Toward a Bioartificial Pancreas: Diffusion of Insulin and IgG Across Immunoprotective Membranes with Controlled Hydrophilic Channel Diameters

Abstract

Research continued toward a bioartificial pancreas (BAP). Our BAPs consist of a perforated nitinol scaffold coated with reinforced amphiphilic conetwork membranes and contain live pancreatic islets. The membranes are assemblages of cocontinuous hydrophobic domains and hydrophilic channels whose diameters were varied by the MW of hydrophilic segments between crosslinks (M(c,HI) = 32, 44, and 74 kg x mol(-1)). We studied the diffusion rate of insulin, BSA, and IgG across the membrane of the BAP in the absence of islets. Membranes of M(c,HI) = 74 kg x mol(-1) showed rapid insulin and BSA transport and negligible IgG diffusion. BAPs containing approximately 300 mouse islets showed appropriate response upon glucose challenge in vitro. The BAP implanted into diabetic mice reduced hyperglycemia and maintained islet viability for at least 4 d.