Volume 128, Issue 3, Pages 728-741 (March 2005) Recapitulation of elements of embryonic development in adult mouse pancreatic regeneration  Jan Nygaard Jensen, Erin Cameron, Maria Veronica R. Garay, Thomas W. Starkey, Roberto Gianani, Jan Jensen  Gastroenterology  Volume 128, Issue 3, Pages 728-741 (March 2005) DOI: 10.1053/j.gastro.2004.12.008 Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 1 Regeneration. (A–E) Hematoxylin staining. (A) PBS-treated pancreas. (B) At day 1 posttreatment, most acinar tissue has been lost. (C–E) Almost full recovery of the exocrine pancreas occurs within 7 days. (F–J) Double immunofluorescence of insulin and amylase. (K–O) In situ hybridization against amylase mRNA reveals a strong reduction in exocrine terminal gene expression. (P) Morphometric analysis of amylase density + SD compared with total area. Data from 3 independent mice at each time point are shown. (Q) Quantification of the frequency of apoptotic nuclei within defined areas. The immunohistologic analysis did not allow for secure definition of apoptotic cell origin/position at d1. (R and S) Sample images of triple staining for TUNEL, insulin, and amylase at d1 and d3. d, duct, i, islet; arrowhead indicates positive TUNEL staining. Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 2 β-catenin and amylase expression. (A–E) Merged images of amylase and β-catenin protein expression. A general overlap of these 2 markers is observed during the early regenerative period. (F–H) In situ hybridization against β-catenin mRNA. In the untreated pancreas, minimal β-catenin expression is observed in the exocrine tissue (F), whereas it is significantly expressed throughout the regenerating area shown at day 1 postcaerulein treatment (G). (I–K) High-magnification images of amylase/β-catenin expression at d1, d3, and d5 postcaerulein treatment. Expression of β-catenin mRNA is almost normalized 5 days posttreatment (K). (L and N) Triple immunofluorescence staining of amylase (red), β-catenin (green), and insulin (blue) in E15.5 (L) and E18.5 (N) pancreas. Inspecting β-catenin expression with insulin (outlined rectangular areas of L and N, shown in M and O, respectively), it is clear that both β cells and exocrine cells display reduced β-catenin expression upon differentiating. Arrowheads in L indicate a recently developed acinus at E15.5 (A’ in M). Three cells have not started to produce amylase protein (arrowheads in M). These express β-catenin, as do their immediate neighbors, whereas a more developed acinar structure (A) does not express significant levels of β-catenin. At E18.5 (O), all acinar cells (A) express very low levels of β-catenin, and this is maintained at high levels in the ducts (D). Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 3 Ductal (DBA-expressing) cells in regeneration. (A–E) Confocal scans of triple immunofluorescence analysis of β-catenin (red), amylase (blue), and FITC-DBA lectin (arrows) during regeneration. (F) Higher power image of d1 following caerulein treatment. Insert shows magnification of the membrane boundary between an intercalated ductal cell (green) and the adjacent acinar cell (blue). Because expression of β-catenin and DBA is not entirely overlapping, we conclude that the acinar cell membrane contains relatively more β-catenin when compared with the intercalated ductal cell. &Acini. Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 4 Definition of cell proliferation compartments in regeneration. Confocal scans (A–E) of coexpression analysis of amylase (blue), FITC-DBA-lectin (green) and proliferating M-phase cells (arrows, pHH3, red). (F) Quantification of proliferative indices (% pHH3 nuclei/total nuclei) in various pancreatic compartments. Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 5 Expression of Pdx1 and Nkx6.1 during regeneration. Double immunofluorescence analysis of Pdx1 and Nkx6.1. (A–C) Pdx1 and Nkx6.1 are expressed in islet β-cells in the PBS-treated pancreas. (D–F) At d1, only low levels of Pdx1 expression is observed in surviving epithelial cells. This is contrasted at d3, at which significant expression of Pdx1 (H) but not Nkx6.1 (G) is observed in the redifferentiating exocrine cells. (K–N) The extraislet epithelial expression of Pdx1 is gradually reduced as the pancreas regenerates. (P–R) Expression of Pdx1 and Nkx6.1 in E15.5 embryonic pancreas reveals coexpression of both markers in remaining epithelial-type progenitor cells and the loss of Nkx6.1 within the peripheral cells developing as exocrine cells. Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions

Figure 6 Analysis of Notch-signaling components. (A) Hes1 protein (red) is not expressed in PBS-injected pancreas. (B) Acinar structures are outlined (white). Hes1 is expressed in cells of the acinar stem. (A and B) Background autofluorescence signals (green) were overlaid to enhance the histologic appearance in the image. (C–H) In situ hybridization for Hes1; I–N, Notch1; and O–T, Jagged2. Hes1, Notch1, and Jagged2 are expressed within the embryonic pancreatic epithelium (C, I, and O). Gastroenterology 2005 128, 728-741DOI: (10.1053/j.gastro.2004.12.008) Copyright © 2005 American Gastroenterological Association Terms and Conditions