Improving stem cell-derived pancreatic islets using single-cell multiome-inferred regulomes [CDX1 snRNA-seq]

Pancreatic islet cells derived from human pluripotent stem cells hold great promise for modeling and treating diabetes. Differences between stem cell-derived and primary islets remain, but molecular insights to inform improvements are limited. Here, we acquire single-cell transcriptomes and accessible chromatin profiles during in vitro islet differentiation and from primary childhood and adult pancreas for comparison. We delineate major cell types, define their regulomes, and describe spatiotemporal regulatory relationships between transcription factors. CDX2 emerged as a regulator of enterochromaffin-like cells, which we show resemble a previously unrecognized, transient CDX2-expressing β-cell-related population in fetal pancreas, arguing against a non-pancreatic origin as proposed. Furthermore, we observe insufficient activation of signal-dependent transcriptional programs during in vitro β-cell maturation and identify sex hormones as drivers of childhood β-cell proliferation. Altogether, our analysis provides a comprehensive understanding of cell fate acquisition in stem cell-derived islets and a framework for manipulating cell identities and maturity. In this analysis, we used single nucleus RNA-seq (snRNA-seq) to profile 11,201 cells from D21 SC-islets derived from wild type (WT) or CDX2 knockout (CDX2 KO) H1 hESC lines. In both cell lines, we characterized transcriptomic signatures of pancreatic progenitors, endocrine progenitors, and fully differentiated SC-islet endocrine cell types. We found a significant reduction of SC-β-cell and SC-EC populations, which are compensated for by an increase of SC-α-cell numbers. Comparing WT and CDX2 KO transcriptomes in each cell type, we identified lower expression levels of genes involved in serotonin synthesis in CDX2 KO SC-ECs.