to changed land use from agriculture to coal mining then development of nature reserves and golf courses. Contemporary ponds on nature reserves, golf courses and subsidence ponds supported rather different plant communities to each other, with non-native invasives in golf and nature reserve sites, whilst individual reserves differed from one another perhaps due to intentional planting. Surviving old farm ponds were usually degraded. The results show that the history of ponds in a region can create an important cultural biodiversity which pond conservation strategies should incorporate