What are the Relevant Parameters for the Geometrical Optimization of an Implantable Bioartificial Pancreas?

Abstract

A sphere within a cylinder representing the islet encapsulated in a hollow fiber can model an implantable bioartificial pancreas. Based on a finite element model for insulin response to a glucose load in the presence of various oxygen supplies, the present study aimed at pointing out the major parameters influencing this secretion. The computational results treated with the Taguchi method clearly demonstrated that geometrical parameters (fiber length and islet density) should be precisely optimized for an enhanced insulin response. This requires the collection of more relevant experimental data concerning the islet oxygen consumption. Moreover, the relative errors on glucose consumption or insulin secretion by the islets do not seem to affect the whole optimization process, which should focus on the oxygen supply to islets.

A theoretical study of oxygen transfer including cell necrosis for the design of a bioartificial pancreas

“…The computational analysis clearly outlined that axial transport to supply cells with oxygen should not be neglected , and that oxygenation and fiber geometry were the main factors influencing BAP functions (Dulong and Legallais, 2005). However, these models were too simplistic in terms of geometry since they accounted for a single islet located on the fiber's longitudinal axis.…”

“…We estimated that this specific location did not fully represent islet status within a fiber. We thus proposed a more complex model in terms of geometry, focusing on oxygen mass transport, which has been shown to limit insulin secretion mainly (Dulong and Legallais, 2005). In the present study, several islets could be placed randomly in the hollow fiber at different densities.…”

Permeability of subcutaneous tissues surrounding long-term implants to oxygen

“…And, What is the permeability to oxygen of tissues that surround implants? These questions are central to the function of implanted devices that depend on the transport of oxygen from the subcutaneous tissues in which they are implanted, such as biosensors for oxygen and other analytes [1,2], polymer-encapsulated pancreatic islets for use in diabetes [3,4], tissue engineered devices containing metabolically active cells [5,6], and implantable electronic devices [7] or fuel cells that rely on the transport of oxygen and metabolic fuels from the tissue environment.…”

Enhancing Clinical Islet Transplantation through Tissue Engineeering Strategies

“…Mathematical modeling predicts inadequate transport profiles, indicating scalability of these devices to larger animal models will be problematic after islet density optimization, thereby rendering such implants bulky or requiring multiple devices. 71,78,[81][82][83][84] More recently, Gimi and coworkers 85 reported on a microcontainer made from an epoxy-based polymer with 50 µm thick walls and a nanoporous lid assembled through adhesion layering techniques. Advantages of these microcontainers include reproducibility and precision due to the automated nature of the manufacturing process, increased mechanical strength, small size resulting in proper transport properties, and the ability to monitor in vivo islet function noninvasively through functional magnetic resonance imaging.…”