Background.The present study concerns the influence of acinar contamination on pancreatic islets encapsulated in an artificial membrane (AN 69).Methods.Pure, handpicked pancreatic islets were contaminated by the addition of acinar tissue (ratio, 1:1). The morphological aspect and insulin release of both pure (n=12) and contaminated (n=12) encapsulated islets were assessed after 10 days of culture or implantation in the peritoneal cavity of rats.Results.After implantation, the encapsulated islets, irrespective of their purity, were totally altered, whereas the morphological aspect of the cultivated islets remained intact only in the absence of acinar tissue contamination. This contamination induced a significant decrease in the stimulation index of insulin release. The stimulation index decreased by 42% for fresh islets and by 52% and 34% for cultivated and implanted islets, respectively, without modification in their basal release of insulin.Conclusions.The acinar tissue proved detrimental to the encapsulated implanted and cultivated islets.