Pancreatic stellate cells contribute to regeneration early after acute necrotising pancreatitis in humans.

BACKGROUND AND AIM The aim of this study was to systematically analyse the pattern of regeneration in human acute pancreatitis by testing whether pancreatic stellate cells, their myofibroblastic offspring, and pancreatic ductules are involved in the regenerative process. PATIENTS AND METHODS Between January 1994 and November 2000, 24 necrosectomy specimens containing vital tissue were obtained for pathological examination. Formalin fixed tissue samples were routinely processed and immunostained for cytokeratins 7 and 19, smooth muscle actin, desmin, Ki-67, and CD68. Pancreatic tissue from organ donors served as normal controls. RESULTS Necrosectomy specimens were obtained between 11 and 41 days after the onset of symptoms. In vital areas of necrosectomy samples, spherical hypercellular spheres consisting of loose vascular connective tissue occurred, in part showing duct-like profiles which sprouted from remnant exocrine tissue almost perpendicular to the periphery of the spheres. In normal tissue, only a few stellate cells and myofibroblasts were present around ducts and ductules. In contrast, numerous stellate cells and myofibroblasts were detected in the hypercellular regenerative spheres after acute pancreatitis, both being situated within the loose tissue and forming compact periductular sheaths. Stellate cells/myofibroblasts and ductule cells exhibited increased proliferative activity. CONCLUSIONS Pancreatic stellate cells and their activated myofibroblastic offspring may participate in regeneration after acute necrotising pancreatitis in humans. Time course studies are needed to further strengthen this regeneration concept.