Abstracts
1999 Digestive Disease Week

# 2160 EXTRACELLULAR MATRIX (ECM) PROTEINS ARE PRODUCED BY ISOLATED PANCREATIC MYOFIBROBLASTS
E K Ng, B L Barent, G S Smith, K M Murayama, Saint Louis Univ Health Sci Ctr, Saint Louis, MO

Pancreatic myofibroblasts may be central to the development of pancreatic fibrosis which is characterized by increased deposition of the ECM proteins fibronectin (FN), laminin (LN), and collagen (CN). Myofibroblasts characteristically express a-smooth muscle actin (a-SMA). Our aim was to isolate and characterize pancreatic myofibroblasts in a severe hyperstimulation/obstruction pancreatitis (SHOP) rat model of early pancreatic fibrosis. Methods: SHOP rats underwent surgical pancreatic duct obstruction followed by cerulein (50 mg/kg/d) hyperstimulation. Pancreatic fibroblast-like cells (PF) were isolated by harvesting pancreata from SHOP-96hr rats, infiltrating with type IV collagenase (80 units/ml) and culturing early adherent cells with fibroblast morphology. Pancreatic tissue specimens were taken from unoperated control (CT) and SHOP-96hr animals for comparison. Cells and tissues were stained for FN, LN, CN, and a-SMA. Relative quantities of these proteins were examined using immunoblots. Results: Tissue-Immunostaining for FN and a-SMA increased in SHOP-96hr compared to control, while LN was unchanged. Immunoblots demonstrated increased expression of FN, LN and a-SMA in SHOP-96hr tissue homogenates. Cultured PF-Immunostaining demonstrated the presence of CN, FN, LN and a-SMA in PF. Immunoblots of cultured PF cell lysates confirmed a-SMA expression. Conclusions: Increased deposition of ECM proteins FN and LN, combined with previously demonstrated increases in collagen, supports SHOP as a model of pancreatic fibrosis. a-SMA expression in cultured PF and SHOP-96hr pancreatic tissue indicates differentiation or activation of fibroblast-like cells to a myofibroblast phenotype. Expression of FN, LN, and collagen by these myofibroblasts suggest an integral role for these cells in pancreatic fibrosis.

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