Machine Learning Algorithms, Applied to Intact Islets of Langerhans, Demonstrate Significantly Enhanced Insulin Staining at the Capillary Interface of Human Pancreatic β Cells

Pancreatic β cells secrete the hormone insulin into the bloodstream and are critical in the control of blood glucose concentrations. β cells are clustered in the micro-organs of the islets of Langerhans, which have a rich capillary network. Recent work has highlighted the intimate spatial connections between β cells and these capillaries, which lead to the targeting of insulin secretion to the region where the β cells contact the capillary basement membrane. In addition, β cells orientate with respect to the capillary contact point and many proteins are differentially distributed at the capillary interface compared with the rest of the cell. Here, we set out to develop an automated image analysis approach to identify individual β cells within intact islets and to determine if the distribution of insulin across the cells was polarised. Our results show that a U-Net machine learning algorithm correctly identified β cells and their orientation with respect to the capillaries. Using this information, we then quantified insulin distribution across the β cells to show enrichment at the capillary interface. We conclude that machine learning is a useful analytical tool to interrogate large image datasets and analyse sub-cellular organisation.

Immunomodulatory and Antidiabetic Effects of a New Herbal Preparation (HemoHIM) on Streptozotocin-Induced Diabetic Mice

HemoHIM (a new herbal preparation of three edible herbs:Angelica gigasNakai,Cnidium officinaleMakino, andPaeonia japonicaMiyabe) was developed to protect immune, hematopoietic, and self-renewal tissues against radiation. This study determined whether or not HemoHIM could alter hyperglycemia and the immune response in diabetic mice. Both nondiabetic and diabetic mice were orally administered HemoHIM (100 mg/kg) once a day for 4 weeks. Diabetes was induced by single injection of streptozotocin (STZ, 200 mg/kg, i.p.). In diabetic mice, HemoHIM effectively improved hyperglycemia and glucose tolerance compared to the diabetic control group as well as elevated plasma insulin levels with preservation of insulin staining in pancreaticβ-cells. HemoHIM treatment restored thymus weight, white blood cells, lymphocyte numbers, and splenic lymphocyte populations (CD4+T and CD8+T), which were reduced in diabetic mice, as well as IFN-γproduction in response to Con A stimulation. These results indicate that HemoHIM may have potential as a glucose-lowering and immunomodulatory agent by enhancing the immune function of pancreaticβ-cells in STZ-induced diabetic mice.

Functional Plasticity of the Human Infant β-Cell Exocytotic Phenotype

Our understanding of adult human β-cells is advancing, but we know little about the function and plasticity of β-cells from infants. We therefore characterized islets and single islet cells from human infants after isolation and culture. Although islet morphology in pancreas biopsies was similar to that in adults, infant islets after isolation and 24–48 hours of culture had less insulin staining, content, and secretion. The cultured infant islets expressed pancreatic and duodenal homeobox 1 and several (Glut1, Cav1.3, Kir6.2) but not all (syntaxin 1A and synaptosomal-associated protein 25) markers of functional islets, suggesting a loss of secretory phenotype in culture. The activity of key ion channels was maintained in isolated infant β-cells, whereas exocytosis was much lower than in adults. We examined whether a functional exocytotic phenotype could be reestablished under conditions thought to promote β-cell differentiation. After a 24- to 28-day expansion and maturation protocol, we found preservation of endocrine markers and hormone expression, an increased proportion of insulin-positive cells, elevated expression of syntaxin 1A and synaptosomal-associated protein 25, and restoration of exocytosis to levels comparable with that in adult β-cells. Thus, human infant islets are prone to loss of their exocytotic phenotype in culture but amenable to experimental approaches aimed at promoting expansion and functional maturation. Control of exocytotic protein expression may be an important mechanism underlying the plasticity of the secretory machinery, an increased understanding of which may lead to improved regenerative approaches to treat diabetes.

KU-32, a Novel Drug for Diabetic Neuropathy, Is Safe for Human Islets and ImprovesIn VitroInsulin Secretion and Viability

KU-32 is a novel, novobiocin-based Hsp90 inhibitor that protects against neuronal glucotoxicity and reverses multiple clinical indices of diabetic peripheral neuropathy in a rodent model. However, any drug with potential for treating diabetic complications must also have no adverse effects on the function of pancreatic islets. Thus, the goal of the current study was to assess the effect of KU-32 on thein vitroviability and function of human islets. Treating human islets with KU-32 for 24 hours showed no toxicity as assessed using the alamarBlue assay. Confocal microscopy confirmed that with a minimum of 2-day exposure, KU-32 improved cellular viability by blocking apoptosis. Functionally, isolated human islets released more glucose-stimulated insulin when preincubated in KU-32. However, diabetic BKS-db/db mice, a model for type 2 diabetes, administered KU-32 for 10 weeks did not show any significant changes in blood glucose and insulin levels, despite having greater insulin staining/beta cell in the pancreas compared to untreated BKS db/db mice. In summary, KU-32 did not harm isolated human islets and may even be protective. However, the effect does not appear significant enough to alter thein vivometabolic parameters of diabetic mice.