Comparative Analysis of Induced Pancreatic Stem Cells Generated with Different Factors

Recently, our research group generated induced tissue-specific stem/progenitor (iTS/iTP) cells. Compared with induced pluripotent stem (iPS) cells, iTS/iTP cells offer several advantages, that is, easy generation, higher differentiation efficiency, and no teratoma formation. In this study, iTS cells were generated from mouse pancreatic tissues (iTS-P cells) using two different methods. Plasmid vectors were used for expressing Oct3/4, Sox2, Klf4, c-Myc (OSKM), or Yap1 (YAP) to evaluate the efficiency and differentiation potential of the resulting cells. No significant difference in reprogramming efficiency between the OSKM- and YAP-based methods was observed. Among the established clones, iTS-P OSKM2 and iTS-P YAP9 cells, which demonstrated high efficiency in differentiating to insulin-producing cells (IPCs), were selected for further comparison. Both iTS-P OSKM2 and iTS-P YAP9 cells expressed genetic markers of endoderm and pancreatic progenitors and differentiated into IPCs more efficiently than the embryonic stem (ES) cells. Genomic bisulfite sequencing revealed that the pluripotency factors Oct3/4 and Nanog were partially methylated in both iTS-P OSKM2 and iTS-P YAP9 cells. Unsupervised hierarchical clustering of gene expression profiles showed that iTS-P YAP9 cells clustered more closely with the ES cells than with the iTS-P OSKM2 cells. However, the expression levels of Oct3/4 and Nanog were significantly lower in both iTS-P OSKM2 and YAP9 cells than in the ES cells. These results conclude that no substantial difference is present in the characteristics between iTS-P cells induced by OSKM or YAP, and that their higher differentiation efficiency than the ES cells indicates promising potential for clinical applications.