Introduction: The existence of progenitor cells in the non-endocrine compartments of the adult human pancreas has been hypothesized for decades, but has not been conclusively demonstrated yet. We reasoned that, if such progenitors existed, they would respond to bone morphogenetic protein 7 (BMP-7), a TGF-β family member with dual TGF-β inhibition and BMP stimulation abilities. These two concerted actions have been widely linked to the expansion of progenitor pools in multiple tissues. We have now reported the BMP-7-mediated conversion of human non-endocrine pancreatic tissue (hNEPT) into functional endocrine cells.

Methods: cGMP-grade hNEPT were sorted using P2RY1 and ALK3 surface markers. The P2RY1+/ALK3bright+ fraction was cultured and analyzed for multipotency.

Results: We show that BMP-7 acts on extrainsular cells expressing PDX1 and the BMP receptor activin-like kinase 3 (ALK3/BMPR1A). In vitro lineage tracing indicates that ALK3+ cell populations are multipotent. PDX1+/ALK3+ cells are absent from islets but prominently represented in the major pancreatic ducts and pancreatic duct glands. We identified the purinergic receptor P2Y1 (P2RY1) as a novel surrogate surface marker for PDX1. Sorted P2RY1+/ALK3bright+ cells form BMP-7-expandable colonies characterized by NKX6.1 and PDX1 expression. Unlike the negative fraction controls, these colonies can be differentiated into multiple pancreatic lineages upon BMP-7 withdrawal. RNA-seq further corroborates the progenitor-like nature of P2RY1+/ALK3bright+ cells and their multilineage differentiation potential. Our studies confirm the existence of progenitor cells in the adult human pancreas and suggest a specific anatomical location within the ductal and glandular network.

Conclusion: The demonstration that resident progenitor-like cells within the pancreas could be converted into β-like cells through a non-genetic intervention with single, FDA-approved agents could open the door to the design of potentially transformative therapies for diabetes.

Authors:  Mirza Muhammad Fahd Qadir, Silvia Álvarez-Cubela, Dagmar Klein, Giacomo Lanzoni, Carlos García-Santana, Michael Bellio, Camillo Ricordi, Luca Inverardi, Ricardo L. Pastori, and Juan Domínguez-Bendala