Pancreatic mesenchyme regulates epithelial organogenesis throughout development

Area of Science:

• Developmental Biology
• Endocrinology
• Regenerative Medicine

Background:

• The developing pancreatic epithelium relies on signals from the mesenchyme for organogenesis.
• Previous research using explants and knockouts highlighted mesenchyme's role in early pancreas development.
• In vivo roles of mesenchyme in later pancreas organogenesis remained unclear due to limited genetic tools.

Purpose of the Study:

• To investigate the in vivo role of pancreatic mesenchyme in regulating pancreas organogenesis at different developmental stages.
• To elucidate the molecular mechanisms underlying mesenchymal function and survival.
• To explore the implications for pancreas progenitor and beta-cell expansion for clinical transplantation.

Main Methods:

• Utilized transgenic tools and fetal surgical techniques to ablate mesenchyme.
• Employed Cre-mediated expression of Diphtheria Toxin (DT) and in utero injection of DT into Diphtheria Toxin receptor (DTR) expressing mice.
• Investigated the role of beta-catenin signaling by eliminating it in mesenchymal cells.

Main Results:

• Mesenchymal ablation impaired pancreatic growth and branching at both early and late developmental stages.
• Proliferation of both precursor and differentiated cells was supported by mesenchyme, affecting endocrine and exocrine compartments equally.
• Beta-catenin signaling was identified as critical for mesenchyme survival and growth, while cell differentiation remained unaffected.

Conclusions:

• The embryonic mesenchyme provides essential signals to the pancreatic epithelium throughout organogenesis.
• Mesenchyme plays a critical role in the late expansion of both endocrine and exocrine pancreatic compartments.
• Beta-catenin signaling is a key mediator of mesenchymal expansion and survival, with implications for regenerative strategies.