Analysis of pancreatic development using a cell lineage label

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Organogenesis

Background:

• Understanding pancreatic development is crucial for regenerative medicine and treating diabetes.
• Previous studies suggested endodermal origin for pancreatic cells but lacked definitive proof.
• The need for advanced in vitro systems to study embryonic organ development.

Purpose of the Study:

• To develop and validate a new in vitro culture system for mouse embryonic pancreatic buds.
• To definitively determine the origin of pancreatic exocrine, endocrine, and smooth muscle cells.
• To investigate the developmental potential of pancreatic and stomach mesenchyme.

Main Methods:

• Development of a novel flat-sheet culture system for embryonic pancreatic buds.
• Utilizing ROSA-26 gene trap mouse strain for lineage tracing (lacZ expression).
• Chimeric recombination assays combining lacZ-labeled epithelia with unlabeled mesenchyme (pancreatic and stomach).

Main Results:

• Formal proof that both exocrine and endocrine pancreatic cells originate from the endodermal epithelium.
• Pancreatic smooth muscle cells are derived from the mesenchyme.
• Stomach mesenchyme supports pancreatic bud development similarly to pancreatic mesenchyme.
• Pancreatic acini and islets are formed from multiple progenitor cells, not clonal growth.

Conclusions:

• The study provides the first definitive evidence for the endodermal origin of both pancreatic exocrine and endocrine cells.
• The developed culture system is effective for wholemount immunostaining and analyzing pancreatic development.
• Pancreatic and stomach mesenchyme exhibit similar trophic effects on developing pancreatic epithelium.
• Pancreatic structural units (acini and islets) arise from polyclonal progenitors.