Pancreatic ductal myofibroblasts - Proliferative patterns in various pathologic situations

Myofibroblasts in the periacinar area of the pancreas have been demonstrate d to mediate fibrogenesis in pancreatic fibrosis. However, only a few repor ts have described myofibroblasts in the pancreatic duct. To elucidate the p resence of myofibroblasts in the pancreatic ductal wall, we performed an im munohistochemical study, using immunostains for both alpha -smooth muscle a ctin (alpha SMA) and desmin, and an electron microscopic study on surgicall y resected pancreatic specimens from 10, 23, 23, and 56 cases of focal panc reatitis (EP), chronic pancreatitis (CP), pancreatic carcinoma (PCa), and c arcinoma of the papilla of Vater (VPCa), respectively. All cases showed loc alized stenosis of the main pancreatic duct by means of preoperative pancre atography. As controls, 20 autopsy cases were studied, alpha SMA-positive a nd desmin-negative cells existed in the ductal walls of controls and were r evealed as myofibroblasts by means of electron microscopy. In six FPs, prol iferation of myofibroblasts was observed at the stenotic portion. In VPCas, myofibroblasts mainly proliferated in the pancreatic ductal wall. In CPs a nd PCas, no myofibroblast proliferation was observed at the stenotic portio n. The proliferation of myofibroblasts might occur as a wound healing proce ss in FP, while acting against elevation of intraductal pressure in VPCa. I n conclusion, proliferation of myofibroblasts plays an important role in du ctal changes in various pathological situations.