The type of polymer influenced the functional survival of human islets. In islets cultured on PDLLCL the glucagon-producing alpha-cells and insulin-producing beta-cells contained more hormone... Show moreThe type of polymer influenced the functional survival of human islets. In islets cultured on PDLLCL the glucagon-producing alpha-cells and insulin-producing beta-cells contained more hormone granules than in islets in contact with PEOT/PBT or polysulfone. This was studied with ultrastructural analysis by electron microscopy (nanotomy) during 7 d of culture. PDLLCL was also associated with statistically significant lower release of double-stranded DNA (dsDNA, a so called danger-associate molecular pattern (DAMP)) from islets on PDLLCL when compared to the other polymers. DAMPs support undesired immune responses. Hydrophilicity of the polymers did not influence dsDNA release. Islets on PDLLCL also showed less cellular outgrowth. These outgrowing cells were mainly fibroblast and some beta-cells undergoing epithelial to mesenchymal cell transition. None of the polymers influenced the glucose-stimulated insulin secretion. As PDLLCL was associated with less release of DAMPs, it is a promising candidate for creating a scaffold for human islets. Our study demonstrates that for sensitive, rare cadaveric donor tissue such as pancreatic islets it might be necessary to first select materials that do not influence functionality before proposing the biomaterial for in vivo application. Our presented platform may facilitate this selection of biomaterials. Show less
Derailment of immune responses can lead to autoimmune type 1 diabetes, and this can be accelerated or even induced by local stress caused by inflammation or infection. Dendritic cells (DCs) shape... Show moreDerailment of immune responses can lead to autoimmune type 1 diabetes, and this can be accelerated or even induced by local stress caused by inflammation or infection. Dendritic cells (DCs) shape both innate and adaptive immune responses. Here, we report on the responses of naturally occurring human myeloid BDCA1(+) DCs towards differentially stressed pancreatic beta cells. Our data show that BDCA1(+) DCs in human pancreasdraining lymph node (pdLN) suspensions and blood-derived BDCA1(+) DCs both effectively engulf beta cells, thus mimicking physiological conditions. Upon uptake of enterovirus-infected, but not mock-infected cells, BDCA1(+) DCs induced interferon (IFN)-alpha/beta responses, co-stimulatory molecules and proinflammatory cytokines and chemokines. Notably, induction of stress in beta cells by ultraviolet irradiation, culture in serum-free medium or cytokineinduced stress did not provoke strong DC activation, despite efficient phagocytosis. DC activation correlated with the amount of virus used to infect beta cells and required RNA within virally infected cells. DCs encountering enterovirus-infected beta cells, but not those incubated with mock-infected or stressed beta cells, suppressed T helper type 2 (Th2) cytokines and variably induced IFN-gamma in allogeneic mixed lymphocyte reaction (MLR). Thus, stressed beta cells have little effect on human BDCA1(+) DC activation and function, while enterovirus-infected beta cells impact these cells significantly, which could help to explain their role in development of autoimmune diabetes in individuals at risk. Show less
