Transcriptional and epigenetic program changes of induced beta cells over time [RRBS-seq]

Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, it is often unclear whether lineage-reprogrammed cells remain stable long-term and whether the properties of the reprogrammed cells evolve over time. Here, using an improved method of converting pancreatic acinar cells to beta-cells, we show that induced beta-cells persist in the adult pancreas for up to 14 months and form islet-like structures. Detailed analyses of induced cells over 7 months reveal that global DNA methylation changes occur rapidly whereas transcription network remodeling evolves over two months to resemble that of endogenous beta-cells and then stabilizes thereafter. Progressive gain of beta-cell function by converted cells during the 7 month period coincides with both transcriptional changes and the formation of islet-like structures. These studies demonstrate the ability of lineage-reprogrammed cells to achieve a stable state and identify key cellular and molecular milestones during their long-term evolution.