There is a growing understanding that adult pancreas may be a true source for islet progenitor cells, and that this tissue therefore represents a viable option for cell therapy in diabetes. However, a lacking understanding of progenitor/stem cell niches in the organ at post-embryonic stages, hinders experimental manipulation towards this end. We have obtained evidence for two specific populations in adult pancreas, that fulfill criteria of 1) a pancreatic progenitor epithelial population, exhibiting multi-lineage potency, and 2) a pancreatic mesenchymal cell population, that when cultured together with the multipotent epithelial cells, allows for ex-vivo expansion. Both populations are characterized by retinoic acid production. We have here formed a multi-investigator team to address specific issues related to the existence, the function and lineage potency, as well as the controlled differentiation of such retinoic acid producing epithelial cells. This will cover studies of adult human pancreatic tissue employing genetic engineering using lentiviral vectors designed to express self-cleavable polyproteins modeled over recent successful work in somatic cell reprogramming by others. We demonstrate the successful development of a multiple-gene/single vector method that allows insulin gene activation in non-pancreatic cells. Our specific goals are as follows: Leach group: to characterize the two aldefluor-positive cell populations from the murine pancreas with respect to forward differentiation and continuous growth. Oberholzer group: to identify and characterize Aldefluor-positive cells in the adult human endocrine pancreas comparatively to the murine cells. Jensen group: Complement the Leach and Oberholzer groups in studies of the Aldefluor populations, using bioinformatics and to functionally test and develop modified multiple gene/single-vector delivery vectors. Salmon group: to provide to other members a series of lentiviral vectors encoding individual proteins, or cleavable polyproteins, for testing in programming of adult murine, and human, pancreatic progenitors.
This project is relevant for the advance of cell-based therapy in Diabetes, the project integrates efforts to understand the isolation and culture of pancreatic retinoic-acid producing progenitor cells, and seeks to differentiate such into fully function pancreatic insulin producing cells. The furthermore employs advanced gene delivery systems incorporating self-cleavable polyproteins capable of endocrine cellular programming.