Direct Reprogramming of Human Cell Lines in vitro Towards a β-Cell Phenotype

Abstract

Type 1 diabetes results from the loss of insulin producing β-cells of the pancreas, causing dependence on exogenous insulin for those affected. β-cell transplantation has been a promising treatment method, but lack of donor cells and requirement for repeated treatments currently limit this approach. Alternative treatments for type 1 diabetes are investigating reprogramming cell types toward a β-cell-like phenotype to generate a reliable source of insulin-secreting cells for transplant therapies. The pancreatic transcription factors Pdx1, Ngn3, and MafA have been combined in an adenoviral vector (Ad-PNMa) and used to reprogram rodent cells to generate insulin-secreting cells both in vivo and in vitro. However, studies examining similar reprogramming of human cell lines have met with little success to date. Here, we attempt to reprogram a human hepatocarcinoma cell line with the Ad-PNMa vector, and human pancreatic epithelial ductal (HPDE) cell lines with the Ad-PNMa vector and new Ad-PN and Ad-PNMb vectors expressing human Pdx1, Ngn3, and MafB. It was found that qRT-PCR detected weak insulin gene expression in Ad-PNMa infected HepG2 cells. Infection of HPDE cells with Ad-PNMb vector caused approximately 64% of cells to express the three vector cargo genes when treated at a concentration of 1.7x1010 ifu/ml. No insulin production was detected in HDPE cells following vector treatments, indicating that expression of these genes is not sufficient to induce insulin expression in HPDE cells. It may be possible to reprogram the HPDE cells to a β-cell phenotype with the expression of additional genes.