Contributions of a finite element model for the geometric optimization of an implantable bioartificial pancreas.

The extravascular implantation of islets of Langerhans immunoprotected within a permselective membrane is a promising method to treat diabetes mellitus. However, oxygen limitation due to purely diffusive solute transport was considered to provoke tissue necrosis and graft failure. We built a solute transport model based on a finite element method aiming at optimizing the hollow fiber geometry. With a low islet density, the influence of oxygen axial flux inside the fiber was underlined and a characteristic length for oxygen supply was introduced. This study allowed the conclusion that islet density must be adapted to the fiber diameter chosen for implantation.