Roles of Pancreatic Stellate Cells in Pancreatic Inflammation and Fibrosis  Atsushi Masamune, Takashi Watanabe, Kazuhiro Kikuta, Tooru Shimosegawa  Clinical Gastroenterology and Hepatology  Volume 7, Issue 11, Pages S48-S54 (November 2009) DOI: 10.1016/j.cgh.2009.07.038 Copyright © 2009 AGA Institute Terms and Conditions

Figure 1 Stimulants of PSC activation. Quiescent PSCs undergo morphologic and functional changes to become activated myofibroblast-like cells. In vitro studies have identified a variety of soluble factors such as cytokines and growth factors, ethanol and its metabolites, oxidative stress, and pressure, as well as extensive changes in the composition and organization of ECM, as regulators of PSC activation. During pancreatic injury, inflammation, and pancreatic cancer in vivo, PSCs are likely to be exposed to these stimuli. Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions

Figure 2 Conditioned media of hypoxia-treated PSCs induced angiogenesis in vitro and in vivo. (A) Human umbilical vein endothelial cells (HUVECs) were added to each well onto solidified ECM gel in 600 μL of serum-free medium or of conditioned media of hypoxia-treated PSCs (PSC-CM). After 18-hour incubation, endothelial cell tube formation was assessed under light microscopy. Original magnification, ×4 objective. (B) Pre-chilled, semi-closed silicone cylinders (angioreactors) were filled with 20 μL of a basement membrane extract premixed with a control serum-free medium or 10-fold concentrated conditioned media from hypoxia-treated PSCs. After forming a gel, angioreactors were implanted subcutaneously in the dorsal flanks of nude mice. After 14 days, angioreactors were removed from mice, and vessel formation was assessed. Arrows indicate the direction of vessel formation. Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions

Figure 3 Postactivation events. After initiation of activation, PSCs might have 2 fates. If inflammation and injury are sustained or repeated, PSC activation is perpetuated, leading to development of pancreatic fibrosis. However, if inflammation and injury are limited, PSCs might undergo apoptosis or revert to quiescent stage. In the latter scenario, fibrosis will not develop. Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions

Figure 4 Interactions between PSCs and cancer cells promote progression of pancreatic cancer. In vitro studies have shown that conditioned media of pancreatic cancer cells induced proliferation, production, and degradation of ECM and angiogenesis in PSCs, at least in part through PDGF, TGF, and fibroblast growth factor-2. Conversely, conditioned media of PSCs stimulated cancer cell proliferation and migration and protected them from radiation and gemcitabine-induced apoptosis, in part through the action of PDGF. In addition, PSCs can create a tumor-supportive microenvironment enriched with matricellular proteins that include periostin, galectins, connective tissue growth factor, cysteine-rich acidic secreted protein, and fibrinogen. Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions

Figure 5 PSCs support the growth of cancer cells in vivo. PC-1 pancreatic cancer cells were injected subcutaneously into nude mice either alone (left side of the back) or together with PSCs (right side). After 4 weeks, the size of subcutaneous tumor was greater if PSCs were injected together with cancer cells (right side) (unpublished observations: Masamune A, et al). Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions

Figure 6 BM-derived cells contributed to the population of activated PSCs in pancreatic fibrosis in mice. Eight weeks after cross-gender BM transplantation, CP was induced by 6 intra-abdominal injections of cerulein at 1-hour intervals, 3 days each week, for total of 6 weeks in recipient female mice. The pancreata were removed 6 weeks after the beginning of cerulein treatment. Immunofluorescent staining for α-SMA (shown in red) was performed, along with fluorescence in situ hybridization for the Y chromosome. Nuclei were counterstained with DAPI (blue). Arrows indicate representative α-SMA+/Y+ cells. Original magnification, ×400 (unpublished observations: Watanabe T, et al). Clinical Gastroenterology and Hepatology 2009 7, S48-S54DOI: (10.1016/j.cgh.2009.07.038) Copyright © 2009 AGA Institute Terms and Conditions