Progenitor cell niches in the human pancreatic duct system and associated pancreatic duct glands: an anatomical and immunophenotyping study

Abstract

Pancreatic duct glands (PDGs) are tubule-alveolar glands associated with the pancreatic duct system and can be considered the anatomical counterpart of peribiliary glands (PBGs) found within the biliary tree. Recently, we demonstrated that endodermal precursor niches exist fetally and postnatally and are composed functionally of stem cells and progenitors within PBGs and of committed progenitors within PDGs. Here we have characterized more extensively the anatomy of human PDGs as novel niches containing cells with multiple phenotypes of committed progenitors. Human pancreata (n = 15) were obtained from cadaveric adult donors. Specimens were processed for histology, immunohistochemistry and immunofluorescence. PDGs were found in the walls of larger pancreatic ducts (diameters > 300 μm) and constituted nearly 4% of the duct wall area. All of the cells identified were negative for nuclear expression of Oct4, a pluripotency gene, and so are presumably committed progenitors and not stem cells. In the main pancreatic duct and in large interlobular ducts, Sox9(+) cells represented 5-30% of the cells within PDGs and were located primarily at the bottom of PDGs, whereas rare and scattered Sox9(+) cells were present within the surface epithelium. The expression of PCNA, a marker of cell proliferation, paralleled the distribution of Sox9 expression. Sox9(+) PDG cells proved to be Pdx1(+) /Ngn3(+/-) /Oct4A(-) . Nearly 10% of PDG cells were positive for insulin or glucagon. Intercalated ducts contained Sox9(+) /Pdx1(+) /Ngn3(+) cells, a phenotype that is presumptive of committed endocrine progenitors. Some intercalated ducts appeared in continuity with clusters of insulin-positive cells organized in small pancreatic islet-like structures. In summary, PDGs represent niches of a population of Sox9(+) cells exhibiting a pattern of phenotypic traits implicating a radial axis of maturation from the bottoms of the PDGs to the surface of pancreatic ducts. Our results complete the anatomical background that links biliary and pancreatic tracts and could have important implications for the common patho-physiology of biliary tract and pancreas.

Increased Proliferation of the Pancreatic Duct Gland Compartment in Type 1 Diabetes

“…PDGs have been recognized for many years (23,24) and their extent in human pancreas has recently been delineated (14). Like Carpino et al, we have noted that the pancreatic duct gland compartment is present in head, body and tail regions, thus extending throughout the length of the organ.…”

“…The pancreatic duct glands (PDGs) have been proposed as a potential pancreatic stem cell niche (12)(13)(14). The purpose of the present investigation was to investigate the PDG compartment of the pancreas in humans as a potential source of newly forming beta-cells in T1D.…”

β-cell replacement sources for type 1 diabetes: a focus on pancreatic ductal cells

“…Microarrays showed the enrichment of ESC markers, including SOX2 and NANOG, in the PDGs compared with the ductal epithelium. A more extensive anatomical characterization of PDGs and their role as a niche of pancreatic precursors was performed on healthy human pancreata [Carpino et al 2015]. PDGs were identified as heterogeneous populations of OCT4 -/PDX1 + /SOX9 + cells associated with pancreatic ducts and occasionally localized in continuity with islet cluster.…”

“…Because of potential implications of gastrin in β-cell mass regeneration in rodents [Suarez-Pinzon et al 2008;Suissa et al 2013], a recent study evaluated the role of gastrin in promoting β-cell neogenesis from ductal cells in 90% Px rats [Tellez and Montanya, 2014]. In the gastrin-treated mice, strong proliferation activity was Xu et al [2006] In vivo Treatment with exendin-4 facilitated β-cell neogenesis in pancreatic ducts Tokui et al [2006] In vivo Betacellulin promoted ductal differentiation towards insulin-expressing cells Inada et al [2008] In vivo β-cell mass replenishment occurred from ductal cells 2 weeks post PDL Bonner-Weir et al [2008] In vivo Partial pancreatic tissue regeneration occurred from ductal cells Xu et al [2008] In vivo Re-expression of NGN3 in ductal lining cells occurred 1 week after PDL Criscimanna et al [2011] In vivo Proliferative ducts expressed acinar and endocrine markers 3/4 weeks post-DT injection Wang et al [2012] In vivo Administration of gastrin and EGF increased β-cell neogenesis Pfeifer et al [2013] In vivo Requirement of EMT for duct-lining cells differentiation into endocrine cells In vivo Continuous activation of NGN3 + cells along the lining duct occurred after ARX inhibition Téllez et al [2014] In vivo Appearance of β-cell clusters from ductal epithelium occurred 3 days post 90% Px Lemaire et al [2015] In vivo Bicaudal C1 expressed in duct lining cells was essential for progenitor differentiation Yamaguchi et al [2015] In vivo Pancreatic ductal glands contained niches of progenitor cells Carpino et al [2015] In vivo Pancreatic ductal glands as container of niches for pancreatic precursors Napolitano et al [2015] In vivo Continuous activation of NGN3 + cells along the lining duct occurred after PAX4 overexpression El-Gohary et al [2016] In vivo Duct-to-β-cell conversion occurred after partial Px in mice overexpressing TGF-β receptor Zhang et al [2016] In vivo Conversion of SOX9 + cells into insulin-producing cells occurred after administration of gastrin and EGF Seaberg et al [2004] In vitro Progenitor colonies arose from islet and ducts cultured with EGF and FGF2 Rovira et al [2010] In vitro Centroacinar/terminal ductal cells with progenitor-like phenotype ARX, aristaless related homeobox; DT, diphtheria toxin; EGF, epidermal growth factor; EMT, epithelial-mesenchymal transition; PDL, pancreatic duct ligation; Px, pancreatectomy; TGF, transforming growth factor.…”

Adult human pancreas-derived cells expressing stage-specific embryonic antigen 4 differentiate into Sox9-expressing and Ngn3-expressing pancreatic ducts in vivo

“…However, when using the anti-SSEA-4 antibody to separate the cells, only cells expressing SSEA-4 were more effectively purified than when using anti-CA19-9 antibodies. These results were intriguing because almost all SSEA-4 + cells were present in pancreatic ducts, which are known to contain stem/progenitor cells and multipotent stem cells [17, 18]. Notably, the distribution of SSEA-4 + cells was not associated with cell size.…”