V-maf musculoaponeurotic fibrosarcoma oncogene homolog A synthetic modified mRNA drives reprogramming of human pancreatic duct-derived cells into insulin-secreting cells

β-Cell replacement therapy represents the most promising approach to restore β-cell mass and glucose homeostasis in patients with type 1 diabetes. Safety and ethical issues associated with pluripotent stem cells stimulated the search for adult progenitor cells with endocrine differentiation capacities. We have already described amodel for expansion and differentiation of human pancreatic duct-derived cells (HDDCs) into insulin-producing cells. Here we show an innovative and robust in vitro system for large-scale production of β-like cells from HDDCs using a nonintegrative RNA based reprogramming technique. Synthetic modified RNAs for pancreatic transcription factors (pancreatic duodenal homeobox 1, neurogenin3, and V-Mafmusculoaponeurotic fibrosarcoma oncogene homolog A [MAFA]) were manufactured and daily transfected in HDDCs without strongly affecting immune response and cell viability. MAFA overexpression was efficient and sufficient to induce β-cell differentiation of HDDCs, which acquired a broad repertoire of mature β-cell markers while downregulating characteristic epithelial-mesenchymal transition markers. Within 7 days, MAFA-reprogrammed HDDC populations contained 37% insulin-positive cells and a proportion of endocrine cells expressing somatostatin and pancreatic polypeptide. Ultrastructure analysis of differentiated HDDCs showed both immature and mature insulin granules with lightbackscattering properties. Furthermore, in vitro HDDC-derived β cells (called β-HDDCs) secreted human insulin and C-peptide in response to glucose, KCl, 3-isobutyl-1-methylxanthine, and tolbutamide stimulation. Transplantation of β-HDDCs into diabetic SCID-beige mice confirmed their functional glucose-responsive insulin secretion and their capacity to mitigate hyperglycemia. Our data describe a new, reliable, and fast procedure in adult human pancreatic cells to generate clinically relevant amounts of new β cells with potential to reverse diabetes.