The macrobead is a form of a biohybrid artificial pancreas (BAP), which is being developed to treat type 1 diabetes. A hypothetical human transplant would require 125 rat equivalent macrobeads. For intraperitoneal transplantation a mode of delivery that allows the placement of several hundred macrobeads into a basket or pouch type device is required.

In this study, four commercially available materials were studied as possible candidates for creating a pouch. These materials are polyvinyl chloride acrylic copolymer (PVC), polyethersulfone (PES), polyvinylidenedifluoride (PVDF), and polytetrafluorethylene (PTFE). Tubular pouches of each material were designed. They then underwent in vivo biocompatibility and in-vitro permeability examinations. Biocompatibility was evaluated by semi-quantitatively analyzing the degree of tissue reaction on the materials surface. Permeability to insulin was quantitatively determined by assaying samples of medium in which pouches containing functioning macrobeads were cultured.

Based on the results two materials PES and PVDF appear suitable for creating a pouch to hold a large number of macrobeads. Additionally, parameters such as pore size and shape of pouch are also critical and require attention.