Preparation and characterization of permselective, biocompatible membranes for the macroencapsulation of pancreatic islets

Abstract

Polymeric membranes were prepared by mixing poly (vinyl alcohol) (PVA) and poly (acrilic acid) (PAA) solutions (10/90 weight ratio), freeze-drying and crosslinking under vacuum. The membranes were then coated with alginic acid sodium salt, and gelation was accomplished by calcium chloride. The resulting membrane structure was essentially trabecular, with pore size ranging from 50 to 100 μm. Glucose and insulin diffusions reached a plateau at 2 and 32 min, respectively. Immunoglobulins and red blood cells did not cross the membranes. Gelpermeation HPLC showed that the membrane wall was impermeable to compounds with a molecular weight higher than 100 000 D. Biocompatibility of the membranes was demonstrated by showing minimal fibrotic reaction at 3 weeks after intraperitoneal implantation into mice. Porcine islets were placed into the membranes and cultured at 37°C for 7 days, at which time the incapsulated were shown to release insulin in response to glucose. These results support the use of PVA/PAA membranes for bioartificial pancreas studies.