Abstract 18470: The Human Pancreas Contains a Compartment of Insulin-Producing Stem Cells

Diabetes is a major cause of human heart failure, and despite of the progress made in the control of this illness, a cure able to reverse the process and interfere with its systemic consequences is lacking. The recognition of a human pancreatic stem cell (hPSC) that regulates β-cell turnover and regeneration would provide, theoretically, a novel therapeutic target for this devastating disease. The c-kit epitope has been employed previously for the identification of hematopoietic, cardiac and lung stem cells, raising the possibility that this receptor tyrosine kinase may be expressed in other classes of tissue specific adult stem cells. Based on this simple hypothesis, we tested whether the presence of c-kit uncovered a pool of hPSCs, which, by analogy to stem cells in other organs, are self-renewing, clonogenic and multipotent. Twenty-nine samples of normally appearing human pancreas discarded at surgery were studied. Histologically, c-kit-positive tryptase-negative putative hPSCs were identified in all cases examined. They were located within the islets, in proximity of acinar cells, or within the epithelium of pancreatic ducts. Following isolation and in vitro expansion, c-kit-positive cells were FACS-sorted, seeded individually in single wells of 96-well-plates, and in 3 weeks, multi-cellular clones were obtained. Clonal cells had the ability to commit to endocrine β-cells and α-cells, and exocrine acinar-cells, generating the corresponding hormones and enzyme. qRT-PCR and NanoString technology were employed to determine whether clonal hPSCs possessed a transcriptional profile consistent with the undifferentiated and multipotent state of established pancreatic progenitors. Clonal hPSCs expressed c-kit, together with Pdx1, Sox9, Ngn3 and Nkx6.1, major determinants of progenitor cell fate. During differentiation, the components of the Notch pathway were downregulated pointing to their acquisition of the β-cell lineage. Thus, we suggest a new paradigm of pancreas biology in which hPSCs are critical determinants of endocrine and exocrine cell renewal. Understanding the mechanisms of β-cell formation may provide the opportunity to potentiate this naturally occurring process offering a novel strategy for the management of human diabetes.