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 <i>Oct3/4</i>, <i>Sox2</i>, <i>Klf4</i>, <i>c-Myc</i> (<i>OSKM</i>), or <i>Yap1</i> (<i>YAP</i>) to evaluate the efficiency and differentiation potential of the resulting cells. No significant difference in reprogramming efficiency between the <i>OSKM</i>- and <i>YAP</i>-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 <i>Oct3/4</i> and <i>Nanog</i> 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 <i>Oct3/4</i> and <i>Nanog</i> 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 <i>OSKM</i> or <i>YAP</i>, and that their higher differentiation efficiency than the ES cells indicates promising potential for clinical applications.