Carbonic anhydrase II-positive pancreatic cells are progenitors for both endocrine and exocrine pancreas after birth

Abstract

The regenerative process in the pancreas is of particular interest because diabetes results from an inadequate number of insulinproducing beta cells and pancreatic cancer may arise from the uncontrolled growth of progenitor/stem cells. Continued and substantial growth of islet tissue occurs after birth in rodents and humans, with additional compensatory growth in response to increased demand. In rodents there is clear evidence of pancreatic regeneration after some types of injury, with proliferation of preexisting differentiated cell types accounting for some replacement. Additionally, neogenesis or the budding of new islet cells from pancreatic ducts has been reported, but the existence and identity of a progenitor cell have been debated. We hypothesized that the progenitor cells are duct epithelial cells that after replication undergo a regression to a less differentiated state and then can form new endocrine and exocrine pancreas. To directly test whether ductal cells serve as pancreatic progenitors after birth and give rise to new islets, we generated transgenic mice expressing human carbonic anhydrase II (CAII) promoter: Cre recombinase (Cre) or inducible CreER TM to cross with ROSA26 loxP-Stop-loxP LacZ reporter mice. We show that CAII-expressing cells within the pancreas act as progenitors that give rise to both new islets and acini normally after birth and after injury (ductal ligation). This identification of a differentiated pancreatic cell type as an in vivo progenitor of all differentiated pancreatic cell types has implications for a potential expandable source for new islets for replenishment therapy for diabetes.diabetes ͉ islets of Langerhans ͉ lineage tracing

Reciprocal modulation of adult beta cell maturity by activin A and follistatin

“…Emerging evidence of pancreatic tissue plasticity suggests that normally quiescent, terminally differentiated pancreatic cells retain the potential to dedifferentiate, transdifferentiate or increase their proliferation after specific molecular cues in vitro and in vivo [3][4][5]35]. Our findings support the notion that beta cell plasticity can be modified by external molecular cues.…”

Complete disassociation of adult pancreas into viable single cells through cold trypsin-EDTA digestion

“…Currently, common procedures for preparation of single-cell suspensions from adult mouse pancreata include subjecting the excised tissue to digestive fluid supplemented with collagenase alone or a combination of collagenase and trypsin at 37 °C, followed by mechanical shearing (Kayali et al, 2003;Suzuki et al, 2004;Inada et al, 2008). Collagenase provides gentle, selective digestion of the intercellular matrix, but is unable to completely disassociate organ tissue into single cells (Gross et al, 1974).…”

Quelles cellules souches pour une réparation du pancréas endocrine ?

“…En effet, plusieurs laboratoires ont recherché -et trouvé -la présence de cellules souches dans les canaux du pancréas. Une étude très élégante de marquage génétique a démontré que des cellules canalaires qui expriment le gène de l'anhydrase carbonique II (CAII) ont la capacité de se différencier en cellules β [30]. Lorsque des souris transgéniques, exprimant la recombinase Cre sous contrôle du promoteur du gène CAII (CAII-Cre) sont croisées avec des souris Rosa26, les cellules d'origine canalaire et leurs descendantes sont marquées de façon définitive.…”

“…Or, ce marquage est détecté quatre semaines plus tard à la fois dans les îlots et dans le tissu exocrine. De plus, lorsque la recombinase est induite à l'âge adulte dans les cellules canalaires (souris transgéniques pour une construction inductible CAII-CreER TM ) et que l'on procède à une ligature canalaire, 42 % des îlots sont positifs pour la β-galactosidase deux semaines plus tard [30]. Ceci démontre que des cellules souches existent dans les canaux pancréatiques et peuvent se différencier en cellules β.…”