Insulin-Producing Acinar Cells in Adult Human Pancreas

Abstract

The aim of this study was to characterize cells expressing insulin and amylase in adult human pancreas. We applied serial section and immunohistochemistry to pancreas samples from 5 adult nondiabetic subjects (2 men and 3 women;mean age, 65.8 years; random plasma glucose level, 5.1 mM). Cells expressing insulin and amylase were captured by immunofluorescence and confocal miscroscopy. We found a widespread occurrence of insulin-producing cells in exocrine acini and amylase-reactive acinar cells in well-formed islets. The insulin-producing cells in exocrine acini predominantly formed single and double cell units though cell clusters, and islands occurred. Acini containing insulin-producing cells outnumbered the islets with a factor of approximately 5. Confocal microscopy and double immunostaining identified acinar A-cells coexpressing both amylase and insulin. The acinar A-cells represent a distinct category of pancreatic cell populations and might be possible endogenous progenitors of insulin-producing cells in normal and abnormal metabolic homeostasis.