IsletSwipe, a mobile platform for expert opinion exchange on islet graft images

We previously developed a deep learning-based web service (IsletNet) for an automated counting of isolated pancreatic islets. The neural network training is limited by the absent consensus on the ground truth annotations. Here, we present a platform (IsletSwipe) for an exchange of graphical opinions among experts to facilitate the consensus formation. The platform consists of a web interface and a mobile application. In a small pilot study, we demonstrate the functionalities and the use case scenarios of the platform. Nine experts from three centers validated the drawing tools, tested precision and consistency of the expert contour drawing, and evaluated user experience. Eight experts from two centers proceeded to evaluate additional images to demonstrate the following two use case scenarios. The Validation scenario involves an automated selection of images and islets for the expert scrutiny. It is scalable (more experts, images, and islets may readily be added) and can be applied to independent validation of islet contours from various sources. The Inquiry scenario serves the ground truth generating expert in seeking assistance from peers to achieve consensus on challenging cases during the preparation for IsletNet training. This scenario is limited to a small number of manually selected images and islets. The experts gained an opportunity to influence IsletNet training and to compare other experts' opinions with their own. The ground truth-generating expert obtained feedback for future IsletNet training. IsletSwipe is a suitable tool for the consensus finding. Experts from additional centers are welcome to participate.

Combining Donor Characteristics with Immunohistological Data Improves the Prediction of Islet Isolation Success

Variability of pancreatic donors may significantly impact the success of islet isolation. The aim of this study was to evaluate donor factors associated with isolation failure and to investigate whether immunohistology could contribute to organ selection. Donor characteristics were evaluated for both successful (n = 61) and failed (n = 98) islet isolations. Samples of donor pancreatic tissue (n = 78) were taken for immunohistochemical examination. Islet isolations with 250000 islet equivalents were considered successful. We confirmed that BMI of less than 25 kg/m² (P < 0.001), cold ischemia time more than 8 hours (P < 0.01), hospitalization longer than 96 hours (P < 0.05), higher catecholamine doses (P < 0.05), and edematous pancreases (P < 0.01) all unfavorably affected isolation outcome. Subsequent immunohistochemical examination of donor pancreases confirmed significant differences in insulin-positive areas (P < 0.001). ROC analyses then established that the insulin-positive area in the pancreas could be used to predict the likely success of islet isolation (P < 0.001). At the optimal cutoff point (>1.02%), sensitivity and specificity were 89% and 76%, respectively. To conclude, while the insulin-positive area, determined preislet isolation, as a single variable, is sufficient to predict isolation outcome and helps to improve the success of this procedure, its combination with the established donor scoring system might further improve organ selection.

The effect of epigenetic factors on differentiation of pancreatic progenitor cells into insulin-producing cells

Differentiation of pancreatic progenitors into insulin-producing β cells is regulated by various transcription factors. To be expressed the genes coding these transcription factors need to be in accessible DNA. Whether a particular gene is present in a form of active euchromatin structure with accessible DNA or in an inactive heterochromatin structure with inaccessible DNA is determined by various epigenetic modifications. We studied the effect of epigenetic modifiers on differentiation of human nonendocrine cells into insulin-producing cells with the aim to evaluate the effect of epigenetic modifications in that process. Within 3 days of cultivation nonendocrine cells form isletlike cell clusters (ILCCs) containing mainly cytokeratin-19-positive cells. After cultivation with epigenetic modifiers and further differentiation, the highest number of C-peptide-positive cells (10.3% ± 2.9%) as well as glucagon-positive cells (7.2% ± 2.8%) was observed in a sample supplemented with a combination of 5-Aza-2'-deoxycytidine modifiers, BIX01294 and MC1568. In response to glucose stimulation (5 vs 20 mmol/L) these ILCCs secreted increased amounts of C-peptide (0.45 vs 1.05 pmol C-peptide/μg DNA). Control samples treated without any epigenetic modifiers showed significantly lower numbers of C-peptide-positive cells (3.5% ± 1.6%). These results showed that a combination of epigenetic modifiers 5-Aza-2'-deoxycytidine (BIX01294 and MC1568) significantly improved reproducible differentiation of nonendocrine pancreatic cells into insulin-producing cells.

Protein microarray analysis as a tool for monitoring cellular autoreactivity in type 1 diabetes patients and their relatives

BACKGROUND

Autoreactive T cells have a crucial role in type 1 diabetes (T1D) pathogenesis.

OBJECTIVES

The aim of our study was to monitor the in vitro production of cytokines by peripheral blood mononuclear cells (PBMCs) after stimulation with diabetogenic autoantigens.

SUBJECTS

Ten T1D patients (tested at the time of diagnosis and 6 and 12 months later), 10 first-degree relatives of the T1D patients, and 10 controls underwent the study.

METHODS

PBMCs were stimulated with glutamic acid decarboxylase 65 (GAD65) amino acids (a.a.) 247-279, 509-528, and 524-543; proinsulin a.a. 9-23; and tyrosine phosphatase (islet antigen-2)/R2 a.a. 853-872. Interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, IL-13, interferon (IFN)-gamma, tumor necrosis factor beta, transforming growth factor beta1, and granulocyte colony-stimulating factor (GCSF) were analyzed by protein microarray.

RESULTS

Differences in cytokine(s) poststimulatory and mainly in basal production were observed in all groups. The most prominent findings were in controls, the higher basal levels of IL-2, IL-4, IL-5, IL-13, and GCSF were observed when compared with relatives (p < 0.05, for all). After stimulation in controls, there was a significant decrease in IL-2, IL-13, GCSF, and IFN-gamma (p < 0.05, for all). The group of relatives was the most variable in poststimulatory production. A strong correlation between cytokines production was found but groups differed in this aspect.

CONCLUSION

By multiplex analysis, it may be possible, for example, to define the risk immunological response pattern among relatives or to monitor the immune response in patients on immune modulation therapy.

High T-helper-1 cytokines but low T-helper-3 cytokines, inflammatory cytokines and chemokines in children with high risk of developing type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is suggested to be of T-helper (Th)1-like origin. However, recent reports indicate a diminished interferon (IFN)-gamma secretion at the onset of the disease. We hypothesize that there is a discrepancy in subsets of Th-cells between children with a high risk of developing T1D, children newly diagnosed with T1D and healthy children.

METHODS

Peripheral blood mononuclear cells (PBMC) were collected from children at high risk for T1D (islet cells antibodies [ICA] >/= 20 IJDF-U), those newly diagnosed and healthy children carrying the HLA-risk gene DQB1*0302 or DQB1*0201 and DQA1*0501. Th1- (IFN-gamma, tumour necrosis factor [TNF]-beta, interleukin [IL]-2), Th2- (IL-4,-5,-13), Th3- (transforming growth factor [TGF-beta], IL-10) and inflammatory associated cytokines (TNF-alpha, IL-1alpha,-6) and chemokines (monocyte chemoattractant protein [MCP]-1,-2,-3, Monokine unregulated by IFN-gamma [MIG], Regulated on Activation, Normal T-cell Expressed and Secreted [RANTES], IL-7,-8,-15) were detected in cell-culture supernatants of PBMC, stimulated with glutamic acid decarboxylase 65 (GAD(65)) and phytohaemagglutinin (PHA), by protein micro array and enzyme linked immunospot (ELISPOT) technique.

RESULTS

The Th1 cytokines IFN-gamma and TNF-beta, secreted both spontaneously and by GAD(65)- and mitogen stimulation, were seen to a higher extent in high-risk children than in children newly diagnosed with T1D. In contrast, TNF-alpha and IL-6, classified as inflammatory cytokines, the chemokines RANTES, MCP-1 and IL-7 as well as the Th3 cytokines TGF-beta and IL-10 were elevated in T1D children compared to high-risk children.

CONCLUSION

High Th-1 cytokines were observed in children with high risk of developing TID, whereas in children newly diagnosed with T1D Th3 cytokines, inflammatory cytokines and chemokines were increased. Thus, an inverse relation between Th1-like cells and markers of inflammation was shown between children with high risk and those newly diagnosed with T1D.

Vitality of pancreatic islets labeled for magnetic resonance imaging with iron particles

We previously described an in vivo method for pancreatic islet visualization using magnetic resonance imaging with the aid of superparamagnetic nanoparticles of iron oxide (Resovist) or by magnetic beads precoated with antibodies (Dynabeads). The aim of this study was to investigate the in vitro effect of islet labeling on their quality. Isolated rat islets were cultivated for 48 hours with a contrast agent or, in the case of magnetic antibody-coated beads, for only 2 hours. The ability to secrete insulin was tested by a static insulin release assay and the results were expressed as a stimulation index. Staining with propidium iodide and acridine orange was performed to determine the ratio of live to dead cells. Stimulation indices in the Resovist islets (n = 23) vs controls (n = 14) were 15.3 and 15.0, respectively, and in the Dynabeads islets (n = 15) vs controls (n = 12) 21.3 and 19.9, respectively. The vitality of the Resovist islets vs controls determined by live/dead cells ratio was 90.8% and 91.1%, respectively (n = 20), and in the Dynabeads islets vs controls was 89.4% and 91.8%, respectively (n = 11). Islet labeling with the contrast agent as well as with specific antibodies with iron beads did not change the vitality and insulin-secreting capacity assessed in vitro (P > .05). Magnetic resonance using iron nanoparticles represents the only method for in-vivo visualization of transplanted islets so far. Our data represent an important contribution for its clinical use.

Magnetic resonance imaging of intrahepatically transplanted islets using paramagnetic beads

Superparamagnetic agents can be reliably used for magnetic resonance imaging (MRI) of pancreatic islets located in the liver sinusoids. However, the main disadvantages seemed to be the rather long culture time necessary for islet labeling and the low specificity of these agents. In the present study we investigated a more specific approach with a shorter labeling time using immunomagnetic particles. Isolated rat islets were cultivated with immunomagnetic beads coated with antibody against rat MHC class I antigen. Labeled islets were transplanted into the livers of syngeneic rats. The animals were examined weekly by MRI or livers explanted 10 minutes after islet transplantation for in vitro experiments. In both in vitro and in vivo studies, labeled transplanted islets were imaged as hypointensive spots, diffusely distributed throughout the liver. This experiment represents an alternative way of islet imaging by magnetic resonance, which is as effective as the use of known superparamagnetic contrast agents and more specific owing to targeting to specific donor antigens.

Magnetic Resonance Imaging of Pancreatic Islets in Tolerance and Rejection

BACKGROUND

We have recently described a magnetic resonance (MR) method for detection of rat pancreatic islets transplanted into the liver after labeling with superparamagnetic iron oxide nanoparticles. The aim of this work was to study whether this technique could be applicable over a longer period after transplantation and whether it could help to detect islet rejection.

METHODS

Islets from Lewis and Wistar rats were cultured in the presence of iron oxide nanoparticles. Two thousand of Lewis (n=6) or Wistar (n=8) iron-labeled islets were transplanted into the portal vein of Lewis diabetic animals. Serial MR imaging of the liver were performed at 1, 2, 3, 4, 5, and 6 weeks.

RESULTS

Although all allogeneic islets were rejected by 12 days, syngeneic animals remained normoglycemic throughout the study. At week 1, the labeled islets were visualized on MR scans as distinct hypointense spots homogeneously distributed in the liver. While their number declined only insignificantly in the syngeneic group, in the allogeneic group the number of spots gradually decreased until approximately 35% of their initial count. Although syngeneic islets showed a normal histology, the allogeneic islets were completely rejected. Iron particles, localized in macrophages, were detected only in the syngeneic islets and were absent in the rejected islet structures. In vitro incubation tests did not reveal any differences in insulin secretion between labeled and nonlabeled islets.

CONCLUSIONS

MR imaging of iron-labeled pancreatic islets can be used for verification of the technical success of the transplantation procedure itself and for the detection of the decreasing relative islet mass due to rejection.

In Vitro Assessment of Pancreatic Islet Vitality by Oxymetry

In order to assess the quality of freshly isolated and cultivated pancreatic islets designed for experimental transplantation in rats we combined the vitality staining test, in vitro measurement of insulin secretion capacity, and assessment of islet respiration. Oxygen consumption was measured using the respirometer Oxygraph 2K equipped with polarographic oxygen sensors. The results of oxymetry demonstrated a linear correlation between islet number and oxygen consumption. Respiration per unit of viable islet tissue was constant. Oxygen consumption tests were in good correlation with the results of insulin release assays, with a correlation coefficient of 0.82. We found no significant differences in all three vitality-testing methods performed with fresh and 24-hour cultivated islets (P > .05). We conclude that polarographic oxymetry provides a fast and easy evaluation test of islet quality. After appropriate standardization, the oxymetric technique can be used for routine clinical pretransplant islet quality testing. In addition, cell membrane integrity and mitochondrial function could be assessed after addition of specific respiration inhibitors or stimulators.