Direct Cell Conversion of Human Fibroblasts to Monocytic phagocytes by Forced Expression of Monocytic Regulatory Network Elements

Direct cell conversion is now expected to apply to therapeutic purposes. Although that has been succeeded in several cell types, the mechanism or general way to identify the key transcription factors are still unclear. In addition, most of the cases are not completely identical with the target cells. In previous work, we suggested that cell status is maintained by a homeostatic network of limited number of TFs and no single transcription factor is both necessary and sufficient to drive the differentiation process. Here, identifying the key TFs of human monocyte by combining comparative gene expression analysis and literature based text-mining, we mimicked the monocytic regulatory network in human dermal fibroblasts to induce direct cell conversion of the fibroblasts to monocytes. We suggested that although it is a primary master TF, single TF is not sufficient to induce the direct cell conversion and orchestrated TF regulation is necessary to complete the cell conversion. Total RNA obtained from human dermal fibroblasts(FIB), human CD14+ monocytes(MON), mock lentivirus vector transduced fibroblasts (FIB-mock), SPI1 transduced fibroblasts (FIB-SPI1), and SPI1, CEBPA, MNDA, IRF8 transduced fibroblasts(FIB-4Fs). The fold change was computed compared with fibroblasts or FIB-mock.