Biomimetic Surfaces Supporting Dissociated Pancreatic Islet Cultures

This study describes a method to screen biomimetic surfaces based on intracellular insulin content of either fully or partly dissociated primary endocrine islet tissue. It is challenging to maintain endocrine pancreatic islets and more so, dissociated ones. Physiological activity of isolated islet cells in vitro declines due to loss of cell-to-cell and cell-to-extracellular matrix interactions. An in vitro model was developed to evaluate specific extracellular binding components potentially affecting islet biology, with the intention to identify in vivo-like peptides promoting survival and function. Synthetic peptides were bound to low-fouling carboxy-methyl-dextran surfaces, effectively presenting defined surfaces while minimizing non-specific interactions. These biomimetic surfaces were screened based on intracellular insulin content of applied mouse primary islet tissue by analysis with an anti-insulin cell-ELISA. Three active biomimetic surfaces were identified, two laminin- (IKLLI and PDSGR) and one cadherin (HAVDI)-derived, which supported adhesion and survival of insulin-containing cultures for 5days, respectively suggesting a benefit from both cell-extracellular matrix and cell-cell interactions. Cells from dissociated islets show progression over 10days on the HAVDI-biomimetic for the insulin immunoreactivity and cell density. The three surfaces did not act additively or synergistically. A favorable reaction to glucose-stimulated insulin secretion on the cadherin-biomimetic indicated the cultures were physiologically functional. This supportive role of biomimetic peptides represents initial progress in defining minimal extracellular binding requirements influencing islet cell physiology. This will influence further optimization of growth surfaces and promote the basic understanding of islet biology. Low-fouling biomimetics are predicted to be applicable to additional diverse culture systems.