In vitro generation of myofibroblasts-like cells from liver epithelial progenitor cells of rhesus monkey (Macaca mulatta)

The origin of the myofibroblast, the primary effector cell of liver fibrosis, is still elusive. Here, we report that fluorescence-activated cell sorting purified E-cad + rhesus monkey liver epithelial progenitor cells (mLEPCs) may serve as a potential source for liver myofibroblasts. Adult mLEPCs colonies were cultured in medium containing 2 ng/ml transforming growth factor beta (TGF-beta) and 10% fetal bovine serum (FBS) to induce differentiation. Phenotypic changes of cells were analyzed by morphological observation, immunostaining, and reverse transcription-polymerase chain reaction (RT-PCR). After cultured with TGF-beta and FBS, some cells in adult mLEPCs colonies converted to fibroblasts-like cells. Immunostaining showed that fibroblasts-like cells had acquired the expression of mesenchymal cell marker vimentin but lost the expression of epithelial cell marker CK8. Fibroblasts-like cells were maintained in culture for up to 40 passages. RT-PCR analysis revealed that fibroblasts-like cells had acquired the expression of mesenchymal genes (snail, PAI-1, and collagen I) and lost the expression of epithelial specific genes (E-cad, ZO-1, CK18, and occludin). In addition, more than 60% of fibroblasts-like cells expressed myofibroblastic-related proteins such as alpha SMA, vimentin, and N-cad, which were not presented in mLEPCs. Furthermore, increased cell motility was also detected in these fibroblasts-like cells by time-lapse video observation. Our results demonstrate that hepatic epithelial progenitor cells, mLEPCs, transform to myofibroblast-like cells via epithelial-mesenchymal transition. This finding will facilitate understanding of the origin of myofibroblasts in liver fibrosis.