Histology and immunohistochemistryFor quantitative analyses of HS, HSPGs, insulin and glucagon localization in human islets, paraffin sections (4 μm thickness) of nPOD human pancreases and isolated human islets fixed in 10% neutral-buffered formalin were stained with hematoxylin and eosin (H&E) or by immunohistochemistry. Antigen retrieval for HS and Col18 was performed using 0.05% pronase (Calbiochem, Japan) [27, 28], whereas heat/citrate buffer (pH 6) was used for Sdc1 and heparanase [27, 28]. HS and HSPG core proteins were detected immunohistochemically using 10E4 anti-HS (1/5-1/10; https://dx.doi.org/10.17504/protocols.io.kvzcw76), anti-Col18 (1/100; https://dx.doi.org/10.17504/protocols.io.kvzcw76) and rat anti-mouse Sdc1 (CD138, 1/10; BD Biosciences) (https://dx.doi.org/10.17504/protocols.io.kv3cw8n) mAbs, with horseradish peroxidase-conjugated rabbit anti-mouse or anti-rat Ig (Dako, Carpinteria, USA). Heparanase was localized using the HP130 mouse anti-human heparanase mAb (1/5; Insight Biopharmaceuticals, Rehovot, Israel), biotinylated anti-mouse IgG (1/250) and avidin-biotin-complex (ABC reagent; PK-2200, Vector Laboratories, Burlingame, CA) (https://dx.doi.org/10.17504/protocols.io.kv4cw8w). Background staining was checked using the corresponding isotype control Ig and human pancreatic lymph node (PLN) was used as a positive control. Insulin and glucagon were detected using mouse anti-insulin (ascites; 1/250) or mouse anti-glucagon (ascites; 1/500) mAbs (Sigma-Aldrich) and biotinylated anti-mouse IgG/ABC reagent (https://dx.doi.org/10.17504/protocols.io.kv6cw9e). 3-amino-9-ethylcarbazole (AEC; Sigma-Aldrich) was used as the chromogen. Specimens were de-identified prior to morphometric analysis. Image J software with color deconvolution plugin was used for the quantitative analysis of the % of islet area stained [27, 28] in 7–10 islets/donor pancreas.