COMSOL Multiphysics-Based Exploratory Insulin Secretion Model for Isolated Pancreatic Islets
Insulin released by the beta-cells of pancreatic islets is the main regulator of glucose homeostasis, hence, insulin secretion models are of considerable interest for many possible applications. Building on our previous oxygen consumption and cell viability model for avascular islets of Langerhans, we developed an exploratory insulin secretion model that couples the hormone production rate to the local (cellular-level) glucose and oxygen concentrations. COMSOL Multiphysics was used to combine reactive rates with mass transport by convection and diffusion as well as with fluid-mechanics (incompressible Navier-Stokes), and experimental results from dynamic glucose-stimulated insulin release (GSIR) perifusion studies with isolated islets were used to calibrate the parameters of the model. Dynamic insulin responses to stepwise increments in the glucose content of the incoming perifusate solution were calculated for the out-flowing fluid by boundary integration on the exiting surface, and good quantitative fit could be obtained with detailed experimental insulin release data such as those of Henquin and co-workers for glucose dependence and Dionne and co-workers for oxygen dependence.